Medtronic 7288 Reference Guide

INTRINSIC™/INTRINSIC

™

30

7288/7287

Dual Chamber Implantable Cardioverter Defibrillator
(VVE-DDDR)

Reference Manual

Caution: Federal Law (USA) restricts this device to sale
by or on the order of a physician (or properly licensed
practitioner).

INTRINSIC™/INTRINSIC

™

30

7288/7287

Reference Manual

A guide to the operation and programming of the Intrinsic Model
7288 and Intrinsic 30 Model 7287 Dual Chamber Implantable
Cardioverter Defibrillators

The following are trademarks of Medtronic:

Active Can, Cardiac Compass, Checklist, Flashback, Intrinsic, Leadless ECG,
MVP, Marker Channel, Medtronic, Medtronic CareLink, PR Logic, Patient Alert,
Quick Look, QuickLink

Table of Contents

Introduction 11

Part I Quick overview 15

1 Quick reference 17

1.1 New to Intrinsic 18

1.2 Physical characteristics 18

1.3 Magnet application 20

1.4 Longevity projections 21

1.5 Replacement indicators 23

1.6 Typical charge times 23

1.7 High voltage therapy energy 24

1.8 Stored data and diagnostics 26

2 The Intrinsic system 29

2.1 System overview 30

2.2 Indications and usage 33

2.3 Contraindications 33

2.4 Patient screening 33

3 Emergency therapy 35

3.1 Delivering emergency therapies 36

3.2 Delivering an emergency defibrillation therapy 37

3.3 Delivering an emergency cardioversion therapy 38

3.4 Delivering emergency fixed burst pacing 39

3.5 Enabling emergency VVI pacing 40

Part II Device implant and patient follow-up

procedures 43

4 Implanting the device 45

4.1 Overview 46

4.2 Preparing for an implant 46

4.3 Replacing a device 48

4.4 Positioning the leads 49

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

6

Table of Contents

Part III Configuring the device for the patient 67

4.5 Testing sensing and pacing thresholds 51

4.6 Connecting the leads to the device 52

4.7 Testing defibrillation operation and effectiveness 54

4.8 Positioning and securing the device 58

4.9 Completing the implant procedure 58

5 Conducting a patient follow-up session 61

5.1 Patient follow-up guidelines 62

5.2 Verifying the status of the implanted system 62

5.3 Verifying accurate detection and appropriate
therapy 63

5.4 Verifying effective bradycardia pacing 64

6 Detecting tachyarrhythmias 69

6.1 Detection overview 70

6.2 Setting up sensing 73

6.3 Detecting VF episodes 78

6.4 Detecting VT episodes 81

6.5 Detecting FVT episodes 87

6.6 Detecting tachyarrhythmia episodes with Combined
Count 92

6.7 Monitoring episodes for termination or
redetection 94

6.8 Enhancing detection with PR Logic criteria 98

6.9 Enhancing VT detection with the Stability
criterion 106

6.10 Detecting double tachycardias 108

6.11 Detecting prolonged tachyarrhythmias with High Rate
Timeout 109

7 Treating tachyarrhythmia episodes 113

7.1 Treating VF with defibrillation 114

7.2 Treating VT and FVT with antitachycardia
pacing 123

7.3 Treating VT and FVT with cardioversion 133

7.4 Optimizing therapy with Smart Mode and Progressive
Episode Therapies 141

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Table of Contents

8 Treating bradycardia 147

8.1 Providing basic pacing therapy 148

8.2 Dual chamber pacing 152

8.3 Single chamber pacing 162

8.4 MVP (Managed Ventricular Pacing) 165

8.5 Enhancing pacing for optimal cardiac output 170

8.6 Adjusting the pacing rate with Mode Switch 184

8.7 Preventing competitive atrial pacing 186

8.8 Detecting and preventing pacemaker-mediated
tachycardia 192

8.9 Providing Ventricular Safety Pacing 196

8.10 Providing pacing after high voltage therapies 200

9 Optimizing charge time and device longevity 203

9.1 Optimizing charge time 204

9.2 Optimizing device longevity 207

Part IV Evaluating and managing patient treatment 209

7

10 Using the programmer 211

10.1 Setting up and using the programmer 212

10.2 Display screen features 213

10.3 Viewing and programming device parameters 218

10.4 Starting and ending patient sessions 222

10.5 Viewing live waveform traces 225

10.6 Recording live waveform strips 232

10.7 Saving and retrieving device data 234

10.8 Printing reports 238

11 Using system evaluation tools 245

11.1 A summary of system evaluation tools 246

11.2 Taking a quick look at device activity 247

11.3 Using the Patient Alert feature 249

11.4 Streamlining follow-ups with Checklist 256

12 Setting up and viewing collected data 261

12.1 A summary of data collection 262

12.2 Setting up data collection 263

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

8

Table of Contents

12.3 Collecting lead performance data 267

12.4 Viewing the episode and therapy efficacy
counters 269

12.5 Viewing episode data 272

12.6 Viewing Flashback Memory 280

12.7 Viewing battery and lead status data 281

12.8 Viewing lead performance trends 283

12.9 Using Cardiac Compass to view long ter m clinical
trends 285

12.10 Viewing and entering patient information 292

12.11 Automatic device status monitoring 295

13 Testing the system 297

13.1 Testing overview 298

13.2 Evaluating the underlying rhythm 298

13.3 Measuring pacing thresholds 299

13.4 Measuring lead impedance 302

13.5 Measuring EGM amplitude 303

13.6 Testing the device capacitors 305

14 Conducting Electrophysiologic Studies 307

14.1 EP Study overview 308

14.2 Inducing VF with T-Shock 309

14.3 Inducing VF with 50 Hz Burst 313

14.4 Inducing an arrhythmia with Manual Burst 315

14.5 Inducing an arrhythmia with PES 318

14.6 Delivering a manual therapy 320

15 Solving system problems 325

15.1 Overview 326

15.2 Solving sensing problems 326

15.3 Solving tachyarrhythmia detection problems 328

15.4 Solving tachyarrhythmia therapy problems 329

15.5 Solving bradycardia pacing problems 330

15.6 Responding to device status indicators 331

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Appendices 333

A Warnings and precautions 335

A.1 General warnings 336

A.2 Storage and handling 336

A.3 Resterilization 337

A.4 Device operation 338

A.5 Lead evaluation and lead connection 339

A.6 Follow-up testing 340

A.7 Explant and disposal 340

A.8 Medical therapy hazards 341

A.9 Home and occupational environments 343

B Device parameters 345

B.1 Emergency settings 346

B.2 Detection parameters 347

B.3 Therapy parameters 348

B.4 Pacing parameters 350

B.5 System maintenance parameters 353

B.6 Data collection parameters 354

B.7 System test and EP study parameters 355

B.8 Fixed parameters 357

B.9 Patient information parameters 359

B.10 Programmer symbols 360

B.11 Parameter interlocks 361

Table of Contents

9

Glossary 363

Index 371

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Introduction

About this manual

Introduction

This manual describes the operation and intended use of the
Intrinsic Model 7288 and Intrinsic 30 Model 7287 systems.

In these systems, both devices provide 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 both devices.

The full delivered energy is different for Intrinsic Model 7288
devices and Intrinsic 30 Model 7287 devices. Intrinsic devices can
be programmed to deliver a full energy of up to 35 J. Intrinsic 30
devices can be programmed to deliver up to 30 J. Throughout
the manual, the term "full-energy" refers to either 35 J or 30 J,
depending on the device model.

Programmer hardware and screen images

11

The screen image examples in this document show the Medtronic
CareLink Model 2090 programmer screen. Wherever possible,
these screen images show the application for an Intrinsic Model
7288 device.

The information provided in this manual about using the
programmer assumes the Medtronic CareLink Model 2090
Programmer is used. For information about using the Model
9790C Programmer, see the

Manual

Manual conventions

Throughout this document, the word “device” refers in general to
both Intrinsic and Intrinsic 30 devices.

The
nominal value for that parameter.

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

.

symbol in parameter tables indicates the Medtronic

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

9790/9790C Programmer Instruction

12

Introduction

Additional literature

Technical support

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.

Medtronic employs highly trained representatives and engineers
located throughout the world to ser ve 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 medical
consultation, Medtronic can often refer product users to outside
medical consultants with appropr iate expertise.

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

References

The primary reference for background information is Zacouto FI,
Guize LJ. Fundamentals of Orthorhythmic Pacing. In: Luderitz B,

Cardiac Pacing Diagnostic and Therapeutic Tools.

ed.
Springer-Verlag; 1976: 212-218.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

New York:

Notice

Introduction

See these additional references for more background information:

Estes M, Manolis AS, Wang P, Eds.

•

Cardioverter-Defibrillators

Inc. 1994.

Kroll MW, Lehmann MH, Eds.

•

Cardioverter-Defibrillator Therapy: The Engineering-Clinical
Interface

Singer I, Ed.

•

NY: Futura Publishing Co. 1994.

Singer I, Barold SS, Camm AJ, Eds.

•

Therapy of Arrhythmias for the 21st Century: The State of
the Art

This software 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 data input into the
software. Medtronic SHALL NOT BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES TO
ANY THIRD PARTY WHICH RESULTS FROM THE USE OF THE
INFORMATION PROVIDED IN THE SOFTWARE.

. Norwell, MA: Kluwer Academic Publishers 1996.

Implantable Cardioverter-Defibrillator

. Armonk, NY: Futura Publishing Co. 1998.

. New York, NY: Marcel Dekker,

Implantable

Implantable

. Armonk,

Nonpharmacological

13

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Quick overview

Part I

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

1Quick reference

1.1 New to Intrinsic 18

1.2 Physical characteristics 18

1.3 Magnet application 20

1.4 Longevity projections 21

1.5 Replacement indicators 23

1.6 Typical charge times 23

1.7 High voltage therapy energy 24

1.8 Stored data and diagnostics 26

1

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

18

Chapter 1

New to Intrinsic

1.1 New to Intrinsic

MVP (Managed Ventricular Pacing) – The MVP modes promote

intrinsic conduction by reducing unnecessary right ventricular
pacing. The MVP modes are indicated by AAIR<=>DDDR and
AAI<=>DDD on the mode selection screen. These modes
provide atrial-based pacing with ventricular backup. For loss of
AV conduction, the device switches to DDDR or DDD mode.
Periodic checks are performed, and if AV conduction resumes,
the device switches back to AAIR or AAI mode.

1.2 Physical characteristics

Table 1-1. Device physical characteristics

Volume

3

Intrinsic

Intrinsic 30

Mass

Intrinsic

Intrinsic 30

H x W x D

Surface area of device
can

Radiopaque ID

Materials in contact with
human tissue

b

Intrinsic

Intrinsic 30

Intrinsic

Intrinsic 30

c

Intrinsic PUB

Intrinsic 30 PUA

d

38 cm

3

36 cm

76 g

75 g

68 mm x 51 mm x 15 mm

68 mm x 51 mm x 14 mm

2

67 cm

2

66 cm

Titanium/polyurethane/silicone rubber

a

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

1Quick reference

A

V

1

2

3

4

5

Physical characteristics

Table 1-1. Device physical characteristicsa(continued)

Battery Lithium silver vanadium oxide

Connectors Two IS-1 connectors for pacing and

a

Measurements are nominal values based on CAD (computer aided design)
model measurements and are rounded to the nearest unit.

b

Grommets may protrude slightly beyond the can surface.

c

Engineering series number follows the radiopaque code.

d

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.

Table 1-2. Lead connections

Device port Connector type Software name

SVC DF-1 HVX

RV DF-1 HVB

Can n/a HVA; Can

V IS-1 bipolar

A IS-1 bipolar

sensing, Two DF-1 connectors for high
voltage therapy, Active Can electrode
(programmable)

—

—

19

Figure 1-1. 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, V
5 IS-1 connector port, A

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

20

Chapter 1

Magnet application

Figure 1-2. Suture holes

1.3 Magnet application

Bringing a magnet close to the device triggers changes in device
operation as shown in Table 1-3. When the magnet is removed,
the device returns to its programmed operations.

Table 1-3. Effects of magnet application on the device

Pacing mode as programmed

Pacing rate and interval as programmed

VF, VT, and FVT detection suspended

Patient Alert audible tones
(20 s or less)

a

b

c

a

b

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 Patient Alert tone sounds.

Detection resumes if telemetry is established and the application software is
running, or it resumes after the application software has started.

The Test tone does not sound if “VF Detection/Therapy Off” is the only alert
enabled.

c

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

1Quick reference

Longevity projections

1.4 Longevity projections

1.4.1 Intrinsic Model 7288 longevity projections

Longevity estimates are based on accelerated battery discharge
data and device modeling with EGM pre–storage off and a
60 ppm pacing rate. The estimates provided in Table 1-4 apply to
a delivered therapy energy of 35 J and pacing pulses having a

0.4 ms pulse width and either a 2.5 V or 3 V amplitude.

This model assumes default automatic capacitor formation
setting. As a guideline, each full-energy charge decreases device
longevity by approximately 31 days.

Table 1-4. Intrinsic Model 7288: Projected longevity in years with 0.4 ms pulse width and 60 ppm
pacing rate

Maximum

Pacing

DDD, 0%

energy charging
frequency

a

Semi-annual Off

Pre-arrhythmia
EGM storage

On

Quarterly Off

On

DDD, 50%

Semi-annual Off

On

Quarterly Off

On

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

Semi-annual Off

On

Quarterly Off

On

DDD, 100%

Semi-annual Off

On

Quarterly Off

On

a

Maximum energy charging frequency may include full-energy therapy shocks or capacitor formations.

b

The data provided for programming Pre-arrhythmia EGM on is based on a 6 month period (two 3 month

follow-up intervals) over the life of the device. Additional use of Pre-arrhythmia EGM reduces longevity by
approximately 27% or 3 months per year.

500pacing
impedance

b

2.5 V 3.0 V 2.5 V 3.0 V

8.5 8.5 8.5 8.5

8.3 8.3 8.3 8.3

7.1 7.1 7.1 7.1

7.0 7.0 7.0 7.0

7.4 7.1 7.9 7.6

7.2 6.9

6.4 6.1 6.7 6.5

6.2 6.0 6.5 6.4

7.6 7.4 7.9 7.8

7.4 7.2

6.5 6.4 6.7 6.6

6.4 6.2 6.6 6.5

6.6 6.1 7.3 6.9

6.4 5.9 7.2 6.8

5.7

5.4 6.3 6.0

5.6 5.2 6.2 5.9

900pacing
impedance

7.7

7.7

7.4

7.6

21

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

22

Chapter 1

Longevity projections

1.4.2 Intrinsic 30 Model 7287 longevity projections

Longevity estimates are based on accelerated battery discharge
data and device modeling with EGM pre–storage off and a
60 ppm pacing rate. The estimates provided in Table 1-5 apply to
a delivered therapy energy of 30 J and pacing pulses having a

0.4 ms pulse width and either a 2.5 V or 3 V amplitude.

This model assumes default automatic capacitor formation
setting. As a guideline, each full-energy charge decreases device
longevity by approximately 24 days.

Table 1-5. Intrinsic 30 Model 7287: Projected longevity in years with 0.4 ms pulse width and
60 ppm pacing rate

Maximum

Pacing

DDD, 0%

energy charging
frequency

a

Semi-annual Off

Pre-arrhythmia
EGM storage

On

Quarterly Off

On

DDD, 50%

Semi-annual Off

On

Quarterly Off

On

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

Semi-annual Off

On

Quarterly Off

On

DDD, 100%

Semi-annual Off

On

Quarterly Off

On

a

Maximum energy charging frequency may include full-energy therapy shocks or capacitor formations.

b

The data provided for programming Pre-arrhythmia EGM on is based on a 6 month period (two 3 month

follow-up intervals) over the life of the device. Additional use of Pre-arrhythmia EGM reduces longevity by
approximately 25% or 3 months per year.

500pacing
impedance

b

2.5 V 3.0 V 2.5 V 3.0 V

8.6 8.6 8.6 8.6

8.5 8.5 8.5 8.5

7.5 7.5 7.5 7.5

7.3 7.3 7.3 7.3

7.5

7.2 8.0 7.8

7.4 7.0 7.9 7.6

6.6 6.4 7.0 6.8

6.5 6.2 6.8 6.7

7.8 7.6 8.1 7.9

7.6 7.4 7.9 7.8

6.8 6.7 7.0 6.9

6.7 6.5 6.9 6.8

6.7 6.2

6.5 6.0 7.3 7.0

6.0

5.5

5.8 5.4 6.4 6.1

900pacing
impedance

7.5

7.1

6.6 6.3

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

1.5 Replacement indicators

Battery voltage and messages about replacement status appear
on the programmer display and on printed reports. Table 1-6 lists
the Elective Replacement Indicator (ERI) and the End of Life
(EOL) conditions.

Table 1-6. Replacement indicators

Elective Replacement (ERI) ≤ 2.62 V

End of Life (EOL) 3 months after ERI

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

Temporary voltage decrease – The battery voltage temporarily
decreases following a high voltage charge. If a battery
measurement is taken immediately after a high voltage charge,
ERI or EOL indicator may be displayed. However, this is a
temporary status which will return to normal when the battery
has recovered from the charge.

EOL indication – If the programmer indicates that the device is
at EOL, replace the device immediately.

1Quick reference

Replacement indicators

23

Post-ERI conditions – EOL device status is defined as three
months following an ERI indication assuming the following
post-ERI conditions: 100% DDD pacing at 60 ppm, 3 V, 0.4 ms;

pacing load; and six full-energy charges. EOL may be

500
indicated before the end of three months if the device exceeds
these conditions.

1.6 Typical charge times

The most recent capacitor charge time appears on the
programmer display and on printed reports and can be evaluated
using the Charge/Dump test (see Table 1-7 and Table 1-8).

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

24

Chapter 1

High voltage therapy energy

Table 1-7. Intrinsic Model 7288: typicalafull energy charge times

At Beginning of Life (BOL)

At Elective Replacement (ERI)

a

These charge times are typical when the capacitors are fully formed.

Table 1-8. Intrinsic 30 Model 7287: typicalafull energy charge times

At Beginning of Life (BOL)

At Elective Replacement (ERI)

a

These charge times are typical when the capacitors are fully formed.

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 1-9 compares the programmed energy
levels delivered by the Intrinsic to the energy levels stored in
the capacitors before delivery. Table 1-10 makes the same
comparison for the Intrinsic 30 device.

7.0 s

8.9 s

5.9 s

7.5 s

Table 1-9. Intrinsic Model 7288: delivered (programmed) and stored energy levels

Energy ( J)

Delivereda/
Programmed Stored

35 39 7.0

32 37 6.4

30 34 6.0

28 32 5.6

26 30 5.2

25 29 5.0

24 27 4.8

22 25 4.4

20 23 4.0

18 21 3.6

16 19 3.2

15 17 3.0

14 16 2.8

13 15 2.6

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

b

Charge
Timec( s)

Delivereda/
Programmed Stored

Energy ( J)

b

10 12 2.0

9 10.5 1.8

8 9.3 1.6

7

6 7.1 1.2

5

4 4.8 0.8

3 3.6 0.6

2 2.4 0.4

1.8 2.2 0.4

1.6 2.0 0.3

1.4 1.7 0.3

1.2 1.5 0.2

1.0 1.2 0.2

8.2 1.4

5.9 1.0

Charge
Timec( s)

1Quick reference

High voltage therapy energy

Table 1-9. Intrinsic Model 7288: delivered (programmed) and stored energy levels (continued)

25

Energy ( J)

Delivereda/
Programmed Stored

12 14 2.4

11 13 2.2

b

Charge
Timec( s)

Delivereda/
Programmed Stored

Energy ( J)

Charge

b

Timec( s)

0.8 1.0 0.2

0.6 0.8 0.1

0.4 0.5 0.1

a

Energy delivered at connector block into a 75

b

Energy stored at end of charge on capacitor.

c

Typical charge time at Beginning of Life (BOL) with fully formed capacitors, rounded to the nearest tenth

of a second.



load.

Table 1-10. Intrinsic 30 Model 7287: delivered (programmed) and stored energy levels

Energy ( J)

Delivereda/
Programmed Stored

b

Charge
Timec( s)

Delivereda/
Programmed Stored

30 35 5.9

28 33 5.6

26 31 5.2

24 28 4.7

22 26 4.4

20 24 4.0

18 21 3.5

16 19 3.2

15 18 3.0

14 16 2.7

13 15 2.5

12 14 2.4

11 13 2.2

10 12 2.0

9 11 1.9

a

Energy delivered at connector block into a 75

b

Energy stored at end of charge on capacitor.

c

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



load.

Energy ( J)

Charge

b

Timec( s)

8 9.4 1.6

7

8.3 1.4

6 7.1 1.2

5

5.9 1.0

4 4.7 0.8

3 3.6 0.6

2 2.4 0.4

1.8 2.2 0.4

1.6 2.0 0.3

1.4 1.7 0.3

1.2 1.5 0.3

1.0 1.2 0.2

0.8 1.0 0.2

0.6 0.8 0.1

0.4 0.5 0.1

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

26

Chapter 1

Stored data and diagnostics

1.8 Stored data and diagnostics

Table 1-11. Stored data and diagnostics

Episode data

Tachy episodes 150 VF/VT/FVT episodes: intervals, text, EGM

EGM capacity for tachy episodes 14 minutes of dual-channel EGM, or 23.5 minutes of

SVT/NST episodes 50 SVT/NST episodes: intervals, text, EGM (the device

EGM capacity for SVT/NST
episodes

Brady episodes 53 mode switch episodes

EGM sources 9 options: atrial/ventricular/far-field

EGM options Store before onset; Store during charging

Flashback memory 2000 intervals (containing both A-A and V-V): before latest

Counter data

Detection counters Lifetime total, since cleared, and since last session

Episode counters Episodes:

Therapy efficacy counters Counts for each VF, FVT, VT Therapy:

Other stored data

Patient Alert events Up to 10 log entries: text and date for the first time an alert

single-channel EGM

does not usually store detailed episode records for NST
episodes)

2 minutes of dual-channel EGM, or 3.6 minutes of
single-channel EGM

VF, before latest VT, and before interrogation

•

•

•

•

•

•

Percentage pacing:

•

Additional counters:

•

•

•

•

•

•

Total number of aborted shocks

is triggered between interrogations

VF, FVT, and VT
Atrial Fibrillation/Atrial Flutter episodes
Sinus Tach episodes
Other 1:1 SVT episodes
NST episodes
Mode switch episodes

AS-VS, AS-VP, AP-VS, AP-VP percentages

Single PVCs and PVC runs
Rate stabilization pulses and runs

Delivered
Successful
Unsuccessful
Intervention (manually aborted)

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Table 1-11. Stored data and diagnostics (continued)

1Quick reference

Stored data and diagnostics

27

Battery and lead measurements Battery voltage, last capacitor formation, last charge, lead

Lead performance trends 14 days of daily measurements plus 80 weeks of weekly

Cardiac Compass trends 14 months of measurement trends:

impedance, EGM amplitude measurements, last high
voltage therapy, and sensing integrity counter

minimum and maximum measurements:

Lead impedance: atrial pacing, ventricular pacing,

•

defibrillation pathway, and SVC lead (if used)
EGM amplitude: atrial (P-waves), ventricular

•

(R-waves)

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

•

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

2The Intrinsic system

2.1 System overview 30

2.2 Indications and usage 33

2.3 Contraindications 33

2.4 Patient screening 33

2

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30

Chapter 2

System overview

2.1 System overview

The Intrinsic and Intrinsic 30 Dual Chamber Implantable
Cardioverter Defibrillator (ICD) systems are implantable medical
device systems that automatically detect and treat episodes of
ventricular fibrillation, ventricular tachycardia, fast ventricular
tachycardia, and bradyarrhythmia. The device system includes
three major components:

ICD

•

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

Leads

•

The ICD can be used with transvenous or epicardial
defibrillation leads. The lead system should consist
of bipolar or paired unipolar1pacing/sensing leads in
each chamber of the hear t and one or two high voltage
cardioversion/defibrillation electrodes. You can program
the Active Can device case as a high voltage electrode.
The pacing and sensing electrodes in each chamber sense
cardiac activity and deliver pacing stimuli.

Programmer and software

•

The Medtronic programmer and application software (Model
9997 for Intrinsic and Model 9996 for Intrinsic 30) 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

1

With an appropriate unipolar to bipolar adapter kit.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

2The Intrinsic system

System overview

The Intrinsic devices and 9997/9996 application software are
compatible with the following programmer systems:

Medtronic CareLink Model 2090 programmer with a Model

•

2067 or 2067L programming head

Medtronic Model 9790C programmer with a Model 9767

•

or 9767L programming head

For information about:

indications, contraindications, lead compatibility, warnings

•

and precautions, and patient selection, see the implant
manual accompanying the device.

basic programmer and software desktop functions

•

that are not included in Chapter 10, “Using the
programmer”, page 211, see the manual accompanying
the programmer.

installing the programming head, see the manual

•

accompanying the programming head.

implanting leads, refer to the manuals accompanying

•

the leads.

31

2.1.1 Detecting and treating tachyarrhythmias

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

Upon detection of VF, the device delivers a biphasic

•

defibrillation shock of up to full energy. If the VF episode
persists, up to five more individually programmed
defibrillation shocks can be delivered.

Upon detection of VT, the device delivers either a Ramp,

•

Ramp+, or Burst antitachycardia pacing therapy or a biphasic
cardioversion shock of up to full energy synchronized to a
ventricular depolarization. If the VT episode persists, up
to five more individually programmed VT therapies can be
delivered. You can also program the ICD to monitor the VT
episode without delivering therapy.

Upon detection of FVT, the device delivers either a Ramp,

•

Ramp+, or Burst antitachycardia pacing therapy or a biphasic
cardioversion shock of up to full energy synchronized to a
ventricular depolarization. If the FVT episode persists, up
to five more individually programmed FVT therapies can
be delivered.

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32

Chapter 2

System overview

2.1.2 Treating bradycardia

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

To ensure proper detection and therapy during double tachycardia
episodes (VT, FVT, or VF in the presence of SVT), the device
provides double tachyarrhythmia detection whenever PR Logic
detection criteria are enabled. The device detects double
tachycardia episodes using both rate and PR Logic pattern and
rate analysis information.

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. The device
provides 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 by reducing unnecessary right
ventricular pacing.

2.1.3 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, therapies delivered, physical activity, heart rate, and
bradycardia pacing activities.

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

2.1.4 Conducting electrophysiologic tests

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

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

2.1.5 Alerting the patient to system events

You can use the programmable Patient Alert monitoring feature to
notify the patient with audible tones if certain conditions related to
the leads, battery, charge time, and therapies occur. The patient
can then respond based on your prescribed instructions.

2.2 Indications and usage

The implantable cardioverter defibrillator is intended to provide
ventricular antitachycardia pacing and ventricular defibrillation for
automated treatment of life threatening ventricular arrhythmias.

2.3 Contraindications

The Intrinsic Model 7288 and Intrinsic 30 Model 7287 ICD
systems are contraindicated for:

patients whose tachyarrhythmias may have transient or

•

reversible causes, such as acute myocardial infarction,
digitalis intoxication, drowning, electric shock, electrolyte
imbalance, hypoxia, or sepsis

patients with incessant VT or VF

•

patients who have a unipolar pacemaker

•

patients whose primary disorder is bradyarrhythmias or atrial

•

arrhythmias

2The Intrinsic system

Indications and usage

33

2.4 Patient screening

Prior to implant, patients should undergo a complete
cardiac evaluation, including electrophysiologic testing. Also,
electrophysiologic evaluation and testing of the safety and efficacy
of the proposed tachyarrhythmia therapies are recommended
during and after the implantation of the device.

Other optional screening procedures could 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 and/or medical therapy.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

3Emergency therapy

3.1 Delivering emergency therapies 36

3.2 Delivering an emergency defibrillation therapy 37

3.3 Delivering an emergency cardioversion therapy 38

3.4 Delivering emergency fixed burst pacing 39

3.5 Enabling emergency VVI pacing 40

3

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36

Chapter 3

Delivering emergency therapies

3.1 Delivering emergency therapies

The device provides the following emergency therapies:

defibrillation

•

cardioversion

•

fixed burst pacing

•

emergency VVI pacing

•

The default emergency therapy is full-energy defibrillation. When
you select [Emergency] and [DELIVER], the device charges and
delivers a biphasic full-energy shock along the AX>B pathway.

The programmer sets the emergency defibrillation energy to
full energy each time you select [Emergency]. Emergency
cardioversion and fixed burst values remain as selected for the
duration of the session.

To return to other programming functions from an Emergency
screen, select [Exit Emergency].

1

3.1.1 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. Removing the programming head or
pressing [Resume] turns detection on again.

3.1.2 Aborting an emergency therapy

As a safety precaution, the programmer also displays an [ABORT]
button which immediately terminates any emergency therapy in
progress.

1

If Active Can is turned off, the defibrillation is delivered between the HVX
and HVB electrodes.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

3Emergency therapy

Delivering an emergency defibrillation therapy

3.1.3 Mechanical Emergency buttons on the Model 9790C programmer

If you press the red mechanical Emergency button on the
programmer display panel, the programmer displays the
Emergency screen. The mechanical yellow-on-blue deliver button
activates the emergency therapy displayed on the programmer
screen. This button functions only when the Emergency screen is
displayed.

3.1.4 Mechanical Emergency VVI button on the Medtronic CareLink
Model 2090 programmer

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.

3.1.5 Temporary parameter values

37

Emergency tachyarrhythmia therapies use temporary values
that do not change the programmed parameters of the device.
These values are not in effect until you select [DELIVER]. After
the tachyarrhythmia therapy is complete, the device reverts to
its programmed values.

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.

3.2.1 Parameters

Energy – Amount of energy

delivered to the heart by the therapy.

Intrinsic

10; 11 … 16; 18; 20; 22; 24; 25;
26; 28; 30; 32; 35

2

J

2

Delivery of Emergency VVI Pacing changes the programmed bradycardia
pacing values to the emergency values (see Section 3.5.2, page 41).

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38

2

3

4

Chapter 3

Delivering an emergency cardioversion therapy

Intrinsic 30

Pathwaya– Direction the electrical
current flows through the heart.

a

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

3.2.2 How to deliver emergency defibrillation

10; 11 … 16; 18; 20; 22; 24; 26;
28; 30

AX>B (fixed)

1. Position the programming head
over the device.

2. Select [Emergency].

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

4. Select [DELIVER].

If delivery is not confirmed,
verify that the programming
head is properly positioned, and
select [Retry] or [Cancel].

J

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 7.3.5.6, “Synchronizing cardioversion after
charging”, page 138.

3.3.1 Parameters

Energy – Amount of energy

delivered to the heart by the therapy.

Intrinsic

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

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

J

35

3Emergency therapy

3

2

5

4

Delivering emergency fixed burst pacing

39

Intrinsic 30

Pathwaya– Direction the electrical
current flows through the heart.

a

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

3.3.2 How to deliver emergency cardioversion

0.4; 0.6 … 1.8; 2; 3 … 16; 18;
20; 22; 24; 26; 28; 30

J

AX>B (fixed)

1. Position the programming head
over 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].

If delivery is not confirmed,
verify that the programming
head is properly positioned, and
select [Retry] or [Cancel].

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.

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40

2

5

3

4

Chapter 3

Enabling emergency VVI pacing

3.4.1 Parameters

Interval – Time interval between

pacing pulses delivered during the
fixed burst therapy.

V. Amplitude – Voltage of the
ventricular pacing pulses delivered
during the fixed burst therapy.

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

100; 110 … 350
370 … 600 ms

8 V (fixed)

1.6 ms (fixed)

3.4.2 How to deliver emergency fixed burst pacing

1. Position the programming head
over the device.

2. Select [Emergency].

3. Select [Fixed Burst].

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

5. Select [BURST Press and
Hold].

If delivery is not confirmed,
the programmer displays an
error window. Verify that the
programming head is properly
positioned. Select [OK] from the
window and reselect [BURST
Press and Hold].

… 360;

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 the Medtronic CareLink Model 2090 programmer display panel.
To disable emergency VVI pacing, reprogram the bradycardia
pacing parameters from the Brady Pacing Parameters screen.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

3.5.1 Parameters

4

2

3

3Emergency therapy

Enabling emergency VVI pacing

41

Pacing Mode – NBG Codeafor the pacing
mode provided during emergency VVI pacing.

Lower Rate – Minimum pacing rate to maintain
adequate heart rate during periods of inactivity.

V. Amplitude – Voltage of the ventricular
pacing pulses delivered during emergency VVI
pacing.

V. Pulse Width – Duration of the ventricular
pacing pulses delivered during emergency VVI
pacing.

V. Pace Blanking – Time interval during which
sensing is disabled after a pacing pulse.

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.

a

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

3.5.2 How to deliver emergency VVI pacing

VVI

70 ppm

6 V

1.6 ms

240 ms

Off

Off

1. Position the programming head
over the device.

2. Select [Emergency].

3. Select [VVI Pacing].

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

If programming is not confirmed,
verify that the programming
head is properly positioned and
select [Retry] or [Cancel].

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Part II

Device implant and patient follow-up
procedures

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

4Implanting the device

4.1 Overview 46

4.2 Preparing for an implant 46

4.3 Replacing a device 48

4.4 Positioning the leads 49

4.5 Testing sensing and pacing thresholds 51

4.6 Connecting the leads to the device 52

4.7 Testing defibrillation operation and effectiveness 54

4.8 Positioning and securing the device 58

4.9 Completing the implant procedure 58

4

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46

Chapter 4

Overview

4.1 Overview

The tasks for implanting a device include:

1. Preparing for an implant (see Section 4.2, page 46)

2. Replacing a device (see Section 4.3, page 48)

3. Positioning the leads (see Section 4.4, page 49)

4. Testing sensing and pacing thresholds (see Section 4.5,
page 51)

5. Connecting the leads to the device (see Section 4.6,
page 52)

6. Testing defibrillation operation and effectiveness (see
Section 4.7, page 54)

7. Positioning and securing the device (see Section 4.8,
page 58)

8. Completing the implant procedure (see Section 4.9, page 58)

These tasks are described in the sections that follow.

4.2 Preparing for an implant

Warning: Keep a backup external defibrillator available

during the implant for transthoracic rescue when arrhythmias
are induced.

4.2.1 Equipment for an implant

Medtronic CareLink Model 2090 programmer with a Model

•

2067 or 2067L programming head, or a Model 9790C
programmer with a Model 9767 or 9767L programming head

Model 9997 and Model 9996 software applications

•

Model 2290 or 8090 Analyzer lead analysis device or

•

equivalent pacing system analyzer

external defibrillator

•

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Preparing for an implant

4.2.2 Sterile supplies for an implant

The sterile supplies that are needed for an implant are as follows:

implantable device and lead system components

•

programming head sleeve or programming head

•

analyzer cables

•

lead introducers appropriate for the lead system

•

extra stylets of appropriate length and shape

•

4.2.3 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 Model 9997 and Model 9996 software applications on
the programmer, if they are not already installed.

3. Place the programming head over the device and start the
application. Select the device model or select [Auto identify].

Note: The programmer automatically interrogates the device when
the application starts.

4Implanting the device

47

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

48

Chapter 4

Replacing a device

4.2.4 Preprogram the device

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

1. Check the “use by” date printed on the package. Do not implant
the device after the “use by” date because the battery’s longevity
could be reduced.

2. Interrogate the device, and print a full summary report.

3. Confirm that the battery voltage is at least 3.0 V at room
temperature.

If the device has been exposed to lower temperatures or has
delivered a recent high voltage charge, the battery voltage will be
temporarily lower.

4. Set up data collection parameters and the device internal clock
(see Section 12.2.3, page 265).

5. Perform a manual capacitor formation (see Section 13.6, page 305).

6. Program the therapy and pacing parameters to values appropriate
for the patient (see Section 8.1.4, page 151). Ensure that all
tachyarrhythmia detection is programmed Off (see Section 6.1,
page 70).

1

4.3 Replacing a device

If you are replacing a previously implanted device, turn off device
detection and therapies 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.

Perform chronic pacing and sensing measurements.

•

Measure high voltage lead impedances.

•

Test defibrillation efficacy.

•

Confirm adequate sensing during VF.

•

Ensure proper fit of the lead connectors in the device

•

connector block.

1

Use the Quick Look screen to verify the voltage, see Section 11.2, page 247.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Notes:

To meet the implant requirements, it may be necessar y to

•

reposition or replace the chronic leads or to add a third high
voltage electrode.

Any unused leads that remain implanted must be capped.

•

4.3.1 How to explant and replace a device

1. Program all tachyarrhythmia detection Off.

2. Dissect the leads and the device free from the surrounding tissues
in the surgical pocket. Be careful not to nick or breach the lead
insulation during the process of exposing the system.

3. Loosen each setscrew, and gently retract the lead from the
connector block.

4. Remove the device from the surgical pocket.

5. If the connector pin of any implanted lead shows signs of pitting
or corrosion, replace the implanted lead with a new lead. The
damaged lead should be discarded and replaced to assure the
integrity of the device system.

6. Measure sensing, pacing, and defibrillation efficacy using the
replacement device.

7. Evaluate the defibrillation efficacy of the replacement system.

4Implanting the device

Positioning the leads

49

4.4 Positioning the leads

Implant endocardial 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 (refer to the implant manual accompanying the
device). Transvenous or epicardial leads may be used. A bipolar
atrial lead with closely spaced pacing and sensing electrodes
is recommended.

4.4.1 Using transvenous leads

Use standard transvenous implant techniques to position the
ventricular lead tip in the right ventricular apex and the atrial
pacing lead tip high on the right atrial appendage.

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50

Chapter 4

Positioning the leads

4.4.2 Using epicardial leads

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 (2 in) 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.

CS lead: Advance the lead tip to just under the left atrial

•

appendage, if possible.

If using a subclavian approach, position the lead laterally 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.

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 RV (HVB) and a posterolateral left ventricular patch as
SVC (HVX).

Follow the general guidelines below for positioning epicardial
leads:

If unipolar epicardial pacing leads are used, position the

•

electrodes about 1 cm to 2 cm (0.4 in to 0.8 in)apart to
reduce electromagnetic interference, and route the leads
together with several loose twists.

Suture the smooth face of each patch lead against the

•

epicardium or pericardium in locations that produce optimal
defibrillation.

Place the patches so that they encompass the maximum

•

amount of cardiac mass and they have approximately equal
amounts of mass between them.

Ensure that the patches do not overlap and the electrode

•

portions do not touch.

Avoid placing extra-pericardial patches over the phrenic

•

nerve.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

4Implanting the device

Testing sensing and pacing thresholds

4.4.3 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 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 far medially to
keep the leads away from the axilla. Make sure that the upper
edge of the device remains inferior to the incision.

4.5 Testing sensing and pacing thresholds

Sensing and pacing tests include the following measurements:

EGM amplitude

•

slew rate

•

pacing threshold

•

pacing lead impedance

•

51

4.5.1 Parameters

Medtronic recommends that you use a Model 2290 or 8090
Analyzer lead analysis device to perform sensing and pacing
measurements. If you use a Pacing System Analyzer (PSA),
perform both atrial and ventricular measurements via the
ventricular channel of the PSA.

Refer to the technical manual for the Analyzer you use to find
details on performing sensing and pacing measurements.

Measured sensing and pacing values must meet the following
specific requirements at implant.

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52

Chapter 4

Connecting the leads to the device

4.5.2 Considerations

Table 4-1. Sensing and pacing values at implant

Measurement Acute transvenous leads

R-wave amplitude ≥ 5 mV ≥ 3 mV

P-wave amplitude ≥ 2 mV ≥ 1 mV

Slew rate:

atrial ≥ 0.5 V/s ≥ 0.3 V/s

ventricular ≥ 0.75 V/s ≥ 0.5 V/s

Capture thresholda:

atrial ≤ 1.5 V ≤ 3.0 V

ventricular ≤ 1.0 V ≤ 3.0 V

a

At 0.5 ms pulse width

Chronic
leads

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

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

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

4.6 Connecting the leads to the device

For more detailed information about lead/connector compatibility,
see the implant manual accompanying the device, or contact your
Medtronic representative.

Table 4-2. Lead connections

Device port Connector type Software name

SVC DF-1 HVX

RV DF-1 HVB

Can n/a HVA, Can

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

4Implanting the device

A

V

1

2

3

4

5

Connecting the leads to the device

Table 4-2. Lead connections (continued)

Device port Connector type Software name

V IS-1 bipolar

A IS-1 bipolar

—

—

Figure 4-1. 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, V
5 IS-1 connector port, A

Warning: Loose lead connections may result in inappropriate
sensing and failure to deliver necessary arrhythmia therapy.

53

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

For easier lead insertion, insert the ventricular IS-1 leg before
the other legs.

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54

Chapter 4

Testing defibrillation operation and effectiveness

4.6.1 How to connect the lead to the device

1

b

a

2

1. Insert the torque wrench into
the appropriate setscrew.

a. If the port is obstructed,

retract the setscrew to
clear it. 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.

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

3. Tighten the setscrew by turning
clockwise until the torque
wrench clicks.

4. Tug gently on the lead to
confirm a secure fit. Do not pull
on the lead until all setscrews
have been tightened.

5. Repeat these steps for each
lead.

4.7 Testing defibrillation operation and effectiveness

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

Note: If the 10 J (minimum) safety margin cannot be ensured,
see Section 15.4, “Solving tachyarrhythmia therapy problems”,
page 329.

4.7.1 High-voltage implant values

Measured values must meet the following requirements at implant.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

4Implanting the device

Testing defibrillation operation and effectiveness

Table 4-3. High-voltage therapy values at implant

Measurement Acute or chronic leads

V. Defib impedance

SVC (HVX) impedance (if applicable)

20 – 200

20 – 200

Defibrillation threshold

Intrinsic ≤ 25 J

Intrinsic 30 ≤ 20 J

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

4.7.2 How to prepare for defibrillation threshold testing

1. Place the programming head over the device, start a patient
session, and interrogate the device, if you have not already done so.

2. Observe the Marker Channel telemetry annotations and the
programmer ECG display to verify that the device is sensing
properly.

2

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

Recheck lead connections and electrode placement.

•

Repeat the measurement.

•

Inspect the bipolar EGM for abnormalities.

•

Measure the defibrillation impedance with a manual test shock.

•

4. Program the device or support instrument to properly detect VF
with an adequate safety margin (1.2 mV sensitivity).

to verify the defibrillation

55





2

See Section 13.4, “Measuring lead impedance”, page 302.

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56

1

2

3

4

12

14

8

9

13

5

6

7

11

10

Chapter 4

Testing defibrillation operation and effectiveness

4.7.3 How to perform defibrillation threshold testing using T-Shock

1. Select Tests > EP Study.

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

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

4. Select [Adjust Permanent …].

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

6. Select [Program].

7. Select [Close].

8. Select Enable.

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 Params > Detection,
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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4Implanting the device

1

2

4

12

13

5

7

6

8

11

10

3

9

Testing defibrillation operation and effectiveness

4.7.4 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 [Resume at BURST] to
resume arrhythmia detection
after induction delivery.

4. Select [Adjust Permanent …].

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

6. Select [Program].

7. Select [Close].

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

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

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

11. Wait until the on-screen timer
reaches 5 minutes, then repeat
Step 8 through Step 11 as
needed.

12. Select the Params > Detection
and disable VF, FVT, and VT
detection before closing the
pocket.

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

57

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58

Chapter 4

Positioning and securing the device

4.8 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.

Program tachyarrhythmia detection Off before closing.

•

4.8.1 How to position and secure the device

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

2. Coil any excess lead length
beneath the device. Avoid kinks
in the lead conductors.

3. Implant the device within 5 cm
of the skin. This position
optimizes the ambulatory
monitoring operations.

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

4.9 Completing the implant procedure

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

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Completing the implant procedure

4.9.1 How to complete programming the device

1. After closing the pocket, program detection On. Program ventricular
tachyarrhythmia therapies On as desired.

2. Do not enable the Other 1:1 SVTs PR Logic detection criterion until
the atrial lead has matured (approximately one month post implant).

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

4. Program patient information. See Section 12.10.1, “How to view
and enter new patient information”, page 294.

5. Configure the Patient Alert feature. See Section 11.3, “Using the
Patient Alert feature”, page 249.

6. Set up data collection parameters. See Section 12.2, “Setting up
data collection”, page 263.

7. Interrogate the device after any spontaneous episodes to evaluate
the detection and therapy parameter settings.

8. 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 14, “Conducting Electrophysiologic Studies”,
page 307.

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

4Implanting the device

59

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5Conducting a patient follow-up session

5.1 Patient follow-up guidelines 62

5.2 Verifying the status of the implanted system 62

5.3 Verifying accurate detection and appropriate therapy 63

5.4 Verifying effective bradycardia pacing 64

5

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62

Chapter 5

Patient follow-up guidelines

5.1 Patient follow-up guidelines

Schedule regular patient follow-up sessions to monitor the
condition of the device and leads and to verify that the device is
configured appropriately for your patient.

During the first few months after receiving a new device, the
patient may require close monitoring. Schedule an office visit at
least every three months.

The Quick Look screen, which is displayed after you interrogate
the device, provides a good beginning for the follow-up review.
Using this screen you can:

verify that the device is functioning correctly.

•

review the clinical performance and long term trends.

•

print appropriate reports1to compare the results to the

•

patient’s history and to retain for future reference.

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 if you wish. See Section 11.4, “Streamlining
follow-ups with Checklist”, page 256 for more information.

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

•

Elective Replacement Indicator value (see Section 1.5,
page 23). Remember that battery voltage may be low if high
voltage charging has occurred within 24 hours.

Review the last full energy charge.

•

– For information about adjusting the capacitor formation

interval, see Section 4.2, “Preparing for an implant”,
page 46.

– If the programmer displays an Excessive Charge Time

ERI, the device should be replaced immediately.

1

See Section 12.9, “Using Cardiac Compass to view long term clinical trends”,
page 285 for information on this new report.

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5Conducting a patient follow-up session

Verifying accurate detection and appropriate therapy

Review the defibrillation and pacing lead impedance values

•

for inappropriate values or large changes since the last
follow-up. See Section 13.4, “Measuring lead impedance”,
page 302.

Perform an EGM Amplitude test in each chamber for

•

comparison to previous EGM Amplitude measurements.
See Section 13.5.4, “How to perform an EGM Amplitude
test”, page 305.

To review longer term trends in sensing and impedance

•

measurements, select the [>>] button from the lead
impedance area of the Quick Look screen. The programmer
displays a detailed history of automatic sensing and
impedance measurements. See Section 11.2, “Taking a
quick look at device activity”, page 247.

5.3 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:

63

•

•

•

•

5.3.1 Considerations

Review the following information before verifying detection and
therapy.

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

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

Review any Patient Alerts listed in the Observations of the
Quick Look screen. For the most detailed information about
Patient Alerts, select Patient Alert from the Data icon and
select [Events].

Check stored episode records for appropriate sensing and
detection of arrhythmias. See Section 12.5, page 272.

Check stored SVT episode records for appropriate
identification of SVTs.

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64

Chapter 5

Verifying effective bradycardia pacing

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 12.3.2, “Sensing integrity counter”,
page 268.

If the device is oversensing, consider these programming options:

Increase the Pace Blanking value.

•

Increase the sensitivity threshold.

•

Caution: Do not reprogram the device to decrease
oversensing without assuring that appropriate sensing is
maintained. See Section 6.2, “Setting up sensing”, page 73.

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:

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.

Consider enabling FVT via VF detection. See Section 6.5,

•

“Detecting FVT episodes”, page 87.

If the SVT episode records include episodes of true VT, review
the SVT episode record to identify the SVT detection criterion that
withheld detection. Adjust the SVT detection criteria parameters
as necessary. See Section 6.8, “Enhancing detection with PR
Logic criteria”, page 98, and Section 6.9, “Enhancing VT detection
with the Stability criterion”, page 106.

5.4 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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•

•

•

5.4.1 Considerations

Review the following information before verifying bradycardia
pacing.

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:

•

•

5Conducting a patient follow-up session

Verifying effective bradycardia pacing

Review the recorded Mode Switch episodes for comparison
to the patient’s atrial arrhythmia history. A dramatic increase
in frequency or duration of atrial episodes may indicate a
need for investigation and analysis.

To display more detailed information about the Mode
Switch episodes, perform these steps: select Episodes
and Counters from the Data icon; select the Mode Switch
Episodes from the listed episode counters; then select the
[Open Data] button.

Review the Cardiac Compass report for comparison to
patient history (see Section 12.9, page 285).

Conduct pacing threshold tests (see Section 13.3, page 299)
to verify that the programmed pacing outputs provide a
sufficient safety margin.

Decrease the Lower Rate.

Decrease the rate response or increase the activity
threshold.

65

Conduction history – If the reported percentages in the
conduction history do not add up to 100, the percentages may be
rounded. Frequent premature contractions or A: V dissociation
may also be the cause.

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Part III

Configuring the device for the patient

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6Detecting tachyarrhythmias

6.1 Detection overview 70

6.2 Setting up sensing 73

6.3 Detecting VF episodes 78

6.4 Detecting VT episodes 81

6.5 Detecting FVT episodes 87

6.6 Detecting tachyarrhythmia episodes with Combined Count 92

6.7 Monitoring episodes for termination or redetection 94

6.8 Enhancing detection with PR Logic criteria 98

6.9 Enhancing VT detection with the Stability criterion 106

6.10 Detecting double tachycardias 108

6.11 Detecting prolonged tachyarrhythmias with High Rate Timeout 109

6

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70

Chapter 6

Detection overview

6.1 Detection overview

The device detects ventricular tachyarrhythmias (VF, VT, and
FVT) by comparing the time intervals between sensed ventricular
events to a set of programmable detection intervals. If enough
intervals occur that are shorter than the programmed intervals,
the device detects a tachyarrhythmia, and responds automatically
with a programmed therapy. After delivering the therapy, the
device either redetects the arrhythmia and delivers the next
programmed therapy or detects episode termination.

To avoid detecting rapidly conducted SVTs (for example, sinus
tachycardia or atrial fibrillation) as ventricular tachyarrhythmias,
the device provides several detection enhancements, including
PR Logic and Stability detection criteria.

All of the detection features interact during initial detection (see
Figure 6-1). During redetection, the device does not apply the PR
Logic detection criterion.

Note: Detection functions can be turned off by programming the
VF Enable, FVT Enable, and VT Enable parameters to Off. For
an example, see Section 6.3.4, “How to program VF detection”,
page 80.

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6Detecting tachyarrhythmias

Ventricular Event

No

No

No

Yes

Yes

Yes

Yes

Yes

Yes

No

No

No

No

Yes

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)

Has a tachyarrhythmia event count reached an NID?

Are one or more PR Logic criteria on?

No/suspended by High Rate

Timeout

Tachy

Episode

Detected

Is the median ventricular interval less than the SVT Limit?

Is there a double tachycardia in progress?

Are one or more PR Logic criteria withholding detection?

Figure 6-1. How detection features interact during initial detection

71

Detection overview

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.

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72

Chapter 6

Detection overview

Detection is suspended:

when the device senses the presence of a strong magnet.

•

The programmer head contains a magnet which suspends
detection, but once telemetry between the device and
programmer is established, detection resumes.

while performing any of the manual system tests, including

•

Underlying Rhythm, Pacing Threshold, Lead Impedance,
EGM Amplitude, and Charge/Dump. Detection automatically
resumes once the test is complete.

while performing a T-Shock, 50 Hz Burst, Manual Burst,

•

or PES Induction. You can choose to have the device
automatically resume detection after delivering the induction.

when you deliver a Manual or Emergency therapy. You

•

can resume detection by selecting the [Resume] button or
removing the programming head from the device.

when you select the on-screen [Suspend] button. You can

•

resume detection by selecting the [Resume] button or by
removing the programming head from the device.

during the automatic daily lead impedance measurements.

•

Detection resumes when the measurements are complete.

while the device is delivering an automatic tachyarrhythmia

•

therapy (including capacitor charging for defibrillation and
cardioversion). However, the device does continue to
confirm the detected episode during charging. Detection
resumes when the therapy is complete.

Note: The device suspends VT detection (and Combined
Count detection; see Section 6.6, page 92) for 17 events
following a defibrillation therapy delivered in response to
a detected VF.

during charging for Automatic Capacitor Formation.

•

Detection resumes when charging is complete.

1

1

If the defibrillation therapy is delivered as a result of a High Rate Timeout
Therapy operation, VT detection is not suspended (see Section 6.11.4.1,
page 111).

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6.2 Setting up sensing

The device provides bipolar sensing in both the atrium and
ventricle via 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.

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

auto-adjusting atrial and ventricular sensing thresholds

•

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

•

no cross-chamber blanking after sensed events

•

See details about sensing on Section 6.2.4, page 76.

6.2.1 Parameters

6Detecting tachyarrhythmias

Setting up sensing

73

V. Sensitivity – Minimum amplitude of
electrical signal that registers as a sensed
ventricular event.

A. Sensitivity – Minimum amplitude of
electrical signal that registers as a sensed
atrial event.

6.2.2 Considerations

Review the following information before programming sensing
parameters.

Dual chamber sensing and bradycardia pacing modes – The
device senses in both the atrium and the ventricle at all times,
except when the programmed bradycardia pacing mode is DOO
or VOO. When the pacing mode is programmed to DOO or VOO
mode, there is no sensing in the ventricle. In order to program
either DOO or VOO mode, you must first disable detection.

Sensitivity thresholds – The programmed atrial and ventricular
sensitivity thresholds apply to all features related to sensing,
including detection and bradycardia pacing.

0.15; 0.3

0.6; 0.9; 1.2 mV

0.15; 0.3

0.6; 0.9; 1.2; 1.5;

2.1 mV

; 0.45;

; 0.45;

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74

Chapter 6

Setting up sensing

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

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 V. Sensitivity
to a value greater than 0.6 mV is not recommended except for
testing. Doing this may cause undersensing, which can cause
any of the following situations:

delayed or aborted cardioversion therapy

•

delayed defibrillation therapy (when VF confirmation is

•

active)

asynchronous pacing

•

underdetection of tachyarrhythmias

•

Low ventricular sensitivity threshold – If you set V. Sensitivity
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 PR Logic detection criteria and atrial 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 SVTs and sinus rhythm.

Low atrial sensitivity threshold – If you set the A. Sensitivity
value to its most sensitive value of 0.15 mV, the device will
be more susceptible to EMI, far-field R-wave sensing, and
oversensing.

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

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Atrial pacing and ventricular sensing – If you program the

1

2

3

device to an atrial pacing mode, make sure that it does not sense
atrial pacing pulses as ventricular events.

Sensing during VF – Always verify that the device senses
properly during VF. If the device is not sensing or detecting
properly, program detection and therapies off, 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.

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

Repositioning the atrial lead – You may need to reposition
or replace the atrial sensing lead if reprogramming the atrial
sensitivity threshold does not provide reliable atrial sensing during
SVTs and sinus rhythm.

6.2.3 How to program sensitivity

6Detecting tachyarrhythmias

Setting up sensing

1. Select Params > Detection.

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

3. Select [PROGRAM].

75

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76

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

3

4

5

Chapter 6

Setting up sensing

6.2.4 Details about sensing

6.2.4.1 Auto-adjusting sensitivity thresholds

The device automatically adjusts the sensitivity thresholds after
certain paced and sensed events to help reduce oversensing
from T-waves, cross-chamber events, and pacing. You can see
how sensitivity thresholds are adjusted after different types of
events (see Figure 6-2).

Figure 6-2. Auto-adjusting sensitivity thresholds

1 After an atrial sensed event, the atrial sensitivity threshold increases

to 75% of the EGM peak (maximum: 8x the programmed value,
decay constant: 200 ms).

2 After a ventricular sensed event, the ventricular sensitivity threshold

increases to 75% of the EGM peak (maximum: 8x the programmed
value, decay constant: 450 ms).

3 After an atrial paced event, the device does not adjust the atrial

sensitivity threshold. The ventricular sensitivity threshold increases
by 0.45 mV (decay constant: 60 ms).

4 After a ventricular paced event, the atrial sensitivity threshold

increases to 4x the programmed value (maximum: 1.8 mV,
immediate return after 60 ms).

5 After the ventricular pace blanking period is finished, the ventricular

threshold increases to 4.5x the programmed value (maximum:

1.8 mV, decay constant: 450 ms).

2

The exponential decay continues through a subsequent ventricular pacing
pulse and its blanking period.

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2

3

3

6Detecting tachyarrhythmias

Setting up sensing

6.2.4.2 Blanking periods

During a blanking period, the device does not sense
electrical signals. This helps prevent sensing of device
pacing, cardioversion and defibrillation pulses, post-pacing
depolarization, T-waves, and multiple sensing of the same event.
The blanking periods following paced events are longer than
those following sensed events to avoid sensing the atrial and
ventricular depolarizations.

Notes:

To enhance sensing and detection during tachyarrhythmias,

•

the device does not apply cross-chamber blanking (blank
sensing in the opposite chamber) after a sensed event.

Atrial sensing is still active during the Post-Ventricular

•

Atrial Blanking (PVAB) period (see Section 8.2.4.4,
“Post-Ventricular Atrial Blanking period”, page 159).

The duration of the fixed blanking periods is shown in Table 6-1.
For information on programmable pace blanking periods, see
Section 8.1, page 148.

Table 6-1. Fixed blanking periods

Cross-chamber blanking after atrial or ventricular
pacing pulse

Atrial blanking after sensed atrial event

Ventricular blanking after sensed ventricular event

Atrial and ventricular blanking after delivered
cardioversion or defibrillation therapy

30 ms

100 ms

120 ms

520 ms

77

6.2.4.3 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.

3

If the programmed sensitivity value exceeds 0.3 mV (ventricular) or 1.2 mV
(atrial), the threshold is not adjusted.

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78

Chapter 6

Detecting VF episodes

Synchronization refractory periods help prevent the device
from delivering cardioversion and defibrillation therapies at
inappropriate times. See Section 7.1.5.5, “Synchronizing
defibrillation without confirming VF”, page 118 and Section 7.3.5.6,
“Synchronizing cardioversion after charging”, page 138.

Note: Refractory periods do not affect tachyarrhythmia detection.

6.3 Detecting VF episodes

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

See Section 6.3.5, “Details about VF detection”, page 80.

6.3.1 Parameters

VF Detection Enable – Turns VF

detection on or off.

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

VF Initial NID – Number of Intervals to
Detect: number of VF events the device
must count to detect a VF episode.

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

6.3.2 Considerations

Review the following information before programming VF
Detection parameters.

VF Interval minimum setting – To ensure proper VF detection,
you should not program the VF Interval less than 300 ms.

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; Off

On

240; 250 … 320
400 ms

12/16; 18/24
30/40; 45/60; 60/80;
75/100; 90/120; 105/140;
120/160

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

…

; 24/32;

; 18/24;

6Detecting tachyarrhythmias

Detecting VF episodes

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 Redetect NIDs lower than the Initial
NIDs.

Enabling VF detection – When VF Detection Enable is
programmed On for the first time, the device

enables Automatic Capacitor Formation

•

starts recording Cardiac Compass data

•

starts recording lead performance trends (starting at

•

3:00 AM, by the device clock)

clears all brady pacing counters

•

VF detection and PR Logic criteria – You can program the
device to exclude rapidly conducted SVTs from 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 6.8,
“Enhancing detection with PR Logic criteria”, page 98.

79

6.3.3 Restrictions

Double tachycardia detection – When any PR Logic detection

criteria are enabled, the device also enables double tachycardia
detection (VF, VT, or FVT in the presence of an SVT). See
Section 6.10, “Detecting double tachycardias”, page 108.

Review the following information before programming VF
Detection parameters.

Tachyarrhythmia detection and bradycardia pacing – To
ensure reliable ventricular tachyarrhythmia detection, the
programmer regulates the values available for bradycardia pacing
and tachyarrhythmia detection. See Section B.11, “Parameter
interlocks”, page 361.

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1

2

3

Chapter 6

Detecting VF episodes

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

6.3.4 How to program VF detection

1. Select Params > Detection.

2. Select the desired values for
VF Enable, VF Initial NID, VF
Redetect NID, and VF Interval.

3. Select [PROGRAM].

6.3.5 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 Interval.
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 NID (for example, 24 events if the
VF Initial NID is 18/24).

The threshold for detecting VF is the first number in the
programmed VF NID (for example, 18 events if the VF Initial
NID 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 6-3).

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 Redetect NID, the device redetects

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

VF and delivers the next programmed VF therapy.

Note: The device can also detect VF Episodes via the Combined
Count detection criterion (see Section 6.6, page 92).

Figure 6-3. Device detects VF

A
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200 ms

2

3

1

VF Event Count

ECG

Marker Channel

VF Interval

1 VF starts, and the device begins counting VF events (intervals less

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 NID value of 18

events out of 24, and the device detects VF.

6Detecting tachyarrhythmias

Detecting VT episodes

81

6.4 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, 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 with VT therapies by setting VT Detection
Enable to Monitor. If a patient’s VT episodes are well-tolerated,
this feature allows you to collect data about these episodes
without delivering therapy or affecting VF detection.

See Section 6.4.5, “Details about VT detection”, page 83.

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Chapter 6

Detecting VT episodes

6.4.1 Parameters

VT Detection Enable – Turns VT

detection on or off, or enables VT
monitoring.

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

VT Initial NID – Number of Intervals
to Detect: number of VT events the
device must count to detect a VT
episode.

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

6.4.2 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, 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 Redetect NIDs lower than the Initial
NIDs.

On; Off

280; 290 … 400

12; 16

4; 8; 12

; or Monitor

…52; 76; 100

… 52

… 600 ms

VT Detection Enable, AFib/AFlutter, and Sinus Tach – When
you set VT Detection Enable to On or Monitor, the AFib/AFlutter
and Sinus Tach parameters are also automatically set to On.

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 set to Off or Monitor. See Section 6.6, “Detecting
tachyarrhythmia episodes with Combined Count”, page 92.

VT detection and rapidly conducted SVTs – You can program
the device to exclude rapidly conducted SVTs from VT detection
by enabling the PR Logic or Stability detection criteria. See
Section 6.9, “Enhancing VT detection with the Stability criterion”,
page 106, and Section 6.8, “Enhancing detection with PR Logic
criteria”, page 98.

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Double tachycardia detection – When any PR Logic detection

1

2

3

criteria are enabled, the device also enables double tachycardia
detection (VF, VT, or FVT in the presence of an SVT; see
Section 6.10, page 108).

6.4.3 Restrictions

Review the following information before programming VT
detection parameters.

Tachyarrhythmia detection and bradycardia pacing – To
ensure reliable ventricular tachyarrhythmia detection, the
programmer regulates the values available for bradycardia pacing
and tachyarrhythmia detection. See Section B.11, “Parameter
interlocks”, page 361.

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

6.4.4 How to program VT detection

6Detecting tachyarrhythmias

Detecting VT episodes

1. Select Params > Detection.

2. Select the desired values for
VT Enable, VT Initial NID, VT
Redetect NID, and VT Interval.

3. Select [PROGRAM].

83

6.4.5 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 NID, the device detects VT (see Figure 6-4).

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Chapter 6

Detecting VT episodes

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 Redetect NID, the device redetects VT and delivers the
next programmed therapy.

Note: The device can also detect VT Episodes via the Combined
Count detection criterion (see Section 6.6, page 92).

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Figure 6-4. Device detects VT

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1 0 1 2 3 4 5 6

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3

VT Event Count

ECG

Marker Channel

VT Interval

VT Event Count

ECG

Marker Channel

VT Interval

6Detecting tachyarrhythmias

Detecting VT episodes

85

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 VT detection zone. The VT event

count resets to zero.

3 The VT event count reaches the programmed VT NID of 16 events,

and the device detects VT.

6.4.5.1 VT monitoring

You can program the device to record VT episodes without
delivering VT therapy by setting VT Detection to Monitor. When
VT monitoring is enabled, the device detects VT episodes but
does not deliver VT therapy (see Figure 6-5). Instead, it records
VT episodes, labeling them as “monitored,” and waits for episode
termination to occur.

When VT Detection is set to Monitor, several detection operations
work differently.

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Chapter 6

Detecting VT episodes

VT event counting – Before the device detects an episode, it
counts VT events normally. However, once the VT Initial NID is
reached, the device sets the VT event count to zero and suspends
VT event counting for the rest of the episode.

VF and FVT detection – VF and FVT detection operate as if
VT detection is off. Specifically, Combined Count detection
is disabled, and FVT via VT detection is not selectable. If a
monitored VT episode accelerates into the FVT or VF detection
zone, the device applies the VF Initial NID to detect the new
tachyarrhythmia. Once an episode is in progress, VT event
counting doesn’t resume until the episode ends.

Caution: Programming the VF Interval greater than 350 ms
may result in 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.

PR Logic and Stability criteria – Before the device detects a
tachyarrhythmia episode, the PR Logic and Stability criteria, if
turned on, are applied. If a monitored VT episode accelerates
into the FVT or VF detection zone, the device continues to apply
PR Logic criteria as initial VF or FVT detection begins. However,
because the Stability feature does not affect VF detection or FVT
via VF detection, it is not applied.

Episode termination – The device compares ventricular intervals
to the VT Interval to identify when a VT monitored episode has
ended. However, if a VF episode or FVT via VF episode occurs
when VT monitoring is enabled, the device compares ventricular
intervals to the VF Interval to identify episode termination.

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Figure 6-5. Device detects and monitors VT

200 ms

1 2 3 4

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13 14 15 16 0 0 0

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T ST ST ST DT ST ST

S

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1

VT Event Count

ECG

Marker Channel

VT Interval

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 The VT event count reaches the programmed VT NID of 16 events,

and the device detects VT.

3 After detecting the VT episode, the device resets the VT event count

to zero and monitors the episode until termination.

6Detecting tachyarrhythmias

Detecting FVT episodes

87

6.5 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, 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.

See Section 6.5.5, “Details about FVT detection”, page 90.

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Chapter 6

Detecting FVT episodes

6.5.1 Parameters

FVT Detection Enable – Enables FVT

detection via the VF or the VT detection
algorithm.

FVT Interval (Rate) – V-V intervals between
this value and the programmed VF Interval are
marked as FVT events.

6.5.2 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, 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 Redetect NIDs lower than the Initial
NIDs.

FVT detection enable – 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:

•

; via VF; or via

Off
VT

200; 210 … 600 ms

If the patient presents with a clinical VT interval 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 two clinical VTs, both outside the

•

VF zone, select via VT to allow for correct classification of
the faster VT and to offer a separate therapy regimen for
each VT.

If the patient presents with only one clinical VT which is

•

outside the VF zone, select VF and VT Detection only, and
set FVT Enable to Off.

FVT detection and PR Logic criteria – You can program the
device to exclude rapidly conducted SVTs from FVT Detection
by enabling the PR Logic detection 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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6.5.3 Restrictions

6Detecting tachyarrhythmias

Detecting FVT episodes

Double tachycardia detection – When any PR Logic detection
criteria is enabled, the device also enables double tachycardia
detection (VF, VT, or FVT in the presence of an SVT, see
Section 6.10, page 108).

Review the following information before programming FVT
Detection parameters.

Tachyarrhythmia detection and bradycardia pacing – To
ensure reliable ventricular tachyarrhythmia detection, the
programmer regulates the values available for bradycardia pacing
and tachyarrhythmia detection. See Section B.11, “Parameter
interlocks”, page 361.

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

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

VT Detection must be set to On if FVT Detection is set to

•

via VT.

89

If FVT Detection is set to via VF, the FVT Interval must be

•

programmed to a value shorter than the VF Interval.

If FVT Detection is set to via VT, the FVT Interval must be

•

programmed to a value greater than the VF Interval and less
than or equal to the VT Interval.

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1

2

3

Chapter 6

Detecting FVT episodes

6.5.4 How to program FVT detection

6.5.5 Details about FVT detection

You can program the device to detect FVT episodes via the VF
or VT detection zone and NID.

1. Select Params > Detection.

2. Select the desired values for
FVT Enable and FVT Interval.

3. Select [PROGRAM].

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 VF
NID is reached, the device reviews the last eight intervals:

If any of the last eight intervals are in the VF zone, it detects

•

the episode as VF.

If all of the last eight intervals are outside the VF zone, it

•

detects the episode as FVT (see Figure 6-6).

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 VT NID is reached, the device reviews the last eight intervals:

If any of the last eight intervals are in the VF or FVT zones, it

•

detects the episode as FVT.

If all of the last eight intervals are outside the FVT and VF

•

zones, it detects the episode as VT.

Note: The device can also detect FVT episodes via the Combined

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Count detection criterion (see Section 6.6, page 92).

Figure 6-6. Device detects FVT via VF

200 ms

13 14 15 16 17 18

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F

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VF Event Count

ECG

Marker Channel

VF and FVT Intervals

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 zone. The VF event count is not incremented.

3 The device detects FVT after the VF event count reaches the VF

Initial NID.

6Detecting tachyarrhythmias

Detecting FVT episodes

91

6.5.5.1 Zone merging after detection

To ensure that 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 6-7. The merged zone
configuration uses the event counting and therapies for the faster
arrhythmia and remains in effect until episode termination.

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92

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.

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

VF

FVT

VT

VF

FVT

VT

VF

FVT

VT

VF

FVT

VT

VF

FVT

VT

VF

FVT

VT

Chapter 6

Detecting tachyarrhythmia episodes with Combined Count

Figure 6-7. FVT zone merging

6.6 Detecting tachyarrhythmia episodes with Combined
Count

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

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 and VT detection
are programmed On.

The Combined Count criterion compares the sum of the VF
and VT event counts to the Combined Number of Intervals to
Detect (CNID), which the device calculates automatically from
the programmed VF NID values. If the CNID 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.

Detecting tachyarrhythmia episodes with Combined Count

6.6.1 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 on, the device applies Combined Count
detection, which tracks the combined number of VT and VF
events counted. If this sum reaches the Combined Number of
Intervals to Detect (CNID), the device detects VF, FVT, or VT.
Combined Count detection also applies to redetected episodes.

Note: Combined Count detection is off when VT detection is set
to Monitor or Off.

If the VF event counter reaches six, the device automatically
applies the Combined Number of Intervals to Detect (CNID). The
CNID is calculated by multiplying the current VF NID (Initial or
Redetect) by 7/6 and rounding down. Table 6-2 shows the CNID
values that correspond to each VF NID value.

Table 6-2. CNID values for each initial or redetect VF NID value

VF NID CNID VF NID CNID

6/8

9/12

12/16

18/24

7

10

14

21

6Detecting tachyarrhythmias

21/28

24/32

27/36

30/40

24

28

31

35

93

Combined Count detection is fulfilled when the sum of the VF and
VT event counts equals or exceeds the CNID. The device then
reviews the last eight intervals and classifies the episode as

VF, if any of the last eight were in the VF zone.

•

FVT, if FVT Detection is enabled and none of the last eight

•

was in the VF zone, but one or more was in the FVT zone.

VT, if all eight were outside the VF zone (and FVT zone, if

•

FVT detection is enabled).

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94

200 ms

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R

A RA RA RA RA RA RA RA

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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

Chapter 6

Monitoring episodes for termination or redetection

Figure 6-8. Device detects VF with the Combined Count criterion

1 A slow VF episode starts, with a ventricular cycle length that varies

between the VF and VT detection zones.

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 hasn’t yet

reached the VF Initial NID (18/24 in this example). The Combined
Count reaches the CNID value of 21 first.

6.7 Monitoring episodes for termination or redetection

Once the device detects an arrhythmia, it considers the episode

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

ongoing until it detects that the episode has ended. After
delivering therapy, it monitors the ventricular rhythm using the
programmed Redetect NIDs. If one of these NIDs is met, the
device delivers the next programmed therapy for the detected
arrhythmia.

See Section 6.7.4, “Details about episode termination and
redetection”, page 95.

6.7.1 Parameters

1

3

2

6Detecting tachyarrhythmias

Monitoring episodes for termination or redetection

95

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

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

6.7.2 Considerations

Review the following information before programming redetection
parameters.

Initial and Redetect NIDs – You can expedite redetection by
programming the VF and VT Redetect NIDs lower than the Initial
NIDs.

6.7.3 How to program redetection parameters

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

4; 8; 12

1. Select Params > Detection.

2. Select the desired values for VT
Redetect NID and VF Redetect
NID.

3. Select [PROGRAM].

… 52

; 18/24;

6.7.4 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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Chapter 6

Monitoring episodes for termination or redetection

6.7.4.1 Episode termination

The device determines that the episode has terminated if one of
the following conditions occurs:

8 consecutive ventricular intervals are greater than or equal

•

to the programmed VT interval.

20 s elapse with no ventricular intervals shorter than the

•

programmed VT interval.

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.

6.7.4.2 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 Redetect NID or if the combined VF and
VT event count reaches the Redetect CNID (see Section 6.6,
“Detecting tachyarrhythmia episodes with Combined Count”,
page 92).

4

4

The device then delivers the next programmed therapy for the
current arrhythmia and resumes monitoring for the outcome of
that therapy (see Figure 6-9).

4

VF interval if VT Detection is set to Off or Monitor, and the episode is a VF
or an FVT via VF episode.

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Monitoring episodes for termination or redetection

A RA SA SA SA SA SA RA RA RA RA RA RA RA RA RA RA RA RA

R

T
P

T PT

P

T PT DT PT PT PT PT PT ST ST ST ST ST ST ST ST ST ST ST

D

200 ms

016 0 1 2 3 4 5 6 7 8 9 10 11 12

3

2

1

VT Event Count

ECG

Marker Channel

VT Interval

Figure 6-9. 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 Redetect NID, the device

redetects the VT.

Notes:

The device suspends VT detection (and Combined Count

•

detection) for 17 events following a defibr illation therapy
delivered in response to a detected VF.
detection helps avoid detecting transient VTs that can follow
high voltage therapies.

The PR Logic criteria are not applied during redetection.

•

However, the Stability criterion may withhold detection or
redetection of VT (or FVT via VT) throughout an episode.

6Detecting tachyarrhythmias

5

Suspending VT

97

6.7.4.3 VT acceleration

If the device redetects VT, it classifies the rhythm as accelerated
if the average of the four intervals before redetection is at least
60 ms less than the average of the four intervals before initial VT
detection. The most recent interval average is used to identify VT
acceleration if VT is redetected again during the episode.

5

If the defibrillation therapy is delivered as a result of a High Rate Timeout
“Skip to VF Therapy” operation, VT detection is not suspended (see
Section 6.11.4.1, page 111).

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Chapter 6

Enhancing detection with PR Logic criteria

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.

6.8 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.

For more information, see

Section 6.8.5, “Details about PR Logic pattern and rate

•

analysis”, page 101

Section 6.8.6, “Details about the PR Logic detection

•

criteria”, page 105

6.8.1 Parameters

AFib/AFlutter – Identifies rapidly conducted

atrial fibrillation, atrial flutter, or atrial
tachycardia

Sinus Tach – Identifies sinus tachycardia

1:1 VT-ST Boundary – Threshold between

the retrograde and antegrade zones used by
A-V pattern analysis. Allows customizing of
the Sinus Tach criterion for patients with slow
one-to-one conduction.

Other 1:1 SVTs – Identifies other one-to-one
SVTs where the atrial and ventricular
activation are roughly simultaneous

SVT Limit – Defines the minimum ventricular
interval at which the device applies the PR
Logic criteria

a

When you set VT Detection Enable to On or Monitor, the AFib/AFlutter and
Sinus Tach parameters are also automatically set to On.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

Ona; Off

Ona; Off

35; 50

On; Off

240; 250 … 320
330; 340 … 600 ms

; 66; 75; 85%

;

6.8.2 Considerations

Review the following information before programming PR Logic
parameters.

PR Logic criteria and double tachycardia detection – When
any of the PR Logic criteria are enabled, the device also enables
double tachycardia detection (VF, VT, or FVT in the presence of
an SVT; see Section 6.10.1, page 108).

6Detecting tachyarrhythmias

Enhancing detection with PR Logic criteria

Cautions:

Before enabling the Other 1:1 SVTs criterion, ensure

•

that the atrial lead has matured. This criterion could
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 VF/VT therapy in such patients.
See Section 6.8.5.1, “Pattern analysis of A-V and V-A
intervals”, page 102.

Use caution when programming the 1:1 VT-ST

•

Boundary. Incorrect programming of this parameter can
result in inappropriate therapies or underdetection of
tachyarrhythmias.

99

Sinus Tach and 1:1 VT-ST Boundary – When enabling the
Sinus Tach criterion in patients who exhibit slow 1:1 retrograde
conduction during VF or VT or slow antegrade conduction during
SVTs, make sure to set the 1:1 VT-ST Boundary parameter
appropriately. See Section 6.8.2.1, “Customizing PR Logic for
patients with slow conduction”, page 100.

VT Detection Enable, AFib/AFlutter and Sinus Tach – When
you set VT Detection Enable to On or Monitor, the AFib/AFlutter
and Sinus Tach parameters also automatically set to On.

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
less than the programmed SVT Limit (nominally 320 ms) if VT,
VF, or FVT detection criteria are satisfied.

VF Interval and SVT Limit – If you program an SVT Limit greater
than the VF Interval, you are effectively disabling the PR Logic
criteria for VF detection.

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual

100

Chapter 6

Enhancing detection with PR Logic criteria

6.8.2.1 Customizing PR Logic for patients with slow
conduction

Slow antegrade conduction during an SVT or slow 1:1 retrograde
conduction during VT can adversely affect the accuracy of the
Sinus Tach and Other 1:1 SVTs criteria. The 1:1 VT-ST Boundary
parameter allows you to customize the Sinus Tach criterion for
patients who exhibit slow conduction.

Note: Changing the 1:1 VT-ST Boundary parameter does not
affect the operation of the Other 1:1 SVTs criterion. Use caution
when enabling this criterion in patients who exhibit slow antegrade
or retrograde conduction.

The 1:1 VT-ST Boundary parameter represents an A-V interval
that is a percentage of a V-V interval. This value separates
the retrograde and antegrade zones used by PR Logic pattern
analysis operations. See Section 6.8.5.1, “Pattern analysis of A-V
and V-A intervals”, page 102.

If slow retrograde or antegrade conduction causes events to
occur in the incorrect zone, you can use the 1:1 VT-ST Boundary
parameter to increase the size of the appropriate zone. See
Figure 6-10, page 102 .

If a patient exhibits slow antegrade or retrograde conduction and
could benefit from a different 1:1 VT-ST Boundary setting, choose
a new setting as follows:

If the patient exhibits long V-A intervals during VT with 1:1

•

retrograde conduction, select 35%.

If the patient exhibits long A-V intervals during an SVT, select

•

a value that exceeds the A-V/V-V ratio observed during
stored VT/VF or SVT episodes. See Section 12.5.3.1, “EGM
Strip”, page 277.

6.8.3 Restrictions

Review the following information before programming PR Logic
parameters.

Sinus Tach and 1:1 VT-ST Boundary – The Sinus Tach criterion
must be on before 1:1 VT-ST Boundary can be selected.

VT Detection Enable and SVT Limit – The SVT Limit must be
shorter than the VT Interval (or VF Interval if VT Detection is off).

INTRINSIC™/INTRINSIC™30 7288/7287 Reference Manual