Medtronic 7290CX Reference Guide

ONYX™ VR 7290Cx

Single Chamber Implantable Cardioverter Defibrillator (VVEV-VVIR) with 9999 software

System Reference Guide

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

Onyx™ VR Model 7290Cx System Reference Guide

A guide to the operation and programming of the Onyx™ VR Model 7290Cx Implantable Cardioverter Defibrillator with Model 9999 software

The following are trademarks of Medtronic:

Active Can, Medtronic CareLink, Flashback, Marker Channel, Medtronic, Onyx, Patient Alert, QuickLink, Quick Look, T-Shock

Table of contents

1. Quick reference

Table of contents

Introduction ix Abbreviations and Acronyms xi

Primary capabilities 1-2 Physical characteristics 1-5 Electrical characteristics 1-6 Magnet application 1-11 Emergency settings 1-12 Programmable parameters overview 1-13 Detection parameters 1-14 Therapy parameters 1-15 Bradycardia pacing parameters 1-17 Automatic Capacitor Formation parameters 1-18 Data collection parameters 1-19 Patient Alert monitoring system parameters 1-20 Patient Information parameters 1-21 EP studies parameters 1-22 Fixed parameters 1-24 Notes 1-25

2. Emergency therapy

Therapy overview 2-2 Effect on system operation 2-2 On-screen and display panel buttons 2-3 Emergency defibrillation 2-4 Emergency cardioversion 2-5 Emergency Fixed Burst pacing 2-6 Emergency VVI pacing 2-7

3. System overview

System description 3-2 Detection and therapy overview 3-4 Disabling detection and therapies 3-6

4. Tachyarrhythmia detection

Sensing 4-2 VF detection 4-5 VT detection 4-8 Combined Count detection 4-11 VT Stability option 4-13

Onyx VR System Reference Guide v

Table of contents

EGM Width criterion 4-15 FVT detection 4-21 Termination and redetection 4-26

5. Tachyarrhythmia therapies

High voltage therapy overview 5-2 Defibrillation 5-8 Cardioversion 5-15 Antitachycardia pacing therapy overview 5-19 Programming ATP therapies 5-21 Burst pacing 5-23 Ramp pacing 5-25 Ramp+ pacing 5-27 Smart Mode 5-29 Progressive Episode Therapies 5-32

6. Bradycardia pacing

Pacing mode 6-2 Bradycardia pacing parameters 6-4 Post Shock Pacing parameters 6-7 Rate responsive pacing 6-9 Hysteresis 6-15 Ventricular Rate Stabilization 6-18

7. Programmer and software

Setting up and using the programmer 7-2 Using the programmer display screen 7-12 Starting a patient session 7-22 Programming parameter values 7-25 Live Rhythm Monitor 7-27 Recording live waveforms 7-42 Printing reports 7-46 Preferences 7-51 Changes This Session 7-54 Ending a patient session 7-55

8. Conducting system tests

System tests overview 8-2 Underlying Rhythm test 8-3 Pacing Threshold test 8-4 Lead Impedance test 8-6 EGM Width test 8-9 Manual EGM Amplitude test 8-13 Test Charge/Dump 8-15

vi Onyx VR System Reference Guide

Capacitor Formation 8-17

9. EP studies

EP studies overview 9-2 Delivering inductions 9-5 T-Shock induction 9-7 50 Hz Burst induction 9-8 Manual Burst induction 9-8 PES induction 9-9 Delivering manual therapies 9-10 Manual ATP (Antitachycardia Pacing) therapies 9-12

10. Data collection

Data collection overview 10-2 Quick Look 10-4 Setting up data collection 10-6 Counter data 10-10 Episode Data 10-14 Patient Information 10-27 Battery and Lead Measurements 10-31 Device Status Indicators 10-33 Saving and retrieving ICD data 10-35

Table of contents

11. Patient Alert monitoring system

Patient Alert setup 11-2 Instructions for the patient 11-7 Instructions for clinic personnel 11-9 Patient Alert event log 11-10

12. Implant and follow-up

Pre-Implant information 12-2 Operative set-up 12-3 Surgical approach 12-5 Sensing and pacing measurements 12-7 Defibrillation testing 12-8 Placing the ICD 12-14 Replacing the ICD 12-15 Pre-discharge evaluation 12-16 Follow-up recommendations 12-17

A. Appendix A - Warnings and precautions

General warnings A-2 Sterilization, storage, and handling A-2 Implantation and ICD programming A-3

Onyx VR System Reference Guide vii

Table of contents

Lead evaluation and lead connection A-4 Follow-up testing A-5 ICD explant and disposal A-6 Environmental and medical therapy hazards A-7 Home and occupational environments A-9

B. Appendix B - Parameter interlocks

Bradycardia pacing parameter interlocks B-2 Detection parameter interlocks B-3 Resolving Tachy/Brady parameter interlocks B-4

G. Glossary

I. Index

viii Onyx VR System Reference Guide

Introduction

Before implanting the ICD, it is strongly recommended that you follow these instructions:

■

Refer to the product Implant Manual (included in the ICD package) for information about ICD indications.

■

Thoroughly read this manual and the technical manuals for the leads used with the device.

■

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

Customer education

Medtronic invites physicians to attend an education seminar on the complete ICD system. The course includes indications for use, an overview of ICD system functions, implant procedures, and patient management.

Technical support

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

In addition, Medtronic maintains a professional staff of consultants to provide technical consultation to product users. For medical consultation, Medtronic can often refer product users to outside medical consultants with appropriate 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.

Onyx VR System Reference Guide ix

Introduction

References

Automatic defibrillation was invented and patented in 1953 by Dr. F. Zacouto, who designed an external device that delivered a defibrillation impulse to the heart upon detection of very rapid ECG activity in combination with the absence of arterial pulsations.

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

See these additional references for more background information:

■

Singer I, Ed. Implantable Cardioverter-Defibrillator. Armonk, NY: Futura Publishing Co. 1994.

■

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

Futura Publishing Co. 1998.

■

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

■

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

Academic Publishers 1996.

x Onyx VR System Reference Guide

Notice

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.

Abbreviations and Acronyms

ATP Antitachycardia Pacing

BOL Beginning of Life

bpm beats per minute

CNID Combined (VT and VF) Number of Intervals to Detect

CV Cardioversion

DF/Defib Defibrillation

ECG Electrocardiogram

EGM Electrogram

EOL End of Life

ERI Elective Replacement Indicator

FDI Fibrillation Detection Interval

FTI Fast Ventricular Tachycardia Detection Interval

FVT Fast Ventricular Tachycardia

ICD Implantable Cardioverter-Defibrillator

J joules

-1

min

ms milliseconds

mV millivolts

NID Number of Intervals to Detect

PES Premature Electrical Stimulation

POR Power On Reset

ppm paces or pulses per minute

PVC Premature Ventricular Contraction

RCNID Combined (VT and VF) Number of Intervals to Redetect

RNID Number of Intervals to Redetect

RR R-R interval; a ventricular interval

SVT Supraventricular Tachycardia

TDI Tachycardia Detection Interval

Vvolts

V. Ventricular

VF Ventricular Fibrillation

VF NID VF Number of Intervals to Detect

VF RNID VF Number of Intervals to Redetect

reciprocal minutes; for example, pacing pulses per minute

Abbreviations and Acronyms

Onyx VR System Reference Guide xi

Abbreviations and Acronyms

VRS Ventricular Rate Stabilization

VT Ventricular Tachycardia

VT NID VT Number of Intervals to Detect

VT RNID VT Number of Intervals to Redetect

xii Onyx VR System Reference Guide

Quick reference

Primary capabilities 1-2

Physical characteristics 1-5

Electrical characteristics 1-6

Magnet application 1-11

Emergency settings 1-12

Programmable parameters overview 1-13

Detection parameters 1-14

Therapy parameters 1-15

Bradycardia pacing parameters 1-17

Automatic Capacitor Formation parameters 1-18

Data collection parameters 1-19

Patient Alert monitoring system parameters 1-20

Patient Information parameters 1-21

EP studies parameters 1-22

Fixed parameters 1-24

Notes 1-25

Onyx VR System Reference Guide 1-1

Quick reference

Primary capabilities

39 cc Active Can device, 77 g (see page 1-5).

Tachyarrhythmia detection

■

Ventricular fibrillation and ventricular tachycardia detection (VF, VT, and FVT)

■

Single chamber VT Stability criterion

■

Single chamber EGM Width criterion

Tachyarrhythmia therapy

■

Up to six each automatic VF, VT, and FVT therapies

■

Ventricular defibrillation and cardioversion, 30 J delivered (see Table 1-7)

■

50% tilt biphasic waveform (see “Waveform” on page 5-7)

■

Burst, Ramp, and Ramp+ antitachycardia pacing

■

Smart Mode disables ineffective ATP therapies

■

Progressive Episode Therapies ensures increasingly aggressive therapy sequencing

Pacing management

■

Rate responsive bradycardia pacing up to 150 ppm (min-1): VVIR mode

■

Ventricular Rate Stabilization after short ventricular intervals

■

Single chamber hysteresis

1-2 Onyx VR System Reference Guide

Patient management

■

Audible Patient Alert monitoring system

■

Automatic, painless pacing and HV lead impedance testing

■

Programmer-assisted EGM Amplitude Test (see page 8-13)

■

Patient Information that can be entered, viewed, and printed via the programmer

■

Two simultaneous real-time EGMs: ventricular/far-field

■

Two channels stored EGM: ventricular/far-field

■

Marker Channel telemetry

■

256 Kbyte data storage – two EGMs, Markers, and Flashback Memory of V-V intervals

■

Save-to-Disk and Read-from-Disk patient data features

Tab le 1- 1. Onyx VR data collection summary

Tachy episodes

SVT/NST episodesa50 SVT/NST episodes: SVT text, stored EGM, intervals,

EGM capacity 12 minutes (2 channels) or 22 minutes (1 channel)

EGM sources Four options: ventricular near-field or far-field

EGM options Store before onset; Store during charging

Flashback Memory 1000 V-V intervals: before latest VF, before latest VT,

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

Episode counters - VF, FVT, and VT

150 VF/VT/FVT episodes: text, stored EGM, intervals, QRS Snapshot

QRS Snapshot

, NST episode summary

and before interrogation

- Non-sustained tachy episodes and SVTs

- Single PVCs and PVC runs

- Rate stabilizations, pulses and runs

- Percentage paced/sensed rhythm

Quick reference

Primary capabilities

Therapy Efficacy Counters

Counts for each VF, FVT, VT Therapy:

- Delivered

- Successful

- Unsuccessful

- Intervention Total number of aborted shocks

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

alert is triggered between clearing the log entries.

All tachy, NST, and SVT episode data is stored in the same block of memory.

For VT episodes, when EGM Width criterion is On or Passive.

Onyx VR System Reference Guide 1-3

Quick reference

Primary capabilities

Other features

■

Direct replacement for DF-1/IS-1 systems, including all Medtronic “C,” “CX,” and “D” ICDs

■

Medtronic icon-based programmer software interface

■

Quick Look programming summary, with QuickLink to stored episodes and observations

■

Chart ready full-size report printing (Refer to the reference manual provided with your programmer)

■

Non-invasive EP Study functions: ventricular inductions/manual therapies.

■

Auto-Resume feature automatically resumes detection after an induction (see “Auto-Resume” on page 9-3)

■

Smart Auto Cap Formation extends the formation timer after therapeutic charging

1-4 Onyx VR System Reference Guide

Physical characteristics

Tabl e 1-2. Onyx VR physical characteristics

Volume 39 cc

Mass 77 g

H x W x D

Surface area of device can 69.0 cm

Radiopaque IDb

Materials in contact with human tissue

Battery Lithium silver vanadium oxide

Connector configuration One IS-1 connector for pacing and sensing,

Quick reference

Physical characteristics

69.3 mm x 50.8 mm x 13.5 mm

PRP

Titanium/polyurethane/silicone rubber

Two DF-1 connectors for high voltage therapy, Active Can electrode

SVC

(HVX)

IS-1 V

(HVB)

DF-1

Can (HVA)

This measurement refers to the thickness (depth) of the can; grommets may protrude slightly beyond the surface.

Engineering series number follows the radiopaque code.

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.

Onyx VR System Reference Guide 1-5

Quick reference

Electrical characteristics

Longevity

Table 1-3 below provides longevity estimates based on accelerated battery discharge data and device modeling with the following programmed values:

■

60 ppm (min-1) pacing rate

■

2 V pacing pulse amplitude

■

0.6 ms pacing pulse width

■

30 J delivered therapy energy

■

six-month automatic capacitor formation intervals

Note: The EGM pre-storage feature is set to Off.

Tab le 1- 3. Onyx VR Projected longevity in years with 2 V pacing pulse

Percent pacing

0% Semi-annual 7.0 7.0

15% Semi-annual 6.9 7.0

50% Semi-annual 6.6 6.7

100% Semi-annual 6.1 6.5

With two-month extensions per 30 J charge (maximum of 12 months between formations). Therapeutic charging is in addition to capacitor formations.

amplitude and 0.6 ms pacing pulse width

Therapeutic shock frequency

Quarterly 6.4 6.4

Quarterly 6.3 6.3

Quarterly 6.0 6.2

Quarterly 5.7 6.0

500 Ω pacing

impedance

900 Ω pacing

impedance

1-6 Onyx VR System Reference Guide

Quick reference

Electrical characteristics

Table 1-4 below provides longevity estimates based on accelerated battery discharge data and device modeling with the following programmed values:

■

60 ppm (min-1) pacing rate

■

3 V pacing pulse amplitude

■

0.4 ms pacing pulse width

■

30 J delivered therapy energy

■

six-month automatic capacitor formation intervals

Note: The EGM pre-storage feature is set to Off.

Tabl e 1-4. Onyx VR projected longevity in years with 3V pacing pulse

amplitude and 0.4 ms pacing pulse width

Percent pacing

0% Semi-annual 7.0 7.0

15% Semi-annual 6.7 6.9

50% Semi-annual 6.0 6.5

100% Semi-annual 5.4 6.0

Therapeutic shock frequency

500 Ω pacing

impedance

900 Ω pacing

impedance

Quarterly 6.4 6.4

Quarterly 6.2 6.3

Quarterly 5.6 6.0

Quarterly 5.0 5.5

With two-month extensions per 30 J charge (maximum of 12 months between formations). Therapeutic charging is in addition to capacitor formations.

Onyx VR System Reference Guide 1-7

Quick reference

Electrical characteristics

The following factors result in decreased longevity:

■

an increase in pacing rate, pacing amplitude or pulse width, the ratio of bradycardia paced to sensed events, or the charging frequency

■

a decrease in pacing impedance

■

using the pre-onset EGM storage feature or Holter telemetry.

To maximize ICD longevity:

■

Optimize pacing rate and output parameters for the patient.

■

Set the delivered energy value for the first programmed high voltage therapy to a value lower than maximum energy.

■

Set the automatic capacitor formation interval to a longer value (unless a shorter interval is required to maintain clinically acceptable charge times).

■

Use the pre-onset EGM storage feature and Holter telemetry only for short periods of time.

Battery voltage

Battery voltage appears on the programmer display and on printed reports. For more information, see “Replacement indicators” on page 12-18 and “Preparing the ICD for implant” on page 12-4.

Tab le 1- 5. Battery voltage Indicators

Elective Replacement (ERI)

≤ 2.55 V

Pacing mode and rate (magnet and non-magnet) as programmed

End of Life (EOL)

≤ 2.40 V

Pacing mode and rate (magnet and non-magnet) as programmed

The minimum time between ERI and End of Life is three months, assuming 100% VVI pacing at 60 ppm (min

When the battery reaches EOL, immediate replacement is recommended. See also “Charge Circuit Inactive” on page 5-4.

-1

), 3 V, 0.4 ms; 510 Ω pacing load; and six 30 J charges.

1-8 Onyx VR System Reference Guide

Quick reference

Electrical characteristics

Charge time

The high voltage capacitors charge more rapidly just following a capacitor formation, when they are fully formed. Between formations, the capacitors gradually deform, resulting in longer charge times toward the end of the formation interval. See “Using Automatic Capacitor Formation to manage charge time” on page 8-17 for information on managing charge time. Also, see “Test Charge/Dump” on page 8-15 for instructions on using the Test Charge feature to measure charge time. Table 1-6 provides typical full energy charge times at BOL and ERI based on the time interval since the last capacitor formation. A full energy charge is any charge to full energy (either via a capacitor formation or therapy delivery).

Tab le 1- 6. Typical Full Energy (30 J Delivered) charge times

Capacitors

fully formed

At Beginning of Life (BOL)

Near Elective Replacement Indicator (ERI)

Typical values for stated conditions, actual charge time performance may vary.

6 seconds ≈ 1 second

14 seconds ≈ 1 seconds

1 month after

capacitor formation

longer than fully formed

6 months

after capacitor formation

≈ 2 seconds longer than fully formed

≈ 5 seconds longer than fully formed

Onyx VR System Reference Guide 1-9

Quick reference

Electrical characteristics

High voltage therapy energy

Table 1-7 compares delivered energy levels to energy levels stored by the device.

Note: The stored energy of the device is derived from the peak capacitor voltage and is always greater than the energy delivered by the device.

Tab le 1- 7. Comparing programmed (actual delivereda) and storedb energy levels

Programmed (Actual

Delivered) Energy (J)

0.4 0.5 .09 9 11 1.94

0.6 0.8 .13 10 12 2.16

0.8 1.0 .17 11 13 2.38

1.0 1.2 .22 12 14 2.59

1.2 1.5 .26 13 15 2.81

1.4 1.7 .30 14 16 3.02

1.6 2.0 .35 15 18 3.24

1.8 2.2 .39 16 19 3.46

2 2.4 .43 18 21 3.89

3 3.6 .65 20 24 4.32

4 4.7 .86 22 26 4.75

5 5.9 1.08 24 28 5.18

6 7.1 1.30 26 31 5.62

7 8.3 1.51 28 33 6.05

8 9.4 1.73 30 35 6.48

Energy and voltage delivered at connector block into a 75 Ω load.

Energy stored at end of charge on capacitor.

Typical charge time at BOL, with fully formed capacitors.

Stored

Energy (J)

Charge

Time

(sec)

Programmed (Actual

Delivered) Energy (J)

Stored

Energy (J)

Charge

Time

(sec)

1-10 Onyx VR System Reference Guide

Quick reference

Magnet application

Applying a magnet closes a reed switch within the ICD. When the magnet is removed, the ICD returns to its programmed operations.

Tab le 1- 8. Effects of magnet application

Pacing Mode As programmed

Pacing Rate and Interval As programmed

VF, VT, and FVT Detection and Therapy

Patient Alert Audible Tones

The programming head contains a magnet which can suspend detection. However, if the Resume option in the programmer has been enabled, detection will remain enabled.

The alert sounds only if the Patient Alert is programmed On for any alert except POR. A POR alert causes an alarm every 20 hours, even if Patient Alert is programmed to Off.

Suspended

(30 seconds or less) Continuous tone (alarm OK) On/Off intermittent tone (seek follow-up) High/Low dual tone (urgent follow-up)

Onyx VR System Reference Guide 1-11

Quick reference

Emergency settings

The table below lists the values that can be selected for the ICD emergency therapy parameters. Default values are highlighted in bold, italicized text. The Notes column lists letters that correspond to notes on page 1-25.

Tabl e 1-9. Emergency therapy parameters

Parameter Selectable values (and default value)Notes

Defibrillation

Energy (J) 10, 11, . . ., 16,

Pathway AX→B

Cardioversion

Energy (J) 0.4, 0.6, . . ., 1.8,

Pathway AX→B

Fixed Burst

Pacing Interval (ms) 100, 110, . . ., 350,

Pulse Amplitude (V) 8

Pulse Width (ms) 1.6

18, 20, . . ., 30

2, 3, . . ., 16 18, 20, . . ., 30

360, 370, . . ., 600

VVI Pacing

Pacing Mode VVI

Lower Rate (ppm, min

Vent. Rate Stabilization Off

Hysteresis Off

Sensitivity As programmed

Pulse Amplitude (V) 8

Pulse Width (ms) 1.6

Pace Blanking (ms) 320

Post Shock Pace Blanking (ms) 320 A.

-1

)70

1-12 Onyx VR System Reference Guide

Programmable parameters overview

Quick reference

Programmable parameters overview

The tables that follow (Table 1-10 to Table 1-17) list the values that can be selected for all ICD programmable parameters. As applicable, these tables also indicate the Medtronic nominal value, the POR value, and the shipped value for each parameter.

Medtronic nominal values – These values are suggested settings for parameters under nominal conditions. Medtronic nominal values, if applicable, are indicated in the Programmable Values column in bold, italicized text.

POR values – These are the values to which the ICD resets parameters after a power-on reset (POR). If a POR occurs, the ICD sounds a high-urgency Patient Alert tone every 20 hours. See the “Power-On Reset recovery procedure” on page 10-34.

Shipped values – These are the programmed parameter values when the ICD is shipped from Medtronic.

The Notes column in each table lists letters that correspond to notes on page 1-25. These include exceptions or clarifications that relate to the values listed in the programmable parameter tables.

Onyx VR System Reference Guide 1-13

Quick reference

Detection parameters

Table 1-10. Detection parameters

Parameter Programmable values

(and Medtronic Nominal)

VF Detection parameters

Detection Enable On, Off On Off

Interval (ms) 240, 250 . . . 320,

330, 340, . . ., 400

Initial NID 12/16, 18/24, 24/32,

30/40, 45/60, 60/80, 75/100, 90/120, 105/140, 120/160

Redetect NID 6/8, 9/12, 12/16, 18/24,

21/28, 24/32, 27/36, 30/40

V. Sensitivity (mV) 0.15, 0.3, 0.45, 0.6,

0.9, 1.2

FVT Detection parameters

Detection Enable Off, via VF, via VT Off Off

Interval (ms) 200, 210, . . ., 600 — — C., F.

V. Sensitivity (mV) 0.15, 0.3, 0.45, 0.6,

0.9, 1.2

POR

value

320 320 C.

18/24 18/24 B.

12/16 12/16

0.3 0.3 D., E.

Shipped

value

Notes

VT Detection parameters

Detection Enable On, Off Off Off

Interval (ms) 280, 290, . . ., 400,

Initial NID 12, 16, . . ., 52,

Redetect NID 4, 8, 12, . . ., 52 12 12

V. Sensitivity (mV) 0.15, 0.3, 0.45, 0.6,

VT Stability criterion parameters

VT Stability (ms) Off, 30, 40, . . ., 100 Off Off C.

EGM Width criterion parameters

EGM Width Enable On, Passive, Off Off Off G.

Slew threshold (mV/sec) 18, 24, 30, . . ., 144 30 30

Width threshold (ms) 24, 28, 32, . . ., 80, . . ., 152 80 80

1-14 Onyx VR System Reference Guide

400 400 C.

410, 420, . . ., 600

16 16

76, 100

0.3 0.3 D., E.

0.9, 1.2

Quick reference

Therapy parameters

Table 1-11. Therapy parameters (Sheet 1 of 2)

Parameter Programmable values

(and Medtronic Nominal)

VF therapy parameters

Therapy Status On, Off On (all) On (all)

Energy (J) 0.4, 0.6, . . ., 1.8,

2, 3, . . ., 16, 18, 20, . . ., 30

Pathway AX→B, B→AX AX→B

Reconfirm VF Yes , No Yes Yes L.

VT and FVT therapy parameters

Cardioversion therapy parameters

Therapy Status On, Off — —

Energy (J) 0.4, 0.6, . . ., 1.8,

2, 3, . . ., 16, 18, 20, . . ., 30

Pathway AX→B, B→AX — — I.

POR

value

30 (all) 30 (all) I., J., K.

(all)

— — I., K.

Shipped

value

AX→B

(all)

Notes

Burst Pacing therapy parameters

Therapy Status On, Off — —

Initial # Pulses 1, 2, . . ., 6, . . ., 15 — — I.

R-S1 Interval (% of R-R)

Pacing Interval Decrement (ms) 0, 10, . . ., 40 — —

# Sequences 1, 2, 3, . . ., 10 — —

Smart Mode On, Off ——M.

50, 53, 56, 59, 63, 66, . . ., 84, 88, 91, 94, 97

—— I.

Onyx VR System Reference Guide 1-15

Quick reference

Therapy parameters

Table 1-11. Therapy parameters (Sheet 2 of 2)

Parameter Programmable values

Ramp Pacing therapy parameters

Therapy Status On, Off — —

Initial # Pulses 1, 2, . . ., 8, . . ., 15 — — I., X.

R-S1 Interval (% of R-R)

Pacing Interval Decrement (ms) 0, 10, . . ., 40 — — I.

# Sequences 1, 2, 3, . . ., 10 — —

Smart Mode On, Off ——M.

Ramp+ Pacing therapy parameters

Therapy Status On, Off — —

Initial # Pulses 1, 2, 3, . . ., 15 — — I.

R-S1 Interval (% of R-R)

S1-S2 Interval (% of R-R)

S2-Sn Interval (% of R-R)

# Sequences 1, 2, . . ., 5, . . ., 10 — —

Smart Mode On, Off ——M.

(and Medtronic Nominal)

50, 53, 56, 59, 63, 66, . . ., 84, 88, 91, 94, 97

50, 53, 56, 59, 63, 66, . . ., 75, . . ., 84, 88, 91, 94, 97

50, 53, 56, 59, 63, 66, 69, . . ., 84, 88, 91, 94, 97

50, 53, 56, 59, 63, 66, . . ., 84, 88, 91, 94, 97

POR

value

— — I., X.

—— I.

Shipped

value

Notes

Shared Parameters for Tachyarrhythmia therapies

Shared by all Automatic ATP therapies I.

V. Pulse Width (ms) 0.03, 0.06,

V. Amplitude (V) 1, 2, . . ., 6, 8 88

V. Pace Blank (ms) 150, 160, . . ., 240, . . ., 440 240 240

ATP Minimum Interval (ms) 150, 160, . . ., 200, . . ., 400 200 200

Shared by all VF, VT, and FVT therapies

Progressive Episode Therapies Enable

0.1, 0.2, . . ., 1.6

On, Off Off Off

1-16 Onyx VR System Reference Guide

1.6 1.6

Bradycardia pacing parameters

Tab le 1- 12. Bradycardia pacing parameters (Sheet 1 of 2)

Parameter Programmable values

Pacing Mode VVIR, VVI VVI VVI

Lower Rate (ppm, min

Upper Sensor Rate (ppm, min

Sensitivity (mV) 0.15, 0.3, 0.45, 0.6,

Pulse Width (ms) 0.03, 0.06,

Pulse Amplitude (V) 1, 2, 3, . . ., 6, 8 8 3

Pace Blanking (ms) 150, 160, . . ., 200,

-1

)

-1

) 34, 35, 40, . . ., 60,

(and Medtronic Nominal)

70, 75, . . ., 105, 109, 115, 120

80, 85, . . ., 105, 109, 115, 120, 125, 130, 136, 140, 146, 150

0.9, 1.2

0.1, 0.2, . . ., 0.4,

0.5, 0.6, . . . , 1.6

210, 220, . . ., 440

POR

value

65 40 H.

120 120 H.

0.3 0.3 D., E.

1.6 0.4

320 200

Quick reference

Shipped

value

Notes

Post-Shock Pacing parameters

Pulse Width (ms) 0.03, 0.06,

Pulse Amplitude (V) 1, 2, 3, 4, 5, 6, 886

Pace Blanking (ms) 150, 160, . . ., 200,

Rate Response Pacing parameters

Rate Response 1, 2, . . ., 7, 8, 9, 10 7 7

Activity Threshold Low, Medium Low,

Activity Acceleration (sec.) 15, 30, 60 30 30

Activity Deceleration (min.) Exercise, 2.5, 5, 10 5 5

Hysteresis

Enable-Rate (bpm, min

-1

) Off, 34, 40, 50, 60, 70, 80 Off Off N.

0.1, 0.2, . . ., 1.6

210, 220, . . ., 440

Medium, Medium High, High

1.6 1.6

320 200

High Medium

Onyx VR System Reference Guide 1-17

Quick reference

Automatic Capacitor Formation parameters

Tabl e 1 -12. Bradycardia pacing parameters (Sheet 2 of 2)

Parameter Programmable values

(and Medtronic Nominal)

Ventricular Rate Stabilization parameters

Enable On, Off Off Off

Interval Increment (ms) 50, 60, . . ., 150,

160, 170, . . ., 400

Minimum Interval (ms) 500, 550, . . ., 900 500 500

POR

value

150 150

Automatic Capacitor Formation parameters

Table 1-13. Automatic Capacitor Formation parameters

Parameter Programmable values

Automatic Capacitor Formation Interval (months)

(and Medtronic Nominal)

Off, 1, 2, . . ., 6 6OffO.

POR

value

Shipped

value

Notes

1-18 Onyx VR System Reference Guide

Data collection parameters

Tab le 1- 14. Data Collection setup

Parameter Programmable values

EGM Source parameters

EGM Channel 1 Source HVA to HVB, HVA to Vring,

EGM Channel 1 Range (mV) ± 4, ± 8, ± 16 ± 8 ± 8

EGM Channel 2 Source HVA to HVB, HVA to Vring,

EGM Channel 2 Range (mV) ± 4, ± 8, ± 16 ± 8 ± 8

Store EGM Channel 1? Yes, No No No

Store EGM Channel 2 Yes (fixed) Yes Yes

Store EGM during charging? Yes, No Yes Yes

Store EGM before tachycardia starts?

(and Medtronic Nominal)

Vtip to HVB, Vtip to Vring

Ye s , No No No

POR

value

HVA to HVB HVA to HVB Q.

Vtip to Vring Vtip to Vring Q.

Quick reference

Shipped

value

Notes

Device Date/Time

Premature Event Recording parameters

Premature Event Threshold (%)

Holter Telemetry parameters

Duration (hours) Off, 0.5, 1, 2, 4,

(enter time and date) — — T.

56, 59, 62, 66, 69, . . ., 84, 88, 91, 94, 97

8, 16, 24, 36, 46

69 69

Off Off

Onyx VR System Reference Guide 1-19

Quick reference

Patient Alert monitoring system parameters

Table 1-15. Patient Alert setup

Parameter Programmable values

(and Medtronic Nominal)

Alert Time

Hour 0, 1, 2, . . ., 23 — —

Minute 0, 10, . . ., 50 — —

Lead Impedance Out Of Range Alert

Pacing Lead Impedance Alert W.

Enable On, Off Off Off

Minimum Threshold (Ω) 200 (fixed) — —

Maximum Threshold (Ω) 2000 (fixed) — —

Defibrillation Lead Impedance Alert W.

Enable On, Off Off Off

Minimum Threshold (Ω) 10 (fixed) — —

Maximum Threshold (Ω) 200 (fixed) — —

Alert Urgency Low, High — —

POR

value

Shipped

value

Notes

Low Battery Voltage Alert

Alert Enable - Urgency Off, On-Low, On-High Off Off

Battery Voltage Threshold (V) 2.55 (ERI) — —

Excessive Charge Time Alert

Alert Enable - Urgency Off, On-Low, On-High Off Off

Charge Time Threshold (seconds) 15, 16, 17, 18, . . ., 25 — —

Number Of Shocks Delivered In an Episode Alert

Alert Enable - Urgency Off, On-Low, On-High Off Off

Number of Shocks Threshold 1, 2, 3, 4, 5, 6 — —

All Therapies In A Zone Exhausted for an Episode Alert

Alert Enable - Urgency Off, On-Low, On-High Off Off

1-20 Onyx VR System Reference Guide

Patient Information parameters

Quick reference

Patient Information parameters

Tab le 1- 16. Description of Patient Information

Information field Description and action

Patient Enter the patient name or ID number (up to 30 characters).

ID Enter the patient ID.

Date of Birth Select patient’s date of birth.

ICD Number (Not selectable)

Lead 1 . . . Lead 2 . . . Lead 3 . . .

Implant Enter measured values from implant. Using the displayed submenu, enter new

Notes Enter notes about patient or other information.

History (2 fields) Select medical history from list box. If necessary, you can indicate that more

EF, on Select the Ejection Fraction from a table of values. Then enter the date in the

Physician Select or add the name of the physician.

Phone Enter the phone number of the physician.

Hospital Select or add the hospital information.

Last Update (Not selectable)

Screen displays serial number for implanted ICD after interrogation.

Enter detailed information for leads 1, 2, and 3:

• Model

• Pos it io n: Select from the list of positions, or enter position

• Serial Number

• Manufacturer

• Implant date

information from the keyboard and make list box selections.

information is located in the Notes field.

following field.

Screen displays the date of the last Patient Information update.

Onyx VR System Reference Guide 1-21

Quick reference

EP studies parameters

Table 1-17. EP Studies parameters (Sheet 1 of 2)

Parameter Selectable values (and default value)Notes

Inductions

T-Shock Induction parameters

#S1 2, 3, . . ., 8

S1S1 (ms) 350, 360, . . ., 400,

410, 420, . . ., 1760

Delay (ms) 50, 60, . . ., 310,

320, 330, . . ., 600

Energy (J) 0.4, 0.6, . . ., 1.8,

2, 3, . . ., 16, 18, 20, . . ., 30

Pathway AX→B, B→AX

Waveform Monophasic, Biphasic

Pulse Amplitude (V) 8 (fixed)

Pulse Width (ms) 1.6 (fixed)

Enable Enabled, Disabled

Resume at Deliver Enabled, Disabled

50 Hz Burst Induction parameters V.

Interval (ms) 20 (fixed)

Pulse Amplitude (V) 1, 2, . . ., 6, 8

Pulse Width (ms) 0.03, 0.06,

Resume at Burst Enabled, Disabled

Manual Burst Induction parameters V.

Interval (ms) 100, 110, . . ., 600

Pulse Amplitude (V) 1, 2, . . ., 5, 6, 8

Pulse Width (ms) 0.03, 0.06,

Resume at Burst Enabled, Disabled

1-22 Onyx VR System Reference Guide

0.1, 0.2, . . ., 1.6

0.1, 0.2, . . ., 0.5,

0.6, 0.7, . . ., 1.6

Quick reference

EP studies parameters

Table 1-17. EP Studies parameters (Sheet 2 of 2)

Parameter Selectable values (and default value)Notes

PES Induction parameters

#S1 1, 2, . . ., 8,

S1S1 (ms) 100, 110, . . ., 600,

S1S2 (ms) Off, 100, 110, . . ., 400,

S2S3 (ms) Off, 100, 110, . . ., 600 V.

S3S4 (ms) Off, 100, 110, . . ., 600 V.

Pulse Amplitude (V) 1, 2, . . ., 5, 6, 8

Pulse Width (ms) 0.03, 0.06,

Resume at Deliver Enabled, Disabled

9, 10, . . ., 15

610, 620, . . ., 1760

410, 420, . . ., 600

0.1, 0.2, . . ., 0.5,

0.6, 0.7, . . ., 1.6

Manual Therapy parameters

In general, each manual therapy uses the same parameter values as the automatic therapy. See “Therapy parameters” beginning on page 1-15.

Onyx VR System Reference Guide 1-23

Quick reference

Fixed parameters

Table 1-18. Fixed parameters

Parameter Value Notes

Sensing

Blanking periods

After a sensed vent. event 120 ms

After charging ends 300 ms

After HV therapy 520 ms

High Voltage therapies

Maximum charging period 30 seconds

Waveform Biphasic

Tilt 50%

VF Synchronization periods R.

After post-charge blanking 500 ms

After a sensed event 500 ms

Synchronization Refractory periods

After V. sense during CV synch. 200 ms

After charge during DF synch. 400 ms P.

Post-Therapy

Escape interval after CV/Defib 1200 ms

Suspension of VT Detection after Defibrillation therapy

17 V. events

EP studies

T-Shock S1 pacing outputs 1.6 ms at 8 V V.

Hardware parameters

Ventricular rate limit (protective feature)

Input protection 100 kΩ minimum

171 ppm (min-1)S.

1-24 Onyx VR System Reference Guide

Notes

Quick reference

Post-shock Pace Blanking is reprogrammed by Emergency VVI pacing, but is not displayed on the Emergency Screen.

The VF Initial NID cannot be programmed to a value greater than 30/40 if VT Detection is enabled.

The measured intervals are truncated to a 10 ms multiple (for example, 457 ms becomes 450 ms). The device uses this truncated interval value when applying the programmed criteria and calculating interval averages.

With a 40 ms sine2 waveform. When using the CENELEC waveform, the rated sensing threshold value will be 1.5 times the rated sine sensing threshold.

This setting applies to all sensing for both tachyarrhythmia detection and bradycardia pacing operations.

Nominal value is blank until detection is enabled.

EGM width is measured on the intracardiac EGM programmed as Channel 2.

The shortest pacing escape interval must exceed all programmed Detection Intervals by at least 60 ms.

These specifications apply to both automatic and manual therapies, except as noted.

For automatic therapy 3, 4, 5, or 6, energy must be at least 10 J.

Delivered energy based on a biphasic pulse into a 75 Ω load.

Applies only to the first VF therapy that is programmed On.

Smart Mode is available only for Therapies 1, 2, 3, and 4.

Pacing mode must be VVI, and the hysteresis rate must be less than the pacing rate.

The ICD is shipped with Automatic Capacitor Formation Interval set to

Off. However, when VF Detection is set to On for the first time, the

Automatic Capacitor Formation Interval is automatically set to

When Reconfirm VF is active, a refractory period equal to 60 ms plus the greatest programmed detection interval follows the post-charge blanking period and all paced events.

Both channels appear on-screen as real-time telemetered signals.

When Reconfirm VF is active, the VF synchronization (reconfirmation) periods are 60 ms plus the greatest programmed detection interval, and the synchronization escape period is equal to the current lower rate (sensor or programmed lower rate) escape period.

Does not apply during therapies or programmed high rates.

The time stamp on episode records and other stored data is determined by the device’s date/time clock.

Delivered in the VVI mode.

6 month.

Notes

Onyx VR System Reference Guide 1-25

Quick reference

Notes

Delivered in the VOO mode.

After a POR, all programmed Patient Alert conditions are disabled. The Reset condition itself activates a high-urgency alert that sounds every 20 hours until cleared.

For manual ramp therapy, 6 is the nominal number of pulses, and 97% is the nominal value for % of R-R interval.

1-26 Onyx VR System Reference Guide

Emergency therapy

Therapy overview 2-2

Effect on system operation 2-2

On-screen and display panel buttons 2-3

Emergency defibrillation 2-4

Emergency cardioversion 2-5

Emergency Fixed Burst pacing 2-6

Emergency VVI pacing 2-7

Onyx VR System Reference Guide 2-1

Emergency therapy

Therapy overview

The ICD provides the following Emergency therapies:

To deliver an Emergency therapy, the programming head must be positioned over the ICD.

Defibrillation is the default Emergency therapy, and 30 J is the default stored energy. When you select [Emergency] and [DELIVER], the ICD charges and delivers a biphasic 30 J shock along the AX>B pathway.

If you select a different defibrillation energy, the programmer resets the energy to 30 J the next time you select [Emergency]. Emergency Cardioversion and Emergency Fixed Burst values remain as selected for the duration of the session.

■

Defibrillation therapy

■

Cardioversion therapy

■

Fixed Burst pacing therapy

■

Maximum output VVI pacing

Aborting the therapy – As a safety precaution, the programmer also displays an

[ABORT] button, which immediately terminates any

Emergency therapy in progress.

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

Effect on system operation

The ICD suspends its 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] re-enables detection.

2-2 Onyx VR System Reference Guide

On-screen and display panel buttons

On the Model 9790C programmer, the on-screen [Emergency] button and the red mechanical [Emergency] button by the display panel are equivalent at all times.

Red emergency button

On the Model 9790C programmer, the on-screen [DELIVER] button and

the yellow-on-blue mechanical Deliver button by the display panel are equivalent during Emergency operations only. The mechanical Deliver button operates only during emergency operations.

Functions the same as on-screen

[Emergency] at all times.

Emergency therapy

Yellow-on-blue deliver button

Functions the same as on-screen

[DELIVER], but only during

Emergency functions.

Note: A mechanical Deliver button is not available on the Medtronic CareLink

Model 2090 programmer. The [Emergency] button at the bottom

of the display screen provides access to the on-screen [DELIVER] button to deliver emergency tachyarrhythmia therapy.

Emergency VVI button

VVI

On the Model 2090 Programmer, the red

Emergency VVI button by the

display panel provides immediate access for emergency VVI pacing.

Temporary parameter values

Emergency tachyarrhythmia therapies use test values that do not change the permanently programmed parameters of the ICD.1 Test values are not in effect until you begin the temporary operation by selecting After the tachyarrhythmia therapy is complete, the ICD reverts to its permanently programmed values.

[DELIVER].

Delivery of Emergency VVI Pacing permanently changes the programmed bradycardia pacing values to those used during emergency pacing (see page 2-7).

Onyx VR System Reference Guide 2-3

Emergency therapy

Emergency defibrillation

To deliver emergency 30 J defibrillation

1. Position the programming head over the ICD.

2. Select [Emergency].

3. Select [DELIVER].

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

To change the defibrillation energy and deliver

1. From the Emergency Therapy screen, select Energy.

2. Select a new energy value.

3. Select [DELIVER].

Select to change

emergency defibrillation

energy

Select to deliver

emergency defibrillation

2-4 Onyx VR System Reference Guide

Figure 2-1. Emergency defibrillation screen

Emergency cardioversion

To deliver emergency cardioversion

1. Position the programming head over the ICD.

2. Select [Emergency].

3. Select [Cardioversion].

4. Accept the cardioversion energy shown on the screen, or select

Energy and select a new value from the window.

5. Select [DELIVER].

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

Emergency therapy

Emergency cardioversion

Select to change

emergency cardioversion

Select to deliver

emergency cardioversion

energy

Figure 2-2. Emergency cardioversion screen

Onyx VR System Reference Guide 2-5

Emergency therapy

Emergency Fixed Burst pacing

To deliver emergency Fixed Burst pacing

1. Position the programming head over the ICD.

2. Select [Emergency].

3. Select [Fixed Burst].

4. Accept the pacing interval shown on the screen, or select Interval for

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].

Select to change Burst

Interval

Press and hold to deliver

emergency Fixed Burst

pacing

2-6 Onyx VR System Reference Guide

Figure 2-3. Emergency Fixed Burst pacing screen

Emergency VVI pacing

Emergency VVI Pacing programs the device to deliver high-output ventricular pacing. On the Model 2090 programmer, the red Emergency VVI button on the display panel provides immediate access to emergency VVI pacing. You can initiate emergency VVI pacing from the Emergency screen or by pressing the red mechanical button on the programmer display panel and selecting VVI Pacing on the screen.

To deliver emergency VVI pacing

1. Position the programming head over the ICD.

2. Select [Emergency].

3. Select [VVI Pacing].

4. Select [PROGRAM]. If the programming is confirmed, the ICD is set

to the following maximum output bradycardia pacing values.

Pacing Mode VVI

Lower Rate 70 ppm (min

Amplitude 8 V

Width 1.6 ms

Pace Blanking 320 ms

Post-Shock Pace Blanking 320 ms

Hysteresis Off

Ventricular Rate Stabilization Off

Reprogrammed by Emergency VVI operation, but not displayed on Emergency screen.

Emergency therapy

Emergency VVI pacing

-1

)

Onyx VR System Reference Guide 2-7

Emergency therapy

Emergency VVI pacing

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

To disable emergency VVI pacing, reprogram the bradycardia pacing parameters from the Parameters screen.

Emergency VVI pacing

parameters

(fixed)

Select to program

emergency VVI pacing

Figure 2-4. Emergency VVI pacing screen

2-8 Onyx VR System Reference Guide

System overview

System description 3-2

Detection and therapy overview 3-4

Disabling detection and therapies 3-6

Onyx VR System Reference Guide 3-1

System overview

System description

The Onyx VR Model 7290Cx Implantable Cardioverter Defibrillator (ICD) System is an implantable medical device system that automatically detects and treats episodes of ventricular fibrillation (VF), ventricular tachycardia (VT), fast ventricular tachycardia (FVT), and bradyarrhythmia. When a cardiac arrhythmia is detected, the implantable device delivers defibrillation, cardioversion, antitachycardia pacing, or bradycardia pacing therapy.

The VF Detection circuitry monitors the cardiac cycle length to identify a VF episode. Upon detection of VF, the ICD provides a biphasic defibrillation shock of up to 30 J delivered energy. If the VF episode persists, up to five more individually programmed defibrillation shocks can be delivered.

The VT Detection circuitry monitors the cardiac cycle length to identify the presence of a tachycardia. Upon detection of VT, the ICD delivers its first programmed VT therapy to restore the patient’s normal cardiac rhythm. If the VT episode persists, up to five more individually programmed VT therapies can be delivered. Therapy selections include three methods of antitachycardia pacing and synchronized cardioversion.

FVT detection can be programmed through the VT Detection algorithm or through the VF Detection algorithm. As with VF and VT, up to six FVT therapies can be independently programmed. Therapy selections include three methods of antitachycardia pacing and synchronized cardioversion.

The ICD provides rate responsive single chamber bradycardia pacing to optimize hemodynamics. An internal piezoelectric sensor enables the ICD to increase and decrease its pacing rate in response to the patient’s detected physical activity.

The ICD is intended for implantation with transvenous or epicardial defibrillation leads. The lead system should consist of bipolar or paired unipolar pacing/sensing leads in the ventricle, and one or two high voltage cardioversion/defibrillation electrodes. (The Active Can device case also serves as one high voltage electrode.) Sensing of cardiac activity and the delivery of pacing stimuli occur between the ventricular pacing/sensing electrodes.

The physician can use the ICD to conduct noninvasive electrophysiologic studies. The physician can also manually deliver any of the ICD therapies to manage an induced or spontaneous tachyarrhythmia.

3-2 Onyx VR System Reference Guide

System overview

System description

A programmable Patient Alert monitoring feature notifies the patient by audible tones if certain conditions (such as low battery voltage and high lead impedance), selected by the physician, occur. The patient can then respond based on instructions provided by the physician.

The ICD provides the physician with real-time information about its detection and therapy parameters and status. The ICD also provides accumulated data on its operation, including stored electrograms, records of tachyarrhythmia episodes detected and treated, bradycardia interventions, and the efficacy of therapy. All of this information can be printed and retained in the patient's file, saved in the programmer to read back at a later time, or saved in electronic format on a floppy diskette.

Onyx VR System Reference Guide 3-3

System overview

Detection and therapy overview

Implanted sensing electrodes provide a ventricular intracardiac electrogram to the ICD. The ICD measures the time between events to determine V-V intervals and calculates the ventricular rate from these intervals.

When a V-V interval falls within the programmed VF, VT, or FVT detection zone, it increments a VF or VT event counter. If either counter reaches the Number of Intervals to Detect (NID) programmed by the physician, the ICD detects the arrhythmia and delivers the programmed therapy.

Monitor for next

R-wave

Normal sinus rhythm

Detect depolarization and

measure the R-R interval

Classify the interval and

update event counters

Detect an arrhythmia episode

Ye s

Deliver therapy

Monitor for redetection and

termination

Redetection

After a therapy delivery, if the VF or VT event counter reaches the programmed “Number of Intervals to Redetect” (RNID), the episode is redetected and the next programmed therapy is delivered. This progression continues until the ICD confirms termination of the episode (“Therapy efficacy” on page 4-27) or delivers all the therapies programmed for the detected tachyarrhythmia.

3-4 Onyx VR System Reference Guide

Detection and therapy overview

System overview

Ventricular therapies

The ICD provides five ventricular therapies: Burst pacing; Ramp pacing; Ramp+ pacing; synchronized cardioversion; and defibrillation. Each VF episode can be treated with up to six defibrillation shocks. Each VT or FVT episode can be treated with up to six therapies of antitachycardia pacing and/or cardioversion. An FVT therapy set must end with at least one cardioversion therapy.

Suspending detection and therapy

Automatic suspension of detection

Detection is temporarily suspended during:

■

Programming head application (unless [Resume] is programmed) or other magnet application. Detection resumes automatically when the programming head or magnet is removed.

■

Temporary programmer operations such as manual and emergency therapies delivered through the programmer. Detection remains suspended until the programming head is removed or [Resume] is programmed.

Note: If the Resume at Deliver feature is disabled and detection was suspended before a temporary induction is performed, then detection remains suspended.

■

Automatic daily lead impedance and battery voltage measurements (see “How Battery and Lead Measurements work” on page 10-32). Detection resumes when the measurement is complete.

■

Automatic tachyarrhythmia therapy deliveries, including charging periods for high voltage therapy and automatic capacitor formations. Detection resumes automatically when the therapy or charging period is complete.

VT Detection is temporarily suspended during the first 17 ventricular events (paced and sensed) after an automatic ventricular defibrillation therapy.

Onyx VR System Reference Guide 3-5

System overview

Disabling detection and therapies

Manually suspending detection and therapy

ICD detection and therapy capabilities can be temporarily suspended by:

■

positioning the programming head, the Patient Alert patient magnet, or another magnet over the ICD

■

executing a [Suspend] command from the programmer

The bradycardia pacing and manually-initiated therapy capabilities of the ICD are still functional. Suspending detection does not change the permanently programmed settings of the ICD.

Removing the programming head or magnet from its position over the ICD restores the ICD to normal operation. If automatic detection is enabled, the [Resume] button causes the ICD to resume automatic detection even while the programming head is in position over the ICD.

Disabling detection and therapies

Automatically disabling detection and therapies

The ICD turns off VT Detection if a power-on reset (POR) occurs. See “Programmable parameters overview” on page 1-13 for POR parameters.

The ICD automatically turns off all VT and VF automatic therapies if three consecutive 30-second charges have failed to reach the programmed energy level (see “Charge Circuit Inactive” on page 5-4).

Manually disabling detection and therapies

To turn off the automatic detection and therapy functions of the ICD, program the functions Off via the programmer.

1. Select the Params icon and choose the Detection option.

2. Set the Enable parameters to Off.

3. Position the programming head and select [PROGRAM].

To re-enable automatic detection and therapy, reprogramming is required.

3-6 Onyx VR System Reference Guide

Tachyarrhythmia detection

Sensing 4-2

VF detection 4-5

VT detection 4-8

Combined Count detection 4-11

VT Stability option 4-13

EGM Width criterion 4-15

FVT detection 4-21

Termination and redetection 4-26

Onyx VR System Reference Guide 4-1

Tachyarrhythmia detection

Sensing

Appropriate sensing is essential for the safe and effective use of the ICD. To provide appropriate sensing, the ICD uses auto-adjusting sensing thresholds (see page 4-3) after paced and sensed events.

Programming for appropriate sensing

The programmable sensitivity threshold defines the minimum electrical amplitude that the ICD recognizes as a ventricular event.

A combination of high pacing pulse width and/or amplitude with a low sensitivity threshold may cause inappropriate sensing after pacing. Programming a lower pulse width, lower amplitude, longer pace blanking, or a higher threshold may eliminate this inappropriate sensing.

Ventricular sensing

A ventricular sensitivity threshold of 0.3 mV is recommended to maximize the probability that VF will be detected.

■

Always verify that the ICD is sensing and detecting VF properly. You may need to reposition or replace the ventricular sensing lead.

■

A value greater than 0.6 mV is not recommended except for testing and troubleshooting, as it may lead to undersensing or underdetection.

■

Carefully evaluate the potential for increased susceptibility to EMI and oversensing before changing the ventricular sensitivity threshold to its most sensitive setting of 0.15 mV.

■

If you change the sensitivity threshold, evaluate for proper sensing and detection by inducing VF and allowing the ICD to automatically detect and treat the arrhythmia.

■

If the ICD is not sensing or detecting properly, program all automatic therapies to Off and evaluate the ICD system. Monitor the patient continuously for life-threatening arrhythmias until you program automatic therapies On again.

4-2 Onyx VR System Reference Guide

Ventricular EGM

Tachyarrhythmia detection

Sensing

Auto-adjusting sensitivity threshold

The ICD automatically adjusts its sensitivity threshold following certain paced and sensed events (Figure 4-1) to reduce the incidence of T-wave and artifact sensing. The auto-adjusting thresholds increase dramatically (Table 4-1), and then gradually return to their programmed settings. Note that the thresholds may already differ from their programmed values, having been adjusted by the preceding sensed or paced event.

Tab le 4- 1. Auto-adjusting sensitivity threshold values

Event Sensitivity threshold

Increased to 75% of EGM peak

After a sensed event

After a paced event

Up to a maximum of 8x the programmed value.

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

Up to a maximum of 1.8 mV.

Until the preceding 450 ms decay, or the programmed threshold, is restored.

450 ms decay constant

Increased to 4.5x the programmed value. 450 ms decay constant

Changing threshold

Post-Pace Post-Sense

4.5x

Programmed

Sensitivity Threshold

Programmed

Post-Pace Blanking

V P

V S

V P

V S

Figure 4-1. Auto-Adjusting sensitivity threshold

Onyx VR System Reference Guide 4-3

Tachyarrhythmia detection

Sensing

Blanking periods

During a blanking period the ICD does not sense electrical signals. Blanking periods avoid sensing ICD outputs, post-pacing polarization, 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 depolarization signal on the electrodes.

Tab le 4- 2. Programmable blanking periods

Blanking after ventricular bradycardia pace 150 – 440 ms

Pace blanking during high voltage therapy 150 – 440 ms

Blanking after antitachycardia pace 150 – 440 ms

Tab le 4- 3. Non-programmable blanking periods

Blanking after sensed ventricular event 120 ms

Blanking after the end of a cardioversion or defibrillation charging period

Blanking after delivered cardioversion or defibrillation therapy 520 ms

300 ms

Refractory periods

Synchronization refractory periods help prevent delivery of pacing or shock pulses during the ventricular vulnerable period. (Refer to “High voltage synchronization” on page 5-5 for more detail.)

Note: Refractory periods do not affect tachyarrhythmia detection.

Ventricular refractory period after charging ends during defibrillation or cardioversion synchronization

Ventricular refractory period after ventricular sense during cardioversion synchronization

4-4 Onyx VR System Reference Guide

Tab le 4- 4. Refractory periods

400 ms

200 ms

VF detection

Tachyarrhythmia detection

VF detection

The ICD detects VF by applying the VF Interval Criterion. If the ICD senses the programmed number of VF intervals, it detects a VF episode and delivers a VF therapy.

VF Detection details begin on page 4-7.

Tab le 4- 5. VF Detection Programmable parameters

VF Enable On or Off

Sensitivity (mV)

Minimum level of electrical signal that registers as a sensed event

VF Interval (Rate) V-V intervals shorter than the programmed interval

are counted as VF events (Rates are shown in parentheses.)

VF Initial NID Number of Intervals to Detect:

number of VF events the ICD must count to detect a VF episode

VF Redetect NID Number of Intervals to Redetect:

number of VF events the ICD must count to redetect VF after a therapy

The programmed sensitivity value applies to ventricular tachyarrhythmia detection and bradycardia pacing.

Programming VF detection

To ensure proper VF detection, you should not program the VF Interval below 300 ms.

Programming the ventricular sensitivity to 0.3 mV is recommended. A value greater than 0.6 mV is not recommended except for testing and troubleshooting. Also, carefully evaluate the possibility of increased susceptibility to EMI and oversensing before changing the sensitivity to its minimum (most sensitive) setting of 0.15 mV.

You can accelerate redetection by programming the Redetect NID lower than the Initial NID.

When VF Detection is enabled for the first time (at implant), the ICD automatically changes the Automatic Capacitor Formation Interval from Off to 6 month.

Onyx VR System Reference Guide 4-5

Tachyarrhythmia detection

VF detection

VF Detection cannot be programmed Off unless VT Detection is also programmed Off.

To program VF detection

1. Select the Params icon and choose the Detection option. The programmer displays the Detection screen (see Figure 4-2).

2. Turn VF Enable to On and select VF Detection parameters.

3. Position the programming head and select [PROGRAM].

4-6 Onyx VR System Reference Guide

Figure 4-2. VF detection screen example

Tachyarrhythmia detection

VF detection

How VF detection works

VF Interval criterion

When a V-V interval is shorter than the programmed VF Interval, the ICD marks that event as a VF event and tallies it in memory. If the number of VF events reaches the programmed VF Initial NID, the ICD detects a VF episode and delivers the first programmed VF therapy. Following the therapy, if the number of VF events reaches the VF Redetect NID, the ICD redetects VF and delivers the next programmed VF therapy. (See also “Combined Count detection” on page 4-11.) VF NIDs are defined as a number of VF events within the VF detection window (for example, 12 of the last 16 intervals). All NID values are 75% of the detection window, such as 12/16, 18/24.

A VF episode is declared when the VF counter reaches 12 (of the last 16 events).

VF Intervals (< 320 ms)

V S

123456789101112

200 ms

Enable

VF On 12/16 9/12 320 ms

VT On 12 8 400 ms

Sensitivity: 0.3 (mV)

Initial Redetect Interval

Figure 4-3. VF detection example

Onyx VR System Reference Guide 4-7

Tachyarrhythmia detection

VT detection

The ICD detects VT by applying the VT Interval Criterion. If the ICD senses the programmed number of VT intervals, it detects a VT episode and delivers a VT therapy.

VT detection details begin on page 4-10.

Tab le 4- 6. VT detection programmable parameters

or Off

VT Enable

Sensitivity (mV)

VT Interval (Rate)

VT Initial NID

VT Redetect NID

The programmed sensitivity value applies to ventricular tachyarrhythmia detection and bradycardia pacing.

Minimum level of electrical signal that registers as a sensed event.

V-V intervals shorter than the programmed interval are counted as VT events. (Rates are shown in parentheses.)

Number of Intervals to Detect: number of VT events the ICD must count to detect a VT episode.

Number of Intervals to Redetect: number of VT events the ICD must count to redetect VT after a therapy.

4-8 Onyx VR System Reference Guide

Programming VT detection

To ensure proper VT detection, program the VT Interval to a value that is at least 40 ms longer than the patient‘s tachycardia interval, and at least 40 ms longer than the programmed VF Interval.

Programming the ventricular sensitivity to 0.3 mV is recommended. (See “Programming for appropriate sensing” on page 4-2.)

You can accelerate redetection by programming the Redetect NID lower than the Initial NID.

To ensure VF Detection backup during VT episodes, VT Detection cannot be On unless VF Detection is also On.

Tachyarrhythmia detection

VT detection

To program VT detection

1. Select the Params icon and choose the Detection option. The

programmer displays the Detection screen (see Figure 4-4).

2. Turn VT Enable to On and select VT Detection parameters.

3. Position the programming head and select [PROGRAM].

Figure 4-4. VT detection screen example

Onyx VR System Reference Guide 4-9

Tachyarrhythmia detection

VT detection

How VT detection works

VT Interval Criterion

When the V-V interval is shorter than the programmed VT Interval, the ICD marks that event as a VT event and tallies it in memory. (See also “VT Stability option” on page 4-13.) If the number of VT events reaches the programmed VT Initial NID, the ICD detects a VT episode and delivers the first programmed VT therapy. (See also “EGM Width criterion” on page 4-15.)

After the therapy, if the number of VT events reaches the VT Redetect NID, the ICD redetects VT and delivers the next programmed VT therapy. (See also “Combined Count detection” on page 4-11.) The ICD counts consecutive VT events. The event counter resets to zero whenever an interval fails to satisfy the Interval Criterion, or the VT Stability option, if it is On. The VT counter remains at its current value if an interval is shorter than the programmed VF Interval.

VT intervals between 320 and 400 ms

V S

VT Counter Value:

Enable

Initial

123456789101112

Redetect

VF On 12/16 9/12 320 ms

VT On 12 8 400 ms

Sensitivity (mV): 0.3

Figure 4-5. VT detection example

4-10 Onyx VR System Reference Guide

T S

Interval

A VT episode is declared when the VT counter reaches 12.

200 ms

A VT event increases the VT counter by one.

A normal sensed beat (≥ 400 ms) clears the counter to zero.

A VF event suspends, but does not clear, the VT count.

Combined Count detection

Combined Count detection helps the ICD promptly detect or redetect a ventricular tachyarrhythmia when the interval is fluctuating between the VF and VT zones. The ICD tracks the combined number of events registered on the VF and VT counters, and if this sum reaches the Combined Number of Intervals to Detect (CNID), VF or VT is detected. Combined Count Detection also applies to redetected episodes.

Combined Count detection is automatic (not programmable) when VT Detection is enabled, and cannot be disabled.

How Combined Count detection works

Combined Count Detection automatically applies a Combined Number of Intervals to Detect (CNID) when the VF event counter reaches six. The ICD calculates the CNID as follows:

Initial CNID = VF Initial NID x 7/6 (rounded down) Redetect CNID = VF Redetect NID x 7/6 (rounded down)

Tachyarrhythmia detection

Combined Count detection

For example, if the VF Initial NID is programmed to 18, the Initial CNID is 21. If the VF Redetect NID is 12, the Redetect CNID is 14.

Combined Count detection is fulfilled when the sum of the VF and VT event counters equals or exceeds the CNID. The ICD then reviews the eight intervals preceding detection:

■

If any of the eight was in the VF zone, the episode is classified as VF.

■

If all eight were outside the VF zone, the episode is classified as VT.

Onyx VR System Reference Guide 4-11

Tachyarrhythmia detection

Combined Count detection

Surface ECG

Marker Channel

VF Event Count

VT Event Count

Without Combined Count Detection, the arrhythmia would be detected after 18 beats

VF = 12

Counter

VT Counter VT Counter

Figure 4-6. Combined Count detection example

FSF

12 3 45

FSF

VF NID = 12/16, VT NID = 12, CNID = 14

With Combined Count Detection, the arrhythmia is detected after 14 beats

VT = 12

15105

Counter

T S

VF = 12

T S

FSFSF

FSF

Combined Count (VT+VF) = 14

VF = 6

VT = 12

15105

4-12 Onyx VR System Reference Guide

VT Stability option

VT Stability is an optional detection criterion that allows the ICD to withhold VT detection and FVT via VT detection for rapid rhythms (in the VT detection zone) with irregular intervals.

VT Stability (ms) Off, or the maximum acceptable variation among

Programming VT Stability option

Choosing a small VT Stability value (such as 30 ms) may not allow for the normal VT interval variation. Thus, smaller VT Stability values may decrease the sensitivity of the ICD to detect VT.

The VT Stability option compares measured intervals that have been shortened to multiples of 10 ms, permitting a rounding error of up to +10 ms from the programmed VT Stability value.

Tachyarrhythmia detection

VT Stability option

Tabl e 4 -7. VT Stability parameter

measured intervals

To program VT Stability

1. Select the Params icon and choose the Detection option. The

programmer displays the Detection screen.

2. Select a value for VT Stability.

3. Position the programming head and select [PROGRAM].

Onyx VR System Reference Guide 4-13

Tachyarrhythmia detection

VT Stability option

How the VT Stability option works

When the VT Stability option is On, an interval in the VT zone or FVT via VT zone is considered unstable if the difference between it and any of the three previous intervals is greater than the programmed VT Stability interval.

The ICD does not apply the VT Stability option until the VT event count reaches three. When an interval in the VT or FVT via VT zone fails to meet the VT Stability option, it is marked as a normal sensed event and the VT event count resets to zero.

The VT Stability option must be re-satisfied during redetection if it is enabled.

VT Stability is not applied until VT count reaches three.

V S

VT Counter Value:

Unstable event: Varies from previous interval

by 70 ms. Event is marked as a normal sensed

5 1 0

2 30123 2345

beat and VT counter resets to zero.

Enable

Initial Redetect Interval

4 4 0

Stable events: Each differs from the three before it by

50 ms or less, and they are marked as VT events.

4 4 0

Unstable event: Varies from previous interval

by 60 ms. VT counter resets to zero.

VF On 12/16 9/12 320 ms

VT On 12 8 540 ms

Ventricular Sensitivity (mV): 0.3 VT Stability (ms): 50

Figure 4-7. VT Stability option

V S

4 7 0

200 ms

4-14 Onyx VR System Reference Guide

EGM Width criterion

The optional EGM Width criterion can improve the specificity of VT detection by identifying inappropriately detected supraventricular arrhythmias (such as sinus tachycardia and atrial fibrillation or flutter). The ICD measures the QRS complexes during a high rate episode, and detects the episode as VT only if a sufficient number of the QRS complexes are wide.

For more detail on the EGM width criterion, see “How the EGM Width criterion works” on page 4-18.

EGM Width

Width Threshold (ms)

Slew Threshold (mV/s)

Note: The ICD provides three diagnostic tools to evaluate and verify the EGM Width parameter settings:

– The EGM Width test (“Performing an EGM Width test” on

– QRS Snapshots (“QRS Snapshot” on page 10-24) show how the

– The Passive criterion setting (“Programming the EGM Width

Tachyarrhythmia detection

Tab le 4- 8. EGM Width criterion parameters

, Off, or Passive

A sensed event is designated wide if its QRS complex equals or exceeds this width.

Defines the beginning and end of each sensed QRS complex, using the rate of amplitude change in the

EGM2 waveform

page 8-9) helps you find the most effective parameter settings by measuring the patient’s QRS complexes during sinus rhythm.

parameters settings are being applied during automatic detection.

criterion” on page 4-16) provides ambulatory monitoring of the ICD’s ability to discriminate between VT and SVTs.

EGM Width criterion

Onyx VR System Reference Guide 4-15

Tachyarrhythmia detection

EGM Width criterion

Programming the EGM Width criterion

Cautions: The EGM Width criterion should not be used for patients

with fast or poorly tolerated VTs.

The EGM Width criterion is less likely to be effective in patients with narrow complex VTs, with bundle branch block, or whose QRS complexes are affected by antiarrhythmic medications.

When the EGM Width criterion is programmed to Passive, the ICD measures and stores QRS widths during VT episodes, but the criterion is not applied for VT detection.

Select the slew threshold independently of the width threshold to establish proper QRS width measurements during sinus rhythm. Recommended initial threshold settings are:

– the lowest slew threshold that provides predictable, consistent

width measurements (variation of 12 ms or less) during sinus rhythm.

– the lowest width threshold that exceeds all the width

measurements taken during sinus rhythm.

Higher slew thresholds tend to result in narrower and possibly more consistent QRS width measurements. Lower slew thresholds tend to provide wider and possibly more variable QRS width measurements (see the drawing on “Effect of Slew Threshold on rhythm classification” on page 4-20).

A larger width threshold increases the specificity of VT detection, but may also decrease the sensitivity. While evaluating patients with a concomitant pacemaker, measure the intrinsic QRS widths during normal sinus rhythm.

The width threshold and slew threshold parameters can also be programmed from the EGM Width Test screen (when the criterion is set to On or Passive).

4-16 Onyx VR System Reference Guide

Tachyarrhythmia detection

EGM Width criterion

To program the EGM Width criterion

1. Select the Params icon and choose the Detection option. The

programmer displays the Detection screen.

2. Set EGM Width to On or Passive and select values for the Width

Threshold and Slew Threshold.

3. Position the programming head and select [PROGRAM].

EGM Width criterion

parameters

Figure 4-8. EGM Width criterion parameters

Onyx VR System Reference Guide 4-17

Tachyarrhythmia detection

EGM Width criterion

How the EGM Width criterion works

The EGM Width Criterion is based on the premise that QRS complexes of ventricular origin are generally wider than those of supraventricular origin. When a fast ventricular rhythm fulfills the other programmed VT detection criteria and the EGM Width Criterion is programmed On, the ICD reviews the eight preceding QRS complexes, as sensed on the programmed EGM 2 electrode source (see Figure 4-10). If fewer than six of these eight complexes in the “lookback window” are wide, the ICD does not identify the episode as VT.

The EGM Width Criterion is applied only on initial detection of a VT episode. It does not apply to VF detection, FVT detection, or redetection of VT after therapy.

Measuring a QRS complex

The ICD identifies the start and end points of a sensed QRS complex using the slew threshold parameter. Slew rate is the rate of change (in millivolts per second) of the sensed EGM amplitude.

Low rate of

amplitude change

High rate of

amplitude change

Higher slew thresholds give narrower QRS widths. Lower slew thresholds give wider QRS widths. Select the lowest slew threshold that provides predictable, stable QRS width measurements of the patient’s normal sinus rhythm.

Figure 4-9. Effect of Slew Threshold on QRS Width example

The ICD measures the slew rate every 4 ms, and marks the start of the QRS at the earliest point where the slew rate first reaches the programmed threshold (Figure 4-9). The end of the QRS occurs at the last point where the slew rate exceeds the programmed slew threshold. The QRS width is then calculated as the time in milliseconds between the start and end of the QRS.

4-18 Onyx VR System Reference Guide

48 mV/s slew threshold results in 104 ms QRS width 90 mV/s slew threshold results in 84 ms QRS width

104 ms QRS width

48 mV/s slew threshold

90 mV/s slew threshold

84 ms QRS width

Bipolar EGM

Tachyarrhythmia detection

EGM Width criterion

Classifying the QRS complex

If the width of the QRS is less than the programmed width threshold, it is designated as Narrow. If the width equals or exceeds the width threshold, or if it is less than 16 ms (too narrow to represent a normal sinus rhythm), it is designated as Wide.

QRS measurements are made from the programmed

Far Field EGM

EGM source for EGM channel 2

V S

VT Counter Value:

QRS Width in ms:

V S

80 68 96 100 88 96 104 88

EGM Width: ON

Width Threshold (ms): 88

Slew Threshold (mV/s): 30

FVT

Detection Status: ON OFF ON

Interval (ms): 320 500

Initial NID: 18/24 12

Figure 4-10. Example of EGM Width criterion met

Classifying the episode

When a ventricular high rate fulfills the Initial (or Combined) NID, the ICD “looks back” at the eight complexes preceding, but not including, the event that fulfilled detection.

■

If six or more of these eight QRS complexes are wide, the EGM Width criterion is satisfied and the ICD detects the episode as VT (Figure 4-10).

■

If three or more complexes are narrow, the criterion is not satisfied and the VT counter resets to zero. (Figure 4-11: the criterion is not met because the slew threshold is set too high.)

T S

(8 events not including NID event)

When the VT NID is reached, the device reviews the recent QRS measurements.

Six of the eight events were measured “wide” (≥ 88 ms), and the episode is detected as VT.

200 ms

Onyx VR System Reference Guide 4-19

Tachyarrhythmia detection

EGM Width criterion

VT beats are measured narrower than the width threshold.

Far Field EGM

Bipolar EGM

V S

VT Counter Value:

QRS Width in ms:

EGM Width: ON

Width Threshold (ms): 88

Slew Threshold (mV/s): 30

Detection Status: ON OFF ON

Interval (ms): 320 500

Initial NID: 18/24 12

V S

VF FVT VT

76 76 84 92 84 80 88 84

With the slew threshold set to 30 mV/s, several

TST

(8 events not including NID event)

V S

11 (12)0

200 ms

When the episode fails to meet the

EGM Width criterion, the VT counter

Slew = 48 mV/s

84 ms width

resets to zero.

Figure 4-11. Effect of Slew Threshold on rhythm classification

4-20 Onyx VR System Reference Guide

FVT detection

Tachyarrhythmia detection

FVT detection

The ICD can be programmed to further classify a tachycardia as Fast Ventricular Tachycardia (FVT). The ICD provides an FVT episode counter and a separate therapy regimen for FVT episodes.

FVT Detection details begin on page 4-23.

Tab le 4- 9. FVT detection programmable parameters

FVT Enable via VF, via VT, or Off

Sensitivity (mV)

Minimum level of electrical signal that registers as a sensed event

FVT Interval (Rate) V-V intervals between this value and the

programmed events. (Rates are shown in parentheses.)

The programmed sensitivity value applies to tachyarrhythmia detection and bradycardia pacing.

VF Interval are marked as FVT

Programming FVT detection

To ensure VF Detection backup, FVT Detection cannot be On unless VF Detection is also On.

For FVT Detection via VF, the FVT Interval is programmed within the VF zone. For FVT Detection via VT, the FVT Interval is within the VT zone. This choice should depend on the patient’s VF and VT cycle lengths. After determining a reliably sensitive VF Interval, consider the following:

■

If the patient exhibits a clinical VT cycle length in the VF zone, select via VF to ensure reliable detection of VF. (VT Detection need not be enabled at all.)

■

If the patient exhibits two clinical VTs, both outside the VF zone, select via VT to prevent misclassification of VF, and to offer a separate therapy regimen for each VT.

■

If the patient has only one clinical VT that is outside the VF zone, select VF and VT Detection only, with FVT Enable set to Off.

Select the VF, VT, and FVT Intervals at least 40 ms apart to allow for normal variations in the patient’s interval.

FVT Detection uses the VF event counter and the programmed VF NID if set to via VF, or the VT counter and VT NID if set to via VT.

Onyx VR System Reference Guide 4-21

Tachyarrhythmia detection

FVT detection

FVT Detection

parameters

To program FVT detection

1. Select the Params icon and choose the Detection option. The programmer displays the Detection screen.

2. Set FVT Enable to via VT or via VF. Select the FVT Interval and Ventricular Sensitivity values.

3. Position the programming head and select [PROGRAM].

4-22 Onyx VR System Reference Guide

Figure 4-12. Programming FVT detection

Tachyarrhythmia detection

FVT detection

How FVT detection works

FVT detection via VF

When you set FVT Detection to via VF, the ICD detects FVT episodes using the VF event counter.

A V-V interval within the FVT zone is marked as an “FVT via VF” event and tallied on the more sensitive VF event counter. When the VF NID is reached, the ICD reviews the last eight intervals.

■

If any of the last eight intervals is 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 (Figure 4-13).

FVT detection via VT

When you set FVT Detection to via VT, the ICD detects FVT episodes using the VT event counter.

A V-V interval within the FVT zone is marked as an “FVT via VT” event and tallied on the more specific, consecutive VT event counter. The VT Stability option must also be satisfied if it is enabled. When the VT NID is reached, the ICD reviews the last eight intervals.

■

If any of the last eight intervals is 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.

Onyx VR System Reference Guide 4-23

Tachyarrhythmia detection

FVT detection

Combined Count detection of FVT

Combined Count Detection (page 4-11) also applies to the FVT zone. If the VF event counter reaches six, and the sum of the VF and VT event counters equals or exceeds the CNID, the ICD “looks back” at the eight intervals preceding detection:

■

If any of the eight was in the VF zone, the episode is detected as VF.

■

If none was in the VF zone but one or more was in the FVT zone, the episode is detected as FVT.

■

If all eight were outside the VF and FVT zones, the episode is classified as VT.

VF NID reached. Since none of the last eight intervals is a VF interval, the ICD classifies the episode as FVT and

will deliver an FVT therapy.

V S

Enable

VF On 12/16 9/12 320 ms

FVT via VF 260 ms

VT Off

Figure 4-13. FVT Detection Via VF example

4-24 Onyx VR System Reference Guide

V S

VF Counter:

V S

1234567 89101112

LOOK BACK WINDOW

(8 INTERVALS BEFORE NID)

Initial

Redetect

Interval

200 ms

Blanking

Depolarization

Blanking

Depolarization

VF Detection Zone

120 ms

Tachyarrhythmia detection

FVT detection

Zone Merging after detection

For FVT via VF detection, the FVT zone merges with the VF zone after detection or redetection of VF. For FVT via VT detection, the FVT zone merges with the VT zone after detection or redetection of FVT or VF. In both instances, the merged-zone configuration remains until episode termination. The merged zone uses the event counting and therapies for the faster arrhythmia to ensure that the ICD delivers sufficiently aggressive therapies during an extended or highly variable tachyarrhythmia episode. (See also “Progressive Episode Therapies” on page 5-32.)

Before initial detection: three detection zones

Interval

Lower Rate

Period

Lower Rate

Period

FVT Detection Zone

FVT

Interval

VT Detection Zone

Interval

After detection of VF: two zones for redetection

VF Detection Zone VT Detection Zone

Interval

Figure 4-14. Zone Merging (FVT Detection Via VF)

Before initial detection: three detection zones

Interval

Lower Rate

Period

Blanking

Depolarization

VF Detection Zone

120 ms

FVT Detection Zone

VF Interval FVT

Interval

VT Detection Zone

After detection of VF or FVT: two zones for redetection

Interval

Lower Rate

Period

Blanking

Depolarization

120 ms

VF Detection Zone

Interval

FVT Detection Zone

Figure 4-15. Zone Merging (FVT Detection via VT)

Onyx VR System Reference Guide 4-25

Tachyarrhythmia detection

Termination and redetection

Outcome monitoring

After delivering an automatic therapy, the ICD monitors the cardiac interval for three possible outcomes:

■

Termination of the episode.

■

Redetection of the original ventricular tachyarrhythmia.

■

Redetection of a different ventricular arrhythmia, including VT

acceleration.

Further automatic therapies are not delivered unless the patient’s cardiac rhythm fulfills the redetection requirements for a ventricular tachyarrhythmia.

The EGM Width criterion is not applied during redetection. However, the VT Stability criterion must be continually re-satisfied throughout redetection if it is enabled.

Programming considerations

You can accelerate redetection by programming Redetect NIDs lower than the Initial NIDs.

Both the VF Redetect NID and the VT Redetect NID take effect during any type of ventricular arrhythmia episode.

If you program the Progressive Episode Therapies option On (see “Progressive Episode Therapies” on page 5-32), a slower arrhythmia (for example, VT) may receive therapies for a faster arrhythmia (for example, VF) during redetection.

4-26 Onyx VR System Reference Guide

VT Detection is temporarily suspended for 17 events, paced or sensed, following defibrillation therapy.

Tachyarrhythmia detection

Termination and redetection

Therapy efficacy

A therapy is considered successful if arrhythmia termination occurs prior to any redetection. The therapy is considered unsuccessful if redetection occurs before termination.

If all programmed therapies are unsuccessful, the ICD suspends them until one of the following changes occur:

■

the episode terminates

■

Detection is manually reset (by programming Detection Enable Off and then On again) during the episode.

Episode termination

Episode termination occurs when eight consecutive V-V intervals are greater than or equal to the VT detection interval.1 Once the ICD detects an arrhythmia, it considers the episode as ongoing until it detects episode termination. Any subsequent detection after termination marks the start of a new episode.

After antitachycardia pacing therapy, the counter for episode termination begins with the first ventricular cycle. After cardioversion or defibrillation, the counter for episode termination begins with the second ventricular event following the shock. (Due to the extended post shock blanking, this event may be the third event on the electrogram.)

A rhythm that does not satisfy the termination definition is considered part of an ongoing episode, but the ICD does not deliver the next programmed therapy until the redetection criteria are fulfilled.

Redetection

The ICD redetects an arrhythmia if the VF or VT event counter reaches its Redetect NID, or if the combined VF and VT event counters reach the Redetect CNID (see “Combined Count detection” on page 4-11). The ICD then delivers the next programmed therapy for the current arrhythmia, and resumes monitoring for the outcome of that therapy.

VF Interval when VT Detection is programmed Off.

Onyx VR System Reference Guide 4-27

Tachyarrhythmia detection

Termination and redetection

If the ICD redetects VF or an accelerated VT after an antitachycardia pacing sequence delivery, it skips the subsequent pacing therapy sequences for the duration of this episode and proceeds to deliver the next therapy programmed for the current arrhythmia.

Figure 4-16 illustrates redetection of VT after cardioversion therapy.

VT acceleration

The ICD classifies a VT as accelerated when it redetects during a VT episode and the average of the four intervals before redetection has decreased by 60 ms or more, compared to the average of the four intervals before the initial VT detection. to evaluate future VT accelerations under the 60 ms rule above.

If VT acceleration occurs after the delivery of an antitachycardia pacing sequence, the ICD skips the subsequent sequences of the pacing therapy for the duration of this episode and delivers the next programmed VT therapy.

The current redetection is used

4-28 Onyx VR System Reference Guide

Or before the most recent “accelerated” VT redetection.

0.6 joule cardioversion shock.

Not sensed in the blanking period after cardioversion.

Tachyarrhythmia detection

Termination and redetection

Sensed, measured as 660 ms, and marked as a normal sensed event.

T D

VRV

3 3 0

After eight consecutive intervals within the VT zone, the VT Redetect NID is fulfilled and the ICD redetects the VT episode.

Enable

VF On 12/16 9/12 320 ms

VT On 12 8 400 ms

VT Therapy: 1 2 3 4 5 6

Therapy Status: On On On On On On

Therapy Type: CV CV CV CV CV CV

Energy (J): 0.61030303030

Initial Redetect Interval

Figure 4-16. Redetection of VT after therapy

TSTST

3 3 0

The therapy was unsuccessful: the ICD redetected VT before episode termination (eight consecutive beats outside the detection zones).

3 3 0

200 ms

Onyx VR System Reference Guide 4-29

Tachyarrhythmia therapies

High voltage therapy overview 5-2

Defibrillation 5-8

Cardioversion 5-15

Antitachycardia pacing therapy overview 5-19

Programming ATP therapies 5-21

Burst pacing 5-23

Ramp pacing 5-25

Ramp+ pacing 5-27

Smart Mode 5-29

Progressive Episode Therapies 5-32

Onyx VR System Reference Guide 5-1

Tachyarrhythmia therapies

High voltage therapy overview

Defibrillation and cardioversion are the two high voltage therapies provided by the ICD. Up to six defibrillation shocks may be programmed to treat a detected episode of VF. Cardioversion therapy can be programmed as any of the six VT or FVT therapies.

When an arrhythmia is detected and defibrillation or cardioversion is the next programmed therapy, the ICD charges the high voltage capacitors to the programmed energy. When the programmed energy is reached, the ICD initiates a synchronization sequence and attempts to synchronize the pulse to the leading edge of a sensed ventricular event.

Defibrillation and cardioversion therapies can be delivered via the following high voltage electrodes:

■

CAN (HVA) – device can

■

RV (HVB) – RV coil

■

SVC (HVX) – optional supplemental electrode; for example, SVC coil

Each defibrillation or cardioversion therapy has separately programmable energy and pathway polarity (see “High voltage therapy energy” on page 1-10). The ICD automatically regulates the pulse width to obtain 50% tilt.

5-2 Onyx VR System Reference Guide

Comparison of defibrillation and cardioversion

A defibrillation shock is delivered for VF; a cardioversion shock is delivered for VT or FVT.

When the ICD delivers a defibrillation therapy, it attempts to synchronize with a sensed R-wave, but does not require such synchronization. However, a cardioversion therapy requires synchronization to a sensed Rwave for delivery to occur.

Tachyarrhythmia therapies

High voltage therapy overview

Committed vs. Non-Committed therapies – The ICD can be programmed to reconfirm VF before delivering the first programmed defibrillation therapy. Reconfirmation is attempted only for the initial detection of VF, and only if the Reconfirm VF feature is programmed On. Subsequent VF therapies within the same episode are always committed: when the capacitors reach their programmed energy, the shock will be delivered. Cardioversion is a non-committed therapy: if the ICD cannot synchronize to a ventricular sensed event, the therapy aborts.

Table 5-1 summarizes the differences between defibrillation and cardioversion.

Tab le 5- 1. Comparison of defibrillation and cardioversion

Defibrillation Cardioversion

Episode detected VF VT or FVT

Reconfirm arrhythmia First therapy: optional

Later therapies: committed

Synchronization Not required unless

Synchronization successful

Synchronization unsuccessful

Reconfirm VF is active

Delivers high voltage pulse Delivers high voltage pulse

Delivers asynchronous defibrillation pulse at end of synchronization sequence (but if Reconfirm VF is active, the therapy aborts)

All therapies non-committed (require synchronization)

Required

Abort CV pulse at end of synchronization sequence

Onyx VR System Reference Guide 5-3

Tachyarrhythmia therapies

High voltage therapy overview

Charging period

Warning: If a Charge Circuit Timeout (see “Charge Circuit Timeout”

on page 5-4) occurs, please inform a Medtronic representative. Immediate replacement is recommended.

The length of time to charge the ICD high voltage capacitors to the programmed energy (charge time) increases with an increase in programmed energy, battery depletion, or time since the last capacitor formation. Table 1-7 on page 1-10 shows typical charge times to different programmed energy values at BOL and with fully-formed capacitors.

During the capacitor charging period, the ICD operates as follows:

■

operates in its programmed pacing mode

■

applies the programmable Post Shock Pacing parameters (see “To program Post Shock Pacing” on page 6-8)

■

may lose the telemetry link to the programmer due to electrical noise

After the charging period is complete, the ICD starts a 300 ms blanking period.

Charge Circuit Timeout

If a single charging period reaches 30 seconds, the ICD terminates charging, aborts the therapy attempt (but retains the charge on the capacitors), and resumes detection using the programmed detection criteria. The charge circuit is still active. The ICD records the Charge Circuit Timeout Device Status Indicator, which is later sent to the programmer via telemetry. If a Charge Circuit Timeout indicator is displayed, please inform a Medtronic representative and replace the ICD immediately.

Charge Circuit Inactive

If three consecutive charging periods have each reached 30 seconds, the ICD terminates charging, aborts the therapy attempt, and disables the automatic tachyarrhythmia therapies and manual operations, except for Emergency VVI pacing. The charge circuit is inactive. The ICD records the Charge Circuit Inactive Device Status Indicator, which is sent to the programmer via telemetry. If a Charge Circuit Inactive indicator is displayed, do not try to reprogram the ICD. Please inform a Medtronic representative and replace the ICD immediately.

5-4 Onyx VR System Reference Guide

Tachyarrhythmia therapies

High voltage therapy overview

High voltage synchronization

The synchronization sequence is designed to confirm the continued presence of the arrhythmia and synchronize the high voltage pulse to a sensed R-wave. In general:

■

committed defibrillation therapies are timed to the first non-refractory sensed event if possible, or delivered asynchronously if it cannot be synchronized (see “Committed defibrillation synchronization” on page 5-10).

■

non-committed defibrillation therapies (when Reconfirm VF is active) and cardioversion therapies are timed to a non-refractory arrhythmic sensed event if possible, or aborted if they cannot be synchronized (see “Non-Committed defibrillation synchronization” on page 5-12 and “Cardioversion synchronization” on page 5-17).

The ICD high voltage pulses are synchronized to events sensed on the implanted electrodes. Surface ECGs exhibit morphologies and timing that do not necessarily coincide exactly with those taking place at the electrode sites.

Note: For any delivered high voltage therapy, there is a possibility of inducing an atrial arrhythmia.

After a delivered high voltage therapy

Immediately after a delivered high voltage therapy, the ICD starts the following:

■

a post shock blanking period of 520 ms

■

one VVI pacing cycle at 50 ppm (escape interval of 1200 ms)

After the first ventricular event, the programmed bradycardia pacing mode resumes, using the Post Shock Pacing parameters (see “Post Shock Pacing parameters” on page 6-7).

The ICD monitors for an outcome from the delivered therapy either episode termination or redetection. After an automatic defibrillation therapy, VT detection is temporarily suspended for 17 events, or until episode termination is detected, whichever occurs first. This feature is designed to reject transient VTs that may follow the high voltage therapy.

Onyx VR System Reference Guide 5-5

Tachyarrhythmia therapies

High voltage therapy overview

After any manual therapy delivered via the programmer (including emergency HV therapies), automatic detection is suspended for as long as the programming head remains over the device, or until [Resume] is selected.

After an aborted high voltage therapy

Following an aborted defibrillation or cardioversion therapy, or an aborted charging period, the ICD reverts immediately to its programmed bradycardia pacing settings.

The ICD resumes monitoring the cardiac cycle for arrhythmias, using the programmed redetection NIDs, after the next paced or sensed ventricular event. If the ICD redetects the same arrhythmia after an aborted therapy, it attempts to synchronize and deliver the same therapy. However, if the ICD detects episode termination, it resumes normal detection.

Note: If a high voltage therapy aborts, leaving the energy stored on the capacitors, the delivered energy of a subsequent cardioversion or defibrillation therapy could be higher than the programmed value.

High voltage therapy parameters

Energy

The ICD can be programmed to deliver up to 30 J1, which corresponds to a maximum stored energy of 35 J. This value is derived from the peak capacitor voltage, which is always greater than the energy delivered by the device. Table 1-7 on page 1-10 compares all of the programmable delivered energy levels to their corresponding stored energy levels. The defibrillation or cardioversion energy level is programmed independently for each therapy.

Delivered energy of biphasic waveform into 75 Ω

5-6 Onyx VR System Reference Guide

Tachyarrhythmia therapies

High voltage therapy overview

Waveform

The waveform of the cardioversion or defibrillation pulse is biphasic.

The biphasic pulse consists of two phases. In the first phase, current is delivered between the high-voltage electrodes until the pulse decays to 50% of its original voltage. The ICD then truncates the pulse and reverses the current pathway for the second phase by transposing the cathode and anode. After the second phase of the pulse has decayed to 50% of its original voltage, the ICD truncates the pulse.

Second phase

truncated after 50%

pulse decay

Biphasic pulse

inverted after 50%

pulse decay

50% Tilt

Figure 5-1. Biphasic waveform for cardioversion and defibrillation

Tilt

The ICD high voltage pulses are tilt controlled: the output pulse is truncated when it has decayed by a percentage of its initial value, or “tilt.” The ICD uses a fixed tilt value of 50%.

Figure 5-1 shows how the ICD delivers biphasic shocks across a single pathway with 50% tilt. The biphasic pulse is inverted to a negative voltage and then truncated to zero after a 50% decay of its second phase. Negative voltage indicates that the current pathway has been reversed.

Pathway polarity

Pathway polarity assigns the implanted electrodes to serve as the anode and cathode in delivering the high voltage pulse. For example, an ICD implanted with two electrodes, CAN ( programmed to deliver current from CAN to RV (AX>B) or from RV to CAN (

B>AX).

Tab le 5- 2. Modes and polarities for cardioversion and defibrillation

Two HV Electrodes:

CAN and RV

Pathway polarity

options

(anode → cathode)

CAN → RV = AX>B

RV → CAN = B>AX

HVA) and RV (HVB), can be

Three HV Electrodes:

CAN, RV, and SVC

CAN, SVC → RV = AX>B

RV → CAN, SVC = B>AX

Onyx VR System Reference Guide 5-7

Tachyarrhythmia therapies

Defibrillation

Defibrillation shocks are independently programmable for energy and pathway polarity. When Reconfirm VF is enabled, the first defibrillation therapy delivered during an episode is non-committed.

Tab le 5- 3. Defibrillation programmable parameters

VF Therapy Status

Energy (J)

Pathway

Reconfirm VF After Initial Charge

Progressive Episode Therapies

Any of the six VF therapies can be programmed Off. The ICD retains the settings but skips the “Off” therapy and immediately delivers the next available therapy.

On or Off

0.4 – 30 (see page 5-6)

AX>B or B>AX (see “Pathway polarity” on page 5-7)

Yes or No (see “Non-Committed defibrillation synchronization” on page 5-12)

On or Off (see “Progressive Episode Therapies” on page 5-32)

Programming defibrillation therapies

No more than one of the six VF Therapies should be programmed to less than 30 J.

You can program the ICD to reconfirm a VF episode before delivering the first programmed defibrillation therapy only. Subsequent therapies, and re-applications of an aborted first therapy, are always committed.

If the Progressive Episode Therapies feature is enabled, the ICD may deliver a defibrillation therapy at a higher energy level than was programmed. This ensures that each therapy delivered during an ongoing episode is at least as aggressive as the previous therapy (see “Progressive Episode Therapies” on page 5-32).

5-8 Onyx VR System Reference Guide

Tachyarrhythmia therapies

Defibrillation

To program defibrillation therapies

1. Select the Params icon, and choose the Therapies menu option.

2. Select [VF] (see Figure 5-2).

3. Enable VF Therapies by setting VF Therapy Status parameters

to On.

4. Set Energy and Pathway parameters for each enabled VF Therapy.

5. Enable VF reconfirmation by setting Reconfirm VF after initial

charge to Yes.

6. Select [PROGRAM].

VF Therapy screen

selected

Defibrillation

parameters

Shared Therapy parameters

screen selected

Figure 5-2. Programmable defibrillation therapies

7. To program the Progressive Episode Therapies feature, select [Shared] (see Figure 5-3).

8. Set Progressive Episode Therapies to On or Off.

9. Select [PROGRAM].

Progressive Episode

Therapies parameter

Figure 5-3. Shared Therapy parameters screen

Onyx VR System Reference Guide 5-9

Tachyarrhythmia therapies

Defibrillation

Committed defibrillation synchronization

Note: A defibrillation therapy is always committed, unless it is the first

defibrillation shock delivered during an episode and the Reconfirm VF feature is enabled (see page 5-12).

A defibrillation therapy is synchronized to a sensed R-wave if possible. Committed defibrillation uses a synchronization escape period of 500 ms to identify the R-wave for delivering the shock.

At the first non-refractory sensed event, the shock is delivered (Figure 5-4).

However, if the 500 ms synchronization escape period expires without a non-refractory event, the shock is delivered asynchronously (Figure 5-5).

The synchronization interval begins at the end of the 300 ms post-charge blanking period, with an effective refractory period of 100 ms. If the ICD senses a ventricular event during this refractory period, it starts a new synchronization interval. This subsequent synchronization interval begins with a 120 ms blanking period, and no additional refractory period.

When Reconfirm VF is active, the first defibrillation shock is synchronized to a non-refractory arrhythmic event (see “Non-Committed defibrillation synchronization” on page 5-12).

5-10 Onyx VR System Reference Guide

Tachyarrhythmia therapies

Defibrillation

After the charge blanking

period, the synchronization

interval of 500 ms begins with

an effective refractory period of

100 ms.

Refractory

Synchronization

Figure 5-4. Defibrillation synchronized to an arrhythmic event

This refractory sensed

event restarts the

synchronization interval.

Blanking

C E

300 ms

400 ms

500 ms

These two low-amplitude

events go unsensed.

C D

520 ms

At the first non-refractory event, the shock is delivered.

An extended blanking

200 ms

period of 520 ms begins after the shock.

The synchronization sequence times out and the device delivers the defibrillation shock.

Blanking

Refractory

Synchronization

C E

300 ms 120 ms 520 ms

400 ms

V R

500 ms

C D

200 ms

An extended blanking period of 520 ms begins after the shock.

Figure 5-5. Defibrillation delivered after failing to synchronize

Onyx VR System Reference Guide 5-11

Tachyarrhythmia therapies

Defibrillation

Non-Committed defibrillation synchronization

When the Reconfirm VF feature is enabled, the first defibrillation shock delivered during an episode is synchronized to a non-refractory arrhythmic event, but it aborts if the VF terminates spontaneously into bradycardia or sinus rhythm.

The ICD uses a sequence of reconfirmation “windows,” each lasting 60 ms plus the programmed VT Interval

to identify an ongoing tachyarrhythmia. The ICD defines a non-refractory sensed ventricular event within this window as arrhythmic for reconfirmation purposes.

Synchronization begins with a 300 ms post-charge blanking period. After this blanking period, the ICD starts a reconfirmation window and a refractory period of up to the same duration (VT Interval

plus 60 ms; see

Figure 5-6).

If the next ventricular event occurs after the reconfirmation window, it is classified as normal, and the ICD starts a new reconfirmation window. If the event occurs during the reconfirmation window, it also falls within the refractory period, and is therefore classified as refractory. If this occurs, the refractory period is terminated, and the ICD starts a new reconfirmation window.

Subsequent ventricular events during synchronization start new reconfirmation intervals. A sensed event starts a 120 ms post-sense blanking period and a reconfirmation window. Paced events start a programmed post-shock Pace Blanking period, a reconfirmation window, and a refractory period of up to the same duration (VT Interval

plus

60 ms).

VF is reconfirmed and the ICD delivers the defibrillation therapy synchronized with the second arrhythmic ventricular event. However, if four normal ventricular intervals occur without reconfirming VF, the ICD aborts the shock (see Figure 5-7).

5-12 Onyx VR System Reference Guide

Bradycardia pacing during reconfirmation – Each reconfirmation interval also begins an escape period in the VVI mode. If the escape period times out, the ICD paces the ventricle and continues to monitor for reconfirmation of VF. VF cannot be reconfirmed on an event that immediately follows a paced event, because a refractory period of up to 60 ms plus the programmed VT Interval

follows a paced event (see Figure 5-7).

Or VF Interval, if VT Detection is Off

Tachyarrhythmia therapies

Defibrillation

At the second arrhythmic event, the shock is delivered and an extended brady escape period begins.

The first event after

charge end is refractory.

Blanking

Refractory

Reconfirmation

C E

300 ms

The refractory period can last as long as the VT Interval plus 60 ms, but will terminate with the first ventricular event that falls within it.

VT Interval plus 60 ms

120 ms

460 ms

V R

460 ms

Figure 5-6. Defibrillation delivered after reconfirming VF

120 ms 520 ms

1200 ms brady escape interval

If necessary, the device delivers a VVI pacing pulse.

V P

240 ms

200 ms

Onyx VR System Reference Guide 5-13

Tachyarrhythmia therapies

Defibrillation

The VF has terminated spontaneously after it was detected.

C E

300 ms 120 ms 240 ms

Blanking

Refractory

Reconfirmation

460 ms

The refractory period can last as long as the VT interval plus 60 ms but will terminate with the first ventricular event that falls within it.

VT interval of 400 ms plus 60 ms

A paced event occurs, followed by the programmable pace blanking period and a refractory period of 460 ms (VT interval of 400 ms plus 60 ms).

V R

460 ms

V S

460 ms

V P

460 ms

Each event generates a new reconfirmation interval,

but the VF is never reconfirmed during any of them.

Figure 5-7. Defibrillation aborts after failure to reconfirm

After four normal intervals, the

defibrillation therapy aborts.

V S

120 ms 120 ms120 ms

460 ms

V S

200 ms

5-14 Onyx VR System Reference Guide

Cardioversion

Tachyarrhythmia therapies

Cardioversion

Tabl e 5 -4. Cardioversion programmable parameters

VT (or FVT) Therapy Status On or Off

Therapy Type CV

Energy (J) 0.4 – 30 (see “Energy” on page 5-6)

Pathway AX>B or B>AX (see “Pathway polarity”

Progressive Episode Therapies On or Off (see “Progressive Episode

Any of the six VT or six FVT therapies can be programmed Off. The ICD retains the settings, but skips the “off” therapy and immediately delivers the next available therapy.

on page 5-7)

Therapies” on page 5-32)

Programming cardioversion therapies

If VT or FVT Therapy is programmed On, VF Therapy must also be On.

At least one therapy for VT and one therapy for FVT should be programmed to 30 J cardioversion.

The programmer requires that if FVT therapies are On, then at least one must be programmed to cardioversion (any energy).

If the Progressive Episode Therapies feature is enabled, the ICD may deliver a cardioversion therapy at a higher energy level than was programmed. This ensures that each therapy delivered during an ongoing episode is at least as aggressive as the previous therapy (see “Progressive Episode Therapies” on page 5-32).

Onyx VR System Reference Guide 5-15

Tachyarrhythmia therapies

Cardioversion

To program cardioversion therapies

1. Select the Params icon, and choose the Therapies menu option.

2. Select either the [FVT] or [VT] (see Figure 5-8).

3. Set Therapy Type to CV (Therapy Status also turns On).

4. Set Energy and Pathway parameters for each cardioversion therapy.

5. Select [PROGRAM].

VT Therapy screen

selected

Cardioversion

parameters

Shared Therapy

parameters screen

selected

Figure 5-8. Programmable cardioversion parameters

6. To program the Progressive Episode Therapies feature, select [Shared] (see Figure 5-9).

7. Choose a setting for Progressive Episode Therapies.

8. Select [PROGRAM].

Progressive Episode

Therapies parameter

5-16 Onyx VR System Reference Guide

Figure 5-9. Shared Therapy Parameters screen

Tachyarrhythmia therapies

Cardioversion

Cardioversion synchronization

In general, a cardioversion therapy is synchronized to a non-refractory arrhythmic event, but it aborts if the tachycardia terminates spontaneously.

Cardioversion uses a sequence of synchronization “windows,” each lasting 60 ms plus the programmed VT Interval

, to identify an ongoing tachyarrhythmia. The ICD defines a non-refractory sensed ventricular event within this window as arrhythmic for synchronization purposes. The first synchronization window begins after the 300 ms post-charge blanking period, with an effective refractory period of 100 ms.

The ICD delivers the cardioversion therapy on a ventricular event that is:

■

non-refractory and arrhythmic

■

not the first arrhythmic event during synchronization.

If a synchronization window expires without a ventricular event, the shock aborts at the next event or escape period timeout (see Figure 5-10). The shock also aborts if three consecutive ventricular events are sensed during refractory periods.

Any other refractory or arrhythmic ventricular event begins a new synchronization window, with a 120 ms post-sense blanking period and a 200 ms refractory period (see Figure 5-11).

Bradycardia pacing during synchronization – Each synchronization window begins an escape period in the VVI mode. If the escape period times out, the ICD aborts the cardioversion therapy and paces, using its standard output settings. The escape period is the current pacing rate (sensor or programmed lower rate) interval, up to a maximum of 1760 ms.

Or VF Interval, if VT Detection is Off.

Onyx VR System Reference Guide 5-17

Tachyarrhythmia therapies

Cardioversion

This sensed beat generates a second synchronization window of 460 ms.

The next ventricular event comes after the synchronization window has timed out, and the cardioversion therapy aborts.

Blanking

Refractory

Synchronization

Blanking

Refractory

Consecutive Events

Refractory:

Non-refractory:

C E

300 ms 120 ms 120 ms

400 ms 200 ms

(VT interval of 400 ms plus 60)

V R

460 ms

Figure 5-10. Cardioversion aborts after failure to reconfirm

C E

300 ms 120 ms

400 ms

0 0

V R

200 ms

1 0

V R

120 ms 120 ms

2 0

200 ms

V R

200 ms

3 0

V S

200 ms

A post-sense or post-pace blanking

period begins when the shock aborts.

The programmed pacing mode also

resumes.

Each sensed beat generates a new 200 ms refractory period.

Several consecutive refractory events (intervals < 200 ms) indicate that the VT has converted to VF.

After three refractory events in a row, the cardioversion pulse aborts. The capacitors retain their charge and VF Detection resumes.

Figure 5-11. Cardioversion aborts after three refractory beats

5-18 Onyx VR System Reference Guide

Medtronic 7290CX Reference Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Customer education

Technical support

References

Notice

Abbreviations and Acronyms

Quick reference

Primary capabilities

Tachyarrhythmia detection

Tachyarrhythmia therapy

Pacing management

Patient management

Other features

Physical characteristics

Electrical characteristics

Longevity

Battery voltage

Charge time

High voltage therapy energy

Magnet application

Emergency settings

Programmable parameters overview

Detection parameters

Therapy parameters

Bradycardia pacing parameters

Data collection parameters

Patient Information parameters

EP studies parameters

Fixed parameters

Notes

Emergency therapy

Therapy overview

Effect on system operation

On-screen and display panel buttons

Temporary parameter values

Emergency defibrillation

Emergency cardioversion

Emergency Fixed Burst pacing

Emergency VVI pacing

System overview

System description

Detection and therapy overview

Redetection

Ventricular therapies

Suspending detection and therapy

Automatic suspension of detection

Disabling detection and therapies

Tachyarrhythmia detection

Sensing

Programming for appropriate sensing

Ventricular sensing

Auto-adjusting sensitivity threshold

Blanking periods

Refractory periods

VF detection

Programming VF detection

How VF detection works

VF Interval criterion

VT detection

Programming VT detection

How VT detection works

VT Interval Criterion

Combined Count detection

How Combined Count detection works

VT Stability option

Programming VT Stability option

How the VT Stability option works

EGM Width criterion

Programming the EGM Width criterion

How the EGM Width criterion works

Measuring a QRS complex

Classifying the QRS complex

Classifying the episode

FVT detection

Programming FVT detection

How FVT detection works