Medtronic 7275 Reference Guide

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GEM®III DR 7275

Dual Chamber Implantable Cardioverter Defibrillator

System Reference Guide

GEM® III DR System Reference Guide

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

A guide to the operation and programming of the 7275

GEM Implantable Cardioverter Deﬁbrillator

III DR Dual Chamber

GEM, Marker Channel, Decision Channel, PR Logic, T-Shock, Quick Look, QuickLink, Patient Alert, Active Can, and Flashback are trademarks of Medtronic, Inc.

Table of Contents

Introduction vii Abbreviations and Acronyms ix

1. Quick Reference

Primary Capabilities 1-2 Physical Characteristics 1-5 Electrical Characteristics 1-6 Magnet Application 1-10 Emergency Settings 1-11 Programmable Parameters Overview 1-12 Detection Parameters 1-13 Therapy Parameters 1-15 Bradycardia Pacing Parameters 1-17 Automatic Capacitor Formation Parameters 1-19 Data Collection Parameters 1-20 Patient Alert™ Monitoring System Parameters 1-21 Patient Information Parameters 1-23 EP Studies Parameters 1-24 Fixed Parameters 1-26 Notes 1-28

2. Emergency Therapy

Overview 2-2 Effect on System Operation 2-3 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. Overview

System Description 3-2 Detection and Therapy Overview 3-4 Disabling Detection and Therapies 3-9

4. Tachyarrhythmia Detection

Sensing 4-2 VF Detection 4-7 VT Detection 4-10 Combined Count Detection 4-13 VT Stability Option 4-15

GEM®III DR System Reference Guide

iii

Table of Contents

FVT Detection 4-17 Dual Chamber SVT Criteria 4-22 Termination and Redetection 4-35

5. Tachyarrhythmia Therapies

High Voltage Therapy Overview 5-2 Deﬁbrillation 5-9 Cardioversion 5-17 Antitachycardia Pacing Therapy Overview 5-23 Programming ATP Therapies 5-25 Burst Pacing 5-27 Ramp Pacing 5-29 Ramp+ Pacing 5-31 Smart Mode 5-33 Progressive Episode Therapies 5-36

6. Bradycardia Pacing

Pacing Mode 6-2 Bradycardia Pacing Parameters 6-9 Post Shock Pacing Parameters 6-22 Mode Switch 6-25 Rate Responsive Pacing 6-29 Rate Adaptive AV 6-35 Non-Competitive Atrial Pacing 6-38 Single Chamber Hysteresis 6-42 Ventricular Rate Stabilization 6-44 PVC Response 6-47 PMT Intervention 6-49 Ventricular Safety Pacing 6-51

7. Programmer and Software

Connecting the Programmer Hardware 7-2 Setting Up and Using the Programmer 7-12 Using the Programmer Display Screen 7-22 Starting a Patient Session 7-30 Programming Parameter Values 7-32 Checklist 7-35 Live Rhythm Monitor 7-42 Recording Live Waveforms 7-54 Printing Reports 7-62 Changes This Session 7-67 Ending a Patient Session 7-68

GEM®III DR System Reference Guide

8. Conducting System Tests

System Tests Overview 8-2 Underlying Rhythm Test 8-3 Pacing Threshold Test 8-4 Lead Impedance Test 8-6 Manual EGM Amplitude Test 8-9 Test Charge / Dump 8-11 Capacitor Formation 8-13

9. EP Studies

EP Studies Overview 9-2 Delivering Inductions 9-6 T-Shock™ 50 Hz Burst Induction 9-9 Manual Burst Induction 9-10 PES Induction 9-11 Delivering Manual Therapies 9-12 Manual Deﬁbrillation Therapy 9-13 Manual Cardioversion Therapy 9-14 Manual ATP (Antitachycardia Pacing) Therapies 9-14

10. Data Collection

Data Collection Overview 10-2 Quick Look™ 10-4 Setting Up Data Collection 10-6 Counter Data 10-11 Episode Data 10-15 Patient Information 10-28 Battery and Lead Measurements 10-32 Device Status Indicators 10-36 Saving and Retrieving ICD Data 10-38

Induction 9-8

Table of Contents

11. Patient Alert™ Monitoring System

Patient Alert™ Monitoring System 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 12-4 Surgical Approach 12-6 Sensing and Pacing Measurements 12-8 Deﬁbrillation Testing 12-9

GEM®III DR System Reference Guide

Table of Contents

Placing the ICD 12-15 Replacing the ICD 12-16 Pre-Discharge Evaluation 12-17 Follow-Up Recommendations 12-18

A. Appendix A - Warnings and Precautions

General Warnings A-2 Sterilization, Storage, and Handling A-3 Implantation and ICD Programming A-4 Lead Evaluation and Lead Connection A-5 Follow-up Testing A-6 ICD Explant and Disposal A-7 Environmental and Medical Therapy Hazards A-7 Home and Occupational Environments A-10

B. Appendix B - Parameter Interlocks

Bradycardia Pacing Parameter Interlocks B-2 Detection Parameter Interlocks B-6 Resolving Tachy / Brady Parameter Interlocks B-8

G. Glossary

I. Index

GEM®III DR System Reference Guide

Introduction

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

■

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

■

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 patient information packaged with the ICD.

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.

GEM®III DR System Reference Guide

vii

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.

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

Futura Publishing Co. 1994.

■

Singer I, Barold SS, Camm AJ, Eds.

Nonpharmacological Therapy of

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

Futura Publishing Co. 1998.

■

Estes M, Manolis AS, Wang P, Eds.

Cardioverter-Deﬁbrillators

■

Kroll MW, Lehmann MH, Eds.

. New York, NY: Marcel Dekker, Inc. 1994.

Therapy: The Engineering-Clinical Interface

Implantable

Implantable Cardioverter-Deﬁbrillator

. Norwell, MA: Kluwer

Academic Publishers 1996.

Cardiac

. Armonk, NY:

viii

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, INCIDENTIAL OR CONSEQUENTIAL DAMAGES TO ANY THIRD PARTY WHICH RESULTS FROM THE USE OF THE INFORMATION PROVIDED IN THE SOFTWARE.

GEM®III DR System Reference Guide

Abbreviations and Acronyms

A- Atrial

AF Atrial Fibrillation

AFib/AFlutter Atrial Fibrillation and/or Atrial Flutter

ARP Atrial Refractory Period

ATP Antitachycardia Pacing

AVP Atrial Vulnerable Period

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

NCAP Non-Competitive Atrial Pacing

NID Number of Intervals to Detect

PAC Premature Atrial Contraction

PAV Paced A-V Delay

PES Programmed Electrical Stimulation

PMT Pacemaker-Mediated Tachycardia

POR Power On Reset

PP P-P interval; an atrial interval

ppm paces or pulses per minute

reciprocal minutes; for example, pacing pulses per minute

Abbreviations and Acronyms

GEM®III DR System Reference Guide

Abbreviations and Acronyms

PR P-R interval; an interval between a P-wave and the

PVAB Post Ventricular Atrial Blanking period

PVARP Post Ventricular Atrial Refractory Period

PVC Premature Ventricular Contraction

RAAV Rate Adaptive A-V delay

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

RNID Number of Intervals to Redetect

RP R-P interval; an interval between an R-wave and the

RR R-R interval; a ventricular interval

SAV Sensed A-V Delay

ST / Sinus Tach Sinus Tachycardia

SVT Supraventricular Tachycardia

TDI Tachycardia Detection Interval

V volts

V- Ventricular

VF Ventricular Fibrillation

VF NID VF Number of Intervals to Detect

VF RNID VF Number of Intervals to Redetect

VRS Ventricular Rate Stabilization

VSP Ventricular Safety Pacing

VT Ventricular Tachycardia

VT NID VT Number of Intervals to Detect

VT RNID VT Number of Intervals to Redetect

subsequent R-wave

subsequent P-wave

GEM®III DR System Reference Guide

Quick Reference

Primary Capabilities 1-2

Physical Characteristics 1-5

Electrical Characteristics 1-6

Magnet Application 1-10

Emergency Settings 1-11

Programmable Parameters Overview 1-12

Detection Parameters 1-13

Therapy Parameters 1-15

Bradycardia Pacing Parameters 1-17

Automatic Capacitor Formation Parameters 1-19

Data Collection Parameters 1-20

Patient Alert™ Monitoring System Parameters 1-21

Patient Information Parameters 1-23

EP Studies Parameters 1-24

Fixed Parameters 1-26

Notes 1-28

GEM®III DR System Reference Guide

1-1

Quick Reference

Primary Capabilities

Pacing Management

Dual chamber rate responsive bradycardia pacing up to 150 ppm (min

Rate Adaptive AV, Sensor Varied PVARP, PMT Intervention, Non-Competitive Atrial Pacing, Ventricular Safety Pacing

Ventricular Rate Stabilization after short ventricular intervals

DDIR Mode Switch during paroxysmal atrial episodes

-1

): DDDR, DDD, DDIR, DDI, VVIR, VVI, AAIR, AAI modes;

Dual Chamber VF/VT/FVT Detection

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

Single chamber VT Stability criterion

PR Logic™ Pattern and Rate Analysis identiﬁes Atrial Fibrillation/Atrial Flutter, Sinus Tachycardia, and Other 1:1 SVTs

Adjustable 1:1 VT-ST Boundary for patients with slow conduction

Tachyarrhythmia Therapy

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

Ventricular deﬁbrillation and cardioversion, 30 joules delivered (35 joules stored) with 50% tilt

1-2

Burst, Ramp, and Ramp+ antitachycardia pacing

Smart Mode disables ineffective ATP therapies

Progressive Episode Therapies ensures increasingly aggressive therapy sequencing

Dual chamber synchronization of high voltage therapies avoids the atrium’s vulnerable period

GEM®III DR System Reference Guide

Quick Reference

Primary Capabilities

Patient Management

Audible Patient Alert™ monitoring system

Automatic, painless pacing and HV lead impedance testing

Lead performance trends report and display

Sensing integrity counter

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

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

Two channels stored EGM: atrial / ventricular / far-ﬁeld

Dual chamber Marker Channel™ telemetry

Supplementary Decision Channel annotations in stored EGM and on real time recordings that indicate detection algorithm status.

256 Kbyte data storage, including two EGMs, Markers, and Flashback™ Memory of A-A and V-V intervals

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

Table 1-1. GEM®III DR ICD Data Collection Summary

Tachy episodes

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

Brady episodes 53 mode switch episodes: episode text

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

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

EGM options Store before onset; Store during charging

Flashback™ Memory

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

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

episode summaries (usually only episode summaries are provided for NSTs)

2000 intervals (containing both A-A and V-V): before latest VF, before latest VT, and before interrogation

GEM®III DR System Reference Guide

1-3

Quick Reference

Primary Capabilities

Table 1-1. GEM®III DR ICD Data Collection Summary

Episode counters Episodes:

- VF, FVT, and VT

- Atrial Fibrillation / Atrial Flutter episodes

- Sinus Tach episodes

- Other 1:1 SVTs episodes

- Non-sustained tachy episodes

- Mode switch episodes Percentage Pacing:

- AS-VS, AS-VP, AP-VS, AP-VP percentages Additional Counters:

- Single PVCs and PVC runs

- Rate stabilization pulses and runs

Therapy Efﬁcacy Counters

Patient Alert™ Events

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

Counts for each VF, FVT, VT Therapy:

- Delivered

- Successful

- Unsuccessful

- Intervention Total number of aborted shocks

Up to 10 log entries: text and date for the ﬁrst time an alert is triggered between interrogations.

Other features

1-4

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

Medtronic icon-based user interface

Full-size report printing

Quick Look™ programming summary with Quick Links™ to stored episodes and observations

Non-invasive EP study functions: atrial inductions, ventricular inductions / manual therapies

Smart Auto Cap Formation extends the formation timer after therapeutic charging

Auto-Resume feature automatically resumes detection after an induction

Checklist feature provides streamlined, customizable navigation through sets of tasks for follow-up and implant visits

GEM®III DR System Reference Guide

Physical Characteristics

Volume 39.7 cc

Mass 78.1 g

H x W x D

Surface area of device can 69.0 cm

Quick Reference

Physical Characteristics

70.1 mm x 50.8 mm x 13.5 mm

Radiopaque ID

Materials in contact with human tissue

PJM

Titanium / polyurethane / silicone rubber

Battery Lithium silver vanadium oxide

Connector conﬁguration Two IS-1 connectors for pacing and sensing,

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

IS-1

SVC

(HVX)

(HVB)

DF-1

Can (HVA)

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

GEM®III DR System Reference Guide

1-5

Quick Reference

Electrical Characteristics

Longevity

Table 1-2 below provides longevity estimates based on accelerated battery discharge data and device modeling with 60 ppm (min-1) pacing

rate, 2 V pacing pulse amplitude, 0.6 ms pacing pulse width, and 30 J delivered therapy energy

Table 1-2. GEM®III DR Projected Longevity in Years with 2 V Pacing Pulse Amplitude

and 0.6 ms Pacing Pulse Width

Percent pacing

0% Semi-Annual 7.0 7.0 7.0 7.0

15% Semi-Annual 6.7 6.9 6.8 7.0

50% Semi-Annual 6.1 6.6 6.5 6.8

100% Semi-Annual 5.5 6.2 6.1 6.5

Maximum Energy Charging Frequency

Quarterly 6.3 6.3 6.3 6.3

Quarterly 6.0 6.2 6.1 6.3

Quarterly 5.6 6.0 5.9 6.1

Quarterly 5.1 5.7 5.5 6.0

500 ohm pacing

impedance

DDD Pacing VVI Pacing DDD Pacing VVI Pacing

900 ohm pacing

impedance

1-6

GEM®III DR System Reference Guide

Quick Reference

Electrical Characteristics

Table 1-3 below provides longevity estimates based on accelerated battery discharge data and device modeling with 60 ppm (min-1) pacing

rate, 3 V pacing pulse amplitude, 0.4 ms pacing pulse width, and 30 J delivered therapy energy

Table 1-3. GEM®III DR Projected Longevity in Years with 3 V Pacing Pulse Amplitude

and 0.4 ms Pacing Pulse Width

Percent pacing

0% Semi-Annual 7.0 7.0 7.0 7.0

15% Semi-Annual 6.4 6.7 6.6 6.9

50% Semi-Annual 5.5 6.2 6.0 6.5

100% Semi-Annual 4.5 5.5 5.3 6.1

Maximum Energy Charging Frequency

DDD Pacing VVI Pacing DDD Pacing VVI Pacing

Quarterly 6.3 6.3 6.3 6.3

Quarterly 5.8 6.0 6.0 6.2

Quarterly 5.0 5.6 5.5 5.9

Quarterly 4.2 5.1 4.9 5.5

500 ohm pacing

impedance

900 ohm pacing

impedance

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, or

■

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.

EGM pre-storage feature set to Off.

GEM®III DR System Reference Guide

1-7

Quick Reference

Electrical Characteristics

Battery Voltage

Battery voltage appears on the programmer display and on printed reports. See “Preparing the ICD for Implant” on page 12-5, and “Replacement Indicators” on page 12-19 for more information.

Table 1-4. Battery Voltage Indicators

Elective Replacement (ERI)

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

End of Life (EOL)

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

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

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

-1

), 3 V, 0.4 ms; 500 Ω pacing load; and six 30 J charges.

≤ 2.55 V

≤ 2.40 V

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 page 8-13 for information on managing charge time. See page 8-12 for instructions on using the Test Charge feature to measure charge time. Table 1-5 provides typical full energy charge times at BOL and ERI based on the time interval since the last capacitor formation.

Table 1-5. Typical Full Energy (30 J Delivered) Charge Times

Capacitors

fully formed

At Beginning of Life (BOL) 7 seconds ≈ 1 second

Near Elective Replacement Indicator (ERI)

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

14 seconds ≈ 3 seconds

3 months after

capacitor

formation

longer than fully formed

6 months after

capacitor formation

≈ 2 seconds longer than fully formed

≈ 5 seconds longer than fully formed

1-8

GEM®III DR System Reference Guide

Quick Reference

Electrical Characteristics

High Voltage Therapy Energy

Table 1-5 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.

Table 1-6. 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 2.15

0.8 1.0 .17 11 13 2.37

1.0 1.2 .22 12 14 2.58

1.2 1.5 .26 13 15 2.80

1.4 1.7 .30 14 16 3.01

1.6 2.0 .34 15 18 3.23

1.8 2.2 .39 16 19 3.44

2 2.4 .43 18 21 3.87

3 3.6 .65 20 24 4.30

4 4.7 .86 22 26 4.73

5 5.9 1.08 24 28 5.16

6 7.1 1.29 26 31 5.59

7 8.3 1.51 28 33 6.02

8 9.4 1.72 30 35 6.45

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

Energy stored at end of charge on capacitor.

Typical charge time at BOL, with fully formed capacitors.

Stored

Energy (J)

Charge

Timec (sec)

Programmed

(Actual Delivered)

Energy (J)

Stored

Energy (J)

Charge

Timec (sec)

GEM®III DR System Reference Guide

1-9

Quick Reference

Magnet Application

Applying a magnet closes a reed switch within the ICD (see Table 1-6 for magnet effects). When the magnet is removed, the ICD returns to its programmed operations.

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 has been enabled via the programmer, detection will remain enabled.

The alert sounds only if 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 Off.

Table 1-7. Effects of Magnet Application

suspended

(30 seconds or less) continuous tone (Alarm OK) on/off intermittent tone (seek follow-up) high/low dual tone (urgent follow-up)

1-10

GEM®III DR System Reference Guide

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

notes on page 1-28.

Table 1-8. Emergency Therapy Parameters

Parameter Selectable Values (and

Deﬁbrillation

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

18, 20, . . .,

Pathway AX→B

Cardioversion

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

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

Pathway AX→B

Fixed Burst

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

360, 370, . . ., 600

Pulse Amplitude (V) 8

Pulse Width (ms) 1.6

text. The Notes column lists letters than correspond to

350

default value

Quick Reference

Emergency Settings

) Notes

VVI Pacing

Pacing Mode VVI

Lower Rate (ppm, min-1)70

Vent. Rate Stabilization Off

Hysteresis Off

V. Sensitivity/A.Sensitivity As programmed

Pulse Amplitude (V) 6 V

Pulse Width (ms) 1.6 ms

Pace Blanking (ms) 240 ms

Post Shock Pace Blanking (ms) 240 ms A.

GEM®III DR System Reference Guide

1-11

Quick Reference

Programmable Parameters Overview

The tables that follow (from “Detection Parameters” on page 1-13 to “Patient Information Parameters” on page 1-23) 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 – are suggested settings for parameters under nominal conditions. Medtronic nominal values, if applicable, are indicated in the Programmable Values column with

POR values – 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 twenty hours. See the “Power-On Reset Recovery Procedure” on page 10-37.

Shipped values – 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 1-28. These include exceptions or clariﬁcations that relate to the values listed in the programmable parameter tables.

bold, italicized

text.

1-12

GEM®III DR System Reference Guide

Detection Parameters

Table 1-9. Detection Parameters (Sheet 1 of 2)

Parameter Programmable Values

VF DETECTION PARAMETERS

Detection Enable

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

Initial NID 12/16,

Redetect NID 6/8, 9/12,

V. Sensitivity (mV) 0.15,

A. Sensitivity (mV) 0.15,

(and

Medtronic Nominal

, Off On Off

320

330, 340, . . ., 400

18/24

12/16

0.3

, 0.45, 0.6,

0.3

, 0.45, 0.6,

, 24/32,

, 18/24,

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

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

0.9, 1.2

0.9, 1.2, 1.5, 2.1

Quick Reference

Detection Parameters

)

POR

Value

320 320 C.

18/24 18/24 B.

12/16 12/16

0.3 0.3 D, E.

Shipped

Value

Notes

FVT DETECTION PARAMETERS

Detection Enable

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

V. Sensitivity (mV) 0.15,

A. Sensitivity (mV) 0.15,

Off

, via VF, via VT Off Off

0.3

0.9, 1.2

0.9, 1.2, 1.5, 2.1

, 0.45, 0.6,

0.3

, 0.45, 0.6,

0.3 0.3 D, E.

GEM®III DR System Reference Guide

1-13

Quick Reference

Detection Parameters

Table 1-9. Detection Parameters (Sheet 2 of 2)

Parameter Programmable Values

VT DETECTION PARAMETERS

Detection Enable On,

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

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

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

V. Sensitivity (mV) 0.15,

A.Sensitivity (mV) 0.15,

VT Stability Criterion Parameters

VT Stability (ms)

(and

Medtronic Nominal

)

Off

400

410, 420, . . ., 600

76, 100

0.3

0.9, 1.2

0.9, 1.2, 1.5, 2.1

Off

, 0.45, 0.6,

0.3

, 0.45, 0.6,

, 30, 40, . . ., 100 Off Off C.

POR

Value

Off Off

400 400 C.

16 16

0.3 0.3 D, E.

Shipped

Value

Notes

DUAL CHAMBER SVT DETECTION

AFib / AFlutter

Sinus Tach

1:1 VT-ST Boundary (%) 35, 50, 66, 75, 85 50 50

Other 1:1 SVTs On,

SVT Limit (ms) 240, 250, . . .,

, Off Off Off H.

Off

320

330, 340, . . ., 600

Off Off

320 320 C, F.

1-14

GEM®III DR System Reference Guide

Therapy Parameters

Table 1-10. Therapy Parameters (Sheet 1 of 2)

Parameter Programmable Values

VF THERAPY PARAMETERS

Therapy Status

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

Pathway

Reconﬁrm VF

VT and FVT THERAPY PARAMETERS

Cardioversion Therapy Parameters

Therapy Status

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

Pathway

(and

Medtronic Nominal

, Off On (all) On (all)

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

AX→B

Yes

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

AX→B

, B→AX AX→B (all) AX→B (all) J.

, No Yes Yes M.

, Off --- ---

, B→AX --- --- J.

Quick Reference

Therapy Parameters

)

POR

Value

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

--- --- J, L.

Shipped

Value

Notes

Burst Pacing Therapy Parameters

Therapy Status

Initial # Pulses 1, 2, . . ., 6, . . ., 15 --- --- J.

R-S1 Interval (% of R-R)

Pacing Interval Decrement (ms) 0,

# Sequences 1, 2, 3, . . ., 10 --- ---

Smart Mode On,

, Off --- ---

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

, . . ., 40 --- ---

Off

--- --- J.

--- --- N.

GEM®III DR System Reference Guide

1-15

Quick Reference

Therapy Parameters

Table 1-10. Therapy Parameters (Sheet 2 of 2)

Parameter Programmable Values

Ramp Pacing Therapy Parameters

Therapy Status

Initial # Pulses 1, 2, . . ., 8, . . ., 15 --- --- J, AB.

R-S1 Interval (% of R-R)

Pacing Interval Decrement (ms) 0, 10, . . ., 40 --- --- J.

# Sequences 1, 2, 3, . . ., 10 --- ---

Smart Mode On,

Ramp+ Pacing Therapy Parameters

Therapy Status

Initial # Pulses 1, 2, 3, . . ., 15 --- --- J.

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,

(and

Medtronic Nominal

, Off --- ---

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

)

Off

, Off --- ---

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

Off

POR

Value

--- --- J, AB.

--- --- N.

--- --- J.

--- --- N.

Shipped

Value

Notes

SHARED PARAMETERS FOR TACHYARRHYTHMIA THERAPIES

Shared by all Automatic ATP Therapies J.

V. Pulse Width (ms) 0.03, 0.06,

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

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

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

Shared by all VF, VT, and FVT Therapies

Progressive Episode Therapies Enable

1-16

GEM®III DR System Reference Guide

0.1, 0.2, . . .,

On,

Off

1.6

240

, . . ., 440 240 240

200

, . . ., 400 200 200

1.6 1.6

Off Off

Bradycardia Pacing Parameters

Table 1-11. Bradycardia Pacing Parameters (Sheet 1 of 3)

Parameter Programmable Values

Pacing Mode

Lower Rate (ppm, min-1) 34, 35, 40, . . ., 60,

Upper Tracking Rate (ppm, min-1) 80, 85, . . ., 105,

Upper Sensor Rate (ppm, min-1)

A. Sensitivity (mV) 0.15,

A. Pulse Width (ms) 0.03, 0.06,

A. Pulse Amplitude (V) 1, 2, 3, . . ., 6 4 3

A.Pace Blanking (ms) 200, 210, . . .,

V. Sensitivity (mV) 0.15,

V. Pulse Width (ms) 0.03, 0.06,

V. Pulse Amplitude (V) 1, 2,

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

(and

Medtronic Nominal

DDDR

, DDD, DDIR, DDI, AAIR,

AAI, VVIR, VVI

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

109, 115, 146, 150

80, 85, . . ., 105, 109, 115, 146, 150

0.9, 1.2, 1.5, 2.1

0.1, 0.2, . . .,

0.5, 0.6, . . ., 1.6

120

, 125, 130, 136, 140,

120

, 125, 130, 136, 140,

0.3

, 0.45, 0.6,

0.4

240

0.3

0.9, 1.2

0.1, 0.2, . . .,

0.5, 0.6, . . . , 1.6

, 0.45, 0.6,

0.4

, . . ., 6 6 3

200

210, 220, . . ., 440

)

, 250 240 240

POR

Value

VVI DDD

65 60 G.

120 120 G.

0.3 0.3 D, E.

0.4 0.4

0.3 0.3 D, E.

1.6 0.4

240 200

Quick Reference

Shipped

Value

Notes

Post-Shock Pacing Parameters

A. Pulse Width (ms) 0.03, 0.06,

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

A. Pace Blanking (ms) 200, 210, . . .,

V. Pulse Width (ms) 0.03, 0.06,

V. Pulse Amplitude (V) 1, 2, 3, 4, 5,

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

0.1, 0.2, . . .,

1.6

240

0.1, 0.2, . . .,

1.6

200

210, 220, . . ., 440

, 250 240 240

1.6 1.6

240 200

GEM®III DR System Reference Guide

1-17

Quick Reference

Bradycardia Pacing Parameters

Table 1-11. Bradycardia Pacing Parameters (Sheet 2 of 3)

Parameter Programmable Values

Intervals

PAV (ms) 30, 40, . . .,

SAV (ms) 30, 40, . . .,

PVARP (ms) Varied,

A. Refractory (ms) 150, 160, . . .,

PVAB (ms) 100, 110, . . .,

Mode Switch Parameters

Enable On,

A. Detect Rate (bpm, min-1) 120, 125, 130, 136, 140, 146, 150,

Rate Response Pacing Parameters

Rate Response 1, 2, . . ., 7,

Activity Threshold Low, Medium Low,

Activity Acceleration (sec.) 15,

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

(and

Medtronic Nominal

180

190, 200, . . ., 350

150

160, 170, . . ., 350

150, 160, . . ., 320, 330, . . ., 500

310

320, 330, . . ., 500

150

160, 170, . . ., 350

)

Off

154, 158, 167, 171,

8, 9, 10

Medium

Medium High, High

, 60 30 30

176

POR

Value

180 180

150 150

310 310 O.

310 310

150 150 O.

Off Off

176 176

High Medium

Shipped

Value

Notes

Rate Adaptive AV Parameters

Enable On,

Start Rate (bpm, min-1) 50, 55, 60, . . ., 105, 109,

Stop Rate (bpm, min-1) 50, 55, . . ., 105, 109,

Minimum PAV (ms) 30, 40, . . .,

Minimum SAV (ms) 30, 40, . . .,

1-18

GEM®III DR System Reference Guide

Off

115, 120, 125, 130, 136, 140, 146, 150, 154, 158, 167, 171, 176, 182

115,

120

150, 154, 158, 167, 171, 176, 182

150, 160, . . ., 350

120, 130, . . ., 350

, 125, 130, 136, 140, 146,

140

110

Off Off

60 60

120 120

140 140

110 110

Table 1-11. Bradycardia Pacing Parameters (Sheet 3 of 3)

Parameter Programmable Values

Non-Competitive Atrial Pacing

Enable

Single Chamber Hysteresis

Enable-Rate (bpm, min-1)

Ventricular Rate Stabilization Parameters

Enable On,

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

Minimum Interval (ms)

PMT Intervention Parameters

Enable On,

PVC Response Parameters

Enable

Ventricular Safety Pacing Parameters

Enable

(and

Medtronic Nominal

, Off On On

Off

, 34, 40, 50, 60 , 70, 80 Off Off P.

Off

150

160, 170, . . ., 400

500

, 550, . . ., 900 500 500

Off

, Off On On

Quick Reference

Automatic Capacitor Formation Parameters

)

POR

Value

Off Off

150 150

Off Off

Shipped

Value

Notes

Automatic Capacitor Formation Parameters

Table 1-12. Automatic Capacitor Formation Parameters

Parameter Programmable Values

Automatic Capacitor Formation Interval (months)

(and

Medtronic Nominal

Off, 1, 2, . . .,

)

GEM®III DR System Reference Guide

POR

Value

6 Off Q.

Shipped

Value

Notes

1-19

Quick Reference

Data Collection Parameters

Table 1-13. 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?

Store EGM Channel 2 Yes (ﬁxed) --- ---

Store EGM during charging?

Store EGM before tachycardia starts?

(and

Medtronic Nominal

HVA to Aring, Vtip to HVB, Vtip to Vring, Vtip to Atip, Atip to HVB,

Vtip to HVB,

Yes

, No Yes Yes

Yes

, No Yes Yes

Ye s ,

Atip to Aring

Vtip

)

Vring

POR

Value

Atip to Aring Atip to Aring S.

Vtip to Vring Vtip to Vring S.

No No

Shipped

Value

Notes

Device Date/Time

Premature Event Recording Parameters

Premature Event Threshold (%)

Holter Telemetry Parameters

Duration (hours)

1-20

GEM®III DR System Reference Guide

(enter time and date) --- --- X.

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

Off

, 0.5, 1, 2, 4,

8, 16, 24, 36, 46

69 69

Off Off

Quick Reference

Patient Alert™ Monitoring System Parameters

Table 1-14. Patient Alert™ Setup (Sheet 1 of 2)

Parameter Programmable Values

ALERT TIME

Hour 0, 1, 2, . . ., 23 --- ---

Minute 0, 10, . . ., 50 --- ---

LEAD IMPEDANCE OUT OF RANGE ALERT

Atrial Pacing Lead Impedance Alert AA.

Enable On, Off Off Off

Minimum Threshold (ohms) 200 Ω (ﬁxed) --- ---

Maximum Threshold (ohms) 2000 Ω (ﬁxed) --- ---

Ventricular Pacing Lead Impedance Alert AA.

Enable On, Off Off Off

Minimum Threshold (ohms) 200 Ω (ﬁxed) --- ---

Maximum Threshold (ohms) 2000 Ω (ﬁxed) --- ---

Deﬁbrillation Lead Impedance Alert AA.

Enable On, Off Off Off

Minimum Threshold (ohms) 10 Ω (ﬁxed) --- ---

Maximum Threshold (ohms) 200 Ω (ﬁxed) --- ---

Alert Urgency

(and

Medtronic Nominal

Low

, High --- ---

)

POR

Value

Shipped

Value

Notes

AA.

GEM®III DR System Reference Guide

1-21

Quick Reference

Patient Alert™ Monitoring System Parameters

Table 1-14. Patient Alert™ Setup (Sheet 2 of 2)

Parameter Programmable Values

LOW BATTERY VOLTAGE ALERT

Alert Enable - Urgency Off,

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

(and

Medtronic Nominal

On-Low

, On-High Off Off

)

POR

Value

Shipped

Value

Notes

AA.

EXCESSIVE CHARGE TIME ALERT

Alert Enable - Urgency Off,

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

NUMBER OF SHOCKS DELIVERED IN AN EPISODE ALERT

Alert Enable - Urgency 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

On-Low

, On-High Off Off

On-Low

, On-High Off Off

AA.

1-22

GEM®III DR System Reference Guide

Quick Reference

Patient Information Parameters

Table 1-15. 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 of the physician.

Hospital Select or add the hospital information.

Last Update (Not selectable)

Displays serial number for implanted ICD after interrogation.

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

•

Model

•

Position:

pick from 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.

Displays the date of the last Patient Information update.

GEM®III DR System Reference Guide

1-23

Quick Reference

EP Studies Parameters

Table 1-16. EP Studies Parameters (Sheet 1 of 2)

Parameter Selectable Values (and

INDUCTIONS

T-Shock™ Induction Parameters

#S1 2, 3, . . .,

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

410, 420, . . ., 1760

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

320, 330, . . ., 600

Energy (J) 0.4,

Pathway

Waveform

Pulse Amplitude 6 V (ﬁxed)

Pulse Width 1.6 ms (ﬁxed)

Enable Enabled,

Resume at Deliver

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

AX→B

Monophasic

Enabled

0.6

, . . ., 1.8,

, B→AX

, Disabled

400

310

, Biphasic

Disabled

default value

) Notes

50 Hz Burst Induction Parameters Z.

Interval (ms) 20 ms (ﬁxed)

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

Pulse Width (ms) 0.03, 0.06,

Resume at Burst

Manual Burst Induction Parameters

Chamber

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

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

Pulse Width (ms) 0.03, 0.06,

Resume at Burst

1-24

GEM®III DR System Reference Guide

0.1, 0.2, . . .,

Enabled

Ventricle

0.1, 0.2, . . .,

0.6, 0.7, . . ., 1.6

Enabled

1.6

, Disabled

, Atrium Z.

600

0.5

, Disabled

Quick Reference

EP Studies Parameters

Table 1-16. EP Studies Parameters (Sheet 2 of 2)

Parameter Selectable Values (and

PES Induction Parameters

Chamber

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

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

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

S2S3 (ms)

S3S4 (ms)

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

Pulse Width (ms) 0.03, 0.06,

Resume at Deliver

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.

Ventricle

9, 10, . . ., 15

, Atrium

600

610, 620, . . ., 1760

410, 420, . . ., 600

Off

, 100, 110, . . ., 600 Z.

Off

, 100, 110, . . ., 600 Z.

0.1, 0.2, . . .,

0.6, 0.7, . . ., 1.6

Enabled

0.5

, Disabled

400

default value

) Notes

GEM®III DR System Reference Guide

1-25

Quick Reference

Fixed Parameters

Table 1-17. Fixed Parameters (Sheet 1 of 2)

Parameter Value Notes

SENSING

Atrial Blanking Periods

After a sensed atrial event 100 ms

After a paced vent. event 30 ms

After charging ends 300 ms

After HV therapy 520 ms

Ventricular Blanking Periods

After a sensed vent. event 120 ms

After a paced atrial event 30 ms

After charging ends 300 ms

After HV therapy 520 ms

Atrial Refractory Periods

Non-Competitive Atrial Pacing Interval 300 ms

BRADYCARDIA PACING

Ventricular Safety Pacing Intervals 110 ms

PVC Response (PVARP extension)

PMT Intervention (PVARP extension)

1-26

GEM®III DR System Reference Guide

70 ms

Extended to 400 ms U.

Extended to 400 ms

Quick Reference

Fixed Parameters

Table 1-17. Fixed Parameters (Sheet 2 of 2)

Parameter Value Notes

HIGH VOLTAGE THERAPIES

Maximum charging period 30 seconds

Waveform Biphasic

Tilt 50%

VF Synchronization Periods V.

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 R.

Atrial Vulnerable Period 250 ms

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 6 V Z.

HARDWARE PARAMETERS

Atrial rate limit (protective feature)

Ventricular rate limit (protective feature)

Input protection 100 kΩ minimum

171 ppm (min-1)W.

-1

171 ppm (min

)W.

GEM®III DR System Reference Guide

1-27

Quick Reference

Notes

Post-shock V. 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 (e.g., 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 (ventricular sensitivity) or a 20 ms sine waveform (atrial sensitivity). 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 in this chamber, for both tachyarrhythmia detection and bradycardia pacing operations.

Nominal value is blank until detection is enabled.

The shortest pacing escape interval must exceed all programmed Detection Intervals by at least 60 ms. In dual chamber modes, the shortest VA interval must equal or exceed any programmed Detection Interval.

The ICD is shipped with the Sinus Tach and A.Fib / A.Flutter criteria Off. However, when VT Detection is programmed On for the ﬁrst time, these criteria are automatically enabled.

Double tachycardia (i.e. “VF/FVT/VT plus SVT”) detection is automatically enabled when any Dual Chamber SVT criterion is enabled.

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 joules.

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

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

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

PVAB is the minimum value that PVARP is shortened to, under sensor-varied PVARP operation. Atrial events that fall within the PVAB are ignored by the Mode Switch, NCAP, PVC Response, and PMT Intervention features.

Pacing mode must be VVI or AAI, 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 6 month.

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.

1-28

GEM®III DR System Reference Guide

Quick Reference

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

The shorter VSP interval takes effect when the pacing rate exceeds [60,000 divided by 2x (ventricular pace blanking plus 110)] per minute.

PVARP is only extended to 400 ms if the current PVARP (either the programmed PVARP value or the current Sensor-Varied PVARP value) is less than 400 ms.

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 (i.e., sensor, Mode Switch, or programmed lower rate) escape period.

Does not apply during therapies, programmed high rates, or ventricular safety pacing.

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

Delivered in the VVI or AAI mode (as applicable)

Delivered in the VOO or AOO mode (as applicable)

AA.

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

twenty hours

AB.

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

until cleared.

Notes

GEM®III DR System Reference Guide

1-29

Quick Reference

Notes

1-30

GEM®III DR System Reference Guide

Emergency Therapy

Overview 2-2

Effect on System Operation 2-3

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

GEM®III DR System Reference Guide

2-1

Emergency Therapy

Overview

The ICD provides the following Emergency therapies:

■

Deﬁbrillation therapy

■

Cardioversion therapy

■

Fixed Burst pacing therapy

■

Maximum output VVI pacing

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

Deﬁbrillation is the default Emergency therapy, and 30 joules is the default delivered energy. When you select

[Emergency] and [DELIVER], the ICD

charges and delivers a biphasic 30 joule shock along the AX>B pathway.

If you select a different deﬁbrillation energy, the programmer resets the energy to 30 joules the next time you select

[Emergency]. Emergency

Cardioversion and Emergency Fixed Burst values remain as selected for the duration of the session.

2-2

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].

GEM®III DR System Reference Guide

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.

On-Screen and Display Panel Buttons

The on-screen [Emergency] button and the red mechanical Emergency button by the programmer display panel are equivalent at all times.

Emergency Therapy

Effect on System Operation

Red Emergency Button

The on-screen

[DELIVER] button and the yellow-on-blue mechanical

Functions the same as on-screen

[Emergency]

at all times.

Deliver button by the programmer display panel are equivalent during Emergency operations only. The mechanical Deliver button operates only during Emergency operations.

Yellow-on-Blue

Deliver Button

Functions the same as on-screen

[DELIVER], but only during

Emergency functions.

Temporary Parameter Values

Emergency tachyarrhythmia therapies use the permanently programmed parameters of the ICD. in effect until you begin the temporary operation by selecting After the tachyarrhythmia therapy is complete, the ICD reverts to its permanently programmed values.

test values

that do not change

Test values are not

[DELIVER].

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

GEM®III DR System Reference Guide

2-3

Emergency Therapy

Emergency Deﬁbrillation

How to Deliver Emergency 30 Joule 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

How to Change the Deﬁbrillation Energy and Deliver

♦

1. From the Emergency Therapy screen, select Energy.

2. Select a new energy value.

3. Select [DELIVER].

[Retry] or [Cancel].

Select to Change

Emergency Deﬁbrillation

Select to Deliver

Emergency Deﬁbrillation

2-4

GEM®III DR System Reference Guide

Energy

Figure 2-1. Emergency Deﬁbrillation Screen

Emergency Cardioversion

How 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

Emergency Therapy

Emergency Cardioversion

[Retry] or [Cancel].

Emergency Cardioversion

Select to Change

Energy

Select to Deliver

Emergency Cardioversion

Figure 2-2. Emergency Cardioversion Screen

GEM®III DR System Reference Guide

2-5

Emergency Therapy

Emergency Fixed Burst Pacing

How 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.

Select to Change

Burst Interval

Press and Hold to Deliver

Emergency Fixed

Burst Pacing

5. Select

If delivery is not conﬁrmed, the programmer displays an error window. Verify that the programming head is properly positioned. Select the window and reselect

[BURST Press and Hold].

[OK] from

[BURST Press and Hold].

Figure 2-3. Emergency Fixed Burst Pacing Screen

2-6

GEM®III DR System Reference Guide

Emergency VVI Pacing

How to Deliver Emergency VVI Pacing

♦

1. Position the programming head over the ICD.

2. Select [Emergency].

3. Select [VVI Pacing].

4. Select [PROGRAM]. A successful programming sets the ICD to the

following maximum output bradycardia pacing values.

Pacing Mode VVI

Lower Rate 70 ppm (70 min-1)

V. Amplitude 6 V

V. Width 1.6 ms

V. Pace Blanking 240 ms

V. Post Shock Pace Blanking 240 ms

Hysteresis Off

Ventricular Rate Stabilization Off

Emergency Therapy

Emergency VVI Pacing

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

If programming is not conﬁrmed, verify that the programming head is properly positioned and select

[Retry] or [Cancel].

GEM®III DR System Reference Guide

2-7

Emergency Therapy

Emergency VVI Pacing

Parameters (ﬁxed)

Select to Program

Emergency VVI Pacing

Figure 2-4. Emergency VVI Pacing Screen

2-8

GEM®III DR System Reference Guide

Overview

System Description 3-2

Detection and Therapy Overview 3-4

Disabling Detection and Therapies 3-9

GEM®III DR System Reference Guide

3-1

Overview

System Description

The GEM®III DR Model 7275 Dual Chamber 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 joules 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.

3-2

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 can be programmed to discriminate between true ventricular arrhythmias and rapidly-conducted supraventricular tachyarrhythmias (SVTs), using PR Logic™ Pattern and Rate Analysis. The ICD also can detect an unrelated ventricular arrhythmia occurring simultaneously with an SVT, so that recognition of an SVT does not impede ventricular detection.

The ICD provides dual 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.

GEM®III DR System Reference Guide

Overview

System Description

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 each chamber of the heart, 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 pacing/sensing electrodes in each chamber.

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.

A programmable Patient Alert™ monitoring feature notiﬁes the patient by audible tones if certain conditions (low battery voltage, high lead impedance, etc.), 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.

GEM®III DR System Reference Guide

3-3

Overview

Detection and Therapy Overview

Implanted sensing electrodes provide atrial and ventricular intracardiac electrograms to the ICD. The ICD measures the time between events to determine A-A and V-V intervals, and calculates the atrial and ventricular rates from these intervals.

The ICD can operate in:

■

Single chamber detection (with all Dual Chamber SVT Criteria programmed using only the ventricular rate, or

■

Dual chamber detection (with any Dual Chamber SVT Criterion programmed using both the rate measurements and PR Logic™ Pattern and Rate Analysis results.

Figure 3-1 represents the detection paths with Dual Chamber SVT Criteria programmed chamber detection).

Single Chamber Detection – 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.

Off), in which the ICD detects ventricular arrhythmias

On), in which the ICD detects ventricular arrhythmias

Off (single chamber detection) and On (dual

3-4

GEM®III DR System Reference Guide

Overview

Detection and Therapy Overview

Dual Chamber Detection – If the number of VF or VT intervals reaches the programmed NID, the ICD applies PR Logic™ Pattern and Rate Analysis to classify the rhythm as either:

■

a ventricular tachyarrhythmia,

■

a rapidly conducted SVT (page 4-28),

■

or a double tachycardia (page 4-33).

PR Logic™ evaluates the rates, patterns, and relative timing of atrial and ventricular activation to identify conducted SVTs (page 4-28). The ICD delivers ventricular therapy for ventricular or double tachycardias, but withholds therapy for rapidly conducted SVTs.

Ventricular Event

Update A-V Pattern and Intervals

Ventricular Tachyarrhythmias Detected by

One or More Dual-Chamber SVT Criteria On?

Single-Chamber Detection

Ye s

No/Redetection

Ye s

Deliver

Ventricular

Therapy

Median Ventricular Interval

Less than SVT Limit?

VT/VF or Fast VT during AF/AFlutter?

Dual-Chamber SVT Criteria Met?

Ye s

Figure 3-1. GEM®III DR Detection and Therapy Operation

GEM®III DR System Reference Guide

3-5

Overview

Detection and Therapy Overview

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 (page 4-36) or delivers all the therapies programmed for the detected tachyarrhythmia. The ICD does not apply the dual chamber detection and PR Logic™ algorithms during redetection.

Therapy

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.

3-6

GEM®III DR System Reference Guide

Detection and Therapy Overview

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 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 is programmed.

[Resume]

Overview

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 measurements (see page 8-8). 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.

GEM®III DR System Reference Guide

3-7

Overview

Detection and Therapy Overview

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

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.

3-8

GEM®III DR System Reference Guide

Disabling Detection and Therapies

Automatically Disabling Detection and Therapies

The ICD turns off VT Detection if a power-on reset (POR) occurs. The programmable parameter tables starting on page 1-13 list the POR values for all programmable 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

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].

Off via the programmer.

Overview

Disabling Detection and Therapies

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

GEM®III DR System Reference Guide

3-9

Overview

Disabling Detection and Therapies

3-10

GEM®III DR System Reference Guide

Tachyarrhythmia Detection

Sensing 4-2

VF Detection 4-7

VT Detection 4-10

Combined Count Detection 4-13

VT Stability Option 4-15

FVT Detection 4-17

Dual Chamber SVT Criteria 4-22

Termination and Redetection 4-35

GEM®III DR System Reference Guide

4-1

Tachyarrhythmia Detection

Sensing

The ICD provides bipolar sensing in both the atrium and ventricle via the sensing electrodes of the implanted atrial and ventricular leads. The ICD

senses in both chambers, regardless of the programmed bradycardia pacing mode.

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

■

Auto-adjusting atrial and ventricular sensing thresholds (see page 4-4),

■

Short (30 ms) cross-chamber blanking after paced events, and

■

No cross-chamber blanking after sensed events.

Programming for Appropriate Sensing

Separately programmable sensitivity thresholds deﬁne the minimum electrical amplitude that the ICD recognizes as an atrial or ventricular event.

4-2

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.

■

When the ICD is programmed to an atrial pacing mode, make sure that it does not sense atrial pacing pulses in the ventricle.

■

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.

GEM®III DR System Reference Guide

Tachyarrhythmia Detection

Sensing

■

If you change the ventricular 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.

Atrial Sensing

The ICD provides a nominal atrial sensitivity threshold of 0.3 mV to maximize the effectiveness of PR Logic™ Pattern and Rate Analysis and atrial pacing operations. Select an atrial threshold that does not sense far-ﬁeld R-waves, but provides reliable sensing during SVTs.

■

Any Medtronic bipolar IS-1 compatible atrial lead may be used. Atrial leads with minimal tip to ring spacing may reduce far-ﬁeld R-wave sensing.

■

A less sensitive atrial threshold could lead to undersensing of P-waves or inappropriate ventricular detection. Verify that the ICD senses properly in the atrium, both during sinus rhythm and during SVTs.

■

Verify that the ICD does not sense far-ﬁeld R-waves by viewing the atrial Marker annotations.

■

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

■

You may need to reposition or replace the atrial sensing lead if none of the programmable atrial thresholds provides both reliable SVT sensing and exclusion of far-ﬁeld R-wave sensing.

GEM®III DR System Reference Guide

4-3

Tachyarrhythmia Detection

Sensing

Auto-Adjusting Sensitivity Thresholds

The ICD automatically adjusts its sensitivity thresholds following certain paced and sensed events (Figure 4-1) to reduce the incidence of T-wave sensing and cross-chamber 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.

Table 4-1. Auto-Adjusting Sensitivity Threshold Values

Atrial Sensitivity Ventricular Sensitivity

Post-atrial sense

Post-atrial pace

Post-ventricular sense

Post-ventricular pace

Increased to 75% of EGM peak. 200 ms decay constant.

None Increased by 0.45 mV.

None Increased to 75% of EGM peak.

Increased by 4x the programmed value.

b,e

Immediate return after 60 ms.

Up to a maximum of 8x the programmed value.

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

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

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

Up to a maximum of 1.8 mV.

None

60 ms decay constant.

450 ms decay constant

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

4-4

Ventricular EGM

4.5x

Programmed

Sensitivity Threshold

Programmed

Post-Pace Blanking

Figure 4-1. Auto-Adjusting Sensitivity Threshold (Ventricular Shown)

GEM®III DR System Reference Guide

Changing Threshold

Post-Pace Post-Sense

A S

V P

A S

V P

V S

A S

V P

V S

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.

Notes:

■

To enhance sensing and detection during tachyarrhythmias, the ICD does not cross-blank (blank sensing in the opposite chamber) after a sensed event.

■

During the programmable “Post-Ventricular Atrial Blanking” (PVAB) period, the atrial sensing circuit is active. PVAB is described brieﬂy on page 4-6, and in more detail on page 6-18.

Table 4-2. Programmable Blanking Periods

Atrial blanking after atrial pace 200 – 250 ms

Atrial pace blanking during high voltage therapy 200 – 250 ms

Ventricular blanking after ventricular bradycardia pace 150 – 440 ms

Ventricular pace blanking during high voltage therapy 150 – 440 ms

Ventricular blanking after antitachycardia pace 150 – 440 ms

Table 4-3. Non-Programmable Blanking Periods

Cross-chamber blanking after atrial or ventricular pacing pulse

Atrial blanking after sensed atrial event 100 ms

Ventricular blanking after sensed ventricular event 120 ms

Atrial and ventricular blanking after the end of a cardioversion or deﬁbrillation charging period

Atrial and ventricular blanking after delivered cardioversion or deﬁbrillation therapy

30 ms

300 ms

520 ms

GEM®III DR System Reference Guide

4-5

Tachyarrhythmia Detection

Sensing

Refractory Periods

Pacing refractory periods prevent certain pacing timing intervals from being started by inappropriate sensed signals such as far-ﬁeld R-waves or electrical noise. Synchronization refractory periods help prevent delivery of pacing or shock pulses during the atrial and ventricular vulnerable periods. (Refer to “Non-Competitive Atrial Pacing” on page 6-38 and “High Voltage Synchronization” on page 5-5 for more detail.)

Note: Refractory periods do not affect tachyarrhythmia detection.

Table 4-4. Refractory Periods

Post-Ventricular Atrial Refractory Period (PVARP) 150 – 500 ms

Post-Ventricular Atrial Blanking (PVAB) 100 – 350 ms

Atrial Refractory Period (ARP) 150 – 500 ms

Ventricular refractory period after charging ends during deﬁbrillation or cardioversion synchronization

Ventricular refractory period after ventricular sense during cardioversion synchronization

or Sensor Varied

400 ms

200 ms

4-6

In dual chamber pacing modes, the Post-Ventricular Atrial Refractory Period (PVARP) controls how the device responds to retrograde

P-waves. Refer to Chapter 6 for more information on PVARP and the PVC Response and PMT Intervention features.

The Post-Ventricular Atrial Blanking (PVAB) period acts as the minimum PVARP value. Sensed atrial events that fall within the PVAB period are ignored by the Mode Switch, PVC Response, PMT Intervention, and NCAP features, but are displayed via Marker Channel™ annotation and are used for Dual Chamber SVT Criteria. Refer to page 6-18 for more information on PVAB.

In the AAI and AAIR modes, the Atrial Refractory Period (ARP) prevents inappropriate atrial inhibition due to sensed far-ﬁeld R-waves or electrical noise. The ﬁrst portion of the ARP is a blanking period that disables atrial sensing.

GEM®III DR System Reference Guide

VF Detection

Tachyarrhythmia Detection

VF Detection

The ICD detects VF as either a primary rhythm or as part of a double tachycardia (VF plus SVT).

VF Detection details begin on page 4-9.

Table 4-5. VF Detection Programmable Parameters

VF Enable On or Off

Ventricular Sensitivity

(mV)

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

VF Initial NID Number of Intervals to Detect:

VF Redetect NID Number of Intervals to Redetect:

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

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

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

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

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

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.

The ICD can be programmed to exclude rapidly conducted SVTs from VF Detection. See “Dual Chamber SVT Criteria” on page 4-22.

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

When VF Detection is enabled for the ﬁrst time (i.e., at implant) the ICD automatically changes the Automatic Capacitor Formation Interval from

Off to 6 month.

GEM®III DR System Reference Guide

4-7

Tachyarrhythmia Detection

VF Detection

♦

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

Off.

How to Program VF Detection

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

programmer displays the Detection screen (shown below).

2. Tu r n

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

VF Enable to On and select VF Detection parameters.

Figure 4-2. Detection Screen Example

4-8

GEM®III DR System Reference Guide

Tachyarrhythmia Detection

VF Detection

How VF Detection Works

If all Dual Chamber SVT Criteria are Off, the ICD detects VF based on the ventricular rate alone. If any Dual Chamber SVT Criterion is also examines the atrial rhythm to exclude SVTs from inappropriate detection as VF (page 4-22) and to identify a possible double tachycardia (VF plus SVT) (page 4-33).

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 episode and delivers the ﬁrst programmed VF therapy. Following the therapy, if the number of VF events reaches the redetects VF and delivers the next programmed VF therapy. (See also “Combined Count Detection” on page 4-13.) VF NIDs are deﬁned as a number of VF events within the last sixteen intervals). All NID values are 75% of the detection window: 12/16, 18/24, etc.

VF Initial NID, the ICD detects a VF

VF Redetect NID, the ICD

VF detection window

(e.g., twelve of the

On, the ICD

A S

V S

VF On 12/16 9/12 320 ms

VT On 12 8 400 ms

Dual Chamber SVT Criteria: All Off

Ventricular Sensitivity: 0.3 (mV)

Enab

A S

V S

A S

V S

VF Event Counter:

Initial

V S

VF Intervals (< 320 ms)

A R

123456789101112

Redetect

Inter

Figure 4-3. VF Detection Example

GEM®III DR System Reference Guide

A R

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

200 ms

4-9

Tachyarrhythmia Detection

VT Detection

The ICD detects VT as either a primary rhythm or as part of a double tachycardia (VT plus SVT).

VT Detection details begin on page 4-12.

Table 4-6. VT Detection Programmable Parameters

VT Enable On or Off

Ventricular Sensitivity

(mV)

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

VT Initial NID Number of Intervals to Detect:

VT Redetect NID Number of Intervals to Redetect:

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

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

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

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

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

4-10

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

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

The ICD can be programmed to exclude rapidly conducted SVTs from VT Detection. See “Dual Chamber SVT Criteria” on page 4-22.

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

When VT Detection is enabled for the ﬁrst time,

Sinus Tach dual chamber SVT detection criteria are automatically

enabled.

GEM®III DR System Reference Guide

VF Interval.

AFib/AFlutter and

Tachyarrhythmia Detection

To ensure VF Detection backup during VT episodes, VT Detection cannot be

On unless VF Detection is also On.

How to Program VT Detection

♦

1. Select the Params icon and choose the Detection option. The programmer displays the Detection screen (shown below).

VT Detection

2. Tu r n

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

VT Enable to On and select VT Detection parameters.

Figure 4-4. Detection Screen Example

GEM®III DR System Reference Guide

4-11

Tachyarrhythmia Detection

VT Detection

How VT Detection Works

If all Dual Chamber SVT Criteria are Off, the ICD detects VT based on the ventricular rate alone. If any Dual Chamber SVT Criterion is also examines the atrial rhythm to exclude SVTs from inappropriate detection as VT (page 4-22) and to identify a possible double tachycardia (VT plus SVT) (page 4-33).

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 4-15.) If the number of VT events reaches the programmed ﬁrst programmed VT therapy. After the therapy, if the number of VT events reaches the programmed VT therapy. (See also “Combined Count Detection” on page 4-13.) 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 value if an interval is shorter than the programmed

VT Initial NID, the ICD detects a VT episode and delivers the

VT Redetect NID, the ICD redetects VT and delivers the next

On. The VT counter remains at its current

VF Interval.

On, the ICD

A S

VF On 12/16 9/12 320 ms

VT On 12 8 400 ms

Dual Chamber SVT Criteria: All Off

Ventricular Sensitivity (mV): 0.3

A S

V S

Enab

A S

V S

A S

V S

VT Counter Value:

Initial

Redetect

A R

V S

A R

123456789101112

Figure 4-5. VT Detection Example

VT intervals > 320 and < 400 ms

4-12

GEM®III DR System Reference Guide

T S

Inter

A R

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 doesn’t 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:

■

any

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

■

all

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

GEM®III DR System Reference Guide

4-13

Tachyarrhythmia Detection

Combined Count Detection

Surface ECG

Marker Channel™

A S

A R

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

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

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

VT = 12

Counter

15105

T S

VF = 12

FSF

FSFSF

Combined Count (VT+VF) = 14

VF = 6

VT = 12

15105

4-14

GEM®III DR System Reference Guide

VT Stability Option

VT Stability is an optional ventricular SVT criterion that allows the ICD to withhold 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.

How to Program VT Stability

♦

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

Tachyarrhythmia Detection

VT Stability Option

Table 4-7. VT Stability Option Programmable Parameter

measured intervals

programmer displays the Detection screen.

2. Select a value for

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

VT Stability.

GEM®III DR System Reference Guide

4-15

Tachyarrhythmia Detection

VT Stability Option

How the VT Stability Option Works

When the VT Stability option is On, an interval in the VT zone is considered 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 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.

unstable

if the difference between it and any of the three

VT Stability is not applied until VT count reaches three.

A S

V S

A S

V S

A S

V S

VT Counter Value:

Unstable event: Varies from previous interval

by 70 ms. Event is marked as a normal sensed

4 8 0

beat and VT counter resets to zero.

Enab

VF On 12/16 9/12 320 ms

VT On 12 8 540 ms

Dual Chamber SVT Criteria: All Off

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

Stable events: Each differs from the three before it by

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

ASA

T S

4 7 0

T S

5 1 0

2 30123 2345

Unstable event: Varies from previous interval

by 60 ms. VT counter resets to zero.

Initial

Redetect

V S

4 7 0

Inter

4 7 0

200 ms

T S

4-16

Figure 4-7. VT Stability Option

GEM®III DR 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 detects FVT as a primary rhythm or as part of a double tachycardia (FVT plus SVT

)

. It provides an FVT

episode counter and a separate therapy regimen for FVT episodes.

FVT Detection details begin on page 4-19.

Table 4-8. FVT Detection Programmable Parameters

FVT Enable via VF, via VT, or Off

Ventricular Sensitivity

(mV)

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

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

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

programmed VF Interval are marked as FVT events. (Rates are shown in parentheses.)

Programming FVT Detection

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

For FVT Detection zone. For FVT Detection

On.

via VF, the FVT Interval is programmed within the VF

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, 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.

The ICD can be programmed to exclude rapidly conducted SVTs from FVT Detection. See “Dual Chamber SVT Criteria” on page 4-22.

GEM®III DR System Reference Guide

4-17

Tachyarrhythmia Detection

FVT Detection

♦

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.

How to Program FVT Detection

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

programmer displays the Detection screen.

2. Set

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

FVT Enable to via VT or via VF. Select the FVT Interval and

Ventricular Sensitivity values.

Figure 4-8. Programming FVT Detection

4-18

GEM®III DR System Reference Guide

Tachyarrhythmia Detection

FVT Detection

How FVT Detection Works

If all Dual Chamber SVT Criteria are Off, the ICD detects FVT based on the ventricular rate alone. If any Dual Chamber SVT Criteria is also examines the atrial rhythm to exclude SVTs from inappropriate detection as FVT (page 4-22) and to identify a possible double tachycardia (FVT plus SVT) (page 4-33).

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.

■

any

of the last eight intervals is in the VF zone, it detects the

episode as VF.

■

all

of the last eight intervals are outside the VF zone, it detects the

episode as FVT (Figure 4-9).

On, the ICD

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.

■

any

of the last eight intervals is in the VF or FVT zones, it detects

the episode as FVT.

■

all

of the last eight intervals are outside the FVT and VF zones, it

detects the episode as VT.

GEM®III DR System Reference Guide

4-19

Tachyarrhythmia Detection

FVT Detection

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

Combined Count Detection of FVT

Combined Count Detection (page 4-13) 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.

will deliver an FVT therapy.

4-20

V S

VF Counter:

1234567 89101112

(8 INTERVALS BEFORE NID)

Enab

Initial

Redetect

VF On 12/16 9/12 320 ms

FVT via VF 260 ms

VT Off

Figure 4-9. FVT Detection Via VF Example

GEM®III DR System Reference Guide

LOOKBACK WINDOW

Inter

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 5-36.)

Before initial detection: three detection zones

Interval

VT Detection Zone

FVT Detection Zone

FVT

Interval

After detection of VF: two zones for redetection

VF Detection Zone VT Detection Zone

Interval

Lower Rate

Period

Lower Rate

Period

Blanking

Depolarization

Blanking

Depolarization

VF Detection Zone

120 ms

VF Detection Zone

120 ms

Figure 4-10. Zone Merging (FVT Detection Via VF)

Before initial detection: three detection zones

FVT Detection Zone

VF Interval FVT

VT Detection Zone

Interval

After detection of VF or FVT: two zones for redetection

FVT Detection Zone

Interval

Figure 4-11. Zone Merging (FVT Detection Via VT)

GEM®III DR System Reference Guide

Lower Rate

Period

Interval

Lower Rate

Period

Interval

4-21

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

The programmable Dual Chamber SVT Criteria are designed to withhold inappropriate ventricular detection during episodes of rapidly conducted supraventricular tachycardia (SVTs). The ICD analyzes the activation patterns and timing in both chambers, using PR Logic™ Pattern and Rate Analysis to identify different SVTs. You can specify a range of ventricular rates over which the ICD applies the SVT Criteria.

See page 4-28 for more details on the Dual Chamber SVT Criteria and PR Logic™ Pattern and Rate Analysis.

Table 4-9. Dual Chamber SVT Criteria Programmable Parameters

AFib/AFlutter Identiﬁes rapidly conducted atrial ﬁbrillation, atrial

Sinus Tach Identiﬁes sinus tachycardia (see page 4-34).

1:1 VT-ST Boundary Threshold between the Retrograde and Antegrade

Other 1:1 SVTs Identiﬁes other 1:1 SVTs where the atrial and

SVT Limit Deﬁnes the minimum ventricular cycle length for the

ﬂutter, or atrial tachycardia (see page 4-34).

zones used by A-V Pattern Analysis (see page 4-29). Allows customization of Sinus Tach criterion for patients with slow 1:1 conduction.

ventricular activation are roughly simultaneous (see page 4-34).

ICD to apply the Dual Chamber SVT Criteria.

4-22

GEM®III DR System Reference Guide

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

Programming Dual Chamber SVT Criteria

Cautions:

■

Before enabling the Other 1:1 SVTs criterion, ensure that the atrial lead has matured. This criterion could inappropriately withhold therapy if atrial sensing is compromised by an unstable or dislodged atrial lead.

■

In patients who exhibit slow 1:1 retrograde conduction during VF or VT, use caution when programming the

Other 1:1 SVTs criterion. This

criterion could inappropriately withhold VF/VT therapy in such patients. (See Figure 4-15 on page 4-29).

When VT Detection is enabled for the ﬁrst time,

Sinus Tach dual chamber SVT detection criteria are automatically

AFib/AFlutter and

enabled.

When enabling the

Sinus Tach criterion in patients who exhibit slow 1:1

retrograde conduction during VF or VT, or slow antegrade conduction during SVTs, make sure to set the

1:1 VT-ST Boundary parameter

appropriately. See “Customizing Detection for Patients with Slow Conduction” on page 4-25.

The nominal atrial sensitivity threshold is 0.3 mV. However, the threshold must not permit far-ﬁeld R-wave sensing. See “Programming for Appropriate Sensing” on page 4-2.

To ensure therapy for hemodynamically compromising rates regardless of origin, the ICD always delivers therapy when the median ventricular cycle length is less than the programmed

SVT Limit (nominally 320 ms) if VT,

VF, or FVT detection criteria are satisﬁed.

If you program an

SVT Limit greater than the VF Interval, the Dual

Chamber SVT Criteria are effectively disabled for VF detection.

GEM®III DR System Reference Guide

4-23

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

♦

How to Program the Dual Chamber SVT Criteria

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

2. Set the AFib/AFlutter, Sinus Tach, or Other 1:1 SVTs parameters,

as appropriate.

3. Select an

4. Select an atrial Sensitivity value.

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

Shading (blue) indicates the cycle lengths where

Dual Chamber SVT criteria are applied

SVT Limit value.

Atrial sensitivity value

4-24

GEM®III DR System Reference Guide

Dual Chamber SVT Criteria

Figure 4-12. Dual Chamber SVT Parameters

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

Customizing Detection for Patients with Slow Conduction

Slow antegrade conduction during an SVT or slow 1:1 retrograde conduction during VT can adversely affect the accuracy of the and Other 1:1 SVTs criteria. The ICD provides the programmable 1:1 VT-ST

Boundary parameter to customize the Sinus Tach criterion for patients that

exhibit slow conduction.

The

1:1 VT-ST Boundary parameter represents an A-V interval that is a

percentage of a V-V interval. This value forms the division between the Retrograde and Antegrade zones used by ICD pattern analysis operations (see “Pattern Analysis of A-V and V-A Intervals” on page 4-29).

If slow conduction causes antegrade events to occur in the Retrograde Zone, or retrograde events to occur in the Antegrade Zone, changing the

1:1 VT-ST Boundary parameter can increase the size of the appropriate

zone. Figure 4-13 below demonstrates the possible settings for the

VT-ST Boundary.

Sinus Tach

1:1

Caution: The Other 1:1 SVTs criterion is

Boundary. However, slow conduction can adversely affect its operation by

not

affected by the 1:1 VT-ST

causing atrial events to occur within junctional zones. Use caution when enabling the

Other 1:1 SVTs criterion in patients with slow antegrade or

retrograde conduction.

1:1 VT-ST Boundary

V-event V-event

Junctional

Zone

50 ms

Retrograde zone

(before boundary)

settings

50%66%75%85%

35%

Antegrade zone (after boundary)

Junctional

Zone

80 ms

Figure 4-13. Possible 1:1 VT-ST Boundary Settings

GEM®III DR System Reference Guide

4-25

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

♦

How to Set the 1:1 VT-ST Boundary

Caution: The 1:1 VT-ST Boundary parameter should

50% if the patient exhibits slow 1:1 retrograde conduction during a VT

(long V-A intervals), or slow antegrade conduction during an SVT (long A-V intervals). Incorrect programming of this parameter may result in inappropriate therapies or underdetection of tachyarrhythmias.

1. Select the

2. Select the Additional Settings... parameter.

3. Select the 1:1 VT-ST Boundary... parameter.

Params icon and choose the Detection option.

only

be changed from

4-26

Figure 4-14. Programming the 1:1 VT-ST Boundary

GEM®III DR System Reference Guide

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

Note: Before 1:1 VT-ST Boundary can be selected, Sinus Tach must be set to

On.

4. Select 1:1 VT-ST Boundary, and set the 1:1 VT-ST Boundary

parameter as follows:

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

retrograde conduction, select

35%.

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

value that exceeds the A-V / V-V ratio observed during stored SVT episodes (see “Atrial Interval Display Options” on page 10-22).

5. Select

[OK] in the 1:1 VT-ST Boundary and Additional Options

dialog boxes.

6. Position the programming head and select

[PROGRAM].

GEM®III DR System Reference Guide

4-27

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

How the Dual Chamber SVT Criteria Work

Elements of PR Logic™ Pattern and Rate Analysis 4-29 Double Tachycardia Detection 4-33 Dual Chamber SVT Criteria Requirements 4-34

When a high ventricular rate fulﬁlls the VF, VT, or FVT detection criteria (NID or CNID – see page 4-9), and the V-V median interval exceeds the

SVT Limit selected by the physician, the ICD applies the Dual

equals or

Chamber SVT Criteria.

The Dual Chamber SVT Criteria use PR Logic™ Pattern and Rate Analysis to evaluate the episode. PR Logic™ analyzes the patterns, rates, and timing of activation in both chambers to identify the high ventricular rate as either a double tachycardia; one of the programmed classes of SVT; or a ventricular arrhythmia.

■

If PR Logic™ identiﬁes a dual tachyarrhythmia (VF, VT or FVT in the presence of an SVT – see page 4-33), the ICD delivers therapy for the ventricular arrhythmia.

■

If any Dual Chamber SVT Criterion is met, PR Logic™ identiﬁes a rapidly conducted SVT. The ICD withholds therapy and continues monitoring the rate, patterns, and timing on each ventricular event.

■

If the Dual Chamber SVT Criteria are not met, PR Logic™ identiﬁes a true ventricular arrhythmia (not related to a conducted SVT), and delivers VF, VT, or FVT therapy as programmed.

Dual Chamber SVT Criteria are applied only during initial detection.

4-28

Median of the 12 most recent ventricular interval values. (Note that the rhythm is detected and treated as VF, VT, or FVT if the V-V median is less than the

GEM®III DR System Reference Guide

SVT Limit.)

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

Elements of PR Logic™ Pattern and Rate Analysis

The ICD uses multiple criteria to evaluate and classify rhythms as a particular type of SVT. PR Logic™ analyzes the following aspects of atrial and ventricular activation to identify SVTs:

■

Pattern of A-V and V-A intervals

■

Rate – atrial and ventricular

■

AF evidence

■

Far-ﬁeld R-wave sensing

■

A:V dissociation

■

V-V regularity

Pattern Analysis of A-V and V-A Intervals

The ICD uses pattern analysis to identify sinus tachycardia, atrial ﬂutter, and other 1:1 SVTs. Within each V-V interval, the ICD categorizes the atrial activation according to the number of intervening atrial events and the zones in which those atrial events occur. (See Figure 4-15 below.) From this information, the ICD assigns pattern codes to the intervals, and interprets the pattern codes to identify different SVTs.

V-event V-event

Atrial events here

indicate:

Programmed

1:1 VT-ST Boundary

(set to 50%)

Junctional Zone

50 ms

PAC, PVC, junctional rhythm, atrial ﬁbrillation, or atrial ﬂutter

Retrograde Zone Antegrade (Normal)

Zone

Retrograde conduction Normal conduction

(sinus rhythm, sinus

tachycardia)

Figure 4-15. Zones Used During A-V Pattern Analysis

GEM®III DR System Reference Guide

Junctional Zone

80 ms

PAC, PVC, junctional rhythm, atrial ﬁbrillation, or atrial ﬂutter

4-29

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

AF Evidence

AF Evidence is provided by a counter that accrues evidence to help identify atrial ﬁbrillation, or to help detect a double tachycardia (VF, VT or FVT in the presence of an SVT).

For each ventricular event, if the ICD identiﬁes A-V pattern information for a high atrial rate, timing consistent with atrial tachyarrhythmia (see Figure 4-15) and greater than 1:1 conduction, the ICD adds one to the AF Evidence counter. If the A-V pattern is inconclusive, inconsistent, or if the ICD detects far-ﬁeld R-wave sensing, the AF counter is unchanged. If no atrial event occurs within the current V-V interval or a consistent 1:1 pattern is present, the ICD subtracts one from the counter.

The AF Evidence criterion is satisﬁed when the AF Evidence count is greater than or equal to 6 (up to a maximum value of 10). Once the criterion is met, it remains satisﬁed for as long as the AF Evidence count is greater than or equal to 5.

4-30

GEM®III DR System Reference Guide

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

Far-Field R-Wave Sensing

The ICD identiﬁes far-ﬁeld R-wave oversensing in the atrium in order to exclude far-ﬁeld R-waves from the process of SVT classiﬁcation.

If there are two atrial events within a ventricular interval, one of the atrial events may actually be a far-ﬁeld R-wave. The ICD identiﬁes a sensed far-ﬁeld R-wave if it detects both:

■

a short-long pattern of A-A intervals, and

■

a short A-V interval (< 60 ms) or a short V-A interval (< 160 ms)

The ICD uses far-ﬁeld R-wave sensing for the Sinus Tach and A.Fib/A.Flutter criteria as follows:

■

To identify Sinus Tach with far-ﬁeld R-wave sensing, the ICD requires a far-ﬁeld R-wave on at least 4 of the most recent 12 ventricular intervals.

■

To identify A.Fib/A.Flutter with far-ﬁeld R-wave sensing, the ICD requires a far-ﬁeld R-wave on at least 10 of the most recent 12 ventricular intervals.

Far-ﬁeld R-wave

Figure 4-16. Intervals Evaluated in Far-Field R-Wave Determination

A:V Dissociation

A:V Dissociation provides cumulative evidence that there is no direct relationship between sensed atrial and ventricular events. The ICD identiﬁes a rhythm as A:V dissociated if at least 4 of the most recent 8 ventricular intervals exhibit either:

■

no atrial events in the ventricular interval, or

■

an A-V interval that differs from the average of the previous eight A-V intervals by more than 40 ms.

GEM®III DR System Reference Guide

4-31

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

The ICD uses this count to help identify a double tachycardia (VF, VT or FVT in the presence of an SVT).

Ventricular Cycle Length Regularity

The ICD uses ventricular cycle length regularity or irregularity to evaluate atrial ﬁbrillation, double tachycardia (VF, VT or FVT in the presence of an SVT), and other 1:1 SVTs.

The ICD continuously measures the regularity of the ventricular cycle lengths. The regularity count indicates how often the two most commonly occurring intervals (of at least 240 ms) occurred among the last 18 ventricular intervals.

For example, the ﬁgure below illustrates the 18 most recent intervals. The two most frequently occurring intervals are 330 ms (ﬁve intervals) and 320 ms (three intervals). Together these two account for eight of the 18 most recent intervals, for a regularity count of 44%.

00 0 0 0 0000000

240

260 280 300 320 340 360 380 400 420 440 460

2 2

1 1 1 11

4-32

■

For a double tachycardia to be detected, the regularity count must be at least 75%.

■

To withhold detection under the atrial ﬁbrillation rule of the

AFib/AFlutter criterion, the regularity count must be 50% or less.

Atrial ﬁbrillation with regularity between 50% and 75% is identiﬁed by the atrial ﬂutter rule, but the count is not required.

■

To withhold detection for Other 1:1 SVTs, the regularity count must be at least 25%.

GEM®III DR System Reference Guide

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

Double Tachycardia Detection

If PR Logic™ Pattern and Rate Analysis identiﬁes double tachycardia, the ICD delivers the programmed ventricular therapies.

The ICD detects VF plus SVT or FVT via VF plus SVT if all of the following occur:

■

an atrial tachyarrhythmia is identiﬁed (page 4-30),

■

ventricular detection via the Interval or Combined Count criterion,

■

V-V median1≥ SVT Limit, and

■

the rhythm is A:V dissociated (page 4-31).

The ICD detects VT plus SVT or FVT via VT plus SVT if all of the above occur and:

■

the ventricular cycle length is very regular (regularity of at least 75% – see page 4-32).

Median of the 12 most recent ventricular interval values. (Note that the rhythm is detected and treated as VF, VT, or FVT if the V-V median is less than the

SVT Limit.)

GEM®III DR System Reference Guide

4-33

Tachyarrhythmia Detection

Dual Chamber SVT Criteria

Dual Chamber SVT Criteria Requirements

The AFib/AFlutter criterion consists of two independent rules: the atrial ﬁbrillation rule and the atrial ﬂutter rule. If either rule is satisﬁed, the

AFib/AFlutter criterion is met and the ICD withholds ventricular detection

and therapy.

■

The atrial ﬁbrillation rule requires that:

– the AF Evidence counter (page 4-30) indicates atrial ﬁbrillation,

exclusive of far-ﬁeld R-wave sensing (page 4-31);

– the A-A median is 94% or less of the V-V median; and

– the ventricular cycle length is not regular (regularity of 50% or

less, see page 4-32).

■

The atrial ﬂutter rule is satisﬁed if A-V pattern information indicates atrial ﬂutter, exclusive of far-ﬁeld R-wave sensing.

The

Sinus Tach criterion is met if A-V pattern analysis indicates a 1:1 sinus

tachycardia (with atrial events primarily in the Antegrade Zone shown in Figure 4-15 on page 4-29), exclusive of far-ﬁeld R-wave sensing. The size and timing of the Antegrade Zone is dependent on the parameter (see page 4-25).

1:1 VT-ST Boundary

4-34

The

Sinus Tach criterion also recognizes and withholds inappropriate

detection for a 1:1 sinus tachycardia when far-ﬁeld R-wave oversensing consistently occurs.

The

Other 1:1 SVTs criterion is satisﬁed when A-V pattern information

indicates a 1:1 SVT in which the atria and ventricles are activated at approximately the same time; i.e., a junctional tachycardia (consistent atrial sensing in a junctional zone; see Figure 4-15 on page 4-29).

GEM®III DR System Reference Guide

Termination and Redetection

Outcome Monitoring

Tachyarrhythmia Detection

Termination and Redetection

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

The Dual Chamber SVT Criteria are 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 page 5-36), a slower arrhythmia (e.g., VT) may receive therapies for a faster arrhythmia (e.g., VF) during redetection.

Progressive Episode Therapies option On (see

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

GEM®III DR System Reference Guide

4-35

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 either:

■

the episode terminates, or

■

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.

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 4-13). The ICD then delivers the next programmed therapy for the current arrhythmia, and resumes monitoring for the outcome of that therapy.

4-36

VF Interval when VT Detection is programmed Off.

GEM®III DR System Reference Guide

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 4-17 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

Or before the most recent “accelerated” VT redetection.

GEM®III DR System Reference Guide

4-37

Tachyarrhythmia Detection

Termination and Redetection

Not sensed in the blanking period after cardioversion.

cardioversion shock.

0.6 joule

VRV

A R

A S

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 Initial Redetect Interval

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): 0.6 10 30 30 30 30

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

A S

3 3 0

TSTST

A R

3 3 0

200 ms

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

4-38

Figure 4-17. Redetection of VT After Therapy

GEM®III DR System Reference Guide

Tachyarrhythmia Therapies

High Voltage Therapy Overview 5-2

Deﬁbrillation 5-9

Cardioversion 5-17

Antitachycardia Pacing Therapy Overview 5-23

Programming ATP Therapies 5-25

Burst Pacing 5-27

Ramp Pacing 5-29

Ramp+ Pacing 5-31

Smart Mode 5-33

Progressive Episode Therapies 5-36

GEM®III DR 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; e.g. SVC coil

Each deﬁbrillation or cardioversion therapy has separately programmable energy and pathway polarity (see “High Voltage Therapy Parameters” on page 5-7). The ICD automatically regulates the pulse width to obtain 50% tilt.

5-2

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 R-wave for delivery to occur.

GEM®III DR System Reference Guide

Medtronic 7275 Reference Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Education

Technical Support

References

Notice

Abbreviations and Acronyms

Primary Capabilities

Pacing Management

Dual Chamber VF/VT/FVT Detection

Tachyarrhythmia Therapy

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

Overview

Effect on System Operation

Temporary Parameter Values

Emergency Cardioversion

Emergency Fixed Burst Pacing

Emergency VVI Pacing

System Description

Detection and Therapy Overview

Redetection

Therapy

Suspending Detection and Therapy

Automatic Suspension of Detection

Disabling Detection and Therapies

Sensing

Programming for Appropriate Sensing

Ventricular Sensing

Atrial Sensing

Auto-Adjusting Sensitivity Thresholds

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

FVT Detection

Programming FVT Detection

How FVT Detection Works

FVT Detection Via VF

FVT Detection Via VT

Combined Count Detection of FVT

Zone Merging After Detection

Dual Chamber SVT Criteria

Programming Dual Chamber SVT Criteria

How the Dual Chamber SVT Criteria Work

Elements of PR Logic™ Pattern and Rate Analysis

Double Tachycardia Detection

Dual Chamber SVT Criteria Requirements

Termination and Redetection