Medtronic D154AWG Reference Guide

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VIRTUOSO® DR/VR D154AWG/ D154VWC

Implantable cardioverter defibrillator systems with OptiVol Fluid Monitoring, and Conexus® Telemetry

Reference Manual

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VIRTUOSO® DR/VR D154AWG/ D154VWC

Reference Manual

A guide to the operation and programming of the Virtuoso Implantable Cardioverter Defibrillator systems

The following list includes trademarks or registered trademarks of Medtronic in the United States and possibly in other countries. All other trademarks are the property of their respective owners.

ATP During Charging, Active Can, Cardiac Compass, CareAlert, CareLink, ChargeSaver, Checklist, Conexus, Flashback, InCheck, Intrinsic, MVP, Marker Channel, Medtronic, Medtronic CareAlert, Medtronic CareLink, OptiVol, PR Logic, Paceart, Quick Look, QuickLink, Reactive ATP, SessionSync, Switchback, T-Shock, Virtuoso

Medtronic VIRTUOSO

DR/VR D154AWG/D154VWC

Introduction .............................................................. 11

Part I Quick overview ......................................... 14

1 Quick reference ................................................... 14

1.1 Physical characteristics, DR devices ................................... 14

1.2 Physical characteristics, VR devices ................................... 15

1.3 Replacement indicators .............................................. 16

1.4 Projected service life ................................................ 17

1.5 Magnet application .................................................. 19

1.6 Typical charge times ................................................ 19

1.7 High-voltage therapy energy .......................................... 19

1.8 Stored data and diagnostics .......................................... 20

2 The Virtuoso system ............................................... 25

2.1 System overview .................................................... 25

2.2 Indications and usage, DR devices .................................... 29

2.3 Indications and usage, VR devices .................................... 30

2.4 Contraindications, DR devices ........................................ 30

2.5 Contraindications, VR devices ........................................ 30

2.6 Patient screening ................................................... 31

3 Emergency therapy ................................................ 32

3.1 Overview of emergency therapies ..................................... 32

3.2 Delivering an emergency defibrillation therapy .......................... 32

3.3 Delivering an emergency cardioversion therapy ......................... 33

3.4 Delivering emergency fixed burst pacing ............................... 34

3.5 Enabling emergency VVI pacing ...................................... 35

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Part II Device implant and patient follow-up

procedures ...................................................... 37

4 Implanting the device .............................................. 37

4.1 Overview .......................................................... 37

4.2 Considerations ..................................................... 37

4.3 Preparing for an implant ............................................. 38

4.4 Verifying lead and connector compatibility .............................. 40

4.5 Positioning the leads ................................................ 40

4.6 Testing the lead system .............................................. 42

4.7 Connecting the leads to the device .................................... 43

4.8 Testing ventricular defibrillation operation and effectiveness .............. 46

4.9 Positioning and securing the device ................................... 51

4.10 Completing the implant procedure ..................................... 53

4.11 Replacing a device .................................................. 54

4.12 Optimizing device longevity .......................................... 55

5 Conducting a patient follow-up session ............................. 57

5.1 Patient follow-up guidelines .......................................... 57

5.2 Verifying the status of the implanted system ............................ 57

5.3 Optimizing charge time .............................................. 58

5.4 Verifying accurate detection and appropriate therapy .................... 60

5.5 Verifying effective bradycardia pacing ................................. 61

Part III Configuring the device for the patient .......... 63

6 Detecting tachyarrhythmias ........................................ 63

6.1 Detection overview .................................................. 63

6.2 Setting up sensing .................................................. 68

6.3 Detecting atrial tachyarrhythmias ...................................... 72

6.4 Detecting VF episodes ............................................... 76

6.5 Detecting VT episodes ............................................... 79

6.6 Detecting FVT episodes ............................................. 83

6.7 Monitoring VT episodes .............................................. 86

6.8 Detecting tachyarrhythmia episodes with combined count ................ 90

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6.9 Determining episode termination or redetection ......................... 92

6.10 Enhancing detection with PR Logic criteria ............................. 95

6.11 Enhancing detection with Wavelet .................................... 100

6.12 Enhancing VT detection with the Onset criterion ........................ 109

6.13 Enhancing VT detection with the Stability criterion ...................... 113

6.14 Detecting double tachycardias ....................................... 115

6.15 Detecting prolonged tachyarrhythmias with High Rate Timeout ........... 115

7 Treating tachyarrhythmia episodes ................................ 118

7.1 Controlling atrial therapy sequencing ................................. 118

7.2 Treating atrial arrhythmias with cardioversion .......................... 127

7.3 Providing patient-activated atrial cardioversion ......................... 133

7.4 Treating atrial arrhythmias with antitachycardia pacing .................. 136

7.5 Treating episodes detected as VF .................................... 145

7.6 Treating VT and FVT with antitachycardia pacing ....................... 157

7.7 Treating VT and FVT with ventricular cardioversion ..................... 164

7.8 Optimizing ventricular ATP therapy with Smart Mode .................... 170

7.9 Optimizing therapy with Progressive Episode Therapies ................. 172

8 Treating bradycardia ............................................. 174

8.1 Providing basic pacing therapy ...................................... 174

8.2 Dual chamber pacing ............................................... 177

8.3 Single chamber pacing ............................................. 187

8.4 MVP (Managed Ventricular Pacing) .................................. 191

8.5 Rate Response .................................................... 195

8.6 Rate Adaptive AV .................................................. 200

8.7 Rate Hysteresis .................................................... 202

8.8 Mode Switch ...................................................... 204

8.9 Non-Competitive Atrial Pacing ....................................... 206

8.10 PMT Intervention .................................................. 209

8.11 PVC Response .................................................... 211

8.12 Ventricular Safety Pacing ........................................... 213

8.13 Atrial Rate Stabilization ............................................. 215

8.14 Atrial Preference Pacing ............................................ 218

8.15 Post Mode Switch Overdrive Pacing (PMOP) .......................... 222

8.16 Ventricular Rate Stabilization (VRS) .................................. 223

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8.17 Post VT/VF Shock Pacing ........................................... 225

8.18 Post Shock Pacing ................................................. 226

DR/VR D154AWG/D154VWC

Part IV Evaluating and managing patient treatment .. 228

9 Using the programmer ............................................ 228

9.1 Setting programmer preferences ..................................... 228

9.2 Establishing telemetry between the device and programmer ............. 228

9.3 Starting a patient session ........................................... 236

9.4 Ending a patient session ............................................ 238

9.5 Device and telemetry effects during a patient session ................... 239

9.6 Display screen features ............................................. 240

9.7 Streamlining follow-up and implant sessions with Checklist .............. 245

9.8 Viewing and programming device parameters .......................... 251

9.9 Saving and retrieving a set of parameter values ........................ 256

9.10 Viewing live waveform traces ........................................ 258

9.11 Recording live waveform strips ....................................... 267

9.12 Freezing and analyzing a waveform strip .............................. 269

9.13 Recalling and viewing waveform strips ................................ 270

9.14 Transferring, saving, and retrieving device data ........................ 271

9.15 Printing reports .................................................... 278

10 Setting up and viewing collected data .............................. 284

10.1 A summary of data collection ........................................ 284

10.2 Setting up data collection ........................................... 285

10.3 Viewing Quick Look data ............................................ 291

10.4 Using the Medtronic CareAlert feature ................................ 295

10.5 Viewing Arrhythmia Episode data .................................... 306

10.6 Viewing Flashback Memory data ..................................... 318

10.7 Using Cardiac Compass to view long-term clinical trends ................ 320

10.8 Using Rate Histograms reports ...................................... 329

10.9 Viewing the counters ............................................... 332

10.10 Viewing Battery and Lead Measurement data .......................... 339

10.11 Viewing Lead Performance Trends data ............................... 342

10.12 Viewing and entering patient information .............................. 345

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10.13 Automatic device status monitoring ................................... 347

11 Testing the system ............................................... 350

11.1 System test overview ............................................... 350

11.2 Evaluating the underlying rhythm ..................................... 351

11.3 Measuring pacing thresholds ........................................ 351

11.4 Testing the Wavelet criterion ........................................ 354

11.5 Measuring lead impedance .......................................... 358

11.6 Performing a Sensing Test .......................................... 360

11.7 Testing the device capacitors ........................................ 362

12 Conducting electrophysiologic studies ............................ 365

12.1 EP Study overview ................................................. 365

12.2 Inducing VF with T-Shock ........................................... 366

12.3 Inducing VF with 50 Hz Burst ........................................ 369

12.4 Delivering an atrial 50 Hz Burst ...................................... 372

12.5 Inducing an arrhythmia with Fixed Burst ............................... 375

12.6 Inducing an arrhythmia with PES ..................................... 378

12.7 Delivering a manual therapy ......................................... 381

13 Solving system problems ......................................... 386

13.1 Overview ......................................................... 386

13.2 Solving sensing problems ........................................... 386

13.3 Solving atrial tachyarrhythmia detection problems ...................... 388

13.4 Solving ventricular tachyarrhythmia detection problems ................. 389

13.5 Solving atrial tachyarrhythmia therapy problems ........................ 390

13.6 Solving ventricular tachyarrhythmia therapy problems ................... 394

13.7 Solving bradycardia pacing problems ................................. 395

13.8 Solving OptiVol fluid monitoring problems ............................. 396

13.9 Responding to device status indicators ............................... 397

Appendices

A Warnings and precautions ........................................ 399

A.1 General .......................................................... 399

A.2 Handling and storage instructions .................................... 399

A.3 Lead evaluation and lead connection ................................. 400

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A.4 Device operation ................................................... 401

A.5 Warnings, precautions, and guidance for clinicians performing medical

procedures on cardiac device patients .............................. 402

A.6 Warnings, precautions, and guidance related to electromagnetic

interference (EMI) for cardiac device patients ........................ 408

B Device Parameters ............................................... 412

B.1 Emergency settings ................................................ 412

B.2 Tachyarrhythmia detection parameters ................................ 412

B.3 Atrial tachyarrhythmia therapy parameters, DR devices ................. 415

B.4 Ventricular tachyarrhythmia therapy parameters ........................ 417

B.5 Bradycardia pacing parameters ...................................... 419

B.6 Medtronic CareAlert parameters ..................................... 423

B.7 Data collection parameters .......................................... 427

B.8 System test parameters ............................................. 429

B.9 EP study parameters ............................................... 430

B.10 Nonprogrammable parameters ...................................... 434

Glossary ................................................................ 437

Index ................................................................... 449

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Introduction

About this manual

This manual describes the operation and intended use of the Virtuoso Model D154AWG and D154VWC systems.

Virtuoso Model D154AWG devices, referred to as “DR” devices in this manual, provide atrial and ventricular tachyarrhythmia detection and therapy and a full range of dual chamber bradycardia pacing modes and associated features. Unless otherwise noted, all information in this manual applies to DR devices.

Virtuoso Model D154VWC devices, referred to as “VR” devices in this manual, provide ventricular tachyarrhythmia detection, ventricular tachyarrhythmia therapy, and single chamber bradycardia pacing. Information in this manual that describes atrial tachyarrhythmia detection, atrial tachyarrhythmia therapy, dual chamber detection, dual chamber pacing features, and atrial pacing modes does not apply to VR devices.

Programmer hardware and screen images

The screen image examples in this manual were taken from the Medtronic CareLink Model 2090 programmer with Conexus Telemetry. Wherever possible, these screen images show the application for a DR device (Virtuoso Model D154AWG).

The information provided in this manual about using the programmer assumes the Medtronic CareLink Model 2090 Programmer with Conexus Telemetry is used. For information about using the Medtronic CareLink Model 2090 Programmer without Conexus Telemetry, see the Medtronic CareLink Model 2090 Programmer Reference Guide.

Manual conventions

Throughout this document, the word “device” refers to the implanted Virtuoso device.

The symbol in parameter tables indicates the Medtronic nominal value for that parameter.

On-screen buttons are shown with the name of the button surrounded by brackets: [Button Name].

Nomenclature for product battery life terms

This manual uses a nomenclature for certain terms related to product battery life as defined in CENELEC pacemaker standard EN 45502-2-1:2003. This standard applies to Active Implantable Medical Devices (AIMD) intended to treat bradyarrhythmias. This standard was approved and published in December 2003.

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Medtronic has adopted this nomenclature to comply with the CENELEC standard and in anticipation of the nomenclature becoming an international standard. The nomenclature defined in EN 45502-2-1:2003 replaces previously used terms related to product battery life.

The nomenclature defined in EN 45502-2-1:2003, and the terms this nomenclature replaces, are presented in the following table:

Nomenclature in EN 45502-2-1: 2003 Previously used nomenclature

BOS Beginning of Service BOL Beginning of Life

EOS End of Service EOL End of Life

RRT Recommended Replacement Time ERI Elective Replacement Indicator

PSP Prolonged Service Period Post-ERI conditions

Projected service life Longevity projections

Additional literature

Before implanting the device, it is strongly recommended that you take the following actions:

●

Refer to the product literature packaged with the device for information about prescribing the device.

●

Thoroughly read the technical manuals for the leads used with the device.

●

Discuss the procedure and the device with the patient and any other interested parties, and provide them with any patient information packaged with the device.

Technical support

Medtronic employs highly trained representatives and engineers located throughout the world to serve you and, upon request, to provide training to qualified hospital personnel in the use of Medtronic products.

In addition, Medtronic maintains a professional staff of consultants to provide technical consultation to product users.

For more information, contact your local Medtronic representative, or call or write Medtronic at the appropriate telephone number or address listed on the back cover.

Customer education

Medtronic invites physicians to attend an educational seminar on the device. The course describes indications for use, system functions, implant procedures, and patient management.

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References

The primary reference for background information is Zacouto FI, Guize LJ. Fundamentals of Orthorhythmic Pacing. In: Luderitz B, ed. Cardiac Pacing Diagnostic and Therapeutic Tools. New York: Springer-Verlag; 1976: 212-218.

See these additional references for more background information:

●

Estes M, Manolis AS, Wang P, Eds. Implantable Cardioverter-Defibrillators. New York, NY: Marcel Dekker, Inc. 1994.

●

Kroll MW, Lehmann MH, Eds. Implantable Cardioverter-Defibrillator Therapy: The Engineering-Clinical Interface. Norwell, MA: Kluwer Academic Publishers 1996.

●

Singer I, Ed. Implantable Cardioverter-Defibrillator. Armonk, NY: Futura Publishing Co.

1994.

●

Singer I, Barold SS, Camm AJ, Eds. Nonpharmacological Therapy of Arrhythmias for the 21st Century: The State of the Art. Armonk, NY: Futura Publishing Co. 1998.

●

Stadler RW, Gunderson BD, Gillberg JM. An Adaptive Interval-Based Algorithm for Withholding ICD Therapy During Sinus Tachycardia. Pace. 2003; 26:1189–1201.

Notice

The Patient Information screen of the programmer software application is provided as an informational tool for the end user. The user is responsible for accurate input of patient information into the software. Medtronic makes no representation as to the accuracy or completeness of the patient information that end users enter into the Patient Information screen. Medtronic SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES TO ANY THIRD PARTY WHICH RESULT FROM THE USE OF THE PATIENT INFORMATION SUPPLIED BY END USERS TO THE SOFTWARE.

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Part I

Quick overview

1 Quick reference

1.1 Physical characteristics, DR devices

Table 1. Model D154AWG physical characteristics

Volume Mass 68 g H x W x D Surface area of device can 59 cm Radiopaque ID PVR Materials in contact with human tissuecTitanium, polyurethane, silicone rubber Battery Lithium silver vanadium oxide hybrid

Volume with connector holes unplugged. Grommets may protrude slightly beyond the can surface. These materials have been successfully tested for the ability to avoid biological incompatibility. The device does not produce an injurious temperature in the surrounding tissue during normal operation.

37 cm

64 mm x 51 mm x 15 mm

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Figure 1. Model D154AWG connector and suture holes

DR/VR D154AWG/D154VWC

1 DF-1 connector port, SVC (HVX) 2 DF-1 connector port, RV (HVB) 3 Device Active Can electrode, Can (HVA)

4 IS-1 connector port, RV 5 IS-1 connector port, A 6 Suture holes

1.2 Physical characteristics, VR devices

Table 2. Model D154VWC physical characteristics

Volume

Mass 68 g H x W x D

Surface area of device can 59 cm Radiopaque ID PVR Materials in contact with human tissuecTitanium, polyurethane, silicone rubber Battery Lithium silver vanadium oxide hybrid

Volume with connector holes unplugged.

Grommets may protrude slightly beyond the can surface.

These materials have been successfully tested for the ability to avoid biological incompatibility. The device does not produce an injurious temperature in the surrounding tissue during normal operation.

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37 cm

64 mm x 51 mm x 15 mm

Medtronic VIRTUOSO

Figure 2. Model D154VWC connector and suture holes

DR/VR D154AWG/D154VWC

1 DF-1 connector port, SVC (HVX) 2 DF-1 connector port, RV (HVB) 3 Device Active Can electrode, Can (HVA)

4 IS-1 connector port, RV 5 Suture holes

1.3 Replacement indicators

Battery voltage and messages about replacement status appear on the programmer display and on printed reports. The Recommended Replacement Time (RRT) and the End of Service (EOS) conditions are listed in Table 3.

Table 3. Replacement indicators

Recommended Replacement Time (RRT) ≤ 2.62 V on 3 consecutive daily automatic meas-

urements

End of Service (EOS) 3 months after RRT

RRT date – The programmer displays the date when the battery reached RRT on the Quick Look and Battery and Lead Measurements screens.

Replace at EOS – If the programmer indicates that the device is at EOS, replace the device immediately.

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Prolonged Service Period (PSP) conditions – The Prolonged Service Period (PSP) is the time between the Recommended Replacement Time (RRT) and End of Service (EOS). EOS device status is defined as 3 months following an RRT indication assuming the following PSP conditions: 100% DDD pacing (VVI in VR devices) at 60 bpm; 2.5 V; 0.4 ms; 500 Ω pacing load; and 6 full-energy charges. EOS may be indicated before the end of 3 months if the device exceeds these conditions.

1.4 Projected service life

Projected service life estimates are based on accelerated battery discharge data and device modeling as specified.

The projected service life of the device is affected by how certain features, such as Pre-arrhythmia EGM storage, are programmed. See Section 4.12, “Optimizing device longevity”, page 55.

1.4.1 DR projected service life projections

The projected service life estimates assume the default automatic capacitor formation setting. As a guideline, each full-energy charge decreases the projected service life of the device by approximately 37 days. The following table displays device projected service life in years with 0.4 ms pulse width, and 60 bpm pacing rate.

Table 4. Projected service life

500 Ω pacing impe-

Maximum energy

% Pacing

DDD, 0% Semiannual 7.4 (9.4) 7.4 (9.4) 7.4 (9.4) 7.4 (9.4)

DDD, 15% Semiannual 7.1 (9.0) 7.1 (8.9) 7.3 (9.2) 7.2 (9.1)

DDD, 50% Semiannual 6.6 (8.1) 6.3 (7.8) 6.9 (8.6) 6.7 (8.4)

AAI<=>DDD, (MVP mode) 50% atrial, 5% ventricular

charging frequency

Quarterly 6.6 (8.2) 6.6 (8.2) 6.6 (8.2) 6.6 (8.2)

Quarterly 6.4 (7.9) 6.3 (7.8) 6.5 (8.0) 6.5 (7.9)

Quarterly 6.0 (7.2) 5.8 (6.9) 6.2 (7.6) 6.1 (7.4) Semiannual 7.0 (8.8) 6.9 (8.5) 7.2 (9.1) 7.1 (8.9) Quarterly 6.3 (7.7) 6.2 (7.5) 6.5 (7.9) 6.4 (7.8)

dance

2.5 V 3.0 V 2.5 V 3.0 V

900 Ω pacing impe-

dance

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Table 4. Projected service life (continued)

500 Ω pacing impe-

dance

2.5 V 3.0 V 2.5 V 3.0 V

% Pacing

Maximum energy charging frequency

DDD, 100% Semiannual 5.9 (7.1) 5.5 (6.6) 6.5 (7.9) 6.2 (7.5)

Quarterly 5.4 (6.4) 5.1 (6.0) 5.9 (7.1) 5.6 (6.7)

Maximum energy charging frequency may include full-energy therapy shocks or capacitor formations. Additional full-energy charges due to therapy shocks, device testing, or capacitor formation reduce longevity by approximately 37 days (0.10 year).

The first data values provided assume that Pre-arrhythmia EGM is programmed On Continuous for the life of the device, which is both the Shipped and nominal value for that parameter. The data values provided in parentheses assume that Pre-arrhythmia EGM storage is programmed Off for the life of the device, which lengthens projected service life by 23% or 2.8 months per year.

900 Ω pacing impe-

dance

1.4.2 VR projected service life projections

The projected service life estimates assume the default automatic capacitor formation setting. As a guideline, each full-energy charge decreases the projected service life of the device by approximately 44 days. The following table displays device projected service life in years with VVI pacing mode, 0.4 ms pulse width, and 60 bpm pacing rate.

Table 5. Projected service life

500 Ω pacing impe-

dance

2.5 V 3.0 V 2.5 V 3.0 V

% Pacing

Maximum energy charging frequency

0% Semiannual 8.3 (10.8) 8.3 (10.8) 8.3 (10.8) 8.3 (10.8)

Quarterly 7.3 (9.2) 7.3 (9.2) 7.3 (9.2) 7.3 (9.2)

15% Semiannual 8.1 (10.5) 8.0 (10.5) 8.2 (10.7) 8.1 (10.6)

Quarterly 7.2 (9.0) 7.1 (9.0) 7.2 (9.1) 7.2 (9.1)

50% Semiannual 7.7 (9.9) 7.6 (9.7) 7.9 (10.3) 7.8 (10.1)

Quarterly 6.9 (8.6) 6.7 (8.4) 7.1 (8.8) 7.0 (8.7)

100% Semiannual 7.2 (9.2) 7.0 (8.7) 7.6 (9.8) 7.4 (9.5)

Quarterly 6.5 (8.0) 6.3 (7.6) 6.8 (8.5) 6.7 (8.2)

900 Ω pacing impe-

dance

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1.5 Magnet application

When a magnet is placed near the device, the device responds as shown in Table 6. When the magnet is removed, the device returns to its programmed operations.

Note: When a monitor alert condition has occurred, a magnet placed near the device will cause the device to emit a high/low dual tone regardless of how the device alert is programmed.

Table 6. Effects of magnet application on the device

Pacing mode As programmed Pacing rate and interval As programmed Tachyarrhythmia detection Suspended Medtronic CareAlert audible tones

(10 s or less)

With programmable alerts enabled:

●

Continuous tone (test)

●

On/off intermittent tone (seek follow-up)

●

High/low dual tone (urgent follow-up)

With programmable alerts disabled:

●

No tone

●

High/low dual tone (urgent follow-up)

Rate Response adjustments are suspended while a Medtronic CareAlert tone sounds.

During a wireless communication session, tachyarrhythmia detection remains suspended if a magnet (or the programming head) is placed over the device. During a conventional telemetry session, tachyarrhythmia detection is suspended when the programming head or a magnet is placed over the device, but detection resumes if telemetry between the device and programmer is established.

Before implant and for the first 6 hours after implant, the device will not sound audible tones when a magnet is placed over the device.

1.6 Typical charge times

The most recent capacitor charge time appears on the programmer display and on printed reports. You can evaluate charge time using the Charge/Dump test (see Table 7).

Table 7. Average full energy charge times at BOS and RRT (2.62 V)

At Beginning of Service (BOS) 8.2 s At Recommended Replacement Time (RRT) 9.8 s (DR devices)

10.0 s (VR devices)

1.7 High-voltage therapy energy

The stored energy of the device is derived from the peak capacitor voltage and is always greater than the energy delivered by the device. Table 8 compares the programmed energy levels delivered by the device to the energy levels stored in the capacitors before delivery.

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Table 8. Programmed (delivered) and stored energy levels

Energy (J) Energy (J)

Programmed/ Delivered

Stored

Charge Time (s)

Programmed/

Delivered

Stored

Charge Time

(s)

35 39 8.2 9 10.5 2.1 32 37 7.5 8 9.3 1.9 30 34 7.0 7 8.2 1.6 28 32 6.6 6 7.1 1.4 26 30 6.1 5 5.9 1.2 25 29 5.9 4 4.8 0.9 24 27 5.6 3 3.6 0.7 22 25 5.2 2 2.4 0.5 20 23 4.7 1.8 2.2 0.4 18 21 4.2 1.6 2.0 0.4 16 19 3.7 1.4 1.7 0.3 15 17 3.5 1.2 1.5 0.3 14 16 3.3 1.0 1.2 0.2 13 15 3.0 0.8 1.0 0.2 12 14 2.8 0.6 0.8 0.1 11 13 2.6 0.4 0.5 0.1 10 12 2.3

Delivered energy values are based on measurements at the connector block during high-voltage therapies into a 75 Ω load. Stored energy values indicate the energy on the capacitor at the end of charging.

Typical charge time at Beginning of Service (BOS) with fully-formed capacitors, rounded to the nearest tenth of a second.

1.8 Stored data and diagnostics

Table 9. Arrhythmia episode data storage

Episode data type DR devices VR devices

Treated VT/VF episode log entries 100 entries 100 entries Treated VT/VF episode EGM, markers, and

intervals Monitored VT episode log entries 15 entries 15 entries Monitored VT episode EGM, markers, and

intervals Non-sustained VT episode log entries 15 entries 15 entries Non-sustained VT episode EGM, markers, and

intervals Treated AT/AF episode log entries 100 entries —

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9.25 min 13.75 min

45 s 51 s

30 s 30 s

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Table 9. Arrhythmia episode data storage (continued)

Episode data type DR devices VR devices

Treated AT/AF episode EGM, markers, and

3.75 min —

intervals Monitored AT/AF episode log entries 50 entries — Monitored AT/AF episode EGM, markers, and

1.0 min —

intervals SVT episode log entries 25 entries 25 entries SVT episode EGM, markers, and intervals 1.25 min 1.4 min Patient activated episode log entries 50 entries 50 entries Flashback memory interval data before each of

the following events:

●

Interrogation

●

Latest VF episode

●

Latest VT episode

Flashback memory interval data before the latest AT/AF episode

2000 events (includes both A- and V-events)

2000 events (V-events only)

—

Table 10. VT/VF episode counters

Counter data type DR devices VR devices

Counts of each VT/VF episode type

Counts of each SVT episode type (VT/VF therapy withheld)

●

FVT

●

VT Monitor

●

VT-NS

●

Runs of PVCs

●

Single PVCs

●

Runs of VRS paces

●

Single VRS paces

●

AF/Afl

●

Sinus Tach

●

Other 1:1 SVTs

●

V. Stability

●

Onset

●

FVT

●

VT Monitor

●

VT-NS

●

Runs of PVCs

●

Single PVCs

●

Runs of VRS paces

●

Single VRS paces

●

V. Stability

●

Onset

●

Wavelet

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Table 11. VT/VF therapy counters

Counter data type DR and VR devices

VT/VF therapy summary counters

VT/VF therapy efficacy counters

●

ATP-terminated episodes

●

Shock-terminated episodes

●

Total VT/VF shocks

●

Aborted charges

For VF Rx1–Rx6 and ATP during/before charging:

●

Delivered therapy counts

●

Successful therapy counts

For FVT Rx1–Rx6:

●

Delivered therapy counts

●

Successful therapy counts

●

Counts of episodes accelerated to VF

For VT Rx1–Rx6:

●

Delivered therapy counts

●

Successful therapy counts

●

Counts of episodes accelerated by 60 ms or to FVT or VF

Table 12. AT/AF episode counters

Counter data type DR devices

AT/AF summary data

Average number per day of each AT/AF episode type

Percent of time in each kind of pacing

Number of AT/AF episodes, presented in different groupings

This counter includes any instance when the device identifies AT/AF Onset. Therefore, the total number of episodes in this counter may exceed the number of detected AT/AF episodes recorded by the device.

●

Percent of time in AT/AF

●

Average time in AT/AF per day

●

Percentage of AT/AF episodes terminated by ATP

●

Monitored AT/AF

●

Treated AT/AF

●

Non-sustained AT

●

Atrial pacing

●

Atrial intervention pacing

●

Grouped by duration

●

Grouped by start time

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Table 13. AT/AF therapy counters

Counter data type DR devices

Number of AT/AF episodes treated and the percentage terminated,

●

Grouped by detection zone and therapy

●

Grouped by atrial cycle length

presented in different groupings Counts of different AT/AF therapy

types

●

Delivered ATP sequences

●

Aborted ATP sequences

●

Delivered automatic atrial CV shocks

●

Automatic atrial CV shocks that failed to terminate the episode

●

Delivered patient-activated shocks

●

Patient-activated shocks that failed to terminate the episode

Table 14. Battery and lead measurement data

DR devices VR devices

●

Battery voltage

●

Last capacitor formation

●

Last charge

●

Lead impedance: – A. pacing

– RV pacing – RV defib – SVC defib (if used)

●

R-wave amplitude

●

P-wave amplitude

●

Last high-voltage therapy

●

Sensing integrity counter

●

Atrial Lead Position Check results

●

Battery voltage

●

Last capacitor formation

●

Last charge

●

Lead impedance: – RV pacing

– RV defib – SVC defib (if used)

●

R-wave amplitude

●

Last high-voltage therapy

●

Sensing integrity counter

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Table 15. Lead performance trend data

14 days of daily measurements, 80 weeks of weekly minimum and maximum measurements, highest value, lowest value, value at implant, and latest value.

DR devices VR devices

Lead impedance measurements:

●

A. Pacing

●

RV pacing

●

RV defibrillation

●

SVC defibrillation (if used)

Sensing amplitude measurements:

●

P-wave

●

R-wave

Lead impedance measurements:

●

RV pacing

●

RV defibrillation

●

SVC defibrillation (if used)

Sensing amplitude measurements:

●

R-wave

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Table 16. Cardiac Compass trend data

Printed report showing up to 14 months of measurement trends and summary data.

DR devices VR devices

●

Annotations of interrogations, programming, and remote sessions

●

VT and VF episodes per day

●

High-voltage therapies delivered per day

●

Ventricular rate during VT or VF

●

Episodes of non-sustained tachycardia per day

●

Heart rate variability

●

Total daily time in AF or AT

●

Ventricular rate during AF or AT

●

Percent pacing per day

●

Patient activity

●

Average day and night ventricular heart rate

●

Thoracic impedance

●

Accumulated differences between the daily

●

Annotations of interrogations, programming, and remote sessions

●

VT and VF episodes per day

●

High-voltage therapies delivered per day

●

Ventricular rate during VT or VF

●

Episodes of non-sustained tachycardia per day

●

Heart rate variability

●

Percent pacing per day

●

Patient activity

●

Average day and night ventricular heart rate

●

Thoracic impedance

●

Accumulated differences between the daily and reference thoracic impedance (OptiVol

fluid index) and reference thoracic impedance (OptiVol fluid index)

Table 17. Rate Histograms report

Data type DR devices VR devices

Graphs displaying the percent of time in each rate range for the listed conditions:

●

Atrial pacing and atrial sensing

●

Ventricular pacing and ven-

tricular sensing

●

Ventricular pacing and ventricular sensing during AT/AF

Percent of time for each event

type:

If more than 2% of atrial sensed events are identified as far-field R-waves, the general percentage range (either “2% to 5%” or “> 5%”) is reported above the atrial rate histogram.

In DR devices, if the programmed pacing mode during the reporting period was a dual chamber mode, the report displays the AS-VS, AS-VP, AP-VS, and AP-VP event sequence data. If a single chamber mode was programmed, the report displays the percent of time spent pacing and sensing. MVP modes (AAIR<=>DDDR and AAI<=>DDD) are considered dual chamber modes for this purpose.

●

AS-VS events

●

AS-VP events

●

AP-VS events

●

AP-VP events

●

Ventricular pacing and ventricular sensing

●

VP events

●

VS events

Table 18. Medtronic CareAlert event data

Log of events that triggered Medtronic CareAlert notifications. Each log entry includes the following information:

●

Date when the event first occurred (since the last interrogation)

●

Description of event that triggered the Medtronic CareAlert notification

●

Programmed threshold for the Medtronic CareAlert notification, if applicable

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2 The Virtuoso system

2.1 System overview

Virtuoso Implantable Cardioverter Defibrillator (ICD) systems are implantable medical devices that automatically detect and treat episodes of ventricular fibrillation (VF), ventricular tachycardia (VT), fast ventricular tachycardia (FVT), and bradyarrhythmia. The Virtuoso DR device also detects and treats atrial tachyarrhythmia episodes.

Each Virtuoso ICD system includes 5 major components: the implanted device, the leads connecting the device to the patient’s heart, the Medtronic programmer with Virtuoso application software installed, the Conexus Activator, and the Medtronic CareLink Monitor. The system uses Conexus wireless telemetry for communication between the device and programmer and between the device and patient’s monitor.

2.1.1 Implanted device

The device senses the electrical activity of the patient’s heart using the sensing electrodes of the implanted leads. It analyzes the heart rhythm based on selectable sensing and detection parameters. If the device detects a ventricular tachyarrhythmia, it can deliver defibrillation, cardioversion, or antitachycardia pacing therapy to the patient’s heart. If the device identifies a bradyarrhythmia, it delivers bradycardia pacing therapy.

2.1.2 Leads

The device can be used with transvenous or epicardial defibrillation leads. The lead system should consist of bipolar or paired unipolar1 leads for pacing and sensing and one or two high-voltage cardioversion/defibrillation electrodes. The pacing and sensing electrodes sense cardiac activity and deliver pacing stimuli. DR devices require both atrial and ventricular leads to be implanted. VR devices require only ventricular leads. The device case may optionally be used as an Active Can high voltage electrode. You can enable or disable this option using the programmable Active Can parameter.

Note: OptiVol fluid monitoring may be adversely affected by the use of an epicardial defibrillation lead instead of an RVcoil (HVB) lead.

With an appropriate unipolar to bipolar adapter kit.

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2.1.3 Programmer and software

The Medtronic programmer and Virtuoso application software allow you to perform the following tasks:

●

configure the detection, therapy, and bradycardia features for your patient

●

perform electrophysiological studies and system tests

●

monitor, display, or print patient cardiac activity information

●

view patient and device diagnostic data

The Virtuoso devices and application software are compatible with the following programmer systems:

●

Medtronic CareLink Model 2090 programmer with Conexus Telemetry

●

Medtronic CareLink Model 2090 programmer with a Model 2067 or 2067L programming head

2.1.4 Network connectivity and data exchange

The system supports network connectivity and the exchange of data between the Medtronic Carelink 2090 programmer and the Medtronic Paceart data management system using the SessionSync feature.

The system supports the use of the Medtronic 2290 Analyzer, which allows you to have a device session and an analyzer session running at the same time, quickly switch from one to the other without having to end or restart sessions, and export data from the analyzer to the device software application.

The system supports Remote View, which allows you to use a personal computer in your office or elsewhere to view the screen displays from a Medtronic CareLink programmer in a clinic, hospital, or other location.

2.1.5 Conexus wireless telemetry

Conexus wireless telemetry is designed to provide clinicians and patients with an easier and more efficient implant, follow-up, and monitoring experience. The system uses radio frequency (RF) telemetry for wireless communication between the implanted device and programmer in the hospital or clinic, and between the implanted device and the patient’s monitor. This eliminates the need to have a programming head over the implanted device for the duration of a programming or monitoring session.

2.1.6 Conexus Activator

The Medtronic Model 27901 Conexus Activator can be used by clinicians to turn on Conexus wireless telemetry for implanted devices that support wireless telemetry.

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2.1.7 Monitor

The patient’s monitor remotely interrogates device parameter settings, episode data, device status data, and patient data from the patient’s device. When a patient receives their monitor, they must perform a manual interrogation session to initialize their monitor to their device. This initialization ensures that the patient’s device and the patient’s monitor will only be able to transmit information between one another.

2.1.8 Patient assistant

Patients can use the Model 2696 InCheck Patient Assistant to perform the following functions:

●

Verify whether the implanted device has detected a suspected atrial tachyarrhythmia (DR devices only).

●

Initiate recording of cardiac event data in the device memory (both DR and VR devices).

●

Request delivery of atrial cardioversion therapy (if the device is programmed to allow patient-activated cardioversion) (DR devices only).

Note: Patient-activated cardioversion is only delivered if the implanted device is currently detecting an AT/AF episode.

2.1.9 Detecting ventricular tachyarrhythmias

The device monitors the cardiac rhythm for short ventricular intervals that may indicate the presence of VF, VT, or FVT.

You can program the device to distinguish between true ventricular arrhythmias and rapidly conducted supraventricular tachycardia (SVT) and to withhold therapy for SVT.

DR devices also have the ability to detect double tachycardias (unrelated ventricular arrhythmias occurring simultaneously with SVTs) so that therapy is not withheld for a ventricular arrhythmia in the presence of an SVT.

2.1.10 Treating ventricular tachyarrhythmias

The device treats detected VF episodes by delivering a biphasic defibrillation shock. If the VF episode persists, up to 5 more individually programmed defibrillation shocks can be delivered.

You also have the option of delivering 1 sequence of ATP therapy before or during charging for a VF therapy. This option can prevent delivery of painful shocks for episodes that are detected as VF but can be terminated by pacing therapy.

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The device treats detected VT episodes by delivering either a Ramp, Ramp+, or Burst antitachycardia pacing therapy or a biphasic cardioversion shock synchronized to a ventricular depolarization. If the VT episode persists, up to 5 more individually programmed VT therapies can be delivered.

The device treats detected FVT episodes by delivering either a Ramp, Ramp+, or Burst antitachycardia pacing therapy or a biphasic cardioversion shock synchronized to a ventricular depolarization. If the FVT episode persists, up to 5 more individually programmed FVT therapies can be delivered.

DR/VR D154AWG/D154VWC

2.1.11 Detecting atrial tachyarrhythmias

If there is no ventricular episode in progress, the device applies the AT/AF detection algorithm, which detects AT/AF episodes by examining the atrial rate and the relationship between atrial and ventricular events. DR devices can detect AT/AF episodes, and respond to detected AT/AF episodes with programmed atrial tachyarrhythmia therapies. DR devices also provide an additional detection zone for Fast AT/AF episodes. This second zone allows the device to treat a second, faster atrial tachyarrhythmia with a separately programmable set of therapies.

2.1.12 Treating atrial tachyarrhythmias

The device treats detected AT/AF episodes by delivering Burst+, Ramp or 50 Hz Burst antitachycardia pacing therapy or by delivering an atrial cardioversion. Each sustained AT/AF episode can be treated with up to 5 automatic therapies per detection zone: 3 antitachycardia pacing therapies and 2 atrial cardioversion therapies. Patient-activated cardioversion is also available to treat AT/AF episodes.

2.1.13 Treating bradycardia

The device provides rate responsive pacing to treat bradycardia. An internal accelerometer senses the patient’s physical activity, allowing the device to increase and decrease the pacing rate in response to changes in the level of activity.

VR devices provide single chamber ventricular pacing modes. DR devices provide dual chamber pacing, single chamber pacing, and MVP (Managed Ventricular Pacing) modes. The MVP modes switch between single chamber atrial pacing and dual chamber pacing to promote intrinsic conduction and manage unnecessary right ventricular pacing.

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2.1.14 Monitoring for real-time and stored data

The device and programmer provide real-time information on detection and therapy parameters and status during a patient session. The device also provides accumulated data on device operation, including stored electrograms, detected and treated tachyarrhythmia episodes, bradycardia interventions, and the efficacy of therapy. The Cardiac Compass report provides up to 14 months of clinically significant data, including arrhythmia episodes, shocks delivered, physical activity, heart rate, bradycardia pacing activities, and thoracic fluid trends. The Rate Histograms report shows the percent of time that cardiac events occurred at different heart rates. In DR devices, this report also shows the distribution of ventricular heart rates during AT/AF episodes.

All of this information can be printed and retained in the patient’s file or saved in electronic format on a floppy diskette.

2.1.15 Conducting electrophysiologic tests

You can use the system to conduct non-invasive electrophysiologic studies, including manual delivery of therapies, to manage an induced or spontaneous tachyarrhythmia.

2.1.16 Alerting the patient to system events

You can use the programmable Medtronic CareAlert monitoring feature to notify the patient with audible tones if certain conditions occur that are related to the leads, battery, charge time, and therapies. The patient can then respond based on your prescribed instructions. The patient’s monitor can then notify the patient or a family member of certain event conditions.

2.2 Indications and usage, DR devices

The device is indicated to provide ventricular antitachycardia pacing and ventricular defibrillation for automated treatment of life-threatening ventricular arrhythmias. In addition, the device is indicated for use in patients with atrial tachyarrhythmias, or those patients who are at significant risk of developing atrial tachyarrhythmias.

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Notes:

●

The use of the device has not been demonstrated to decrease the morbidity related to atrial tachyarrhythmias.

●

The effectiveness of high-frequency burst pacing (atrial 50 Hz Burst therapy) in terminating device classified atrial tachycardia (AT) was found to be 17%, and in terminating device classified atrial fibrillation (AF) was found to be 16.8%, in the VT/AT patient population studied.

●

The effectiveness of high-frequency burst pacing (atrial 50 Hz Burst therapy) in terminating device classified atrial tachycardia (AT) was found to be 11.7%, and in terminating device classified atrial fibrillation (AF) was found to be 18.2%, in the AF-only patient population studied.

2.3 Indications and usage, VR devices

The device is indicated to provide ventricular antitachycardia pacing and ventricular defibrillation for automated treatment of life-threatening ventricular arrhythmias.

2.4 Contraindications, DR devices

The device is contraindicated for patients experiencing any of the following conditions:

●

tachyarrhythmias with transient or reversible causes including, but not limited to, the following: acute myocardial infarction, drug intoxication, drowning, electric shock, electrolyte imbalance, hypoxia, or sepsis

●

incessant ventricular tachycardia or ventricular fibrillation

●

primary disorder of chronic atrial tachyarrhythmia with no concomitant VT or VF

●

present implant of a unipolar implantable pulse generator

●

primary disorder of bradyarrhythmia

2.5 Contraindications, VR devices

The device is contraindicated for patients experiencing any of the following conditions:

●

tachyarrhythmias with transient or reversible causes including, but not limited to, the following: acute myocardial infarction, digitalis intoxication, drowning, electric shock, electrolyte imbalance, hypoxia, or sepsis

●

incessant ventricular tachycardia or ventricular fibrillation

●

present implant of a unipolar implantable pulse generator

●

primary disorder of bradyarrhythmia or atrial arrhythmia

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2.6 Patient screening

Other optional screening procedures may include exercise stress testing to determine the patient’s maximum sinus rate and cardiac catheterization to determine if there is a need for concomitant surgery or medical therapy.

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3 Emergency therapy

3.1 Overview of emergency therapies

The device provides emergency defibrillation, cardioversion, fixed burst pacing, and VVI pacing therapy. You can gain access to emergency therapies by pressing the on-screen [Emergency] button, or by pressing the red mechanical button on the programmer display panel. To return to other programming functions from an Emergency screen, select [Exit Emergency].

Effect on system operation – The device suspends the automatic detection features when emergency defibrillation, cardioversion, or fixed burst pacing therapies are delivered. Detection is not suspended during emergency VVI pacing. Remove the programming head or press [Resume] to enable detection again.

Aborting an emergency therapy – You can immediately terminate an emergency defibrillation or emergency cardioversion therapy by selecting [ABORT]. To stop an emergency fixed burst therapy, remove the programmer stylus from the [BURST Press and Hold] button. To terminate emergency VVI pacing, reprogram the bradycardia pacing parameters from the Parameters screen.

Mechanical Emergency VVI button – If you press the red Emergency VVI button on the programmer display panel, the device initiates emergency VVI pacing and the programmer displays the Emergency screen.

Temporary parameter values – Emergency tachyarrhythmia therapies use temporary parameter values that do not change the programmed parameters of the device. After the tachyarrhythmia therapy is complete, the device reverts to its programmed values.

Note: When you enable emergency VVI pacing, the programmed bradycardia pacing parameters are changed to the emergency settings.

3.2 Delivering an emergency defibrillation therapy

The default emergency therapy is a full-energy defibrillation. When you select [Emergency] and [DELIVER], the device charges and delivers a biphasic full-energy shock. The programmer sets the emergency defibrillation energy to its maximum value each time you select [Emergency] or select the [Defibrillation] option from an Emergency screen.

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3.2.1 Parameters

DR/VR D154AWG/D154VWC

Energy – Amount of energy delivered to the heart by the therapy.

Pathwaya – Direction the electrical current flows through the heart.

If the Active Can feature is Off, the HVA (Can) electrode is not used as part of the high-voltage delivery pathway.

0.4; 0.6 … 1.8; 2; 3 … 16; 18; 20; 22; 24; 25; 26; 28; 30; 32; 35 J

B>AX (fixed)

3.2.2 How to deliver emergency defibrillation

1. Establish telemetry with the device.

2. Select [Emergency].

3. Accept the defibrillation energy shown on the screen, or select a new Energy value.

4. Select [DELIVER].

3.3 Delivering an emergency cardioversion therapy

When you initiate an emergency cardioversion therapy, the device charges its capacitors to the selected energy and attempts to deliver therapy synchronized with a sensed tachyarrhythmia event. If the cardioversion therapy cannot be synchronized, it is aborted. See Section 7.7.5.5, “Synchronizing cardioversion after charging”, page 167.

3.3.1 Parameters

Energy – Amount of energy delivered to the heart by the

therapy. Pathwaya – Direction the electrical current flows through

the heart.

If the Active Can feature is off, the HVA (Can) electrode is not used as part of the high-voltage delivery pathway.

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0.4; 0.6 … 1.8; 2; 3 … 16; 18; 20; 22; 24; 25; 26; 28; 30; 32; 35 J

B>AX (fixed)

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3.3.2 How to deliver emergency cardioversion

1. Establish telemetry with the device.

2. Select [Emergency].

3. Select [Cardioversion].

4. Accept the cardioversion energy shown on the screen, or select a new Energy value.

5. Select [DELIVER].

3.4 Delivering emergency fixed burst pacing

Emergency fixed burst pacing delivers maximum output pacing pulses to the ventricle at a selectable interval. The therapy continues for as long as you keep the programmer stylus on the [BURST Press and Hold] button.

3.4.1 Parameters

Interval – Time interval between pacing pulses deliv-

ered during the fixed burst therapy. RV Amplitude – Voltage of the ventricular pacing

pulses delivered during the fixed burst therapy. RV Pulse Width – Duration of the ventricular pacing

pulses delivered during the fixed burst therapy.

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100; 110 … 350 … 600 ms

8 V (fixed)

1.5 ms (fixed)

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3.4.2 How to deliver emergency fixed burst pacing

1. Establish telemetry with the device.

2. Select [Emergency].

3. Select [Fixed Burst].

4. Accept the pacing interval shown on the screen, or a new Interval value.

5. Select [BURST Press and Hold].

3.5 Enabling emergency VVI pacing

Emergency VVI pacing programs the device to deliver high-output ventricular pacing. You can initiate emergency VVI pacing from the Emergency screen or by pressing the red mechanical button on programmer display panel. To disable emergency VVI pacing, reprogram the bradycardia pacing parameters from the Parameters screen.

3.5.1 Parameters

Pacing Mode – NBG Codea for the pacing mode provided during

emergency VVI pacing. Lower Rate – Minimum pacing rate to maintain adequate heart rate

during periods of inactivity. RV Amplitude – Voltage of the ventricular pacing pulses delivered

during emergency VVI pacing. RV Pulse Width – Duration of the ventricular pacing pulses deliv-

ered during emergency VVI pacing. V. Blank Post VP – Time interval during which sensing is disabled

after a pacing pulse.

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VVI

70 bpm

6 V

1.5 ms

240 ms

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Rate Hysteresis – Enables tracking of intrinsic heart rate below programmed Lower Rate to prevent pacing during extended periods of inactivity, such as when a patient is sleeping.

V. Rate Stabilization – Modifies the pacing rate to eliminate the long pause that typically follows a premature ventricular contraction.

N–North American Society of Pacing and Electrophysiology (NASPE), B–British Pacing and Electrophysiology Group (BPEG), G–Generic Pacemaker Code

Off

3.5.2 How to enable emergency VVI pacing

1. Establish telemetry with the device.

2. Select [Emergency].

3. Select [VVI Pacing].

4. Select [PROGRAM] to change the pacing parameters to the emergency VVI settings.

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Part II

Device implant and patient follow-up procedures

4 Implanting the device

4.1 Overview

Proper surgical procedures and sterile techniques are the responsibility of the physician. The following procedures are provided for information only. Each physician must apply the information in these procedures according to professional medical training and experience.

The implant procedure includes the following steps:

●

Preparing for an implant

●

Verifying lead and connector compatibility

●

Positioning the leads

●

Testing the lead system

●

Connecting the leads to the device

●

Testing ventricular defibrillation operation and effectiveness

●

Positioning and securing the device

●

Completing the implant procedure

For information about replacing a previously implanted device, see Section 4.11, “Replacing a device”, page 54.

4.2 Considerations

Review the following information before implanting the device:

Warning: Do not allow the patient to have contact with grounded electrical equipment that might produce electrical current leakage during implant. Electrical current leakage may induce arrhythmias that may result in the patient’s death.

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Warning: Keep external defibrillation equipment nearby for immediate use whenever arrhythmias are possible or intentionally induced during device testing, implant procedures, or post-implant testing.

Lead coils and Active Can electrodes – Lead coils and Active Can electrodes in contact during a high-voltage therapy may cause electrical current to bypass the heart, possibly damaging the device and leads. While the device is connected to the leads, verify that therapeutic electrodes, stylets, or guide wires are not touching or connected by an accessory low impedance conductive pathway. Move objects made from conductive materials (for example, an implanted guide wire) well away from all electrodes before delivering a high-voltage shock.

The device is intended for implant in the pectoral region with Medtronic transvenous defibrillation leads. Implanting the device outside of the pectoral region, or the use of an epicardial defibrillation lead instead of an RVcoil (HVB) may adversely affect the results of the OptiVol fluid measurements. No claims of safety and efficacy can be made with regard to other acutely or chronically implanted lead systems that are not manufactured by Medtronic.

Use by date – Do not implant the device after the “Use by” date on the package label. Battery longevity may be reduced.

4.3 Preparing for an implant

4.3.1 Equipment and sterile supplies for an implant

The following is the necessary equipment for an implant:

●

Medtronic CareLink Model 2090 programmer with Conexus Telemetry and a Conexus Activator, or a Medtronic CareLink Model 2090 programmer with a Model 2067 or 2067L programming head.

●

Virtuoso Model SW002 software application

●

Model 2290 Analyzer or equivalent pacing system analyzer

●

external defibrillator

The following are the necessary sterile supplies for an implant:

●

implantable device and lead system components

●

programming head sleeve (if using a programming head)

Note: If a sterilized programming head is used during an implant, a sterile programming head sleeve is not necessary.

●

analyzer cables

●

lead introducers appropriate for the lead system

●

extra stylets of appropriate length and shape

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4.3.2 How to set up the programmer and start the application

1. Set up the programmer as described in the instructions provided with the programmer.

2. Install the Virtuoso Model SW002 software on the programmer if it is not already installed.

3. Establish telemetry with the device and start a patient session as described in Section 9.3.

4.3.3 How to prepare the device for implant

Before opening the sterile package, prepare the device for implant:

1. Interrogate the device. Print an initial interrogation report.

Note: If the programmer reports that an electrical reset occurred, do not implant the device. Contact a Medtronic representative.

2. Check the initial interrogation report or the Quick Look screen to confirm that the battery voltage is at least 3.0 V at room temperature. If the device has recently delivered a high-voltage charge or if the device has been exposed to low temperatures, the battery voltage will be temporarily lower and capacitor charge time may increase. Allow the device to warm to room temperature and check the battery voltage again. If an acceptable battery voltage cannot be obtained, contact a Medtronic representative.

3. Set the internal clock of the device (see Section 10.2.3).

4. Perform a manual capacitor formation (see Section 11.7.2 for additional information).

a. Dump any charge on the capacitors. b. Perform a test charge to full energy. c. Retrieve the charge data. d. Do not dump the stored charge. Allow the stored charge to dissipate for at least

10 min; the dissipation forms the capacitors.

e. If the reported charge time is unacceptable, contact a Medtronic representative.

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5. Program the therapy and pacing parameters to values appropriate for the patient (see Chapter 8 and Chapter 7). Ensure that tachyarrhythmia detection is programmed to Off (see Section 6.1).

Note: Do not enable the Atrial Preference Pacing feature (DR devices only) or a rate responsive pacing mode before implanting the device. Doing so may result in a pacing rate that is faster than expected.

Note: Patient information is typically entered at the time of initial implant, and it can be revised at any time. After entering the patient’s name and ID number, the patient name is displayed on the Command bar of the programmer screen. If the patient name has not been entered, then the patient ID number is displayed. If the patient’s name and ID number are not entered, then “(Patient name not entered)” will appear on the Command bar.

4.4 Verifying lead and connector compatibility

Select a compatible lead. Refer to Table 19.

Table 19. Lead and connector compatibility

Port Primary lead Lead adaptor

RV (HVB), SVC (HVX)

A, RV IS-1b bipolar 5866-24M for 5 mm paired unipolar

DF-1 refers to the international standard ISO 11318:2002.

IS-1 refers to ISO 5841-3:2000.

DF-1

6707 for 6.5 mm cardioversion/defibrillation lead

5866-24M for 5 mm bifurcated 5866-38M for IS-1 unipolar 5866-40M for Medtronic 3.2 mm low-profile

4.5 Positioning the leads

Implant transvenous leads according to the supplied instructions unless suitable chronic leads are already in place. Do not use any lead with this device without first verifying connector compatibility. Transvenous or epicardial leads may be used. For DR devices, a bipolar atrial lead with closely spaced pacing and sensing electrodes is recommended.

4.5.1 Using transvenous leads

Use standard transvenous implant techniques to position the ventricular lead tip in the right ventricular apex. For DR devices, use standard transvenous implant techniques to position the atrial pacing lead tip high on the right atrial appendage.

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Follow the general guidelines below for initial positioning of other transvenous leads (the final positions are determined by defibrillation efficacy tests):

●

SVC (HVX) lead: Place the lead tip high in the innominate vein, approximately 5 cm proximal to the right atrium (RA) and SVC junction.

●

SQ patch: Place the patch along the left mid-axillary, centered over the fourth-to-fifth intercostal space.

Note: An SQ patch is not implanted transvenously, but it is used with transvenous lead systems.

●

CS lead: Advance the lead tip to a position just under the left atrial appendage, if possible.

If using a subclavian approach, position the lead using a more lateral approach to avoid pinching the lead body between the clavicle and the first rib.

Warning: Pinching the lead can damage the lead conductor or insulation, which may cause unwanted high-voltage therapies or result in the loss of sensing or pacing therapy.

4.5.2 Using epicardial leads

A variety of surgical approaches can be used to implant epicardial leads, including a limited left thoracotomy or median sternotomy. A typical placement may use an anterior right ventricular patch as the RVcoil (HVB) and a posterolateral left ventricular patch as the SVC (HVX).

Note: Using an epicardial defibrillation lead instead of an RVcoil (HVB) lead may adversely affect the results of the OptiVol fluid measurements.

Follow these general guidelines for positioning epicardial leads:

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If unipolar epicardial pacing leads are used, position the electrodes about 1 to 2 cm apart to reduce electromagnetic interference, and route the leads together with several loose twists.

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Place the patches so that they encompass the maximum amount of cardiac mass and they have approximately equal amounts of mass between them.

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Ensure that the patches do not overlap and that the electrode portions do not touch.

●

Avoid placing extra-pericardial patches over the phrenic nerve.

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Suture the smooth face of each patch lead against the epicardium or pericardium in locations that produce optimal defibrillation.

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4.5.3 Surgical incisions

A single-incision submuscular or subcutaneous approach is recommended when the device is implanted in the pectoral region. Make the implant pocket about 1.5 times the size of the device.

Submuscular implant – An incision extending over the deltoid-pectoral groove typically provides access to the cephalic and subclavian veins as well as to the implant pocket. Place the device sufficiently medial to the humeral head to avoid interference with shoulder motion.

Subcutaneous implant – A transverse incision typically permits isolation of the cephalic vein. Place the device in a far medial position to keep the leads away from the axilla. Make sure that the upper edge of the device remains inferior to the incision.

4.6 Testing the lead system

Sensing and pacing tests include the following measurements:

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P-wave amplitudes (DR devices only)

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R-wave amplitudes

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slew rate

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pacing threshold

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pacing lead impedance

Medtronic recommends that you use a Model 2290 Analyzer to perform sensing and pacing measurements. If you use a Pacing System Analyzer (PSA), such as the Model 5311 or 5311B, perform both atrial and ventricular measurements using the ventricular channel of the PSA.

Refer to the technical manual supplied with the PSA for details about performing sensing and pacing measurements.

4.6.1 Parameters

See Table 20 for information about acceptable measured sensing and pacing values at implant.

Table 20. Acceptable implant values

Measurements required Acute transvenous leads Chronic leads

R-wave amplitude ≥ 5 mV ≥ 3 mV P-wave amplitude ≥ 2 mV ≥ 1 mV Slew rate

≥ 0.5 V/s (atrial) ≥ 0.3 V/s (atrial) ≥ 0.75 V/s (ventricular) ≥ 0.5 V/s (ventricular)

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Table 20. Acceptable implant valuesa (continued)

Measurements required Acute transvenous leads Chronic leads

Capture threshold (0.5 ms pulse width)

≤ 1.5 V (atrial) ≤ 3.0 V (atrial) ≤ 1.0 V (ventricular) ≤ 3.0 V (ventricular)

The measured pacing lead impedance is a reflection of measuring equipment and lead technology. Refer to the lead technical manual for acceptable impedance values.

Chronic leads are leads implanted for 30 days or more.

4.6.2 Considerations

Note: Do not measure the intracardiac EGM telemetered from the device to assess sensing.

When measuring sensing and pacing values, measure between the tip (cathode) and ring or coil (anode) of each bipolar pacing/sensing lead.

For paired unipolar epicardial pacing leads, either electrode can be the cathode; use the configuration that yields the lower pacing threshold.

4.7 Connecting the leads to the device

Warning: Verify that the lead connections are secure. Loose lead connections may result

in inappropriate sensing and failure to deliver arrhythmia therapy.

Caution: Use only the wrench supplied with the device. The wrench is designed to prevent damage to the device from overtightening a setscrew.

See the following figures for information about lead connections. Figure 3 shows the DR device ports for lead connections. Figure 4 shows the VR device ports for lead connections.

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Figure 3. DR device ports for lead connections

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1 DF-1 connector port, SVC (HVX) 2 DF-1 connector port, RV (HVB) 3 Device Active Can electrode, Can (HVA)

4 IS-1 connector port, RV 5 IS-1 connector port, A

Figure 4. VR device ports for lead connections

1 DF-1 connector port, SVC (HVX) 2 DF-1 connector port, RV (HVB) 3 Device Active Can electrode, Can (HVA)

4 IS-1 connector port, RV

Note: For easier lead insertion, insert the ventricular IS-1 connector leg first.

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4.7.1 How to connect the lead to the device

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1. Insert the torque wrench into the appropriate setscrew.

a. If the corresponding port is obstructed by the setscrew, retract the setscrew to clear

the port. Take care not to disengage the setscrew from the connector block.

b. Leave the torque wrench in the setscrew until the lead is secure. This allows a

pathway for venting trapped air when the lead is inserted.

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2. Push the lead or plug into the connector port until the lead connector pin is clearly visible in the pin viewing area. No sealant is required, but sterile water may be used as a lubricant.

3. Visually confirm that the lead is fully inserted into the connector pin cavity by viewing the device connector block from the side or end.

a. The lead connector pin for each lead should be clearly visible beyond the setscrew

block.

b. The lead connector ring for each lead should be fully inside the spring contact block.

There is no setscrew in this location.

4. Tighten the setscrew by turning it clockwise until the torque wrench clicks. Remove the torque wrench.

5. Tug gently on the lead to confirm a secure fit. Do not pull on the lead until the setscrew has been tightened.

6. Repeat these steps for each lead.

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4.8 Testing ventricular defibrillation operation and effectiveness

Warning: Ensure that an external defibrillator is charged for a rescue shock before

delivering a test shock.

Demonstrate reliable defibrillation effectiveness with the implanted lead system by using your preferred method to establish that a 10 J (minimum) safety margin exists.

4.8.1 High-voltage implant values

See Table 21 for information about measured high-voltage therapy values recommended at implant.

Table 21. High-voltage therapy values recommended at implant

Measurement Acute or chronic leads

RV Defib impedance 20–200 Ω SVC Defib impedance (if applicable) 20–200 Ω Defibrillation threshold ≤ 25 J

4.8.2 How to prepare for defibrillation threshold testing

1. Establish telemetry between the device and programmer and start a patient session. Interrogate the device if it has not been interrogated.

2. Observe the Marker Channel annotations to verify that the device is sensing properly.

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3. Conduct a manual Lead Impedance Test to verify defibrillation lead connections. Perform this test with the device in the surgical pocket. Keep the surgical pocket very moist. If the lead impedance is out of range, perform one or more of the following tasks:

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Recheck the lead connections and lead electrode placement.

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Repeat the lead impedance measurements.

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Inspect the EGM for abnormalities.

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Measure the defibrillation impedance with a manual test shock.

4. Program the device to detect VF with an adequate safety margin. An adequate safety margin is typically attained by setting the sensitivity to 1.2 mV.

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4.8.3 How to perform defibrillation threshold testing using T-Shock

1. Select Tests > EP Study.

2. Select T-Shock from the Inductions/Therapies box.

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3. Select the [Resume at DELIVER] check box to resume arrhythmia detection after induction delivery.

Note: If in a wireless telemetry session, you cannot deliver a T-Shock induction when there is a magnet over the device and the [Resume at DELIVER] check box is selected. An error message will appear informing you to remove the magnet or to deselect the [Resume at DELIVER] check box.

4. Select [Adjust Permanent…].

5. Set the VF detection, RV Sensitivity, and VF therapy parameters. VF Enable should be On, and the Energy parameter for VF Therapies 2 through 6 should be set to the maximum value.

6. Select [PROGRAM].

7. Select [Close].

8. Select the [Enable] check box.

9. Select [DELIVER T-Shock]. If necessary, you can abort an induction or therapy in progress by selecting [ABORT].

10. Observe the live rhythm monitor for proper post-shock sensing.

11. Use the [Adjust Permanent…] button to program a new energy level, if desired.

12. Wait until the on-screen timer reaches 5 minutes, then repeat Step 8 through Step 12 as needed.

13. Select the Params icon and disable VF, FVT, and VT detection before closing the pocket.

14. Interrogate the device, and print an episode summary report.

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4.8.4 How to perform defibrillation threshold testing using 50 Hz Burst

1. Select Tests > EP Study.

2. Select 50 Hz Burst from the Inductions/Therapies box.

3. Select [RV] as the chamber for induction/therapy.

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4. Select the [Resume at BURST] check box to resume arrhythmia detection after induction delivery.

Note: If in a wireless telemetry session, you cannot deliver a 50 Hz Burst induction when there is a magnet over the device and the [Resume at BURST] check box is selected. An error message will appear informing you to remove the magnet or to deselect the [Resume at BURST] check box.

5. Select [Adjust Permanent…].

6. Set the VF detection, RV Sensitivity, and VF therapy parameters. VF Enable should be On, and the Energy parameter for VF Therapies 2 through 6 should be set to the maximum value.

7. Select [PROGRAM].

8. Select [Close].

9. Press and hold [50 Hz BURST Press and Hold]. If necessary, you can abort an induction or therapy in progress by selecting [ABORT].

10. Observe the live rhythm monitor for proper post-shock sensing.

11. Use the [Adjust Permanent…] button to program a new energy level, if desired.

12. Wait until the on-screen timer reaches 5 minutes, then repeat Step 9 through Step 12 as needed.

13. Select the Params icon and disable VF, FVT, and VT detection before closing the pocket.

14. Interrogate the device, and print an episode summary report.

4.9 Positioning and securing the device

Cautions:

●

If no SVC electrode is implanted, the pin plug provided with the device must be secured in the SVC port to avoid damage to the device.

●

Program tachyarrhythmia detection to Off before closing the pocket to avoid inappropriate detection and shock while closing the pocket.

Note: Implant the device within 5 cm (2 in) of the surface of the skin to optimize post-implant ambulatory monitoring. The side of the device engraved with the Medtronic logo should face toward the skin to optimize the Medtronic CareAlert feature.

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4.9.1 How to position and secure the device

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1. Verify that each lead connector pin or plug is fully inserted into the connector port and that all setscrews are tight.

2. To prevent twisting of the lead body, rotate the device to loosely wrap the excess lead length. Do not kink the lead body.

3. Place the device and leads into the surgical pocket.

4. Suture the device securely within the pocket. Use non-absorbable sutures. Secure the device to minimize post-implant rotation and migration. Use a surgical needle to penetrate the suture holes on the device (indicated by arrows in the drawing).

5. Suture the pocket incision closed.

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4.10 Completing the implant procedure

Warning: For DR devices, do not enable the Other 1:1 SVTs PR Logic detection criterion

until the atrial lead has matured, approximately one month after implant. This criterion may inappropriately withhold therapy if atrial sensing is compromised by an unstable or dislodged atrial lead.

After implanting the device, obtain an x-ray of the patient to verify device and lead placement. To complete programming the device, select parameters that are appropriate for the patient.

Note: The high-voltage capacitors should be formed (or conditioned) periodically to maintain quick charging for high-voltage therapy. You can use the Automatic Capacitor Formation feature to ensure that they are formed regularly. See Section 5.3, “Optimizing charge time”, page 58, for details.

4.10.1 How to complete programming the device

1. Enable tachyarrhythmia detection and the desired tachyarrhythmia therapies.

2. Perform a final VF induction, and allow the implanted system to detect and treat the arrhythmia.

3. Program defibrillation and sensitivity parameters to values appropriate for the patient after defibrillation threshold testing is complete.

4. Monitor the patient after the implant, and take x-rays as soon as possible to document and assess the location of the leads.

5. Program patient information (see Section 10.12.1).

6. Configure the Medtronic CareAlert feature (see Section 10.4.7 ).

7. Set up data collection parameters (see Section 10.2.3).

Before the patient is discharged from the hospital, assess the performance of the implanted device and leads.

4.10.2 How to assess the performance of the device and leads

1. If any tachyarrhythmia therapies are enabled while the patient is in the hospital, interrogate the device after any spontaneous episodes to evaluate the detection and therapy parameter settings.

2. If the patient has not experienced spontaneous episodes, you may induce the clinical tachyarrhythmias using the non-invasive EP Study features to further assess the performance of the system. See Chapter 12, “Conducting electrophysiologic studies”, page 365.

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3. Recheck pacing and sensing values, and adjust if necessary.

4. Interrogate the device, and print a Final Report to document the postoperative programmed device status.

4.11 Replacing a device

If you are replacing a previously implanted device, disable detection before explanting.

When implanting the device with a chronic lead system, perform the following evaluations to ensure appropriate detection and therapy:

●

Check the integrity of the chronic high-voltage leads with a test shock, chest x-ray, and inspection.

●

Inspect the chronic lead connector pins for signs of pitting or corrosion.

●

Perform chronic pacing and sensing measurements.

●

Measure lead impedances.

●

Test defibrillation efficacy.

●

Confirm adequate sensing during VF.

●

Ensure proper fit of the lead connectors in the device connector block.

Notes:

●

To meet the implant requirements, it may be necessary to reposition or replace the chronic leads or to add a third high-voltage electrode.

●

Cap abandoned leads to avoid transmitting electrical signals.

4.11.1 How to explant and replace a device

1. Program tachyarrhythmia detection to Off to avoid potential inappropriate shocks to the patient or implanter while handling the device (see Chapter 6).

2. Program the device to a non-rate responsive mode to avoid potential rate increases while handling the device (see Section 8.1.4).

3. Disable Atrial Preference Pacing (DR devices only) (see Section 8.14.4). Disable Ventricular Rate Stabilization (both DR and VR devices) (see Section 8.16.4).

4. Dissect the lead and the device free from the surgical pocket. Do not nick or breach the lead insulation.

5. Use a wrench to loosen the setscrews in the connector port.

6. Gently pull the lead out of the connector port.

7. Evaluate the condition of the lead. Replace the lead if the electrical integrity is not acceptable or if the lead connector pin is pitted or corroded. Return the explanted lead to Medtronic for analysis and disposal.

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8. Connect the lead to the replacement device.

Note: A lead adaptor may be needed to connect the lead to the replacement device. Contact a Medtronic representative for questions about lead adaptor compatibility.

9. Evaluate sensing, pacing, and defibrillation efficacy using the replacement device.

10. After confirming acceptable electrical measurements, suture the pocket incision closed.

11. Return the explanted device to Medtronic for analysis and disposal.

4.12 Optimizing device longevity

The following factors may affect the longevity of the device:

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a greater number of high-voltage charges, either for therapy or for capacitor formation

●

higher programmed cardioversion or defibrillation therapy energies

●

a greater number of bradycardia paced events, for example, an increase in the pacing rate

●

use of Atrial Preference Pacing (DR devices only), which increases the number of bradycardia paced events, and use of Ventricular Rate Stabilization (DR and VR devices).

●

higher programmed pacing amplitude or pulse width

●

pacing outputs or high-voltage therapy energy increased to compensate for a decrease in pacing and high-voltage lead impedance

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use of the Pre-arrhythmia EGM storage or Holter telemetry features

For device longevity estimates, see Section 1.4, “Projected service life”, page 17.

4.12.1 Considerations

Shock energy – If the defibrillation threshold of the patient allows for an appropriate safety

margin (at least 10 J, after the acute implant period), consider programming the first ventricular shock energy below the maximum value. Always program all subsequent shocks to the full available energy.

Note: If VF Detection is enabled, consider programming the Energy parameter for the first VF therapy to at least 20 J if you enable ATP During Charging. The charge times for therapies with energies less than 20 J may be too brief for the device to detect when ATP During Charging has terminated an arrhythmia.

Pacing outputs – If the patient’s pacing threshold allows for an appropriate safety margin (at least a factor of 2 after the acute implant period), consider decreasing the pacing outputs. Always consider the patient’s access to regular follow-up care in selecting a safety margin for chronic pacing.

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Pacing mode – If the patient’s intrinsic rhythm allows for appropriate rate support, you can decrease the pacing burden by programming the Mode, Rate Response, and AV Interval parameters to promote intrinsic activation or conduction.

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5 Conducting a patient follow-up session

5.1 Patient follow-up guidelines

During the first few months after receiving a new device, the patient may require close monitoring. Schedule office visits at least every 3 months to monitor the condition of the device and leads and to verify that the device is configured appropriately for the patient.

The Quick Look screen, which is displayed when you start the application, provides a good beginning for the follow-up. The Quick Look screen allows you to perform these functions:

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Verify that the device is functioning correctly.

●

Review the clinical performance and device trends.

●

Print appropriate reports to compare the results to the patient’s history and to retain for future reference.

Note: To print an Initial Interrogation Report, you may need to change Initial Report preferences and restart the session. See Section 9.15.4, “How to set Initial Reports preferences”, page 280.

Note: The Checklist feature provides a standard list of tasks to perform at a complete follow-up visit. You can also customize your own checklists. See Section 9.7, “Streamlining follow-up and implant sessions with Checklist”, page 245.

5.2 Verifying the status of the implanted system

To verify that the device and leads are functioning correctly, review the following information from the Quick Look screen, and perform follow-up tests as indicated:

●

Review the displayed battery voltage for comparison to the Recommended Replacement Time (RRT) value (see Section 1.3). If the displayed battery voltage is at or below the displayed RRT value or if the RRT indicator is displayed, schedule an appointment to replace the device.

Note: Battery voltage may be low if high-voltage charging has occurred within 24 hours.

●

If the programmer displays the EOS indicator for low battery voltage or excessive charge time, the device should be replaced immediately.

●

Review the last full-energy charge. For information about adjusting the capacitor formation interval, see Section 5.3, “Optimizing charge time”, page 58.

●

Review the lead impedance values for inappropriate values or significant changes since the last follow-up. See Section 11.5, “Measuring lead impedance”, page 358.

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Perform P-wave and R-wave amplitude tests for comparison to previous P-wave and

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R-wave amplitude measurements. See Section 11.6, “Performing a Sensing Test”, page 360.

●

To review trends in sensing and impedance measurements, select the [>>] button from the lead status area of the Quick Look screen. The programmer displays a detailed history of automatic sensing and impedance measurements. See Section 10.11, “Viewing Lead Performance Trends data”, page 342.

5.3 Optimizing charge time

The high-voltage capacitors should be formed (or conditioned) periodically to maintain quick charging for high-voltage therapy. You can use the Automatic Capacitor Formation feature to ensure that they are formed regularly.

The device can be programmed to automatically adjust the capacitor formation interval for interactive management of charge time and device longevity.

Note: The device capacitors have not been fully formed since manufacture. Capacitors should be manually formed before programming the Automatic Capacitor Formation Interval to reduce the device charge time. See Section 11.7.2, “How to perform a Charge/Dump test”, page 363.

5.3.1 Parameters

Minimum Auto Cap Formation Interval Auto ; 1; 2 … 6 months

5.3.2 Considerations

Formation interval and longevity – A shorter formation interval provides faster charge

times by optimizing the efficiency of the capacitors. However, each capacitor formation includes a full-energy charge, reducing the longevity of the device.

Assess the patient’s requirements for faster therapy delivery relative to the effect on device longevity. Each full-energy charge decreases the longevity of DR devices by approximately 37 days and decreases the longevity of VR devices by approximately 44 days.

Programming a new formation interval – When you program a new automatic formation interval, always confirm that the charge time is adequate at present. Either perform a manual capacitor formation or evaluate a recent full-energy charge time recorded in the Battery and Lead Measurements display.

Capacitor formation and Medtronic CareAlert feature – You can use the Medtronic CareAlert monitoring feature to receive prompt notice if a long charge time has occurred.

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5.3.3 How to evaluate charging performance

1. Perform a Charge/Dump test, and review the charge time (see Section 11.7, “Testing the device capacitors”, page 362).

2. Allow the charge to dissipate for 10 min.

3. Select [DUMP Capacitors].

4. Perform another Charge Time test, and review the second charge time.

●

If the second charge time is clinically acceptable, consider reducing the Automatic Capacitor Formation Interval (see Section 5.3.4, “How to program the Automatic Capacitor Formation Interval”, page 59).

●

If the second charge time is not clinically acceptable, contact your Medtronic representative.

5.3.4 How to program the Automatic Capacitor Formation Interval

1. Select the Params icon.

2. Select the Therapies… field for VF, FVT, or VT.

3. Select Auto Cap Formation….

4. Select the Minimum Auto Cap Formation Interval.

5. Return to the Parameters screen and select [PROGRAM].

5.3.5 Details about managing charge time

The device provides the fastest charging and most prompt therapy delivery just following a capacitor formation. During the time between formations, the capacitors gradually lose their efficiency. This results in longer charge times until the next formation.

The charge time also gradually increases over the life of the device as the battery is depleted. This occurs independently of capacitor formation.

Capacitor formation consists of 2 steps: First, the capacitors are charged to their full energy. Then the charge is allowed to dissipate for at least 10 min.

The device records the time and date when a full-energy charge dissipates for 10 min without interruption, and reports it on the programmer as a capacitor formation.

5.3.5.1 Smart Auto Cap

Therapeutic charging can also contribute to the efficiency of the capacitors. This occurs because the capacitors are partially conditioned each time they are charged (for example, during a full-energy defibrillation). In these situations, there is less need for the next scheduled capacitor formation. Automatic capacitor formation is not enabled until the device is implanted.

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More frequent formations decrease the device longevity, with little benefit to the charge time. To optimize the effectiveness of the automatic capacitor formations, the device postpones the schedule when full-energy charging has occurred:

●

Whenever the capacitor formation interval is reprogrammed, the device resets the automatic capacitor formation interval clock.

●

After a manual capacitor formation, the device resets the automatic capacitor formation interval clock.

●

After an incidental capacitor formation (a full-energy charge that dissipates for 10 min), the device resets the automatic capacitor formation interval clock.

●

After a full-energy charge is delivered or dumped, the device extends the automatic capacitor formation interval clock by up to 2 months. The total of these extensions will not exceed the programmed automatic capacitor formation interval.

Parameter set to “Auto” – When the capacitor formation interval parameter is programmed to Auto, the device maintains a 6-month schedule for capacitor formation until the battery is close to end of service.

If a charging period for therapy or capacitor formation exceeds 16 s for DR devices or 19 s for VR devices, the device changes to a 1-month schedule for capacitor formation. If a second charging period exceeds 16 s for DR devices or 19 s for VR devices, the device sets the EOS status message, indicating that the device should be replaced immediately.

The rules for postponing the scheduled automatic formation after a full-energy charge remain in effect if the device changes to a 1-month schedule.

5.4 Verifying accurate detection and appropriate therapy

To verify that the device is providing effective tachyarrhythmia detection and therapy, review the following information from the Quick Look screen, and investigate as indicated:

●

Review Quick Look Observations that relate to patient history and device operation. To display more detailed information about an observation (when available), select the observation and then select the [>>] button.

●

Review any Medtronic CareAlert events listed in the Observations of the Quick Look screen. For the most detailed information about Medtronic CareAlert events, select Alert Events from the Data icon.

●

Check stored episode records for appropriate sensing and detection of arrhythmias (see Section 10.5, “Viewing Arrhythmia Episode data”, page 306).

●

Check stored SVT episode records for appropriate identification of SVTs.

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5.4.1 Considerations

Review the following information before verifying detection and therapy.

Caution: Do not program the device to decrease oversensing without ensuring that appropriate sensing is maintained (see Section 6.2, “Setting up sensing”, page 68).

Flashback memory – In addition to the episode records and stored electrograms, use Flashback memory and interval plots to investigate the accuracy and specificity of atrial and ventricular detection.

Episode misidentification – If the episode records indicate that false detections have occurred, the Sensing Integrity Counter may help in determining the prevalence of oversensing. For more information, see Section 10.10.2.2, “Sensing integrity counter”, page 342.

If the device is oversensing, consider these options:

●

Assess the lead integrity and lead connections.

●

Assess the sensitivity threshold.

If the episode records reveal that a stable monomorphic VT has been identified and treated as VF, consider these options to improve the detection accuracy, which may also improve the therapy accuracy:

●

Review the Interval Plot for the episode, and adjust the VF Interval if necessary. Use caution when reprogramming the VF Interval because changes to this value can adversely affect VF detection.

●

Program the ATP parameter for VF therapies to ATP During Charging (see Section 7.5.4, “How to program VF therapies”, page 148).

●

Enable FVT via VF detection (see Section 6.6.4, “How to program FVT Detection”, page 84).

If the SVT episode records include episodes of true VT, review the SVT episode records to identify the SVT detection criterion that withheld detection. Adjust the SVT detection criteria parameters as necessary.

5.5 Verifying effective bradycardia pacing

To verify that the device is sensing and pacing appropriately, review the following information from the Quick Look screen, and investigate as indicated:

●

Confirm that the patient is receiving adequate cardiac support for daily living activities.

●

Review the pacing conduction history for comparison to the patient history. A sharp increase in the paced beats percentage may indicate a need for investigation and analysis.

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Review the Cardiac Compass report for comparison to patient history (see Section 10.7,

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“Using Cardiac Compass to view long-term clinical trends”, page 320).

●

Conduct pacing threshold tests (see Section 11.3, “Measuring pacing thresholds”, page 351) to verify that the programmed pacing outputs provide a sufficient safety margin.

5.5.1 Considerations

Review the following information for DR devices before verifying bradycardia pacing.

Ventricular Pacing – If the ventricle is predominantly paced and the patient exhibits adequate ventricular response, consider these options:

●

Program the device to an MVP mode (AAIR<=>DDDR or AAI<=>DDD). These modes are designed to manage unnecessary right ventricular pacing.

●

Decrease the Lower Rate.

●

Increase the Sensed AV interval.

●

Increase the Paced AV interval.

Atrial Pacing – If the conduction history shows a predominance of atrial pacing despite a healthy sinus response, consider these options to decrease the atrial pacing burden:

●

Decrease the Lower Rate.

●

Decrease the Rate Response or increase the Activity Threshold.

●

Decrease Paced AV and enable Rate Adaptive AV.

Conduction history – The reported percentages in the conduction history may not add up to 100 because of rounding.

Note: Rate histograms may also be used to assess pacing and sensing history. The pacing and sensing history on the Quick Look screen may not match the data in the histograms because of premature atrial contractions (PACs) and A:V dissociation.

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Part III

Configuring the device for the patient

6 Detecting tachyarrhythmias

6.1 Detection overview

Virtuoso devices provide several different atrial and ventricular tachyarrhythmia detection capabilities.

●

DR devices provide AT/AF detection, AT/AF monitoring, VF/FVT/VT detection, and VT monitoring.

●

VR devices provide VF/FVT/VT detection and VT monitoring.

The device detects atrial tachyarrhythmias (AT/AF) by examining the atrial rate and the relationship between atrial and ventricular events. If the atrial rate is fast enough and if enough evidence of an atrial tachyarrhythmia is accumulated, the device detects an AT/AF episode.

AT/AF detection can be programmed to Monitor or On. If AT/AF detection is programmed to Monitor, the device collects data about the incidence and duration of atrial arrhythmias, but it does not treat episodes with atrial therapies. If AT/AF detection is programmed to On, detected AT/AF episodes can be treated with atrial therapies (see Chapter 7, “Treating tachyarrhythmia episodes”, page 118). The AT/AF Detection Interval, whether programmed to Monitor or On, also triggers mode-switching in the device.

The device detects ventricular tachyarrhythmias (VF, VT, and FVT) by comparing the time intervals between sensed ventricular events to a set of programmed detection intervals. If enough intervals are shorter than the programmed intervals, the device detects a tachyarrhythmia.

In addition to VF, VT, and FVT detection zones, the device provides a VT monitoring zone, which functions as an independent VT zone. When the device detects a VT episode in the VT monitoring zone, it records the episode but does not deliver VT therapy.

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To discriminate between rapidly conducted SVTs (for example, sinus tachycardia or atrial fibrillation) and ventricular tachyarrhythmias, the device provides several detection enhancements such as the following detection criteria:

●

PR Logic with enhanced Sinus Tach criterion in DR devices

●

Wavelet Dynamic Discrimination in VR devices

●

Stability

●

Onset

Figure 5 shows how the ventricular tachyarrhythmia detection features interact in DR devices during initial detection. Figure 6 shows how the ventricular tachyarrhythmia detection features interact in VR devices during initial detection. During redetection of ventricular tachyarrhythmias, devices do not apply Onset, PR Logic, or Wavelet detection criteria.

Note: Detection functions can be disabled by programming the VF, FVT, VT, and VT Monitor detection parameters to Off. For an example, see Section 6.4.4, “How to program VF Detection”, page 78. AT/AF detection can only be programmed to On or Monitor.

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Ventricular Event

Yes

Update counts and pattern information

Is the interval in the

VF, FVT, or VT detection zone?

Has High Rate Timeout suspended detection

enhancements?

Does Stability reset the VT event count?

(VT and FVT via VT detection only)

Is the Onset criterion allowing VT event counting?

(VT and FVT via VT detection only)

Has a tachyarrhythmia event count reached

an Initial Beats to Detect criterion?

Are one or more PR Logic criteria enabled?

Is the median ventricular interval less than

the SVT V. Limit?

Is there a double tachycardia in progress?

Are one or more PR Logic criteria withholding

detection?

No/ Suspended

by High Rate

Timeout

Yes

Tachy

Episode

detected

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Figure 5. How ventricular tachyarrhythmia detection features in DR devices interact during initial detection

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Ventricular Event

Yes

Update counts information

Is the interval in the VF, FVT, or VT detection zone?

Has High Rate Timeout suspended detection enhancements?

Does Stability reset the VT event count? (VT and FVT via VT

detection only)

Yes

Is the Onset criterion allowing VT event counting? (VT and FVT via

VT detection only)

Has a tachyarrhythmia event count reached an Initial Beats to Detect

criterion?

Is Wavelet enabled?

No / Suspended by High

Rate Timeout

Is the median ventricular interval less than the SVT V. Limit?

Is Wavelet withholding detection?

Tachy

Episode

detected

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Figure 6. How ventricular tachyarrhythmia detection features in VR devices interact during initial detection

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6.1.1 Suspending tachyarrhythmia detection

When detection is suspended, the device temporarily stops classifying and counting tachyarrhythmia intervals. Sensing and bradycardia pacing remain active, and the programmed detection settings are not modified.

Note: Suspending detection during a VT Monitor episode terminates the data storage. If the ventricular episode continues following suspension, a new episode is detected.

Note: If detection is suspended during an AT/AF episode, a new episode is not recorded when detection resumes. Redetection of the episode begins when detection resumes.

Detection is suspended during the following occurrences:

●

The device senses the presence of a strong magnet. During a wireless telemetry session, tachyarrhythmia detection remains suspended while a magnet (or the programming head) is placed over the device. During a conventional telemetry session, tachyarrhythmia detection is suspended when the programming head or a magnet is placed over the device, but detection resumes when telemetry between the device and programmer is established.

●

The device is performing any of the manual system tests. Detection automatically resumes once the test is complete.

●

The device is performing an EP Studies induction. You can choose to have the device automatically resume detection after delivering the induction.

●

The device is delivering a manual therapy or emergency therapy. You can resume detection by selecting the [Resume] button, by removing the programming head from the device, or by selecting the wireless telemetry icon (see Figure 69, page 232).

●

You have selected the on-screen [Suspend] button. You can resume detection by selecting the [Resume] button, by removing the programming head from the device, or by selecting the wireless telemetry icon.

●

The device is performing automatic daily lead impedance measurements. Detection resumes when the measurements are complete.

Note: The automatic daily lead impedance measurements are not performed during detected VT/VF episodes. These measurements are, however, performed during VT Monitor episodes.

●

The device is delivering an automatic tachyarrhythmia therapy (including capacitor charging for defibrillation and cardioversion). However, the device does continue to confirm detected ventricular episodes during charging. Detection resumes when the therapy is complete.

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Note: The device suspends VT detection (and combined count detection, see Section 6.8, “Detecting tachyarrhythmia episodes with combined count”, page 90) for 17 events following a defibrillation therapy delivered in response to a detected VF.

●

The device is charging for Automatic Capacitor Formation. Detection resumes when

charging is complete.

6.2 Setting up sensing

The device provides bipolar sensing in both the atrium and ventricle using the sensing electrodes of the implanted atrial and ventricular leads. You can adjust the sensitivity to intracardiac signals using independent atrial and ventricular sensitivity settings. These settings define the minimum electrical amplitude recognized by the device as an atrial or ventricular sensed event.

Dual chamber atrial and ventricular sensing is available only in DR devices. Only ventricular sensing is available in VR devices.

Proper sensing is essential for the safe and effective use of the device. To provide appropriate sensing, the device uses the following features:

●

short (30 ms) cross-chamber blanking after paced events

●

auto-adjusting atrial and ventricular sensing thresholds

6.2.1 Parameters

RV Sensitivity – Minimum amplitude of electrical signal that regis-

ters as a sensed ventricular event. A. Sensitivity – Minimum amplitude of electrical signal that regis-

ters as a sensed atrial event.

0.15; 0.3 ; 0.45; 0.6; 0.9;

1.2 mV

0.15; 0.3 ; 0.45; 0.6; 0.9;

1.2; 1.5; 2.1 mV

6.2.2 Considerations

Review the following information before programming sensing parameters.

Sensitivity thresholds – The programmed sensitivity thresholds apply to all features related to sensing, including detection, bradycardia pacing, and the Sensing Test.

Bradycardia pacing and sensing – A combination of high pacing pulse width or high amplitude with a low sensitivity threshold may cause inappropriate sensing across chambers or in the same chamber. Programming a lower pulse width, lower amplitude,

If the defibrillation therapy is delivered as a result of either a High Rate Timeout Therapy operation or Progressive Episode Therapies operation, VT detection is not suspended (see Section 6.15, “Detecting prolonged tachyarrhythmias with High Rate Timeout”, page 115).

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longer pace blanking, or a higher sensitivity threshold may eliminate this inappropriate sensing.

Dual chamber sensing and bradycardia pacing modes (DR devices) – The device senses in both the atrium and the ventricle at all times, except when the programmed bradycardia pacing mode is DOO, VOO, or AOO. When the pacing mode is programmed to DOO or VOO, there is no sensing in the ventricle. When the pacing mode is programmed to DOO or AOO, there is no sensing in the atrium.

Recommended ventricular sensitivity threshold – A ventricular sensitivity threshold of

0.3 mV is recommended to maximize the probability of detecting VF and to limit the possibility of oversensing and cross-chamber sensing.

High ventricular sensitivity threshold – Setting RV Sensitivity to a value greater than

0.6 mV is not recommended except for testing purposes. Doing this may cause undersensing, which may cause any of the following situations:

●

delayed or aborted cardioversion therapy

●

delayed defibrillation therapy (when VF confirmation is active)

●

asynchronous pacing

●

underdetection of tachyarrhythmias

Testing sensitivity after reprogramming – If you change the ventricular sensitivity threshold, test for proper sensing. If appropriate, test for proper detection by inducing VF and allowing the device to automatically detect and treat the arrhythmia.

Sensing during VF – Always verify that the device senses properly during VF. If the device is not sensing or detecting properly, disable detection and therapies, and evaluate the system (making sure to monitor the patient for life-threatening arrhythmias until you enable detection and therapies again). You may need to reposition or replace the ventricular sensing lead to achieve proper sensing.

Low sensitivity threshold – If you set a sensitivity parameter to its most sensitive value of 0.15 mV, the device will be more susceptible to EMI, cross-chamber sensing, and oversensing.

Recommended atrial sensitivity threshold – An atrial sensitivity threshold of 0.3 mV is recommended to optimize the effectiveness of atrial detection and pacing operations while limiting the possibility of oversensing and cross-chamber sensing.

High atrial sensitivity threshold – If you set the A. Sensitivity value too high, the device may not provide reliable sensing of P-waves during AT/AF episodes and sinus rhythm.

Atrial pacing and ventricular sensing – If you program the device to an atrial pacing mode, make sure that it does not sense atrial pacing pulses as ventricular events.

Atrial lead selection – Atrial leads with minimal (10 mm) tip-to-ring spacing may reduce far-field R-wave sensing.

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Repositioning the atrial lead – If reprogramming the atrial sensitivity threshold does not provide reliable atrial sensing during AT/AF episodes and sinus rhythm, you may need to reposition or replace the atrial sensing lead.

6.2.3 How to program sensitivity

1. Select the Params icon.

2. Select the desired A. Sensitivity and RV Sensitivity parameters.

3. Select [PROGRAM].

6.2.4 Details about sensing

6.2.4.1 Blanking periods

Blanking periods inhibit sensing after paced and sensed events. These periods help prevent the sensing of device pacing, cardioversion and defibrillation pulses, post-pacing depolarization, T-waves, and multiple sensing of the same event. The blanking periods after paced events are longer than or equal to those after sensed events to avoid sensing the atrial and ventricular depolarizations.

Table 22 shows the duration of the fixed blanking periods. See Section 8.1, “Providing basic pacing therapy”, page 174, for more information about programmable pace blanking periods.

Table 22. Duration of fixed blanking periods

Cross-chamber blanking after atrial or ventricular pacing pulse 30 ms Atrial and ventricular blanking after delivered cardioversion or defibrillation

therapy

520 ms

The device does not sense electrical signals during blanking periods, except during the post-ventricular atrial blanking (PVAB) period.

6.2.4.2 Auto-adjusting sensitivity thresholds

The device automatically adjusts sensitivity thresholds after certain paced and sensed events to help reduce oversensing from T-waves, cross-chamber events, and pacing.

Figure 7 shows how sensitivity thresholds are adjusted after different types of events.

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A P

V S

A S

V S

A S

V P

Sensitivity Threshold

Rectified and

Filtered A. EGM

Rectified and

Filtered RV EGM

Marker Channel

1 2

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1 After an atrial sensed event, the atrial sensitivity threshold increases to 75% of the EGM peak

2 After a ventricular sensed event, the ventricular sensitivity threshold increases to 75% of the

3 After an atrial paced event, the device does not adjust the atrial sensitivity threshold. The

4 After a ventricular paced event, the atrial sensitivity threshold increases to 4x the programmed

5 After the ventricular pace blanking period is finished, the ventricular threshold increases to 4.5x

If the programmed ventricular sensitivity threshold exceeds 0.3 mV, the threshold is adjusted to 1.25x the programmed value.

If the programmed atrial sensitivity threshold exceeds 1.2 mV, the threshold is adjusted to 1.25x the programmed value.

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(maximum: 8x the programmed value).

EGM peak (maximum: 10x the programmed value).

ventricular sensitivity threshold increases to 0.45 mV.

value4 (maximum: 2.0 mV).

the programmed value (maximum: 1.8 mV).

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6.2.4.3 Post-ventricular atrial blanking and far-field R-waves

Atrial sensing is active during the post-ventricular atrial blanking (PVAB) interval. When the device senses an atrial event in the PVAB interval, the event is ignored by bradycardia pacing features. However, this event is detected by arrhythmia detection features. See Section 6.3, “Detecting atrial tachyarrhythmias”, page 72, for details about far-field R-wave sensing.

Note: Atrial events in the PVAB interval are not used by NCAP, PVC Response, Atrial Rate Stabilization, Rate Adaptive AV, and PMT Intervention features.5 See Chapter 8, for details.

6.2.4.4 Refractory periods

During a refractory period, the device senses normally but classifies sensed events as refractory and limits its response to these events. Pacing refractory periods prevent inappropriately sensed signals, such as far-field R-waves (ventricular events sensed in the atrium) or electrical noise from triggering certain pacing timing intervals.

Synchronization refractory periods help prevent the device from delivering cardioversion and defibrillation therapies at inappropriate times. See Section 7.5.5.7, “Synchronizing subsequent defibrillation therapies”, page 154, and Section 7.7.5.5, “Synchronizing cardioversion after charging”, page 167.

Note: Refractory periods do not affect tachyarrhythmia detection.

6.3 Detecting atrial tachyarrhythmias

AT/AF detection is available in DR devices. If AT/AF Detection is programmed to Monitor, the device collects data about the incidence and duration of atrial arrhythmias, but it does not treat episodes with atrial therapies.

If AT/AF Detection is programmed to On, detected AT/AF episodes can be treated with atrial therapies (see Chapter 7, “Treating tachyarrhythmia episodes”, page 118). AT/AF Detection also triggers mode-switching in the device.

PVAB does not affect Mode Switch.

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6.3.1 Parameters

AT/AF Detection On; Monitor Number of detection zones 1 ; 2 AT/AF A. Interval (Rate) 150; 160 … 350 … 450 ms Fast AT/AF A. Interval (Rate) 150; 160 … 200 … 250 ms

6.3.2 Considerations

Review the following information before programming AT/AF Detection.

Two-zone AT/AF Detection – If the patient exhibits two distinct atrial tachyarrhythmias, you can program the device to detect each separately. This allows you to deliver a separate therapy set for each tachyarrhythmia. Set the number of detection zones to 2, and program the AT/AF A. Interval (Rate) and Fast AT/AF A. Interval (Rate) parameters to values appropriate for each arrhythmia.

Atrial therapies and AT/AF Detection – If all atrial therapies are programmed Off and you change the AT/AF Detection parameter value from Monitor to On, the programmer automatically sets the first 2 AT/AF therapies to nominal or previously programmed settings.

6.3.3 Restrictions

Review the following information before programming AT/AF detection.

VF detection backup during AT/AF – To ensure VF detection backup during AT/AF episodes, AT/AF Detection cannot be On unless VF Detection is also On.

Asynchronous pacing mode – Atrial detection must be programmed to Monitor when the programmed pacing mode is DOO, VOO, or AOO.

6.3.4 How to program AT/AF Detection

1. Select the Params icon.

2. Select a value for AT/AF Detection.

3. Select a value for the AT/AF A. Interval (Rate).

4. To program Fast AT/AF Detection (only if AT/AF Detection is programmed to On), select the Therapies… field for AT/AF to open the AT/AF Detection and Therapies window.

a. Set Zones to 2. b. Select a value for Fast AT/AF A. Interval (Rate).

5. Return to the Parameters screen and select [PROGRAM].

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6.3.5 Details about AT/AF detection

Atrial tachyarrhythmia (AT/AF) detection has 4 phases:

●

AT/AF onset

●

initial AT/AF detection

●

sustained AT/AF detection

●

AT/AF episode termination

The device begins storing AT/AF data when the AT/AF onset criteria are met. After the AT/AF onset criteria are met, the rhythm is monitored for initial AT/AF detection criteria and then sustained AT/AF detection criteria. Once the rhythm is sustained, it is monitored until it meets AT/AF termination criteria if AT/AF Detection is programmed to Monitor. If AT/AF Detection is programmed to On and the device delivers an atrial therapy, the rhythm is monitored for redetection and termination criteria.

The device uses several detection criteria throughout the phases of AT/AF detection. For more information about AT/AF detection criteria, see Section 6.3.5.2, “AT/AF detection criteria”, page 75.

Note: AT/AF detection can occur only if the device has not detected a ventricular tachyarrhythmia. If VT/VF is detected during an atrial episode, 2 results are possible: If VT/VF occurs immediately after an AT/AF therapy is delivered, the device disables atrial therapies until they are reenabled using the programmer; If VT/VF occurs during an AT/AF episode but this detection is not related to therapy delivery, the device suspends atrial therapies. Atrial therapies can resume when the VT/VF episode ends.

6.3.5.1 AT/AF detection phases

The 4 phases of AT/AF detection are discussed in detail as follows.

AT/AF onset – AT/AF onset occurs when the median atrial interval is less than the AT/AF detection interval and the AT/AF evidence counter has counted at least 3 ventricular events in which the A:V pattern shows evidence of an atrial tachyarrhythmia. The device begins storing episode data after AT/AF onset occurs.

Notes:

●

AT/AF onset data is used to calculate the percentage of time that the patient was experiencing AT/AF.

●

If Mode Switch is enabled, the device starts mode switch operations when AT/AF onset is detected. See Section 8.8, “Mode Switch”, page 204.

Initial AT/AF detection – Initial AT/AF detection occurs when the median atrial interval is less than the AT/AF detection interval and the AT/AF evidence counter has counted at least 32 ventricular events in which the A:V pattern shows evidence of an atrial tachyarrhythmia.

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If the device is programmed for two-zone AT/AF detection, the device identifies the episode in the episode log as a Fast AT/AF episode if the median atrial interval is less than the programmed Fast AT/AF detection interval.

Once initial AT/AF detection occurs, the AT/AF episode continues until episode termination.

Sustained AT/AF detection – Sustained AT/AF detection begins after initial detection. During sustained detection, the device monitors the cardiac rhythm for changes or episode termination. Sustained detection continues until the AT/AF episode termination criteria are met.

When AT/AF Detection is programmed to On, the device can respond to detected episodes with tachyarrhythmia therapies. For more information about the conditions required to deliver atrial therapies, see Section 7.1, “Controlling atrial therapy sequencing”, page 118. If AT/AF Detection is programmed to Monitor, the device delivers no atrial therapy, but monitors the episode until the AT/AF episode ends.

If the device delivers an atrial therapy, the AT/AF evidence counter is reset to zero and redetection begins. The AT/AF episode is redetected if the median atrial interval is less than the AT/AF detection interval and the AT/AF evidence counter reaches 32.

If the device detects a ventricular tachyarrhythmia episode during an AT/AF episode, it suspends AT/AF detection until the ventricular episode terminates. When AT/AF detection resumes, the AT/AF evidence counter is reset to zero and must reach 32 before the atrial episode is redetected.

AT/AF episode termination – Once the device detects an atrial tachyarrhythmia, the episode is considered ongoing until episode termination. The device classifies an AT/AF episode as terminated when one of the following conditions occurs:

●

The device identifies sinus rhythm using the sinus rhythm criterion.

●

The rhythm remains unclassified for 3 min because the median atrial interval is greater than the AT/AF detection interval or the AT/AF evidence counter is less than 27.

If AT/AF episode termination is detected, the AT/AF evidence counter is reset to zero.

6.3.5.2 AT/AF detection criteria

The device applies several criteria during AT/AF detection to help identify the presence of an atrial tachyarrhythmia. These criteria include the median atrial interval, the AT/AF evidence counter, the far-field R-wave criterion, and the sinus rhythm criterion.

Median atrial interval – The device continually updates the median atrial interval. This interval is calculated by finding the median of the 12 most recent atrial intervals. The last 12 atrial intervals are sorted in numerical order, and the median atrial interval is the larger of the middle 2 values in the set. The median atrial interval must be less than the programmed AT/AF detection interval for AT/AF detection to occur.

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AT/AF evidence counter – The AT/AF evidence counter accumulates evidence of an atrial arrhythmia based on the number and location of atrial events during ventricular intervals. On each ventricular event, the device updates the counter as follows:

●

If A:V pattern information indicates the presence of an atrial arrhythmia (that is, greater than 1:1 conduction in the absence of far-field R-wave sensing), the device increments the counter by one.

●

If the counter was incremented on the previous ventricular interval because of A:V pattern information, the device increments the counter by one.

●

If the AT/AF episode terminates or the device delivers an atrial therapy, the counter resets to zero.

●

If none of the previous conditions is true, the device subtracts one from the counter.

Far-field R-wave criterion – If there are 2 atrial events in a ventricular interval, the device analyzes A:V pattern information to determine if one of the atrial events is actually a far-field R-wave. The device identifies a sensed far-field R-wave if it detects both of the following:

●

a short-long pattern of A-A intervals

●

a short AV interval (< 60 ms) or a short VA interval (< 160 ms)

Sinus rhythm criterion – The Sinus rhythm criterion identifies normal sinus rhythm (or a paced rhythm) if 5 consecutive beats exhibit the A:V pattern of sinus rhythm. If this criterion is satisfied after initial AT/AF detection, the device identifies episode termination, and the AT/AF evidence counter resets to zero.

Note: The device also applies the far-field R-wave criterion to identify normal sinus rhythm in the presence of far-field R-wave sensing.

6.4 Detecting VF episodes

The device detects VF episodes by examining the cardiac rhythm for short ventricular intervals. If a predetermined number of intervals occur that are short enough to be considered VF events, the device detects VF and delivers the first programmed VF therapy. After therapy delivery, the device continues to evaluate the ventricular rhythm to determine if the episode is ongoing.

6.4.1 Parameters

VF Detection – Turns VF Detection on or off. On ; OFF VF Initial Beats to Detect – Number of beats to detect: number

of VF events the device must count to detect a VF episode.

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VF Beats to Redetect – Number of beats to redetect: number of VF events the device must count to redetect a continuing VF after a therapy.

VF V. Interval (Rate) – V-V intervals shorter than this value are counted as VF events.

6/8; 9/12; 12/16 ; 18/24; 21/28; 24/32; 27/36; 30/40

240; 250 … 320 … 400 ms

6.4.2 Considerations

Review the following information before programming VF detection parameters.

VF Interval minimum setting – To ensure proper VF Detection, do not program the VF Interval less than 300 ms.

VF Interval maximum setting – Programming the VF Interval to a value greater than 350 ms may cause inappropriate detection of rapidly conducted atrial fibrillation as VF or FVT via VF. Intervals shorter than the VF Interval are counted using the VF event counter, which is more sensitive than the consecutive VT event counter.

VF, FVT, and VT Intervals – To allow for normal variations in the patient’s tachycardia interval, you should program the VF, FVT, and VT Intervals at least 40 ms apart.

Episode redetection – You can expedite redetection by programming the VF and VT Beats to Redetect lower than the VF and VT Initial Beats to Detect.

Enabling VF Detection – When VF Detection is enabled, the device initiates these functions:

●

Automatic Capacitor Formation

●

recording of Cardiac Compass data

●

recording of lead performance trends

●

clearance of all bradycardia pacing counters

VF detection and PR Logic criteria – You can program the device to distinguish between SVT and VF Detection by enabling the PR Logic detection criteria. Note that the SVT Limit must be programmed shorter than the VF Interval in order for the PR Logic criteria to affect VF detection. See Section 6.10, “Enhancing detection with PR Logic criteria”, page 95.

Double tachycardia detection – When any PR Logic detection criterion is enabled, the device also enables double tachycardia detection (VF, VT, or FVT in the presence of an SVT). See Section 6.14, “Detecting double tachycardias”, page 115.

6.4.3 Restrictions

Review the following information before programming VF detection parameters.

AT/AF detection – If AT/AF Detection is On, the VF Initial Beats to Detect must be programmed to a value less than or equal to the AT/AF evidence counter threshold, which

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is 32. The VF Initial Beats to Detect must be programmed to a value less than or equal to 24/32 when AT/AF Detection is On. See Section 6.3, “Detecting atrial tachyarrhythmias”, page 72.

Tachyarrhythmia detection and bradycardia pacing – To ensure reliable ventricular tachyarrhythmia detection, the programmer regulates the values available for bradycardia pacing and tachyarrhythmia detection.

Paced AV and temporary Lower Rate interval automatic adjustment – When VF or VT detection is enabled, the device automatically adjusts the temporary Lower Rate interval and PAV interval when needed. This adjustment maintains a ventricular event to atrial pace interval that is at least 30 ms greater than the ventricular detection interval.

Asynchronous pacing mode – All ventricular detection must be programmed Off and AT/AF Detection must be programmed to Monitor when the programmed pacing mode is DOO, VOO, or AOO.

VF detection backup – To ensure VF detection backup during VT and FVT episodes, VT and FVT detection cannot be enabled unless VF detection is also enabled.

6.4.4 How to program VF Detection

1. Select the Params icon.

2. Select Detection (V.)… from the Parameters screen.

3. Select the desired values for enabling or disabling VF Detection, VF Initial Beats to Detect, VF Beats to Redetect, and VF V. Interval (Rate).

4. Return to the Parameters screen and select [PROGRAM].

6.4.5 Details about VF detection

The device detects VF by counting the number of VF events, which are V-V intervals shorter than the programmed VF V. Interval (Rate). On each event, the device counts the number of recent VF events. The number of recent events examined is called the VF Detection window. The size of the VF Detection window is the second number in the programmed VF Initial Beats to Detect (for example, 24 events if the VF Initial Beats to Detect is 18/24).

The threshold for detecting VF is the first number in the programmed VF Initial Beats to Detect (for example, 18 events if the VF Initial Beats to Detect is 18/24). This threshold is always 75% of the VF Detection window. That is, if 75% of the events in the VF Detection window are VF events, the device detects a VF episode (see Figure 8).

After the device detects VF, it delivers the first programmed VF therapy. Following the therapy, if the number of VF events reaches the programmed VF Beats to Redetect, the device redetects VF and delivers the next programmed VF therapy.

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V SV SV

V S

V SV

V S

A R

1 2 3 4 5 6 6 7 8 9 10 11 12 13 141516 17 18

F SF SF SF SF SF SF SF SF SF

F SF SF

F S

F D

200 ms

VF event count

ECG

Marker Channel

VF interval

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Note: The device can also detect VF episodes using the combined count detection criterion (see Section 6.8, “Detecting tachyarrhythmia episodes with combined count”, page 90).

Figure 8. Device detects VF episode

1 VF starts, and the device begins counting VF events (intervals shorter than the programmed VF

Interval).

2 A ventricular interval occurs outside the VF Detection zone. The VF event count is not

incremented.

3 The VF event count reaches the programmed VF Initial Beats to Detect value of 18 events out

of 24, and the device detects VF.

6.5 Detecting VT episodes

The device detects VT episodes by examining the cardiac rhythm for short ventricular intervals. If enough intervals occur that are short enough to be considered VT events (but are not VF or FVT events), the device detects VT and delivers the first programmed VT therapy. After therapy delivery, the device continues to evaluate the ventricular rhythm to determine if the episode is ongoing.

You can program the device to detect and record VT episodes without treating them by using the VT Monitor zone. This zone is independent from other detection zones. It allows you to collect data without delivering therapy or affecting VF detection. See Section 6.7, “Monitoring VT episodes”, page 86, for details about the VT Monitor zone.

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6.5.1 Parameters

VT Detection – Turns VT Detection on or off. On; OFF VT Initial Beats to Detect – Number of beats to detect:

number of VT events the device must count to detect a VT episode.

VT Beats to Redetect – Number of beats to redetect: number of VT events the device must count to redetect a continuing VT after a therapy.

VT V. Interval (Rate) – V-V intervals shorter than this value are counted as VT events.

12; 16 … 52; 76; 100

4; 8; 12 … 52

280; 290 … 400 … 650 ms

6.5.2 Considerations

Review the following information before programming VT detection parameters.

VF, FVT, and VT Intervals – To allow for normal variations in the patient’s tachycardia interval, program the VF, FVT, and VT V. Intervals (Rate) at least 40 ms apart.

Episode redetection – You can expedite redetection by programming the VF and VT Beats to Redetect lower than the VF and VT Initial Beats to Detect.

VT detection, AF/Afl, and Sinus Tach in DR devices – When you program VT Detection to On in DR devices, the AF/Afl and Sinus Tach parameters are also automatically set to On. See Section 6.10, “Enhancing detection with PR Logic criteria”, page 95, for details about AF/Afl and Sinus Tach parameters.

VT detection and Wavelet in VR devices – When you program VT Detection to On in VR devices, the Wavelet parameters are also automatically programmed to Monitor. See Section 6.11, “Enhancing detection with Wavelet”, page 100 for details about Wavelet parameters.

VT detection and combined count detection – When VT Detection is On, the device applies the combined count detection criterion to help speed detection of rhythms that fluctuate between detection zones. Combined count detection is disabled if VT Detection is Off. See Section 6.8, “Detecting tachyarrhythmia episodes with combined count”, page 90.

VT detection and rapidly conducted SVTs – You can program the device to distinguish between SVT and VT detection by enabling the PR Logic (DR devices only), Wavelet (VR devices only), Onset, or Stability detection criteria. See Section 6.10, “Enhancing detection with PR Logic criteria”, page 95, Section 6.11, “Enhancing detection with Wavelet”, page 100; Section 6.12, “Enhancing VT detection with the Onset criterion”, page 109; and Section 6.13, “Enhancing VT detection with the Stability criterion”, page 113.

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Double tachycardia detection – When any PR Logic detection criterion is enabled, the device also enables double tachycardia detection (VF, VT, or FVT in the presence of an SVT; see page Section 6.14, “Detecting double tachycardias”, page 115).

DR/VR D154AWG/D154VWC

6.5.3 Restrictions

Review the following information before programming VT detection parameters.

AT/AF detection – If AT/AF Detection is On, the VT Initial Beats to Detect must be programmed to a value less than the AT/AF evidence counter threshold, which is 32. Therefore, VT Initial Beats to Detect must be programmed to 28 or less when AT/AF Detection is On. See Section 6.3, “Detecting atrial tachyarrhythmias”, page 72.

Paced AV and temporary Lower Rate interval automatic adjustment – If VF or VT detection is enabled, the device automatically adjusts the temporary Lower Rate interval and PAV interval when needed. This adjustment maintains a ventricular event to atrial pace interval that is at least 30 ms greater than the ventricular detection interval.

Asynchronous pacing mode – All ventricular detection must be programmed Off and AT/AF Detection must be programmed to Monitor when the programmed pacing mode is DOO, VOO, or AOO.

VF detection backup – To ensure VF detection backup during VT and FVT episodes, VT and FVT Detection cannot be enabled unless VF Detection is also enabled.

6.5.4 How to program VT Detection

1. Select the Params icon.

2. Select Detection (V.)… from the Parameters screen.

3. Select the desired values for enabling or disabling VT Detection, VT Initial Beats to Detect, VT Beats to Redetect, and VT V. Interval (Rate).

4. Return to the Parameters screen and select [PROGRAM].

6.5.5 Details about VT detection

The device detects VT by counting the number of consecutive VT events. A VT event is a V-V interval shorter than the programmed VT Interval but greater than or equal to the VF Interval. If the number of consecutive VT events reaches the programmed VT Initial Beats to Detect, the device detects VT (see Figure 9).

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A S

V SV

V S

A RA RA RA RA RA RA

1 0 1 2 3 4 5

T S

T ST ST ST ST

V S

A RA

A RA RA RA RA RA RA RA RA RA RA

76 8 9 10 11 12 13 14 15 16

200 ms

T ST

T ST ST ST ST ST ST ST

T D

VT event count

ECG

VT interval

VT event count

ECG

VT interval

Marker Channel

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The VT event count resets to zero whenever an interval occurs that is greater than or equal to the programmed VT Interval. The count remains at the current value if an interval is shorter than the programmed VF Interval.

After the device detects VT, it delivers the first programmed VT therapy. Following the therapy, if the VT event counter reaches the VT Beats to Redetect, the device redetects VT and delivers the next programmed therapy.

Note: The device can also detect VT episodes using the combined count detection criterion (see Section 6.8, “Detecting tachyarrhythmia episodes with combined count”, page 90).

Figure 9. Device detects VT episode

1 VT starts, and the device begins counting VT events (intervals less than the programmed

VT Interval but greater than or equal to the VF Interval). 2 A ventricular interval occurs outside the VT detection zone. The VT event count resets to zero. 3 The VT event count reaches the programmed VT Initial Beats to Detect of 16 events, and the

device detects VT.

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6.6 Detecting FVT episodes

The device detects episodes of Fast Ventricular Tachycardia (FVT) by examining the cardiac rhythm for short ventricular intervals. If enough intervals occur in the programmed FVT Detection zone, the device detects FVT and delivers the first programmed FVT therapy. After therapy delivery, the device continues to evaluate the ventricular rhythm to determine if the episode is ongoing. To make sure it delivers sufficiently aggressive therapies, the device can merge the programmed detection zones during redetection to increase sensitivity.

6.6.1 Parameters

FVT Detection – Enables FVT detection via the VF or the

VT detection algorithm. FVT V. Interval (Rate) – V-V intervals between this value

and the programmed VF V. Interval (Rate) are marked as FVT events.

OFF ; via VF; via VT

200; 210 … 240 … 600 ms

6.6.2 Considerations

Review the following information before programming FVT detection parameters.

VF, FVT, and VT Intervals – To allow for normal variations in the patient’s tachycardia interval, program the VF, FVT, and VT V. Intervals (Rate) at least 40 ms apart.

Episode redetection – You can expedite redetection by programming the VF and VT Beats to Redetect lower than the VF and VT Initial Beats to Detect.

FVT Detection enabled – Your choice for an appropriate setting for FVT Detection should depend on the patient’s VF and VT cycle lengths. After determining a reliably sensitive VF Interval, consider the following suggestions:

●

If the patient presents with a clinical VT Interval that is in the VF zone, select via VF to ensure reliable detection of VF. (VT Detection need not be enabled at all.)

●

If the patient presents with 2 clinical VT Intervals that are both outside the VF zone, select via VT to allow for correct classification of the faster VT and offer a separate therapy regimen for each VT.

●

If the patient presents with only 1 clinical VT interval that is outside the VF zone, enable VF and VT Detection only, and set FVT Detection to Off.

FVT Detection and PR Logic criteria – You can program the device to distinguish between SVT and FVT detection by enabling the PR Logic criteria. Note that the SVT Limit must be programmed shorter than the VF Interval for the PR Logic criteria to affect FVT via VF Detection.

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Double tachycardia detection – When any PR Logic criterion is enabled, the device also enables double tachycardia detection (VF, VT, or FVT in the presence of an SVT, see Section 6.14, “Detecting double tachycardias”, page 115).

6.6.3 Restrictions

Review the following information before programming FVT detection parameters.

VF detection backup – To ensure VF detection backup during VT and FVT episodes, VT and FVT detection cannot be enabled unless VF detection is also enabled.

Asynchronous pacing mode – All ventricular detection must be programmed Off and AT/AF Detection must be programmed to Monitor when the programmed pacing mode is DOO, VOO, or AOO.

FVT detection parameters – To ensure reliable ventricular tachyarrhythmia detection, the programmer regulates the values available for the FVT parameter as follows:

●

If FVT Detection is set to via VT, VT Detection must be set to On.

●

If FVT Detection is set to via VF, the FVT Interval must be programmed to a value shorter than the VF V. Interval (Rate).

●

If FVT Detection is set to via VT, the FVT V. Interval (Rate) must be programmed to a value greater than the VF V. Interval (Rate) and less than the VT V. Interval (Rate).

6.6.4 How to program FVT Detection

1. Select the Params icon.

2. Select Detection (V.)… from the Parameters screen.

3. Select the desired values for enabling or disabling FVT Detection and FVT V. Interval (Rate).

4. Return to the Parameters screen and select [PROGRAM].

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13 14 15 16 17 18

A RA RA

A RA RA RA RA RA

T F

T FT FT FT FT FV

1 1 2 3 4

A S

A RA RA

A R

V S

T ST

T FT FT FT

11 12

A RA RA

T FT FT

VF Event

Count

VF and FVT

Intervals

ECG

Marker Channel

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6.6.5 Details about FVT detection

You can program the device to detect FVT episodes using the VF or VT Detection zone and VF or VT Initial Beats to Detect.

When FVT Detection is set to via VF, a V-V interval within the FVT Detection zone is marked as an “FVT via VF” event. When the count is reached for the programmable VF Initial Beats to Detect, the device reviews the last 8 intervals:

●

If any one of the last 8 intervals is in the VF Detection zone, the device detects the episode as VF.

●

If all of the last 8 intervals are outside the VF Detection zone, the device detects the episode as FVT (see Figure 10).

When FVT Detection is set to via VT, a V-V interval within the FVT Detection zone is marked as an “FVT via VT” event. When the count is reached for the programmable VT Initial Beats to Detect, the device reviews the last 8 intervals:

●

If any one of the last 8 intervals is in the VF or FVT Detection zones, the device detects the episode as FVT.

●

If all of the last 8 intervals are outside the FVT and VF Detection zones, the device detects the episode as VT.

Note: The device can also detect FVT episodes using the combined count detection criterion (see Section 6.8, “Detecting tachyarrhythmia episodes with combined count”, page 90).

Figure 10. Device detects FVT via VF episodes

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1 A fast ventricular tachycardia starts, and the first event falls into the FVT Detection zone. 2 The second event of the FVT episode has an interval that falls into the VT Detection zone. The

VF event count is not incremented.

3 The device detects FVT after the VF event count reaches the VF Initial Beats to Detect.

Before detection

After VF detection

After FVT detection

FVT set to “via VF”

VF and FVT zones merge, leaving a larger VF zone.

All zones remain unchanged.

FVT set to “via VT”

VT and FVT zones merge, leaving a larger FVT zone.

Detection Intervals: VF Interval: 320 ms, FVT Interval: 280 ms / 360 ms, VT Interval: 400 ms

FVT

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6.6.5.1 Zone merging after detection

To ensure the device delivers sufficiently aggressive therapies during an extended or highly variable tachyarrhythmia episode, the device merges detection zones during redetection in some instances, as shown in Figure 11. The merged zone configuration uses the event counting and therapies for the faster arrhythmia and remains in effect until episode termination.

Figure 11. FVT zone merging

6.7 Monitoring VT episodes

The VT Monitor zone provides a programmable, diagnostic zone used for monitoring tachyarrhythmias. This zone detects and records VT as VT Monitor episodes and does not deliver VT therapy.

The VT Monitor zone can provide additional data about a patient’s condition by detecting arrhythmias that are not programmed for detection by the VF, FVT, and VT Detection zones.

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6.7.1 Parameters

VT Monitor – Enables the VT Monitor. Monitor ; Off VT Monitor Initial Beats to Detect – Number of

beats to detect: number of VT Monitor events that the device must count to detect and classify a VT Monitor event.

VT Monitor V. Interval (Rate) – V-V intervals shorter than this value are counted as VT Monitor events.

16; 20 … 56; 80; 110; 130

280; 290 … 450 … 650 ms

6.7.2 Considerations

Review the following information before programming VT Monitor.

VF Detection – VF Detection must be enabled to have VT Monitor enabled.

Combined count detection – Combined count detection does not include VT Monitor

events.

Sustained rhythm type classification – When a ventricular tachyarrhythmia occurs in the VT Monitor zone, monitoring classification stops until the ventricular arrhythmia termination criteria are met.

SVT discrimination features – The enabled SVT discrimination features are applied in the VT Monitor zone.

6.7.3 Restrictions

Review the following information before programming VT Monitor parameters.

AT/AF detection – If AT/AF Detection is On, the VT Monitor Initial Beats to Detect must be less than or equal to 32, which is the AT/AF evidence counter threshold. See Section 6.3, “Detecting atrial tachyarrhythmias”, page 72.

VF detection backup – To ensure VF detection backup during VT, FVT, and VT Monitor episodes, if VF Detection is disabled, VT Detection, FVT Detection, and VT Monitor must also be disabled.

VT Monitor Initial Beats to Detect – The VT Monitor Initial Beats to Detect must be greater than the VF and VT Initial Beats to Detect.

Pacing rate – The pacing (lower rate, upper tracking rate, and upper sensor rate) interval must be programmed 10 ms greater than the VT Monitor Interval (Rate).

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6.7.4 How to program VT Monitor

1. Select the Params icon.

2. Select Detection (V.)… from the Parameters screen.

3. Select the desired values for enabling or disabling Monitor Detection, Monitor Initial Beats to Detect, and Monitor V. Interval (Rate).

4. Return to the Parameters screen and select [PROGRAM].

6.7.5 Details about VT Monitor detection

The VT Monitor zone functions as an independent VT zone, operating with a lower rate cutoff than any of the enabled detection zones. The enabled SVT discrimination features are applied to the VT Monitor zone.

VT Monitor detection features a programmable number of intervals to detect sustained arrhythmias. When the VT Monitor event count reaches the programmed number of intervals, the rhythm is considered sustained. For DR devices, VT Monitor detection classifies sustained rhythms as either ventricular tachycardia (VTM) or double tachycardia (VTM+SVT). For VR devices, VT Monitor Detection classifies sustained rhythms as ventricular tachycardia (VTM).

Note: A double tachycardia (VTM+SVT) is a detected arrhythmia that comprises a ventricular tachyarrhythmia (VT) with a simultaneous SVT. Double tachycardia detection ensures that the PR Logic criteria do not compromise ventricular arrhythmia monitoring.

Once a ventricular tachycardia or double tachycardia is classified, further classification stops until that sustained rhythm ends or terminates (see Figure 12). Until a sustained rhythm is detected, a rhythm is classified as a rejected SVT rhythm, and VT Monitor continues to look for ventricular tachycardia and double tachycardia. The rejection is based on enabled features.

The device compares ventricular intervals to the VT Monitor Interval to identify when a VT Monitor episode has terminated. Any one of the following criteria terminates an episode:

●

8 consecutive intervals greater than or equal to the VT Monitor Interval.

●

20 s elapse without the median ventricular interval shorter than the programmed VT Monitor Interval.

●

Detection of a VT, FVT, or VF rhythm. Detection of a VT, FVT, or VF rhythm (or a SVT rhythm in the VT, FVT, or VF Detection zones) terminates VT Monitor operation until the rhythm terminates.

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1 2 3 4

A S

A R

A RA RA

V S

V SV SV SV SV

13 18 19 20 0 0 0

A R

A RA RA RA RA

T SV SV SV TV SV SV

1 2

Monitor Interval

Monitor Event

Count

Marker Channel

ECG

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Figure 12. Device detects and monitors VT

1 A VT starts in the VT Monitor zone, and the device begins counting VT events. 2 The VT Monitor event count reaches the programmed VT Monitor Initial Beats to Detect of 20

events, and the device detects a VT Monitor episode.

3 After detecting the VT Monitor episode, the device monitors the episode until termination or

detection of VT, FVT, or VF rhythms.

6.7.5.1 Effects of enabling VT Monitor

Enabling VT Monitor causes the following detection operations to work differently:

VF, VT, and FVT detection – The VT Monitor zone is an independent zone, and it has no effect on the VF, VT, or FVT zones.

PR Logic, Stability, and Onset criteria – Before the device detects a VTM or a VTM+SVT episode, the PR Logic and Stability criteria, if enabled, are applied. If a VT Monitor episode accelerates into the VF, VT, or FVT detection zone, the device continues to apply PR Logic criteria as initial VF, VT, or FVT detection begins. Onset and Stability are independently tracked between the VT Monitor and VT Detection zones.

Wavelet criterion – If Wavelet is programmed to Monitor, and VT Monitor is enabled, SVTs are detected as VT Monitor events.

Detection of a VT, FVT, or VF rhythm (or SVT rhythm in the VT, FVT, or VF Detection zones) terminates monitoring operation until the rhythm terminates.

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If Wavelet is programmed to On and VT Monitor is enabled, SVTs in the VT Monitor zone are detected as SVT-Wavelet stored episodes only. There will be no real-time decision channel annotations or any status line information.

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6.8 Detecting tachyarrhythmia episodes with combined count

Because the device counts VF and VT events separately, rhythms with variable cycle lengths can cause both event counts to increment during an episode. To prevent these rhythms from delaying detection, the device automatically enables the combined count detection criterion if both VF Detection and VT Detection are programmed On.

The combined count criterion compares the sum of the VF and VT event counts to the combined beats to detect criterion, which the device calculates automatically from the programmed VF beats to detect values. If the combined count criterion is met, the device reviews the recent intervals to determine if the episode should be treated as a VF, FVT, or VT episode. The combined count criterion applies during both initial detection and redetection.

6.8.1 Details about combined count detection

The combined count detection algorithm expedites detection or redetection of ventricular tachyarrhythmias with ventricular intervals that fluctuate between the VF and VT detection zones. When VT detection is enabled, the device applies combined count detection, which tracks the combined number of VT and VF events counted. If this sum reaches the combined beats to detect criterion, the device detects VF, FVT, or VT. Combined count detection also applies to redetected episodes.

Note: Events in the VT Monitor zone are not included in the combined count detection.

If the VF event counter reaches 6, the device automatically applies the combined beats to detect criterion. The combined beats to detect criterion is calculated by multiplying the current VF beats to detect (initial or redetect) by 7/6 and rounding down. The combined beats to detect values that correspond to each VF beats to detect value appear in Table 23.

Table 23. Combined beats to detect values for each initial or redetect VF beats to detect value

VF beats to detect Combined beats to detect

6/8 7 9/12 10 12/16 14

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A S

A RA RA RA RA RA RA RA RA RA RA RA

A RA RA RA RA RA RA RA

A R

V SV SF

F S

F SF SF SF SF SF ST SF SF SF SF SF SF SF SF

F S

T ST

F DV

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

1 2 3 4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

VF Event Count

VT Event Count

Combined Count

VF and VT Interval

ECG

Marker Channel

1 2 3

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Table 23. Combined beats to detect values for each initial or redetect VF beats to detect value (continued)

VF beats to detect Combined beats to detect

18/24 21 21/28 24 24/32 28 27/36 31 30/40 35

Note: VT detection cannot be enabled when the VF beat to detect is greater than 30/40.

Combined count detection is fulfilled when the sum of the VF and VT event counts equals or exceeds the combined beats to detect. The device then reviews the last 8 intervals and classifies the episode as one of the following types:

●

VF, if any of the last 8 intervals were in the VF zone (see Figure 13)

●

FVT, if FVT detection is enabled and none of the last 8 intervals were in the VF zone, but one or more were in the FVT zone

●

VT, if all 8 intervals were outside the VF zone and FVT zone

Figure 13. Device detects VF with the combined count criterion

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1 A slow VF episode starts with a ventricular cycle length that varies between the VF and VT

detection zones.

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2 When a VT event occurs, the device increments the VT event count and the combined count. 3 The device detects VF even though the VF event count has not yet reached the VF Initial Beats

to Detect (18/24 in this example). The combined count reaches the combined beats to detect value of 21 first, and there is a VF event in the last 8 intervals.

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6.9 Determining episode termination or redetection

Once the device detects an arrhythmia, it considers the episode ongoing until it detects that the episode has ended. After delivering therapy, it monitors the ventricular rhythm using the programmed Redetect beats criteria. If one of these Redetect criteria is met, the device delivers the next programmed therapy for the detected arrhythmia.

See Section 6.9.4, “Details about episode termination and redetection”, page 92.

6.9.1 Parameters

VF Beats to Redetect – Number of beats to rede-

tect: number of VF events the device must count to redetect a continuing VF after a therapy.

VT Beats to Redetect – Number of beats to redetect: number of VT events the device must count to redetect a continuing VT after a therapy.

6/8; 9/12; 12/16 ; 18/24; 21/28; 24/32; 27/36; 30/40

4; 8; 12 … 52

6.9.2 Considerations

Review the following information before programming redetection parameters.

Initial and redetect beats – You can expedite redetection by programming the VF and VT Beats to Redetect lower than the VF and VT Initial Beats to Detect.

6.9.3 How to program redetection parameters

1. Select the Params icon.

2. Select Detection (V.)… from the Parameters screen.

3. Select the desired values for VF Beats to Redetect and VT Beats to Redetect.

4. Return to the Parameters screen and select [PROGRAM].

6.9.4 Details about episode termination and redetection

After a therapy is delivered, the device evaluates the ventricular rhythm to determine if the episode has terminated, is continuing, or has changed to a different arrhythmia.

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6.9.4.1 Episode termination

The device determines that the episode has terminated if one of the following conditions occurs:

●

Eight consecutive ventricular intervals are longer than or equal to the programmed VT V. Interval (Rate).

●

20 s elapse without the median ventricular interval shorter than the programmed VT V. Interval (Rate).

Note: Detection of a VT, FVT, or VF rhythm terminates VT Monitor episodes and suspends the VT monitoring operation until the rhythm terminates. Detection of a SVT rhythm in the VT, FVT, or VF zones also suspends the VT monitoring operation until the rhythm terminates.

After antitachycardia pacing therapy, the device begins evaluating intervals for episode termination on the first ventricular cycle. After cardioversion or defibrillation, the device begins evaluating intervals for episode termination on the second ventricular event. (Due to the extended post shock blanking, this event may be the third event on the electrogram.)

Note: Any subsequent detection after the end of the episode marks the start of a new episode.

6.9.4.2 Episode redetection

After the device detects a tachyarrhythmia episode and delivers a therapy, the device redetects an arrhythmia if the VF or VT event count reaches the Beats to Redetect or if the combined VF and VT event count reaches the combined redetect beats (see Section 6.8, “Detecting tachyarrhythmia episodes with combined count”, page 90).

The device then delivers the next programmed therapy for the current arrhythmia and resumes monitoring for the outcome of that therapy. Figure 14 shows an example of redetection.

VF V. Interval (Rate) if VT Detection is set to Off, and the episode is a VF or an FVT via VF episode.

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A RA SA SA SA SA SA RA RA RA RA RA RA RA RA RA RA RA RA

T P

T PT

T PT DT PT PT PT PT PT ST ST ST ST ST ST ST ST ST ST ST

200 ms

016 0 1 2 3 4 5 6 7 8 9 10 11 12

VT event count

ECG

Marker Channel

VT interval

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Figure 14. VT episode redetected after therapy

1 A VT episode is detected, and the device delivers a Burst ATP therapy. 2 After therapy, the device continues to detect events in the VT zone. 3 When the VT event count reaches the VT Beats to Redetect, the device redetects the VT.

Notes:

●

The device suspends VT detection, including FVT via VT detection and combined count detection, for 17 ventricular events following a defibrillation therapy delivered in response to a detected VF.8 Suspending VT detection helps avoid detecting transient VTs that can follow high voltage therapies.

●

The PR Logic, Wavelet, and Onset criteria are not applied during redetection. However, the Stability criterion may withhold detection or redetection of VT or FVT via VT throughout an episode.

6.9.4.3 VT acceleration

If the device redetects VT, it classifies the rhythm as accelerated if the average of the 4 intervals before redetection is at least 60 ms less than either the average of the 4 intervals before initial VT detection or the last accelerated VT detection. The most recent interval average is used to identify VT acceleration if VT is redetected again during the episode. The device also identifies VT acceleration if the initial VT episode is redetected as FVT or VF.

If the device redetects VF or an accelerated VT after an antitachycardia pacing sequence delivery, it skips the subsequent pacing therapy sequences for the duration of the episode and delivers the next therapy programmed for the current arrhythmia.

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If the defibrillation therapy is delivered as a result of a High Rate Timeout Therapy operation, VT detection is not suspended (see Section 6.15.4.1, “High Rate Timeout Therapy”, page 116).

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6.10 Enhancing detection with PR Logic criteria

The PR Logic detection criteria are designed to withhold inappropriate ventricular detection during episodes of rapidly conducted supraventricular tachycardia (SVT). The device analyzes the activation patterns and timing in both chambers using PR Logic pattern and rate analysis. This information helps identify evidence of atrial fibrillation, atrial flutter, sinus tachycardia, and other 1:1 SVTs. If this analysis indicates the presence of one or more of these rhythms, the device withholds detection.

PR Logic criteria are available only in DR devices.

6.10.1 Parameters

AF/Afl – Identifies rapidly conducted atrial fibrillation, atrial flutter,

or atrial tachycardia.

Sinus Tach – Identifies sinus tachycardia. On ; Off Other 1:1 SVTs – Identifies other one-to-one SVTs where the atrial

and ventricular activation are roughly simultaneous. SVT V. Limit – Defines the minimum ventricular interval at which

the device applies the PR Logic criteria.

On ; Off

On; Off

240; 250 … 320 … 650 ms

6.10.2 Considerations

Review the following information before programming PR Logic parameters.

Cautions:

●

Before enabling the Other 1:1 SVTs criterion, ensure that the atrial lead has matured. This criterion may inappropriately withhold therapy if atrial sensing is compromised by an unstable or dislodged atrial lead.

●

Use caution when programming the Other 1:1 SVTs criterion in patients who exhibit slow 1:1 retrograde conduction during VF or VT. This criterion could inappropriately withhold VT/VF therapy in such patients. See Section 6.10.5.1, “AV and VA interval patterns”, page 97.

Note: The device is able to discriminate sinus tachycardia with long PR intervals from VT/VF with no additional programming (see Section 6.10.5.2, “Expected range of V-V and AV intervals”, page 97)

PR Logic criteria and double tachycardia detection – If any of the PR Logic criteria are enabled, the device also enables double tachycardia detection (see Section 6.14, “Detecting double tachycardias”, page 115).

SVT Limit – To ensure that therapy is delivered for hemodynamically compromising rates of any origin, the device always delivers therapy when the median ventricular interval is

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shorter than the programmed SVT V. Limit (nominally 320 ms) if VT, VF, or FVT detection criteria are satisfied.

VF Interval and SVT Limit – If you program an SVT V. Limit longer than the VF V. Interval (Rate), you are effectively disabling the PR Logic criteria for VF detection.

PR Logic criteria and detecting VT – If VT Monitor or VT Detection is enabled, the device also enables the PR Logic criteria AF/Afl and Sinus Tach.

6.10.3 Restrictions

Review the following information before programming PR Logic parameters.

Detection intervals and SVT V. Limit – The SVT V. Limit must be less than the VT V. Interval (Rate). If VT Detection is disabled, the SVT V. Limit must be less than or equal to the VF V. Interval (Rate).

6.10.4 How to program the PR Logic criteria

1. Select the Params icon.

2. Select Detection (V.)… from the Parameters screen.

3. Select the desired values for AF/Afl, Sinus Tach, Other 1:1 SVTs, and SVT V. Limit.

4. Return to the Parameters screen and select [PROGRAM].

6.10.5 Details about PR Logic pattern and rate analysis

PR Logic pattern and rate analysis is based on the following aspects of atrial and ventricular activation:

●

AV and VA interval patterns

●

expected range of V-V and AV intervals

●

AF evidence

●

far-field R-wave sensing

●

A:V dissociation

●

V-V regularity

The information collected by PR Logic pattern and rate analysis is used by the PR Logic criteria to identify the presence of SVTs and withhold detection.

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6.10.5.1 AV and VA interval patterns

The device uses pattern analysis to identify sinus tachycardia, atrial flutter, and other 1:1 SVTs. Within each V-V interval, the device categorizes the atrial rhythm according to the number of intervening atrial events and the zones in which those atrial events occur. From this information, the device assigns pattern codes to the intervals and interprets the pattern codes to identify SVTs.

6.10.5.2 Expected range of V-V and AV intervals

The device continuously analyzes the V-V and AV intervals and calculates an expected range of values for each type of interval. The expected range is constructed from the mean of recent interval values and the absolute differences of recent values from the mean intervals.

Intervals that fall within the expected range are included in subsequent expected range calculations. In this way, the expected range adapts to the patient’s current heart rate and variability. If an interval is outside the expected range, it is not included in the expected range calculation.

AV intervals that fall within the expected AV interval range are interpreted as normal conduction in pattern analysis. The expected V-V interval range helps the device recognize gradual rate increases associated with sinus tachycardia.

6.10.5.3 AF evidence

AF evidence is provided by a counter that accrues evidence to help identify atrial fibrillation or detect a double tachycardia (VF, VT, or FVT in the presence of an SVT; see Section 6.14, “Detecting double tachycardias”, page 115).

For each ventricular event, the device increments a running AF evidence count if it identifies all of the following conditions:

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AV pattern information for a high atrial rate

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timing consistent with an atrial tachyarrhythmia (see Section 6.10.5.1, “AV and VA interval patterns”, page 97)

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greater than 1:1 conduction

If the AV pattern is inconclusive, inconsistent, or if the device detects far-field R-wave sensing, the AF evidence count is unchanged. If no atrial event occurs within the current V-V interval or a consistent 1:1 pattern is present, the device subtracts one from the count.

The AF evidence criterion is satisfied when the AF evidence count is greater than or equal to 6. Once the criterion is met, it remains satisfied for as long as the AF evidence count is greater than or equal to 5.

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6.10.5.4 Far-field R-wave sensing

The device identifies far-field R-wave oversensing in the atrium to exclude far-field R-waves from SVT classification.

If there are 2 atrial events within a ventricular interval, 1 atrial event may actually be a far-field R-wave (see Figure 15). The device identifies a sensed far-field R-wave if it detects both of the following conditions:

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a short-long pattern of A-A intervals

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a short AV interval (< 60 ms) or a short VA interval (< 160 ms)

The device uses far-field R-wave sensing for the Sinus Tach and AF/Afl criteria.

Figure 15. Intervals measured for far-field R-wave detection

1 Far-field R-wave

6.10.5.5 A:V dissociation

A:V dissociation provides cumulative evidence that there is no direct relationship between sensed atrial and ventricular events. The device identifies a rhythm as A:V dissociated if at least 4 of the most recent 8 ventricular intervals exhibit either of these characteristics:

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no atrial events in the ventricular interval

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an AV interval that differs from the average of the previous 8 AV intervals by more than 40 ms

The device uses this count to help identify a double tachycardia.

6.10.5.6 V-V regularity

The device uses the regularity and irregularity of the ventricular cycle length to evaluate atrial fibrillation, double tachycardia, and other 1:1 SVTs.

The device continuously measures the regularity of the ventricular intervals. The regularity count indicates how often the 2 most frequently occurring intervals (of at least 200 ms) occurred among the last 18 ventricular intervals.

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For example, Figure 16 illustrates the 18 most recent intervals. The 2 most frequently occurring intervals are 330 ms (5 intervals) and 320 ms (3 intervals). Together these account for 8 of the 18 most recent intervals, for a regularity count of 44%.

Figure 16. Regularity of ventricular cycle length

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For a double tachycardia to be detected, the regularity count must be greater than or equal to 75%.

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To withhold detection under the atrial fibrillation rule of the AF/Afl criterion, the regularity count must be less than or equal to 50%. Atrial fibrillation that exhibits greater regularity (between 50% and 75%) may be identified by the atrial flutter rule, which does not require the regularity count.

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To withhold detection for Other 1:1 SVTs, the regularity count must be greater than or equal to 25%.

6.10.6 Details about the PR Logic criteria

The PR Logic criteria discriminate between SVT and VT if all of the following conditions are true:

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No detected VF, FVT, or VT episode is in progress.

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An Initial Beats to Detect is met (VT Monitor, VT, VF, or combined).

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One or more of the PR Logic criteria are met.

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The median ventricular interval equals or exceeds the SVT V. Limit.

6.10.6.1 AF/Afl criterion

The AF/Afl (atrial fibrillation and/or atrial flutter) criterion consists of 2 independent rules: the atrial fibrillation rule and the atrial flutter rule. If either rule is satisfied, the AF/Afl criterion is met, and the device withholds ventricular detection and therapy.

The atrial fibrillation rule requires that all the following conditions occur:

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The AF evidence counter indicates atrial fibrillation.

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Fewer than 10 of most recent 12 ventricular intervals include a far-field R-wave.

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The median atrial interval is less than or equal to 94% of the median ventricular interval.

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The ventricular cycle length is not regular (regularity of 50% or less).

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The atrial flutter rule is satisfied if AV pattern information indicates atrial flutter without far-field R-wave sensing.

6.10.6.2 Sinus Tach criterion

Note: Sudden onset atrial tachycardia with 1:1 conduction may not be discriminated from

VT/VF by the Sinus Tach criterion.

The Sinus Tach criterion is met if the AV and V-V intervals are within the expected range for the patient, and if AV pattern analysis identifies one of the following conditions:

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1:1 sinus tachycardia

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1:1 sinus tachycardia with far-field R-wave sensing (if at least 4 of the most recent 12 ventricular intervals contain a far-field R-wave)

6.10.6.3 Other 1:1 SVTs criterion

The Other 1:1 SVTs criterion is satisfied when AV pattern information indicates a 1:1 SVT in which the atria and ventricles are activated at approximately the same time, as in a junctional tachycardia (consistent atrial sensing in a junctional zone). The activation of these chambers is considered junctional if the activations produce AV intervals less than 80 ms or VA intervals less than 50 ms. Atrial events in a junctional zone indicate PAC, PVC, junctional rhythms, atrial fibrillation, or atrial flutter.

6.11 Enhancing detection with Wavelet

The Wavelet Dynamic Discrimination criterion is designed to withhold detection of rapidly conducted SVT episodes. It is based on the premise that rhythms of ventricular origin (such as VF and VT) generally have different QRS morphologies than rhythms of supraventricular origin.

When Wavelet is enabled, the QRS complexes that occur during fast ventricular rhythms are compared to a stored template. When Wavelet is programmed to On, the device withholds detection if enough QRS complexes that occur during the fast rate match the stored template.

You can use the Auto Collection option to collect and maintain the template automatically. You can also collect and assess the template manually using the Wavelet test (see Section 11.4, “Testing the Wavelet criterion”, page 354).

You can use the Monitor setting for Wavelet to evaluate its potential effectiveness for the patient. When Wavelet is set to Monitor, the device records Wavelet-related data but does not use the criterion to withhold detection.

Wavelet is available only in VR devices.

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Specifications and Main Features

Frequently Asked Questions

User Manual

Contents

Introduction

About this manual

Programmer hardware and screen images

Manual conventions

Nomenclature for product battery life terms

Additional literature

Technical support

Customer education

References

Notice

1 Quick reference

1.1 Physical characteristics, DR devices

Table 1. Model D154AWG physical characteristics

Figure 1. Model D154AWG connector and suture holes

1.2 Physical characteristics, VR devices

Table 2. Model D154VWC physical characteristics

Figure 2. Model D154VWC connector and suture holes

1.3 Replacement indicators

Table 3. Replacement indicators

1.4 Projected service life

1.4.1 DR projected service life projections

Table 4. Projected service life

1.4.2 VR projected service life projections

Table 5. Projected service life

1.5 Magnet application

Table 6. Effects of magnet application on the device

1.6 Typical charge times

Table 7. Average full energy charge times at BOS and RRT (2.62 V)

1.7 High-voltage therapy energy

Table 8. Programmed (delivered) and stored energy levels

1.8 Stored data and diagnostics

Table 9. Arrhythmia episode data storage

Table 10. VT/VF episode counters

Table 11. VT/VF therapy counters

Table 12. AT/AF episode counters

Table 13. AT/AF therapy counters

Table 14. Battery and lead measurement data

Table 15. Lead performance trend data

Table 16. Cardiac Compass trend data

Table 17. Rate Histograms report

Table 18. Medtronic CareAlert event data

2 The Virtuoso system

2.1 System overview

2.1.1 Implanted device

2.1.2 Leads

2.1.3 Programmer and software

2.1.4 Network connectivity and data exchange

2.1.5 Conexus wireless telemetry

2.1.6 Conexus Activator

2.1.7 Monitor

2.1.8 Patient assistant

2.1.9 Detecting ventricular tachyarrhythmias

2.1.10 Treating ventricular tachyarrhythmias

2.1.11 Detecting atrial tachyarrhythmias

2.1.12 Treating atrial tachyarrhythmias

2.1.13 Treating bradycardia

2.1.14 Monitoring for real-time and stored data

2.1.15 Conducting electrophysiologic tests

2.1.16 Alerting the patient to system events

2.2 Indications and usage, DR devices

2.3 Indications and usage, VR devices

2.4 Contraindications, DR devices

2.5 Contraindications, VR devices

2.6 Patient screening

3 Emergency therapy

3.1 Overview of emergency therapies

3.2 Delivering an emergency defibrillation therapy

3.2.1 Parameters

3.2.2 How to deliver emergency defibrillation

3.3 Delivering an emergency cardioversion therapy

3.3.1 Parameters

3.3.2 How to deliver emergency cardioversion

3.4 Delivering emergency fixed burst pacing

3.4.1 Parameters

3.4.2 How to deliver emergency fixed burst pacing