Medtronic ADDR01 Reference Guide

ADAPTA® / VERSA® / SENSIA® / RELIA™

A family of implantable pulse generators

Pacemaker Reference Guide

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

ADAPTA® / VERSA® / SENSIA® / RELIA™

Reference Manual

A reference guide for Adapta/Versa/Sensia/Relia pacemakers

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

Achieve, Adapta, Capture Management, Intrinsic, Marker Channel, Medtronic, MVP,
Quick Look, QuickLink, Relia, Sensia, TherapyGuide, Versa

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Contents

1 Introduction .......................................................... 9

1.1 Introduction ......................................................... 9

2 Pacing modes ....................................................... 11

2.1 Introduction ........................................................ 11

2.2 Rationale for mode selection ......................................... 13

2.3 MVP modes ........................................................ 13

2.4 DDDR mode ....................................................... 13

2.5 DDD mode ......................................................... 15

2.6 DDIR mode ........................................................ 16

2.7 DDI mode .......................................................... 17

2.8 DVIR mode ........................................................ 18

2.9 DVI mode .......................................................... 18

2.10 VDD mode ......................................................... 19

2.11 AAIR / ADIR modes ................................................. 20

2.12 AAI / ADI modes .................................................... 21

2.13 VVIR / VDIR modes ................................................. 22

2.14 VVI / VDI modes .................................................... 23

2.15 AAT / VVT modes ................................................... 24

2.16 DOOR / AOOR / VOOR modes ....................................... 25

2.17 DOO / AOO / VOO modes ............................................ 26

2.18 ODO / OAO / OVO modes ............................................ 27

3 Rate response ....................................................... 28

3.1 Introduction to rate responsive pacing .................................. 28

3.2 Preset rate response at implant ....................................... 29

3.3 Rate Profile Optimization operation .................................... 30

3.4 Individualizing Rate Profile Optimization ................................ 36

3.5 Activity sensor operation ............................................. 37

3.6 Manual control of Rate Profile Optimization ............................. 41

Reference Manual 5

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4 Pacemaker timing ................................................... 43

4.1 Rates ............................................................. 43

4.2 AV intervals ........................................................ 50

4.3 Rate Adaptive AV ................................................... 52

4.4 Search AV+ and diagnostic ........................................... 55

4.5 Blanking periods .................................................... 58

4.6 Refractory periods .................................................. 60

4.7 High rate atrial tracking .............................................. 68

5 Lead/cardiac tissue interface ......................................... 71

5.1 Implant Detection ................................................... 71

5.2 Automatic polarity configuration ....................................... 72

5.3 Lead Monitor ....................................................... 76

5.4 Lead impedance data ............................................... 78

5.5 Capture Management and diagnostic .................................. 79

5.6 Sensing Assurance and diagnostic .................................... 99

5.7 Manually selecting pacing parameters ................................ 103

5.8 Manually selecting sensing parameters ............................... 105

5.9 Transtelephonic follow-up features .................................... 108

6 Special therapy options ............................................. 111

6.1 Mode Switch and diagnostic ......................................... 111

6.2 Managed Ventricular Pacing (MVP) ................................... 117

6.3 Conducted AF Response ........................................... 122

6.4 Non-competitive atrial pacing ........................................ 123

6.5 PMT intervention ................................................... 125

6.6 PVC Response .................................................... 127

6.7 Ventricular Safety Pacing ............................................ 129

6.8 Sinus Preference .................................................. 130

6.9 Atrial Preference Pacing ............................................ 133

6.10 Rate Drop Response and diagnostic .................................. 137

6.11 Sleep Function .................................................... 143

6.12 Single Chamber Hysteresis .......................................... 145

7 Telemetry data ..................................................... 147

7.1 Establishing telemetry .............................................. 147

6 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

7.2 Parameter summary ................................................ 147

7.3 Patient information ................................................. 149

7.4 Using TherapyGuide to select parameter values ........................ 150

7.5 Battery and lead information ......................................... 151

7.6 Marker Channel telemetry ........................................... 153

7.7 Intracardiac electrograms ........................................... 154

7.8 Extended Telemetry ................................................ 156

8 Miscellaneous operations ........................................... 157

8.1 Magnet mode operation ............................................. 157

8.2 Temporary programming ............................................ 158

8.3 Electrical reset ..................................................... 159

8.4 Recommended Replacement Time (RRT/ERI) ......................... 161

8.5 Emergency pacing ................................................. 162

9 Diagnostics ........................................................ 163

9.1 Introduction to diagnostics .......................................... 163

9.2 Heart Rate Histograms ............................................. 166

9.3 AV Conduction Histograms .......................................... 168

9.4 Search AV+ Histogram ............................................. 170

9.5 Sensor Indicated Rate Profile ........................................ 171

9.6 High Rate Episodes ................................................ 173

9.7 Ventricular Rate Histogram During Atrial Arrhythmias .................... 179

9.8 Atrial Arrhythmia Trend .............................................. 180

9.9 Atrial Arrhythmia Durations .......................................... 181

9.10 Custom Rate Trend ................................................. 181

9.11 Key Parameter History .............................................. 183

10 Troubleshooting the pacing system .................................. 185

10.1 Troubleshooting the pacing system ................................... 185

10.2 Troubleshooting electrical problems .................................. 185

10.3 Troubleshooting hemodynamic problems .............................. 187

A Emergency settings ................................................ 189

A.1 Emergency settings ................................................ 189

Reference Manual 7

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

B Telemetry and diagnostic values ..................................... 190

B.1 Magnet Mode operations ........................................... 190

B.2 Telemetry functions ................................................ 191

B.3 Automatic diagnostics .............................................. 193

B.4 Clinician-selectable diagnostics ...................................... 194

B.5 Cardiac event counters ............................................. 198

C Rate Response programming guidelines ............................. 199

C.1 Rate Response programming guidelines .............................. 199

D Patient counseling .................................................. 201

D.1 Patient counseling information ....................................... 201

Glossary ................................................................ 202

Index ................................................................... 209

8 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

1 Introduction

1.1 Introduction

The information in the Adapta/Versa/Sensia/Relia Pacemaker Reference Guide (PRG)
applies to the following Adapta/Versa/Sensia/Relia pacemakers:

●

Adapta ADDR01/03/06

●

Adapta S ADDRS1

●

Adapta L ADDRL1

●

Adapta ADD01

●

Adapta ADVDD01

●

Adapta ADSR01/03/06

●

Versa VEDR01

●

Sensia SEDR01

●

Sensia L SEDRL1

●

Sensia SED01

●

Sensia SESR01

●

Sensia SES01

●

Relia REDR01

●

Relia RED01

●

Relia RESR01

●

Relia RES01

●

Relia REVDD01

1.1.1 How to use this guide

Product information about Adapta/Versa/Sensia/Relia pacemakers and the associated
software for the programmer is presented in two separate guides.

The Pacemaker Reference Guide (PRG) provides detailed information on the pacemakers.

The Pacemaker Programming Guide (PPG) contains instructions on how to use the
programmer and the programming software.

Reference Manual 9

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

1.1.1.1 About the Pacemaker Reference Guide

The Pacemaker Reference Guide (PRG) describes in detail how the pacemakers operate
and specifies the capabilities of the pacemakers. The PRG includes the following
information:

●

Describes the pacing modes, rate response options, special therapy features, telemetry
types, and data collection options. In some cases, guidelines are given on how to
configure the pacemaker operation.

●

Contains troubleshooting information for electrical and hemodynamic problems.

●

Specifies parameter and data collection capabilities, longevity projections, and
mechanical and electrical specifications.

●

Provides general warnings and cautions, potential interference sources, and general
indications for pacing.

●

Contains a glossary of terms.

1.1.1.2 About the Pacemaker Programming Guide

The Pacemaker Programming Guide describes how to program Adapta/Versa/Sensia/Relia
pacemakers using a programmer. The PPG presents the following information:

●

How to set up and configure the programmer.

●

How to start a patient session, use the various follow-up features during the session, and
properly end the session.

●

How to view and print the patient’s ECG and EGM waveform traces.

●

How to configure the pacemaker to collect diagnostic data and how to retrieve and view
this information.

●

How to measure stimulation thresholds and sensing levels.

●

How to use TherapyGuide to obtain suggested parameter values.

●

How to program parameter values and verify rate response parameters settings.

●

How to run EP Studies.

1.1.1.3 The Implant Manuals supplement these guides

For each pacemaker model in the Adapta/Versa/Sensia/Relia family, there is an implant
manual. The Pacemaker Programming Guide and the Pacemaker Reference Guide do not
specify which features apply to each individual pacemaker model. Refer to the applicable
implant manual for specific capabilities of individual models.

10 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

2 Pacing modes

2.1 Introduction

2.1.1 Pacing mode selection

This chapter provides an introduction to pacemaker modes as an aid to pacing mode
selection. The chapter is organized as follows:

Definition of basic pacing modes – The names for most of the pacing modes are defined
on the 1991 ACC/AHA guidelines for pacemaker implantation.

Rationale for mode selection – In order to get pacing mode suggestions, the use of
TherapyGuide is recommended. TherapyGuide is a programmer feature that suggests
parameter settings based on a patient’s clinical conditions. For models which do not contain
TherapyGuide, refer to the device implant manual for guidance in mode selection.

Mode descriptions – These descriptions provide indications and contraindications for
modes available with the pacemaker and brief descriptions of how these modes operate.

2.1.2 NBG pacing codes

The pacemaker modes are defined in NBG Code.2 Each five-letter NBG code describes a
specific type of operation for implantable pacemakers. For simplicity, this manual uses only
the first three or four letters, such as DDD, DDIR, DVIR, and so forth. Figure 1 describes the
first four letters of the NBG code.

1

1

Dreifus LS, Fisch C, Griffin JC, et al. Guidelines for implantation of cardiac pacemakers and antiarrhythmia
devices. A report of the American College of Cardiology/American Heart Association Task Force on
Assessment of Diagnostic and Therapeutic Cardiovascular Procedures (Committee on Pacemaker
Implantation). Journal of the American College of Cardiology. 1991; 18: 1-13.

2

Bernstein A., et al., “The NASPE/BPEG Pacemaker Code,” PACE, 10(4), Jul-Aug 1987. (“NBG” stands for The
North American Society of Pacing and Electrophysiology [NASPE] and the British Pacing and
Electrophysiology Group [BPEG] Generic. NBG’s five-letter code supersedes the ICHD Code.

Reference Manual 11

Chamber Paced

Chamber Sensed

Mode of Response

Programmable/Rate Response

DDDR

V = Ventricle

A = Atrium

D = Dual Chamber

S = Single Chamber

O = None

T = Triggered

I = Inhibited

D = Double (both)

O = None

V = Ventricle

A = Atrium

D = Dual Chamber

S = Single Chamber

O = None

P = Programmable

M = Multiprogrammable

C = Communicating

R = Rate Responsive

O = None

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 1. NBG pacing codes

2.1.3 Further information

The mode descriptions in this chapter provide only a basic overview of each mode. For
further details on the rate response, timing, and therapy capabilities, refer to Section 3.1.1,
“Rate response”, page 28, Chapter 4, “Pacemaker timing”, page 43, and Chapter 6,
“Special therapy options”, page 111.

12 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

2.2 Rationale for mode selection

TherapyGuide offers a simple clinically-focused method for a clinician to obtain suggested
parameter values. At implant or an early follow-up appointment, the clinician enters
information about the patient’s clinical conditions. Based on those inputs the programmer
suggests parameter settings. The suggestions are based on clinical studies, literature,
current practice, and the consensus of physicians.

TherapyGuide does not replace a physician’s expert judgment. The physician is free to
accept, reject, or modify any of the suggested parameter values.

For more information about TherapyGuide, refer to Section 7.4, “Using TherapyGuide to
select parameter values”, page 150.

For each pacemaker model, TherapyGuide suggests a programmable mode. It bases the
suggestion on clinical conditions such as the condition of the sinus node and the quality of
AV conduction.

TherapyGuide offers a Rationale screen that shows the basis for each setting of pacing
modes and of other parameters. To access the screen, perform the following steps:

1. Interrogate the pacemaker (before or after implant).

2. Select the Params icon. On the Therapy Parameters screen, select the [TherapyGuide]
button to open the TherapyGuide window.

3. Select the [Rationale…] button to open the Rationale window.

4. Select [Close] twice to return to the Therapy Parameters screen.

Note: It is not necessary to do any parameter programming at this time. Refer to
the Adapta/Versa/Sensia/Relia Pacemaker Programming Guide for instructions on
programming parameters using TherapyGuide.

2.3 MVP modes

Two MVP modes are available: AAIR<=>DDDR and AAI<=>DDD.

Note: For information about AAIR<=>DDDR and AAI<=>DDD modes, refer to Section 6.2,
“Managed Ventricular Pacing (MVP)”, page 117.

2.4 DDDR mode

Note: For information about the AAIR<=>DDDR mode, refer to Section 6.2, “Managed

Ventricular Pacing (MVP)”, page 117.

Reference Manual 13

V
P

V
S

V
S

V
P

A
P

A
S

A
P

200 ms

A
P

A
S

V
P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

In the DDDR mode, the pacemaker tracks the faster of the intrinsic atrial rate or the
sensor-indicated rate. If the intrinsic rate is faster, the DDDR mode provides atrial
synchronous pacing; otherwise, AV sequential pacing occurs at the sensor-indicated rate.

●

Rate limits for atrial tracking (Upper Tracking Rate)3 and sensor tracking (Upper Sensor
Rate) are separately programmable.

●

The AV intervals that follow sensed atrial events (SAV) and paced atrial events (PAV) are
separately programmable, and they can be programmed to shorten with increasing
rates (Rate Adaptive AV) or to change with intrinsic conduction times (Search AV+).

●

A nonrefractory sensed event in either chamber inhibits pacing in that chamber. A
ventricular nonrefractory sensed event in the VA interval that is not preceded by an atrial
sense (AS or AR) is a pacemaker-defined PVC and starts a new VA interval.

Figure 2. Example of DDDR mode operation

1 Sensor-indicated interval

Parameters:

Lower Rate = 60 bpm (1000 ms) PAV Interval = 200 ms PVARP = 280 ms
Sensor-indicated Rate =

SAV Interval = 170 ms

90 bpm (667 ms)

3

The Total Atrial Refractory Period (TARP) may limit the tracking rate to a lesser value. Refer to Chapter 4,
“Pacemaker timing”, page 43 for more information on TARP.

14 Reference Manual

V
P

V
S

V
S

A
P

A
S

A
P

A
P

200 ms

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

2.5 DDD mode

Note: For information about the AAI<=>DDD mode, refer to Section 6.2, “Managed

Ventricular Pacing (MVP)”, page 117.

The DDD mode provides atrial synchronous pacing in the presence of intrinsic atrial activity;
otherwise, AV sequential pacing occurs at the Lower Rate.

●

Each atrial paced or nonrefractory atrial sensed event starts an AV interval and a lower
rate interval. The AV intervals that follow sensed atrial events (SAV) and paced atrial
events (PAV) are separately programmable, and the SAV may be optionally
programmed to shorten with increasing rate (Rate Adaptive AV) or to change with
intrinsic conduction times (Search AV+).

●

A ventricular paced event may track an atrial sensed event up to the programmed Upper
Tracking Rate.

●

A ventricular nonrefractory sensed event in the VA interval that is not preceded by an
atrial sense (AS or AR) is a pacemaker-defined PVC and starts a new VA interval.

Figure 3. Example of DDD mode operation

4

1 Lower rate interval

Parameters:

Lower Rate = 60 bpm (1000 ms) PAV Interval = 200 ms

SAV Interval = 170 ms

4

The Total Atrial Refractory Period (TARP) may limit the tracking rate to a lesser value.

Reference Manual 15

V
P

A
P

A
S

A
P

A
P

V
P

V
P

V
P

A
P

A
P

200 ms

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

2.6 DDIR mode

The DDIR mode provides dual chamber, sensor-driven, atrioventricular (AV) sequential
pacing for heart rate variation without atrial tracking.

●

Atrial pacing occurs at the sensor-indicated rate. If it is not inhibited, ventricular pacing
occurs at the end of the PAV interval.

●

The AV intervals that follow paced atrial events (PAV) are separately programmable, and
they can be programmed to shorten with increasing rates (Rate Adaptive AV) or to
change with intrinsic conduction times (Search AV+).

●

An atrial event sensed outside the PVARP will inhibit a scheduled atrial stimulus but will
not start an AV interval. That is, ventricular paced events after such sensed atrial events
occur at the sensor-indicated rate. The following ventriculoatrial (VA) interval may be
extended slightly to avoid an increasing atrial paced rate.

●

A ventricular nonrefractory sensed event in the VA interval starts a new VA interval.

Figure 4. Example of DDIR mode operation

1 Sensor-indicated interval
2 Sensor-indicated VA interval

Parameters:

Lower Rate = 60 bpm (1000 ms) PAV Interval = 200 ms
Sensor-indicated Rate = 90 bpm (667 ms)

16 Reference Manual

V
P

A
P

A
S

A
P

A
P

V
P

V
P

200 ms

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

2.7 DDI mode

The DDI mode provides dual chamber atrioventricular (AV) sequential pacing with atrial
sensing but without atrial tracking.

●

Atrial pacing occurs at the Lower Rate. If it is not inhibited, ventricular pacing occurs at
the end of the PAV interval.

●

The AV intervals that follow paced atrial events (PAV) are separately programmable, and
they can be programmed to change with intrinsic conduction times (Search AV+).

●

An atrial event sensed outside the PVARP will inhibit a scheduled atrial stimulus but will
not start an AV interval. Ventricular paced events after such sensed atrial events occur
at the Lower Rate.

●

A ventricular nonrefractory sensed event in the ventriculoatrial (VA) interval starts a new
VA interval.

Figure 5. Example of DDI mode operation

1 Lower Rate interval
2 Lower Rate VA interval

Parameters:

Lower Rate = 60 bpm (1000 ms) PAV Interval = 200 ms

Reference Manual 17

V
P

V
S

V
S

A
P

200 ms

A
P

A
P

A
P

V
P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

2.8 DVIR mode

The DVIR mode provides AV sequential pacing at the sensor-indicated rate unless inhibited
by ventricular sensed events.

●

Atrial pacing occurs at the sensor-indicated rate. If it is not inhibited, ventricular pacing
occurs at the end of the PAV interval.

●

The AV intervals that follow paced atrial events (PAV) are separately programmable, and
they can be programmed to shorten with increasing rates (Rate Adaptive AV) or to
change with intrinsic conduction times (Search AV+).

●

The DVIR mode ignores intrinsic atrial events. Sensing occurs only in the ventricle. A
ventricular nonrefractory sensed event during the ventriculoatrial (VA) interval starts a
new VA interval.

Figure 6. Example of DVIR mode operation

1 Sensor-indicated interval
2 Sensor-indicated VA Interval

Parameters:

Lower Rate = 60 bpm (1000 ms) PAV Interval = 200 ms
Sensor-indicated Rate = 90 bpm (667 ms)

2.9 DVI mode

The DVI mode provides dual chamber AV sequential pacing without atrial sensing/tracking.

●

Atrial pacing occurs at the Lower Rate. If it is not inhibited, ventricular pacing occurs at

18 Reference Manual

the end of the PAV interval.

V
P

V
S

V
S

A
P

200 ms

A
P

A
P

V
P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

●

The AV intervals that follow paced atrial events (PAV) are separately programmable, and
they can be programmed to change with intrinsic conduction times (Search AV+).

●

Sensing occurs only in the ventricle, and intrinsic atrial events are ignored. A ventricular
nonrefractory sensed event during the VA interval starts a new ventriculoatrial (VA)
interval.

Figure 7. Example of DVI mode operation

1 Lower Rate interval
2 Lower Rate VA interval

Parameters:

Lower Rate = 60 bpm (1000 ms) PAV Interval = 200 ms

2.10 VDD mode

The VDD mode provides atrial synchronous pacing (or VVI pacing at the Lower Rate). The
ventricle is paced synchronously up to the programmed Upper Tracking Rate.5 Sensing
occurs in both the atrium and ventricle, but pacing occurs only in the ventricle.

●

To promote atrial synchronous pacing at slow rates, a sensed atrial event occurring near
the end of the Lower Rate interval will be followed by the programmed SAV interval. The
result is an extension of the ventricular lower rate.

●

The AV intervals that follow sensed atrial events (SAV) are separately programmable,
and they can be programmed to shorten with increasing rates (Rate Adaptive AV) or to
change with intrinsic conduction times (Search AV+).

5

The Total Atrial Refractory Period (TARP) may limit the tracking rate to a lesser value.

Reference Manual 19

200 ms

V
P

A
S

A
S

V
P

V
P

A
S

A
S

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

●

A ventricular nonrefractory sensed event in the V-V interval that is not preceded by an
atrial sense (AS or AR) is a pacemaker-defined PVC, and it starts a new V-V interval.

Figure 8. Example of VDD mode operation

1 Lower Rate interval
2 SAV interval

Parameters:

Lower Rate = 60 bpm (1000 ms) SAV Interval = 200 ms
Upper Tracking Rate = 120 bpm (500 ms) PVARP = 250 ms

2.11 AAIR / ADIR modes

Note: For information about the AAIR<=>DDDR mode, refer to Section 6.2, “Managed

Ventricular Pacing (MVP)”, page 117.

The AAIR mode provides atrial-based rate responsive pacing in patients with intact AV
conduction. Sensing and pacing occur only in the atrium. In the absence of sensed events,
the chamber is paced at the sensor-indicated rate.

The ADIR mode operates the same as the AAIR mode except that events sensed in the
ventricle are recorded by the diagnostics. When used in conjunction with Marker Channel
recordings and concurrent ECG, this mode may be used to observe the conducted
ventricular rhythm without affecting atrial pacing.

Note: In the AAIR and ADIR modes, atrial refractory sensed events do not restart the Upper
Sensor Rate interval.

20 Reference Manual

A
P

A
S

A
P

A
P

A
R

200 ms

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 9. Example of AAIR mode operation

1 Sensor-indicated interval

Parameters:

Sensor-indicated Rate = 75 bpm (800 ms) Atrial Refractory Period = 250 ms
Upper Sensor Rate = 100 bpm (600 ms)

2.12 AAI / ADI modes

Note: For information about the AAI<=>DDD mode, refer to Section 6.2, “Managed

Ventricular Pacing (MVP)”, page 117.

The AAI mode provides single chamber inhibited atrial pacing. Sensing and pacing occur
only in the atrium. Pacing occurs at the programmed Pacing Rate unless inhibited by sensed
events.

The ADI mode operates the same as the AAI mode except that events sensed in the ventricle
are recorded by the diagnostics. When used in conjunction with Marker Channel recordings
and concurrent ECG, this mode may be used to observe the conducted ventricular rhythm
without affecting atrial pacing.

Reference Manual 21

A
P

A
S

A
P

A
P

A
R

200 ms

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 10. Example of AAI mode operation

1 Pacing Rate interval

Parameters:

Pacing Rate = 75 bpm (800 ms) Atrial Refractory Period = 250 ms

2.13 VVIR / VDIR modes

The VVIR mode provides ventricular rate responsive pacing in patients for whom
atrial-based pacing is deemed unnecessary or inappropriate. In the absence of sensed
events, the ventricle is paced at the sensor-indicated rate.

The VDIR mode operates the same as the VVIR mode except that events sensed in the
atrium are recorded by the diagnostics. When used in conjunction with Marker Channel
recordings and concurrent ECG, this mode may be used to observe the underlying atrial
rhythm without affecting ventricular pacing.

Note: In the VVIR and VDIR modes, ventricular refractory sensed events restart the Upper
Sensor Rate interval.

22 Reference Manual

V
P

200 ms

V
P

V
P

V
R

V
P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 11. Example of VVIR mode operation

1 Sensor-indicated interval
2 Upper Sensor Rate interval

Parameters:

Lower Rate = 60 bpm (1000 ms) Upper Sensor Rate = 120 bpm (500 ms)
Sensor-indicated Rate = 90 bpm (667 ms) Ventricular Refractory Period = 300 ms

2.14 VVI / VDI modes

The VVI mode provides single chamber inhibited pacing at the programmed Pacing Rate
unless inhibited by sensed events. Sensing occurs only in the ventricle.

The VDI mode operates the same as the VVI mode except that events sensed in the atrium
are recorded by the diagnostics. When used in conjunction with Marker Channel recordings
and concurrent ECG, this mode may be used to observe the underlying atrial rhythm without
affecting ventricular pacing.

Reference Manual 23

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 12. Example of VVI mode operation

1 Pacing Rate interval

Parameters:

Pacing Rate = 60 bpm (1000 ms)
Ventricular Refractory Period = 300 ms

2.15 AAT / VVT modes

In the AAT and VVT modes, pacing occurs at the programmed Lower Rate, but a
nonrefractory sensed event triggers an immediate pacing output (rather than inhibiting such
output). With the exception that pacing outputs occur when events are sensed, the triggered
modes operate identically to the corresponding inhibited modes.

Note: Programmed triggered pacing will not occur faster than 300 ms (200 bpm) from the
previous paced event. Temporary programmed triggered pacing is not limited to 300 ms
(200 bpm).

24 Reference Manual

200 ms

V
P

V
P

T
P

V
R

V
P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 13. Example of VVT mode operation

1 Pacing Rate interval

Parameters:

Pacing Rate = 60 bpm (1000 ms)
Ventricular Refractory Period = 300 ms

2.16 DOOR / AOOR / VOOR modes

The DOOR, AOOR, and VOOR modes operate as follows:

●

The DOOR mode provides asynchronous AV sequential pacing at the sensor-indicated
rate. Intrinsic events are ignored.

●

The AOOR and VOOR modes provide single chamber pacing at the sensor-indicated
rate. Intrinsic events are ignored.

Reference Manual 25

V
P

200 ms

A
P

V
P

A
P

V
P

A
P

A
P

V
P

A
P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 14. Example of DOOR mode operation

1 Sensor-indicated interval

Parameters:

Lower Rate = 60 bpm (1000 ms) PAV Interval = 200 ms
Sensor-indicated Rate = 90 bpm (667 ms)

2.17 DOO / AOO / VOO modes

Caution: Sensing is disabled in DOO / AOO / VOO modes.

The DOO, AOO, and VOO modes operate as follows:

●

The DOO mode provides AV sequential pacing at the programmed Lower Rate with no
inhibition by intrinsic events.

●

The AOO and VOO modes provide pacing at the programmed Lower Rate with no
inhibition by intrinsic events in the applicable chamber.

In addition to being directly programmable, the DOO mode is the Magnet mode of the
corresponding dual chamber modes, except for the VDD mode, which is the VOO mode.
AOO and VOO modes are the Magnet modes of the corresponding atrial and ventricular
single chamber modes, respectively.

26 Reference Manual

V
P

200 ms

A
P

V
P

A
P

V
P

A
P

A
P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 15. Example of DOO mode operation

1 Lower Rate interval

Parameters:

Lower Rate = 60 bpm (1000 ms) PAV Interval = 200 ms

2.18 ODO / OAO / OVO modes

Warning: ODO / OAO/ OVO modes disable pacing. Never program these modes for

pacemaker-dependent patients. For pacemaker-dependent patients, use the programmer’s
inhibit function for brief interruption of outputs.

In the ODO, OAO, and OVO modes, sensing occurs in the designated chamber or chambers.
When used in conjunction with Marker Channel telemetry and concurrent ECG, these
modes may be used to observe underlying rhythms.

●

Blanking periods in these modes are automatically minimized to maximize the sensing
window or windows. Thus, Marker Channel telemetry may display sense markers for
cardiac events (for example, far-field R waves) that otherwise would not appear due to
longer blanking.

●

No timing intervals or refractory periods are used.

Reference Manual 27

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

3 Rate response

3.1 Introduction to rate responsive pacing

3.1.1 Rate response

The pacemaker may provide appropriate rate response for patients who require cardiac
pacing support at both submaximal and maximal rates. Submaximal rates are moderate
pacing rates near the Activities of Daily Living Rate (ADL Rate) obtained during typical daily
activities, such as walking or daily chores. Maximal rates are rates (at or near the Upper
Sensor Rate) obtained during vigorous activities. To achieve appropriate rate response, the
pacemaker provides activity sensor-driven pacing with rate response control in both the ADL
rate range and the exertion rate range.

The pacemaker provides appropriate rate response by employing the following operations:

●

Three programmable rates control the submaximal and maximal rate ranges: Lower
Rate, ADL Rate (Activities of Daily Living Rate), and Upper Sensor Rate. The ADL Rate
is equivalent to the average target rate that the patient achieves for moderate activities.

●

Independent control of rate response is provided in both the ADL and exertion rate
ranges.

3.1.2 Automatic features

For models in a rate responsive mode, the pacemaker automatically enables rate response
after implant and automatically adjusts rate response, if necessary, once each day.

●

During the first 30 minutes after implant, pacing occurs at the implanted mode but
without rate response. 30 minutes after implant, rate response operation is enabled.

●

Once each day, rate response is assessed and adjusted, if necessary, in the ADL and
exertion rate ranges. The assessment is based on comparing the pacemaker’s historical
sensor-indicated rate profiles against a clinician prescribed target rate profile of the
patient. If the rate profiles differ, rate response is adjusted slightly in the appropriate rate
range, and the assessment is repeated again the next day.

28 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

3.1.3 For further information

Refer to Section 3.3, “Rate Profile Optimization operation”, page 30 for information on how
the pacemaker optimizes rate response.

3.2 Preset rate response at implant

3.2.1 Overview

Pacemakers shipped in rate responsive modes operate in a non-rate-responsive mode until
implant detection is completed, which is typically 30 minutes after implant. Thereafter, the
pacemakers automatically enable rate responsive pacing. Consequently, no programming
is required for rate response operation.

3.2.2 Three pacing rate controls

If customization of rate response is desired, three pacing rates are provided to control the
ADL and exertion rate ranges:

●

Lower Rate defines the slowest rate at which pacing occurs in the absence of a sinus rate
or physical activity.

●

ADL Rate (Activities of Daily Living Rate) is the approximate rate that the patient’s heart
is expected to reach during moderate exercise.

●

Upper Sensor Rate provides the upper limit for the sensor-driven rate during vigorous
exercise.

Refer to Section 4.1, “Rates”, page 43 for additional considerations when selecting
pacemaker rates.

3.2.3 Starting rate response immediately

In situations where the clinician wishes to start rate responsive pacing before the 30-minute
implant detection period is completed, perform the following steps:

1. After the device is implanted, program Implant Detection to “Off/Complete.”

2. Configure pace and sense lead polarities and Lead Monitor.

3. Verify that Rate Profile Optimization is On.

4. Verify that the parameter values for Lower Rate, ADL Rate, and Upper Sensor Rate are
appropriate.

5. Verify that the parameter values for ADL Response, Exertion Response, Activity
Threshold, Activity Acceleration, and Activity Deceleration are appropriate.

Reference Manual 29

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

3.2.4 For further information

Refer to Section 3.3, “Rate Profile Optimization operation”, page 30 and Section 3.4,
“Individualizing Rate Profile Optimization”, page 36.

3.3 Rate Profile Optimization operation

3.3.1 Overview

When Rate Profile Optimization is programmed On, the pacemaker can adapt ADL and
exertion rate response levels once each day by comparing the patient’s current sensor rate
profiles against a target rate profile. This feature is intended to provide automatic and
independent monitoring of rate response at both moderate rates for daily patient activities,
such as walking and daily chores, and at exertion rates for vigorous patient activities.

Optimization can be individualized to the patient’s activity levels. Refer to Section 3.4,
“Individualizing Rate Profile Optimization”, page 36.

Optimization can also operate in the background when a non-rate responsive mode is
programmed. This can provide appropriate rate response to patient activity if rate response
is needed later or for certain therapy features, such as mode switching to a non-atrial tracking
rate responsive mode.

3.3.2 Rate control in the ADL and exertion rate ranges

The pacemaker maintains linear rate control between the activity sensor signal and the
sensor-indicated rate from the Lower Rate to the ADL Rate. Refer to Section 3.5.2, “How
Activity Threshold influences rate”, page 38. It maintains independent linear rate control in
the exertion rate range. Optimization controls how rapidly and to what level the
sensor-indicated rate increases and decreases in these two rate ranges. The three
programmable rate controls [Lower Rate, ADL Rate (Activities of Daily Living Rate), and
Upper Sensor Rate] define the rate ranges (see Figure 16).

●

Moderate pacing rates are achieved during typical daily patient activities. These rates (in
the ADL rate range) are at or near the ADL Rate.

●

Exertion pacing rates are achieved during vigorous activities. These rates (in the
exertion rate range) are at or near the Upper Sensor Rate

Figure 16 shows a graph of sensor-indicated rate as a function of increasing activity. The
sensor-indicated rate curve has two slopes. The first slope, which controls how aggressively
the pacing rate increases from the Lower Rate to the ADL Rate, is determined by the
programmed ADL Response parameter. The second slope, which controls how
aggressively the pacing rate approaches the Upper Sensor Rate, is determined by the
programmed Exertion Response parameter.

30 Reference Manual

Upper Sensor Rate

ADL Rate

Increasing activity

Lower Rate

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

When you program new values for rates or Rate Profile Optimization, immediate changes
occur. The new values are predictions based on automatic diagnostic data and the selected
Rate Profile Optimization settings. The pacemaker continues to adjust Rate Response over
time.

Note: If the patient does not have any data in the Sensor Indicated Rate Profile diagnostic,
optimization does not adjust immediately when these parameters are programmed. 24
hours of diagnostic data are required.

Figure 16. A sensor-indicated rate curve

1 ADL rate range
2 Exertion rate range

3.3.3 Optimization using rate profiles

Optimization of rate response occurs independently in both the ADL rate range and the
exertion rate range. The sensor-indicated rate curve is assessed daily based on the
following rate profile data:

Sensor rate profile – An actual rate versus time distribution of the patient’s averaged
sensor-indicated rates. Once each day, the pacemaker collects a daily sensor rate profile
and cumulates the data into a long-term average. Both the daily and long-term rate profiles
are assessed each day to determine if adjustments to rate response are required. The
long-term sensor rate profile is automatically stored in the Sensor Indicated Rate Profile
diagnostic.

Target rate profile – A programmable rate versus time distribution of the patient’s desired
rates. The ADL Response and Exertion Response parameters define the percentage of time
that the sensor-indicated rate stays in the ADL rate range and in the exertion rate range,
respectively.

Reference Manual 31

30%

20%

10%

Lower Rate

ADL Rate

Upper Sensor Rate

Percentage of time

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 17 shows a typical rate profile (either a sensor rate profile or a target rate profile).

Figure 17. Example of a rate profile

1 ADL rate range
2 Exertion rate range

3.3.4 Daily optimization of rate response

Once each day, the pacemaker evaluates the percentage of time the sensor rate is in the ADL
and exertion rate ranges by comparing the daily and long-term sensor rate profiles against
the target rate profile. This operation follows the sequence shown in Figure 18.

●

The pacemaker calculates the sensor indicated rate based on the activity sensor signal.

●

From the actual sensor indicated rate values, it generates a daily sensor rate profile. It
also merges that data into a long-term sensor rate profile.

●

It compares the target rate profile to the daily and long-term sensor rate profiles. Refer to
Figure 19 and Figure 20 for details.

●

If the sensor rate profiles match the target rate profile or if the daily and long-term sensor
rate profiles contradict each other, no rate response adjustments occur.

●

Otherwise it makes an automatic adjustment to rate response, which affects the
calculation of the sensor-indicated rate in either or both of the rate ranges.

●

This sequence repeats each day.

32 Reference Manual

CompareCompare

Daily sensor rate

profile

Long-term sensor

rate profile

Adjust ADL rate

response as needed

based on comparison

Adjust exertion rate

response as needed

based on comparison

Sensor signal processing

Target rate profile

Rate calculation

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

As a result of this operation, the pacemaker automatically adjusts rate response in the ADL
and exertion ranges, if necessary, based on the following criteria:

●

If the sensor rate profiles show a higher percentage of time spent pacing than the target
rate profile, rate response for the pertinent rate range is set to be less responsive.
Conversely, if a lower percentage of time spent pacing is profiled than targeted for, rate
response is set to be more responsive.

●

If the sensor rate profiles match the target rate profile or the daily and long-term sensor
rate profiles contradict each other, no rate response adjustments occur.

Figure 18. Daily operation of Rate Profile Optimization

The goal of this operation is to keep the patient’s sensor rate profiles equivalent to the target
rate profile. This is shown in two examples.

Reference Manual 33

Percentage of time

Increasing rate

Rate response is made more aggressive

Increasing rate Increasing rate

= Target rate profile

= Sensor rate profile = New rate response curve

= Old rate response curve

Rate response is made less aggressive

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

In Figure 19, a comparison of the sensor rate profile and target rate profile shows that pacing
in the ADL rate range occurs for a larger percentage of time than was targeted. In the sensor
rate curve, rate response is adjusted to be less aggressive in this range.

The same comparison shows that pacing in the exertion rate range occurs for a smaller
percentage of time than was targeted. In the sensor rate curve, rate response is adjusted to
be more aggressive in this range.

Figure 19. Result of comparing rate profiles: first example

1 ADL rate range
2 Exertion rate range

The example in Figure 20 is the opposite of the one in Figure 19. Lower than targeted pacing
in the ADL rate range results in a rate response adjustment to make rate response more
aggressive in this range. Higher than targeted pacing in the exertion rate range results in rate
response that is less aggressive in this range.

34 Reference Manual

Increasing activity

= Target rate profile

= Sensor rate profile

= Old rate response curve

= New rate response curve

Increasing rate

Percentage of time

Rate response is made more aggressive

Rate response is made less aggressive

Increasing rate

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 20. Result of comparing rate profiles: second example

1 ADL rate range
2 Exertion rate range

Note: Two additional cases are possible:

●

Lower than targeted pacing in both the ADL and exertion rate range. Rate response is
adjusted to be more aggressive in both ranges.

●

Higher than targeted pacing in both the ADL and exertion rate range. Rate response is
adjusted to be less aggressive in both ranges.

3.3.5 Adaptations in Optimization operation

The pacemaker adapts rate response more rapidly for the first ten days after Optimization is
first activated post-implant or after certain rate response parameters are manually
reprogrammed (e.g., Lower Rate, ADL Rate, Upper Sensor Rate, ADL Response, or
Exertion Response). The intent is to quickly match rate response to the target rate profile
prescribed by the parameter changes.

When you program new values for rates or Rate Profile Optimization, immediate changes
occur. The new values are predictions based on automatic diagnostic data and the selected
Rate Profile Optimization settings. The pacemaker continues to adjust Rate Response over
time.

Note: If the patient does not have any data in the Sensor Indicated Rate Profile diagnostic,
optimization does not adjust immediately when these parameters are programmed.

Reference Manual 35

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Optimization is skipped on any day that a device interrogation or parameter programming
occurs.

3.4 Individualizing Rate Profile Optimization

3.4.1 Overview

The clinician can prescribe a target rate profile using the ADL Response and Exertion
Response parameters to match the patient’s life-style or activity levels. The programmable
ADL Response parameter alters the targeted rate distribution in the ADL rate range, while
the Exertion Response parameter alters the rate distribution in the exertion rate range.

3.4.2 ADL rate profiles

The nominal setting for the ADL Response parameter is “3.” Programming a higher number
redefines the target rate profile to spend more time pacing at or above the ADL Rate, thereby
increasing rate responsiveness in the ADL rate range. Programming a lower number
redefines the rate profile to spend less time pacing at or above the ADL Rate, thereby
decreasing rate responsiveness.

3.4.3 Exertion rate profiles

The nominal setting for the Exertion Response parameter is “3.” Programming a higher
number redefines the target rate profile to spend more time pacing near the Upper Sensor
Rate, thereby increasing rate responsiveness in the exertion rate range. Programming a
lower number redefines the rate profile to spend less time pacing near the Upper Sensor
Rate, thereby decreasing rate responsiveness.

3.4.4 Programming guidelines

If it is necessary to adjust rate response from the nominal setting, first verify that the three rate
controls are appropriate for the patient. Refer to Section 3.2.2, “Three pacing rate controls”,
page 29.

If these rate control settings are appropriate, the ADL Response and/or Exertion Response
settings can then be adjusted based on the guidelines in Table 1.

36 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Table 1. ADL Response and Exertion Response guidelines

Rate region Patient Select these settings

ADL Response

Lower Rate to ADL Rate Reached ADL Rate too quickly Lower number (less rate

response)

Reached ADL Rate too slowly Higher number (more rate

response)

Exertion Response

ADL Rate to Upper Sensor Rate Reached Upper Sensor Rate

too quickly
Reached Upper Sensor Rate

too slowly

a

If a higher Exertion Response setting has not produced the desired rate response, increase the ADL Response
setting.

Lower number (less rate
response)

Higher number (more rate
response)

a

For more detailed programming guidelines, refer to Table 29, page 199 and
Table 30, page 200, which list the targeted time spent pacing for the five ADL Response and
Exertion Response settings.

3.5 Activity sensor operation

3.5.1 Overview

Activity sensor based pacing is controlled by the following programmable parameters:

●

Activity Threshold determines the minimum intensity of detected physical activity to
which the pacemaker responds.

●

Activity Acceleration and Activity Deceleration times control how rapidly the pacing rate
changes in response to increased or decreased activity. One programmable Activity
Deceleration setting, “Exercise,” provides an extended deceleration period following
prolonged exercise.

Note that Activity Threshold, Activity Acceleration, and Activity Deceleration are
automatically set to shipping settings 30 minutes after implant or can be manually
programmed.

Reference Manual 37

Activity Sensor

Ouput

Time

Activity Threshold = Medium/ Low

High

High

Med/High

Med/High

Med/Low

Med/Low

Low

Low

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

3.5.2 How Activity Threshold influences rate

A transducer, bonded to the pacemaker circuitry, is deflected by physical motion. The activity
sensor converts detected motion into electrical signals. The programmed Activity Threshold
screens out activity signals below the selected setting. Detected sensor signals vary from
patient to patient. Only sensor signals whose amplitude exceeds the programmed Activity
Threshold (as shown in Figure 21) are used in computing the sensor-indicated rate. The
lower the Activity Threshold, the smaller the signal required to influence the sensor-indicated
rate.

Figure 21. Activity sensor signal (threshold set to medium/low)

3.5.3 Evaluating the Activity Threshold setting

Activities such as walking increase the pacing rate; sitting results in pacing at or near the
programmed Lower Rate. Use Table 2 as a guide for selecting an appropriate setting.

Table 2. Activity Threshold guidelines

Programmable set­tings Typical rate performance

Low Responds to most body activity, including minimal exertion.
Medium/Low Limited response to minimal exertion; responds to moderate or greater

exertion.

38 Reference Manual

210 4 53

15 s
30 s
60 s

Upper Sensor Rate

Lower Rate

Time (min)

Activity Acceleration programmable
settings

Rate range

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Table 2. Activity Threshold guidelines (continued)

Programmable set­tings Typical rate performance

Medium/High Limited response to moderate body movements and exertion.
High Responds to only vigorous body movements and exertion.

3.5.4 How Activity Acceleration and Deceleration influence rate

Activity Acceleration and Activity Deceleration times control how rapidly the pacing rate
changes in response to increased or decreased physical activity. One programmable
Activity Deceleration setting, “Exercise,” provides an extended deceleration period following
prolonged exercise.

●

Activity Acceleration time is the time required to achieve approximately 90% of the
difference between the current rate and a higher steady-state rate consistent with the
current level of activity. Figure 22 shows a graphic representation of the acceleration
curves at the onset of strenuous exercise.

●

Activity Deceleration time is the time required to achieve approximately 90% of the
difference between the current rate and a lower steady-state rate consistent with the
current level of activity. Figure 23 shows a graphic representation of the deceleration
curves at an abrupt cessation of strenuous exercise.

Figure 22. Activity Acceleration curves

Reference Manual 39

6543210 7 8 9 10

2.5 min
5 min
10 min

Upper Sensor Rate

Lower Rate

Time (min)

Activity Deceleration programmable
settings

Rate range

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 23. Activity Deceleration curves

3.5.5 Exercise Deceleration operation

Activity Deceleration programmed to “Exercise” extends the rate slowing period following an
exercise episode, providing up to 20 minutes of rate deceleration. When it is programmed
on, the pacemaker uses activity sensor data to detect periods of vigorous, prolonged
exercise. At the end of such an exercise period, the pacemaker uses a longer deceleration
curve for the central portion of the programmed rate range. The actual deceleration rate is
determined dynamically based on the intensity and duration of exercise and the new level of
activity. Figure 24 shows the composite deceleration curve that applies after the abrupt
cessation of sustained exercise.

40 Reference Manual

121086420 14 16 18 20 22

Upper Sensor Rate

Lower Rate

Time (min)

Rate range

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 24. Exercise Deceleration

1 5 min deceleration curve
2 Begins exercise deceleration

3 Ends exercise deceleration
4 5 min deceleration curve

3.6 Manual control of Rate Profile Optimization

3.6.1 Overview

As an alternative to automatic Rate Profile Optimization, a programmer assisted Exercise
test can be used to manually set rate response for the ADL and exertion rate ranges. The
Exercise test is used to immediately set rate response to certain levels. Rate response
parameters remain set to their programmed values if Optimization is Off. When Optimization
is On, it can adjust these parameters once each day.

3.6.2 Evaluate and program rate response

The Exercise test is used to evaluate the patient’s rate response and allow the programmer
to customize two rate response control parameters:

●

ADL Setpoint (Activities of Daily Living Setpoint) determines the minimum sensor
response to pace at the ADL Rate, which falls within the ADL rate range.

●

UR Setpoint (Upper Rate Setpoint) determines the minimum sensor response to pace at
the Upper Sensor Rate, which is at the upper limit of the exertion rate range.

Note: The programmed ADL Setpoint setting must be less than the UR Setpoint setting.

Reference Manual 41

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Refer to the Adapta/Versa/Sensia/Relia Pacemaker Programming Guide for programming
instructions.

42 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4 Pacemaker timing

4.1 Rates

4.1.1 Overview

The following programmable rates control timing in the pacemaker:

●

Normal operating rates:

– Lower Rate

– ADL Rate

– Upper Tracking Rate

– Upper Sensor Rate

●

Other operating rates:

– Sleep Rate (for Sleep function)

– Hysteresis Rate (for single chamber demand and triggered modes)

– Sinus Preference Zone (for Sinus Preference)

– Intervention Rate (for Rate Drop Response)

– Overdrive Rate (for Post Mode Switch Overdrive Pacing)

– Maximum Rate (for Conducted AF Response)

– Maximum Rate (for Atrial Preference Pacing)

Additionally, rates calculated by the pacemaker are used for some operations. These are:

●

Sensor-indicated rate

●

Mean atrial rate

The other operating rates are described in Chapter 6, “Special therapy options”, page 111
along with the functions that use them. The normal rates are described in this chapter.

4.1.2 A-A and V-V timing

A-A timing – In all modes that pace the atrium, the pacemaker times from atrial event to atrial

event (A-A timing). This timing method mimics a natural sinus rhythm, producing A-A
intervals that are nearly equal, except when timing is interrupted by one of the following:

●

PACs in DDIR and DDI modes

●

PVCs in DDDR, DDD, DDIR, DDI modes (PVC Response operation)

Reference Manual 43

200 ms

P

P

V

DDD

A

S

S

P

S

P

P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

●

A ventricular sensed event during the VA interval in the DVIR and DVI modes

●

An atrial refractory sensed event that triggers an NCAP extension

VA intervals vary due to adjustments by A-A timing operations in order to achieve
sensor-indicated or lower rate operation in the presence of varying AV conduction.

V-V timing – In modes that do not pace the atrium (e.g., VDD or VDIR) or single chamber
ventricular modes, the pacemaker times from ventricular event to ventricular event (V-V
timing).

4.1.3 Lower Rate

The programmed Lower Rate defines the slowest rate at which pacing occurs during a
mode’s basic operation. In rate responsive modes, in the absence of sensor-detected
activity, the sensor-indicated rate is equal to the programmed Lower Rate.

Figure 25. Example of Lower Rate operation

1 Lower Rate interval

Parameters: Lower Rate = 60 bpm (1000 ms) PVARP = 300 ms

PAV Interval = 200 ms Ventricular Refractory Period =

240 ms

SAV Interval = 180 ms

44 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.1.4 Operating lower rate

Under certain circumstances, the programmed Lower Rate may be overridden by an
operating lower rate that is higher or lower than the programmed value. The following rates
may become the operating lower rate:

●

Switching from and back to atrial tracking mode (for Mode Switch)

●

Conducted AF Response determined rate

●

Sinus Preference Zone (for Sinus Preference)

●

Sleep Rate (for Sleep function)

●

Intervention Rate (for Rate Drop Response)

●

Hysteresis Rate (for single chamber modes)

●

Threshold Margin Test rate of 100 bpm

●

Magnet Mode rate of 85 bpm

●

Recommended Replacement Time (RRT/ERI) rate of 65 bpm

●

Overdrive Rate (for Post Mode Switch Overdrive Pacing function)

●

Rate determined by Atrial Preference Pacing

●

Rate determined by Capture Management (ACM and VCM)

●

Sensor indicated rate

4.1.5 Selecting a Lower Rate

Program the Lower Rate to maintain adequate heart rates during periods of inactivity or
during pauses in atrial rhythms when the pacemaker is operating in the DDDR, DDD, VDD,
AAIR, ADIR, AAI, and ADI modes.

Note: In the VDD mode, atrial tracking near the Lower Rate may result in V-V intervals that
exceed the Lower Rate interval. This is normal operation.

Lower Rates from 120 to 130 bpm are intended for pediatric patients. Lower Rates below
50 bpm and above 100 bpm are primarily intended for diagnostic purposes.

Reference Manual 45

200 ms

P

V

DDDR

A

S

SS P

PPP

Sensor Sensor Sensor

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.1.6 Sensor-indicated rate

The sensor-indicated rate is the basic pacing rate when the pacemaker is operating in a rate
responsive mode (DDDR, DDIR, DVIR, DOOR, VVIR, VDIR, VOOR, AAIR, ADIR, or AOOR).
It is determined by the pacemaker based on the sensor-detected level of patient activity and
the programmed rate response parameters. The sensor-indicated rate will never be greater
than the Upper Sensor Rate or less than the Lower Rate.

Figure 26. Example of sensor-indicated rate operation

1 Sensor-Indicated interval

Parameters: Sensor-Indicated Rate =

PVARP = 300 ms

90 bpm (667 ms)
PAV Interval = 200 ms Ventricular Refractory Period =

220 ms

SAV Interval = 190 ms

In rate responsive modes, the sensor-indicated rate tracks the activity sensor, which is
detected by the transducer sensor’s frequency and amplitude.

●

In dual chamber rate responsive modes, the sensor-indicated interval is the AS-AP or
AP-AP interval.

●

In single chamber rate responsive modes, the sensor-indicated interval is the A-A or V-V
interval. In these modes, sensor-indicated rate intervals start with a sensed or paced
event in the chamber being paced.

46 Reference Manual

200 ms

S

P

DDD

A

V

S

P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.1.7 Sensor indicated rate effect on other intervals

The sensor-indicated rate is used to determine the values of certain other timing intervals.
These intervals are:

●

Rate adaptive paced AV (PAV) interval

●

Sensor-varied PVARP (even in non-rate responsive DDD and VDD modes)

●

PVARP extension (sensor-corroboration before PMT intervention)

4.1.8 ADL Rate

The ADL Rate (Activities of Daily Living Rate) is the target rate which the patient’s heart rate
is expected to reach during moderate exercise.

4.1.9 Upper Tracking Rate

The programmable Upper Tracking Rate is the maximum rate at which the ventricle may be
paced in response to sensed atrial events when the pacemaker is operating in the DDDR,
DDD, and VDD modes. Sensed atrial events below the Upper Tracking Rate will be tracked
at a 1:1 ratio, but sensed events above the Upper Tracking Rate will result in pacemaker
Wenckebach (for example, 6:5, 4:3, 3:2, or 2:1 block). The Upper Tracking Rate usually
should be programmed to a value less than the 2:1 block rate. Refer to Section 4.7, “High rate
atrial tracking”, page 68 for details.

Figure 27. Example of Upper Tracking Rate (Wenckebach) operation

1 Upper Tracking Rate

Reference Manual 47

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Parameters:

Sensor-indicated Rate =
75 bpm (800 ms)

Upper Tracking Rate = 100 bpm
(600 ms)

SAV Interval = 200 ms

4.1.10 Upper Sensor Rate

In rate responsive modes, the programmable Upper Sensor Rate provides the upper limit for
the sensor-indicated rate during physical activity, particularly during vigorous exercise. In the
DDDR mode, the Upper Sensor Rate may be higher than, lower than, or the same as the
Upper Tracking Rate.

4.1.11 Programming considerations and restrictions

ADL Rate – It is recommended that the ADL Rate be at least 10 bpm less than the Upper

Sensor Rate or 20 bpm greater than the Lower Rate. However, programming the ADL Rate
above or below these limits is permitted.

Upper rates – Programming a combination of high Upper Sensor Rate and Upper Tracking
Rate and a long refractory period may result in a shorter “sensing window.” Loss of sensing
in such cases could result in competitive pacing (unless Non-Competitive Atrial Pacing is
programmed On). See Section 6.4, “Non-competitive atrial pacing”, page 123 for more
information.

●

Programming the Upper Tracking Rate to a value greater than the Upper Sensor Rate
permits the atrial rhythm to be tracked to a rate higher than the sensor-driven rate.

●

The Upper Sensor Rate and/or Upper Tracking Rate must be greater than the Lower
Rate. The Upper Sensor Rate must be greater than the ADL Rate.

4.1.12 Rate limit

An internal circuit, independent of the pacing timers, limits single chamber atrial or
ventricular pacing rates to 200 bpm (±20 bpm) for most single component failures. For dual
chamber modes, atrial and ventricular rates are limited independently to 200 bpm
(±20 bpm). The rate limit is automatically disabled during temporary pacing in the AAI, ADI,
AAT, AOO, VVI, VDI, VVT, and VOO modes to allow high rate pacing for diagnostic or
therapeutic purposes.

Note: When the Upper Tracking Rate is programmed to 190, 200, or 210, the circuit limit is
227 bpm (±17 bpm).

48 Reference Manual

60

80

100

120

140

160

180

200

0 5 10 15 20 25 30 35

Time (seconds)

Rate (min

-1

)

MAR

Intrinsic rate

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.1.13 Possible atrial competition at high rates

At high sensor-driven rates when the pacemaker is operating in the DDDR and DDIR modes,
sensor-driven pacing may approximate the intrinsic atrial rate, with some intrinsic atrial
events falling into the PVARP. This could result in asynchronous pacing with the potential for
competitive atrial pacing. Consider the potential for asynchronous pacing at high rates
before selecting an Upper Sensor Rate, especially for patients known to be susceptible to
induction of atrial tachyarrhythmias. Weigh the benefits of high rate sensor-driven pacing
against the potential for competitive pacing.

Note: Use of the Rate Adaptive AV feature and sensor-varied or automatic PVARP can
reduce the likelihood of the type of asynchronous pacing described above. When the
pacemaker is operating in the DDDR mode, Sinus Preference and NCAP can also be
considered.

4.1.14 Mean atrial rate

The mean atrial rate (MAR) is a running average of the atrial rate for use by the Rate Adaptive
AV and automatic PVARP features. The average uses all A-A intervals (except AS-AP or
AR-AP intervals). In order to respond quickly to rapidly increasing atrial rates, the average
gives preference to shorter A-A intervals over longer intervals when calculating the MAR.
Figure 28 shows how the MAR tracks an increasing intrinsic atrial rate.

Figure 28. Increasing mean atrial rate

Reference Manual 49

P

DDD

P P

A

V

P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.2 AV intervals

4.2.1 Overview

In dual chamber modes, the AV intervals determine the time between the occurrence of an
atrial event and the scheduled delivery of a ventricular stimulus. Separate AV intervals for
paced and sensed atrial events are available. The lengths of these intervals may be
programmed to fixed values or (optionally) rate adaptive or therapeutically determined.

Paced AV Interval (PAV) – PAV follows an atrial pace when the pacemaker is operating in
the DDDR, DDD, DDIR, DDI, DVIR, DVI, DOOR, and DOO modes. The PAV interval duration
may differ from the programmed value due to one of the following operations:

●

Rate Adaptive AV

●

Search AV+

●

Ventricular Safety Pacing

●

Non-Competitive Atrial Pacing

Figure 29. Example of PAV interval operation

1 PAV interval
2 PAV

Sensed AV Interval (SAV) – SAV follows an atrial sensed event when the pacemaker is
operating in an atrial synchronous pacing mode (DDDR, DDD, and VDD). The SAV interval
duration may differ from the programmed value due to one of the following operations:

●

Rate Adaptive AV

●

Automatic PVARP

●

Search AV+

●

Wenckebach

50 Reference Manual

S

P P

DDD

A

V

S

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

For Wenckebach operation, the SAV is extended to avoid violation of the Upper Tracking
Rate or the total atrial refractory period while tracking a fast intrinsic atrial rate.

Figure 30. Example of SAV Interval operation

1 SAV interval
2 SAV

4.2.2 Selecting PAV and SAV

Using MVP or Search AV+ should eliminate the need to manually adjust the AV intervals for
most patients. It is recommended that MVP or Search AV+ be used to reduce pacing in the
right ventricle.

However, when programming AV intervals in patients with third degree block, the general
hemodynamic goal is to assure that, to the extent possible, left-atrial systole is completed
before left-ventricular systole begins. To achieve this, the AV interval durations may be
adjusted independently of each other.

●

To accommodate the difference in interatrial conduction times, the SAV usually should
be programmed to a shorter duration than the PAV, typically 30 to 50 ms shorter. If an SAV
greater than the PAV is selected, the programmer notes that this is not usual, but the
selected values may be programmed if clinically warranted.

●

When the SAV is longer than the PAV, a V pace following an atrial sense will always occur
after the full SAV, even when the sensor-indicated rate or Lower Rate interval expires
first.

●

In certain patients, short AV intervals may be used as a prophylaxis for AV nodal or
accessory pathway reentrant tachycardias in dual chamber modes.

Reference Manual 51

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

●

Long PAV intervals (greater than or equal to 250 ms) should be used with caution. If
intrinsic ventricular events occur and are not sensed, a long PAV may result in pacing into
the ventricle’s relative refractory period, including the T wave, or loss of AV synchrony,
which may precipitate retrograde activation of the atria with corresponding
hemodynamic consequences and symptoms. Long PAV intervals may also result from
some Search AV+ settings (see Section 4.4, “Search AV+ and diagnostic”, page 55
and Section 4.5.3, “Ventricular blanking”, page 59.

4.3 Rate Adaptive AV

4.3.1 Overview

In the normal heart, AV conduction times tend to shorten as the heart rate increases and to
lengthen as the heart rate decreases. The Rate Adaptive AV (RAAV) feature, available when
the pacemaker is operating in the DDDR, DDD, DDIR, DVIR, DOOR, and VDD modes,
mimics this physiologic response. When RAAV is programmed On, the pacemaker shortens
AV intervals for atrial rates within a programmed rate range. This feature provides increased
opportunity for atrial sensing, as follows:

●

Shortened SAV intervals increase the tracking range at fast atrial rates by shortening the
Total Atrial Refractory Period (TARP) and increasing the 2:1 block rate. Refer to
Section 4.6.9, “Total Atrial Refractory Period (TARP)”, page 64 and Section 4.7, “High
rate atrial tracking”, page 68 for more information.

●

Shortened PAV intervals lengthen the atrial sensing window of the VA interval at higher
sensor-driven rates.

Note: RAAV will not shorten PAV intervals to less than 30 ms or shorten SAV intervals to less
than 10 ms.

4.3.2 Programming for Rate Adaptive AV

For RAAV operation, the SAV and PAV are programmed (as applicable) to the values desired
for low rates. Three additional programmable parameters control how AV intervals are
adjusted at higher rates:

Start Rate – RAAV operation of shortening SAV and PAV intervals begins at this rate.

Stop Rate – The shortest SAV and PAV occur at this rate and at all higher rates, up to the

upper rate limits.

Maximum Offset – The maximum amount of time (in ms) by which the SAV and PAV
intervals can be shortened.

52 Reference Manual

Programmed

Start rate

PAV

PAV

SAV

SAV

Rate (min-1)

AV Interval (ms)

Stop rate

MinimumRate Adaptive

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

The PAV minus the Maximum Offset gives the shortest PAV interval at the Stop Rate (e.g.,
200 ms - 100 ms = 100 ms). Subtracting the Maximum Offset from the SAV gives the shortest
SAV interval (e.g., 170 ms - 100 ms = 70 ms).

Figure 31 shows how the SAV and PAV intervals are linearly shortened as the rate increases
from below the Start Rate to above the Stop Rate.

Figure 31. Rate Adaptive AV operation (DDDR Mode)

1 Shortest PAV (PAV minus Maximum Offset)
2 Shortest SAV (SAV minus Maximum Offset)

Parameters: Programmed SAV =

170 ms
Programmed PAV =

200 ms

Start Rate = 80 bpm Maximum Offset =

−30 ms

Stop Rate = 150 bpm

Reference Manual 53

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.3.3 RAAV operations

Shortening of the AV interval(s) occurs when the appropriate rate exceeds the programmed
Start Rate, as follows:

SAV – The mean atrial rate determines SAV adjustments. Because of how the mean atrial
rate is calculated:

●

SAV adjustments will lag during rapid increases or decreases in intrinsic atrial rates.

●

The SAV is not adjusted for isolated events (PACs).

●

AS-AP or AR-AP intervals may affect the SAV value since these intervals are not used in
the mean atrial rate calculation.

PAV – The sensor-indicated rate determines PAV adjustments.

The approximate difference between programmed SAV and PAV is maintained as the SAV
and PAV intervals are adjusted.

4.3.4 Programming considerations and restrictions

Search AV+ – RAAV can be enabled while Search AV+ is enabled. Search AV+ will operate

using the AV intervals determined by the RAAV rather than the programmed AV intervals.

4.3.5 RAAV and sick sinus syndrome

If RAAV is activated for a sick sinus syndrome patient who has AV conduction, consider the
following:

●

The rate at which AV conduction is lost should not be too low (i.e., below 90 bpm).

●

Review of the AV Conduction Histogram diagnostic data may aid in appropriate
programming of Start Rate and Stop Rate to maintain AV conduction as long as possible.

54 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.4 Search AV+ and diagnostic

4.4.1 Overview

The Search AV+ feature is intended to promote intrinsic ventricular activation in patients with
intact or intermittent AV conduction and prevent inappropriate therapy in patients without
conduction. Search AV+ is available when the pacemaker is programmed to the DDDR,
DDD, DDIR, DDI, DVIR, DVI, or VDD mode. The pacemaker searches for the patient’s
intrinsic AV conduction time and adjusts the SAV and PAV intervals either longer or shorter
to promote intrinsic activation of the ventricles. When Rate Adaptive AV is active, the
pacemaker also adjusts the SAV and PAV intervals relative to the rate adaptive values. If the
pacemaker does not observe intrinsic ventricular activation during its periodic searches over
the course of a week, it turns off the Search AV+ feature.

4.4.2 Programming to Search AV+

Programming Search AV+ to “On” requires setting the Max Increase to AV parameter. This
parameter defines the maximum amount of time (in ms) by which the operating SAV and PAV
intervals can be lengthened to allow ventricular sensing to occur. The operating SAV and
PAV intervals will adapt to the observed conduction time, but will not exceed the Max
Increase to AV parameter.

4.4.3 Search AV+ operation

The pacemaker attempts to keep intrinsic conducted events in an “AV delay window” that
precedes scheduled paced events. The AV delay window is set to promote intrinsic
conduction to the ventricles, but end early enough to avoid fusion or pseudo-fusion beats if
pacing is necessary (see Figure 32).

Reference Manual 55

200 ms

PAV is now 212 ms

PAV is now 204 ms

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 32. Search AV+ operation

1 Previous 16 AV events, 8 or more VS events are within 15 ms of the scheduled VP, thus PAV and

SAV are extended by 62 ms to promote intrinsic conduction.

2 Previous 16 AV events, 8 or more VS events occur 55 ms before the scheduled VP, thus PAV and

SAV are shortened by 8 ms to limit long AV delays if ventricular pacing is needed.

Parameters: DDDR SAV = 120 ms

Lower Rate = 60 bpm PAV = 150 ms
Sensor-Indicated Rate =

90 bpm

Max. Increase to AV= 170 ms

To determine when intrinsic conducted events occur, the pacemaker assesses the 16 most
recent AV conduction sequences that start with a nonrefractory atrial sense (when the
pacemaker is operating in the DDDR, DDD, and VDD modes) or an atrial pace (when the
pacemaker is operating in the DDDR, DDD, DDIR, DDI, DVIR, and DVI modes) and end with
a ventricular pace or a nonrefractory ventricular sense.

Search criteria of AV conduction times – The measured AV conduction times are
classified as on time, too short or too long.

●

Too long means 8 or more of the last 16 ventricular sensed events occurred within 15 ms
of the scheduled ventricular pace, or 8 or more of the last 16 ventricular events were
paced events.

●

Too short means 8 or more of the last 16 ventricular sensed events occurred more than
55 ms before the scheduled ventricular pace.

Adjustment of SAV and PAV intervals – If AV conduction times are classified as too long,
the pacemaker lengthens the operating SAV and PAV intervals by 62 ms for the next 16
pacing cycles to promote intrinsic conduction. The maximum that the SAV and PAV can be
lengthened is limited by the Search AV+ Maximum Increase to AV parameter.

56 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

If the previous 16 AV intervals are classified as too short, the pacemaker shortens the
operating SAV and PAV intervals by 8 ms for the next 16 pacing cycles. The maximum that
SAV and PAV can be shortened is limited by the programmed SAV and PAV values or the
RAAV Maximum Offset parameter, if RAAV is On.

4.4.4 Suspension of Search AV+ operation

Search AV+ promotes conduction in patients with intrinsic conduction and prevents
inappropriate therapy for patients without intrinsic conduction. If AV conduction is not found,
Search AV+ suspends operation for progressively longer periods: 15 minutes, 30 minutes, 1,
2, 4, 8, and 16 hours. If AV conduction is not found following 10 consecutive 16-hour
suspensions (approximate duration, 1 week), the device automatically turns Search AV+ to
Off.

4.4.5 Programming considerations and restrictions

Both Automatic PVARP and Rate Adaptive AV can shorten the AV intervals at higher rates
and potentially lead to ventricular pacing.

Automatic PVARP – When automatic PVARP is active and Search AV+ is set to On, the
pacemaker will ignore conduction times that are the result of automatic PVARP shortening
of the SAV interval.

Rate Adaptive AV – RAAV can be enabled while Search AV+ is enabled. Search AV+ will
operate using the RAAV-determined AV intervals rather than the programmed AV intervals.

MVP modes – Search AV+ is not pertinent and cannot be enabled if the pacemaker is
programmed to an MVP mode (AAIR<=>DDDR or AAI<=>DDD).

4.4.6 Recording AV interval adaptations

AV interval diagnostics record data about AV operations for the Search AV+ feature.

4.4.6.1 Automatic Search AV+ Histogram

Programming Search AV+ parameters automatically initiates recording of data by the
Search AV+ Histogram diagnostic. This histogram shows the percentage of A-VS, VS from
Search, and A-VP intervals versus rate. A histogram can be displayed or printed from the
Data icon.

Reference Manual 57

P

P P

DDD

A

V

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.4.6.2 Clearing AV interval data

AV interval data is normally cleared by the pacemaker one hour after a programming
session.

However, you can select the option to clear data immediately. Be sure to save the session
data or print the episode report before ending the patient session.

4.4.6.3 Search AV+ and compromised ventricular function

Consider turning Search AV+ off if intrinsic ventricular activation is not desired.

4.5 Blanking periods

Blanking periods disable sensing for a programmable or nonprogrammable interval. Signals
that are blanked may originate in either chamber or from outside sources such as noise from
muscle movement.

Figure 33. Example of dual chamber blanking operation

1 Nonprogrammable Atrial Blanking
2 Programmable Post-Ventricular Atrial

Blanking

3 Programmable Ventricular Blanking
4 Nonprogrammable Ventricular Blanking

Note: Black bars indicate blanking periods.

4.5.1 Nonprogrammable blanking periods

Immediately following a sensed or paced event in either chamber, sensing for that chamber
is blanked for a nonprogrammable period that may typically vary from 50 to 100 ms. The
actual duration of the blanking period is determined dynamically by the pacemaker, based
on the strength and duration of the signal. Dynamic blanking prevents sensing the same
signal twice, while minimizing total blanking time.

58 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.5.2 Post-Ventricular Atrial Blanking

The programmable Post-Ventricular Atrial Blanking (PVAB) period, used when the
pacemaker is operating in the DDDR, DDD, DDIR, DDI, VDD, VDIR, and VDI modes,
prevents sensing of ventricular paced events or far-field R waves on the atrial lead. Any
ventricular event (paced or sensed) starts the PVAB, which is also the first portion of the
Post-Ventricular Atrial Refractory period (PVARP). The PVAB is limited to values equal to or
less than the programmed PVARP, except in VDIR and VDI modes where PVARP does not
apply.

Note: PVAB is programmed to a value less than or equal to PVARP.

4.5.3 Ventricular blanking

The programmable Ventricular Blanking period, which follows an atrial pacing stimulus when
the pacemaker is operating in the DDDR, DDD, DDIR, DDI, DVIR, and DVI modes, prevents
ventricular inhibition or ventricular safety pacing due to sensing of the atrial stimulus on the
ventricular lead (crosstalk). The Ventricular Blanking period also applies to the ADIR and ADI
modes to prevent sensing of the atrial stimulation.

●

Long blanking periods (36 ms or greater) increase the possibility of unsensed ventricular
events.

●

Long blanking periods used in conjunction with long PAV intervals (250 ms or greater)
may result in pacing into the T wave when intrinsic ventricular events are blanked and not
sensed. PAV values (200 ms or less) should reduce the possibility of T wave pacing.

●

Long PAV intervals may also result from some Search AV+ operation (See Section 4.4,
“Search AV+ and diagnostic”, page 55). To minimize the possibility of undersensing
intrinsic events, Search AV+ reduces ventricular blanking to 20 ms unless Ventricular
Safety Pacing is observed.

4.5.4 Single chamber atrial blanking

The programmable single chamber atrial blanking period, used when the pacemaker is
operating in the AAIR, ADIR, AAI, ADI, and AAT mode, prevents sensing of far-field R waves.
It is started by a paced, sensed, or refractory sensed atrial event.

Note: Atrial Blanking must be programmed at least 50 ms less than the Atrial Refractory
Period.

Reference Manual 59

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.6 Refractory periods

4.6.1 Overview

A refractory period is an interval during which an intrinsic event sensed on a particular lead
channel cannot start certain timing intervals. Each refractory period begins with a blanking
period, during which no sensing occurs. During the unblanked portion of a refractory period,
sensing occurs, but sensed events may not directly affect timing operations. Refractory
periods are intended to prevent certain timing intervals from being started by inappropriate
signals such as retrograde P waves, far-field R waves, or electrical noise.

Though they may not start timing intervals, refractory sensed events are monitored by the
pacemaker, and they affect the operation of PVC Response, Mode Switch, Rate Adaptive AV
operation, automatic PVARP, Non-Competitive Atrial Pacing, and other features for which
the periodicity or number of sensed events are pertinent. Refractory sensed events are
included on Marker Channel recordings.

4.6.2 Post-Ventricular Atrial Refractory Period

The Post-Ventricular Atrial Refractory Period (PVARP) follows a paced, sensed, or refractory
sensed ventricular event when the pacemaker is operating in the DDDR, DDD, DDIR, DDI,
and VDD modes. It is intended primarily to prevent the sensing of retrograde P waves that
might promote Pacemaker-Mediated Tachycardias (PMTs) in atrial tracking modes. When
the pacemaker is operating in the DDIR and DDI modes, PVARP prevents atrial inhibition
from retrograde P waves.

The first portion of the PVARP is the programmable Post-Ventricular Atrial Blanking period
(PVAB). During the remainder of the PVARP, intrinsic atrial events may be sensed as
refractory sensed events (AR) and identified on Marker Channel recordings, but they do not
affect stimulus timing.

●

When the pacemaker is operating in the DDDR, DDD, and VDD modes, an SAV is not
started.

●

When the pacemaker is operating in the DDDR, DDD, DDIR, and DDI modes, the
scheduled atrial pace is not inhibited.

60 Reference Manual

P

DDD

A

V

P P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 34. Example of PVARP operation

1 PVARP

The duration of the PVARP may be selected as follows:

●

The PVARP should be programmed to a value greater than the patient’s ventriculoatrial
(VA) retrograde time when retrograde conduction is present.

●

Excessively long PVARPs may induce 2:1 block at high intrinsic rates when the
pacemaker is operating in an atrial tracking mode (DDDR, DDD, or VDD).

●

To reduce the 2:1 block point, PVARP can be set to vary based on the sensor-indicated
rate (sensor-varied PVARP) or the mean atrial rate (automatic PVARP).

4.6.3 Sensor-varied PVARP

When sensor-varied PVARP is programmed, the pacemaker determines a value for the
PVARP based on the sensor-indicated rate. The intended purpose of the sensor-varied
PVARP depends upon the mode:

●

When the pacemaker is operating in the DDDR, DDD, and VDD modes, sensor-varied
PVARP is intended to do the following:

– Enhance protection against PMT at lower rates by providing longer PVARPs at low

sensor-indicated rates.

– Allow tracking of higher atrial rates (that is, provide a higher 2:1 block rate) by

shortening the PVARP at high sensor-indicated rates.

●

When the pacemaker is operating in the DDIR mode, the sensor-varied PVARP is
intended to promote AV synchrony by preventing inhibition of atrial pacing by an atrial
sense early in the VA interval. It also reduces the likelihood of competitive atrial pacing
at high sensor-indicated rates.

Reference Manual 61

400 ms 300 ms 400 ms

200 ms

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 35. Sensor-varied PVARP operation (DDDR Mode)

1 Upper Sensor Rate
2 Lower Rate

3 PAV
4 PVARP

4.6.4 Determining sensor-varied PVARP

The pacemaker determines the duration of the sensor-varied PVARP as follows:

●

When the pacemaker is operating in the DDDR, DDD, and VDD modes, the
sensor-varied PVARP is limited to 400 ms at low rates and the programmed PVAB at high
rates (as shown in Figure 35).

●

When the pacemaker is operating in the DDIR mode, PVARP is the pacing interval,
minus the PAV interval, minus 300 ms. At high rates, PVARP is limited by the
programmed PVAB.

●

When the pacemaker is operating in the DDDR, DDD, DDIR, and VDD modes, the
sensor-varied PVARP is automatically adjusted to maintain a 300 ms sensing window
(as shown in Figure 35).

62 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.6.5 Automatic PVARP

When automatic PVARP is programmed, the pacemaker determines a value for the PVARP
based on the mean atrial rate (which is an average of all A-A intervals except those starting
with an atrial sense or atrial refractory sense and ending with an atrial pace). When the
pacemaker is operating in the DDDR, DDD, and VDD modes, automatic PVARP is intended
to provide a higher 2:1 block rate by shortening the PVARP and SAV (if necessary) at higher
tracking rates and protect against PMTs at lower rates by providing a longer PVARP.

4.6.6 Determining automatic PVARP

The pacemaker determines the duration of the automatic PVARP as follows:

●

After every four pacing cycles, a 2:1 block rate is calculated that is 30 bpm above the
current mean atrial rate.

●

PVARP is then adjusted so the Total Atrial Refractory Period equals the calculated 2:1
block rate. The programmable Minimum PVARP parameter controls the minimum value
that PVARP can be shortened to.

●

If the minimum PVARP value is reached and the 2:1 block rate is still too low, the SAV
interval can be shortened to increase the 2:1 block rate. The minimum SAV that can be
set is the rate adaptive SAV value (i.e., the programmed SAV value minus the RAAV
Maximum Offset value).

The minimum adjustable 2:1 block rate is 100 bpm. The maximum adjustable 2:1 block rate
is the Upper Tracking Rate plus 35 bpm. If Mode Switch is On, the maximum 2:1 block rate
can be the Detect Rate if this rate is less than the Upper Tracking Rate calculation.

4.6.7 Programming restrictions for automatic PVARP

Rate Drop Response – Automatic PVARP is not available when Rate Drop Response is

programmed On.

4.6.8 Spontaneous PVARP extension

The programmed PVARP duration, the sensor-varied PVARP, and the automatic PVARP
may be overridden by the PVC Response and PMT Intervention features, as follows:

●

When the PVC Response feature is programmed On and a pacemaker-defined PVC
occurs, the PVARP is forced to 400 ms for one cycle if a lesser value is in effect.

●

When PMT Intervention is programmed On and a pacemaker-defined PMT is detected,
the PVARP is forced to 400 ms for one cycle after the ninth paced ventricular event of the
PMT.

Reference Manual 63

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Refer to Section 6.5, “PMT intervention”, page 125 and Section 6.6, “PVC Response”,
page 127 for further details on the PMT Intervention and PVC Response features and their
interactions with PVARP.

4.6.9 Total Atrial Refractory Period (TARP)

In dual chamber modes that sense in the atrium, the Total Atrial Refractory Period (TARP) is
the sum of two intervals, as follows:

AV Interval – The AV interval begins with an atrial event and ends with a ventricular event.
The first portion is a nonprogrammable blanking period. Its complete duration is determined
as follows:

●

When the pacemaker is operating in the DDDR, DDD, and VDD modes, the PAV or SAV
interval is the AV interval.

●

When the pacemaker is operating in the DDIR and DDI modes, the AV interval starts with
the first atrial sensed event in the VA interval or with an atrial pacing stimulus; it ends
when the PAV expires, even when ventricular pacing is inhibited.

Post-Ventricular Atrial Refractory Period (PVARP) – The PVARP is described on
Section 4.6.2.

Figure 36. Total Atrial Refractory Period

1 TARP
2 SAV + PVARP

3 SAV
4 PVARP

During atrial tracking, TARP = SAV + PVARP, and its duration determines the rate at which
2:1 block occurs. Refer to Section 4.7, “High rate atrial tracking”, page 68 for more
information.

64 Reference Manual

P

DDD

A

V

P P

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.6.10 Ventricular Refractory Period

The programmable Ventricular Refractory Period (VRP) follows paced, sensed, and
refractory sensed ventricular events (including PVCs) in all dual chamber and ventricular
modes that sense in the ventricle. The VRP is intended to prevent sensing of the T wave or
a PVC. The first portion of the VRP is a nonprogrammable blanking period. A ventricular
refractory sensed event affects pacemaker timing as follows:

●

Ventricular blanking and refractory periods restart in all modes.

●

When the pacemaker is operating in the DDDR, DDD, and VDD modes, the upper
tracking rate interval, PVARP, and PVAB also restart.

●

When the pacemaker is operating in the VVIR and VDIR modes, the upper sensor rate
interval restarts.

Note: In dual chamber modes, the VRP should be programmed shorter than the PVARP.

Figure 37. Example of Ventricular Refractory Period operation

1 VRP

In dual chamber modes, a ventricular refractory sensed event does not affect a scheduled
sensor-driven or lower rate atrial output. Thus, a sensor-driven atrial output pulse will initiate
a PAV with a ventricular output pulse following, unless inhibited.

4.6.11 Atrial Refractory Period (single chamber)

The programmable Atrial Refractory Period (ARP) follows paced, sensed, and refractory
sensed atrial events. The ARP is used in the AAIR, ADIR, AAI, ADI, and AAT modes. It is
intended to prevent inhibition due to far-field R wave sensing. The first portion of the ARP is
a programmable blanking period. The ARP should be programmed to a value long enough
(180 ms or greater) to prevent far-field R wave sensing but short enough to ensure atrial
sensing up to the programmed Upper Sensor Rate.

Reference Manual 65

DDDR

A

V

P P P

P R R R P P

200 ms

Sensor Sensor Sensor

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

If the pacemaker is programmed to an MVP mode (AAIR<=>DDDR or AAI<=>DDD) and is
operating in AAIR or AAI mode, the ARP is automatically adjusted to 75% of the cardiac cycle
length, up to a maximum of 600 ms.

4.6.12 Noise reversion

When sensing occurs during the Atrial Refractory Period (ARP) or Ventricular Refractory
Period (VRP), the refractory period (and its blanking period) are restarted. The operation
associated with continuous refractory sensing in the ARP or VRP is called noise reversion.
Multiple restarts of the ARP or VRP (continuous noise reversion) do not inhibit scheduled
pacing. Pacemaker behavior during continuous noise reversion is as follows:

●

Pacing occurs at the sensor-indicated rate for all rate responsive modes (except VVIR
and VDIR).

●

Pacing occurs at the programmed Lower Rate for all non-rate responsive modes
(including VVIR and VDIR).

On the ECG, noise reversion may be difficult to distinguish from loss of sensing, but Marker
Channel recordings will show refractory sense markers when noise reversion occurs.

Figure 38. Example of noise reversion in DDDR at sensor-indicated rate.

1 Sensor-indicated interval

Parameters: Lower Rate = 60 bpm (1000 ms

± 17 ms)

Upper Sensor Rate = 120 bpm
(500 ms ± 17 ms)

PAV Interval = 200 ms Ventricular Refractory Period =

240 ms

PVARP = 300 ms PVAB = 200 ms

66 Reference Manual

200 ms

Sensor P

V

R R R R P

VVIR

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Note: In DDDR mode, the sensor-indicated rate occurs anywhere between the Lower Rate
and the Upper Sensor Rate, depending on patient activity.

Note: If an atrial refractory sensed event occurs, the pacemaker does not restart the
refractory period. However, an atrial refractory sensed event will start a short blanking period
of 50 to 100 ms depending on the signal strength and duration of the atrial event.

Figure 39. Example of noise reversion in VVIR at lower rate.

1 Lower Rate

Parameters: Lower Rate = 60 bpm (1000 ms

±17 ms)

Ventricular Refractory Period =
240 ms

Upper Sensor Rate = 120 bpm
(500 ms ±17 ms)

4.6.13 Preventing noise sensing

Noise reversion may be caused by electromagnetic interference (EMI), myopotentials,
excessively high output settings, or low sensitivity settings. When it has been identified,
noise reversion usually can be reduced or eliminated by one of the following actions:

●

Remove patient from EMI environment.

●

Reprogram sensitivity to a less sensitive setting (higher numerical value) or program
Sensing Assurance to On, to monitor and if necessary, adjust the sensitivity value. Refer
to Section 5.6, “Sensing Assurance and diagnostic”, page 99.

●

Reprogram sensing polarity to bipolar polarity (if available).

●

Reduce the amplitude and/or pulse width in the same or opposite chamber.

Reference Manual 67

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

●

Program Capture Management to Adaptive to monitor capture thresholds, and, if
necessary, adjust amplitude and pulse width values. Refer to Section 5.5, “Capture
Management and diagnostic”, page 79.

4.7 High rate atrial tracking

4.7.1 Overview

When the pacemaker is operating in the DDDR, DDD, and VDD modes, the fastest atrial rate
the pacemaker can track is determined by the Total Atrial Refractory Period (TARP), which
is the sum of the SAV and the PVARP. Pacemaker behavior at high atrial rates in these modes
is determined by the relationship between the TARP and the interval corresponding to the
Upper Tracking Rate. In the DDDR mode, the interval corresponding to the Upper Sensor
Rate also must be considered.

4.7.2 2:1 block

When the intrinsic atrial interval is shorter than the TARP, some atrial events will fall in the
PVARP and not be tracked. At the rate where this first occurs, ventricular tracking occurs only
on alternate beats, and 2:1 block ensues. When the pacemaker is operating in the DDD and
VDD modes, the ventricular pacing rate drops precipitously.

●

When sensor-varied PVARP or automatic PVARP is selected, the 2:1 block rate may
occur at a higher rate during activity due to shortening of the PVARP and the SAV
(automatic PVARP only), thus increasing atrial tracking.

●

When Rate Adaptive AV operation is selected, the SAV shortens at high atrial rates,
shortening the TARP and raising the 2:1 block rate.

●

When the 2:1 block rate is less than the Upper Tracking Rate, the Upper Tracking Rate
cannot be achieved.

●

When the pacemaker is operating in DDDR mode, pacing at the sensor-indicated rate
may prevent a precipitous rate drop at the 2:1 block point when activity is present.

●

For patients with a documented propensity for prolonged or sustained atrial fibrillation or
flutter, the clinician can select Upper Tracking Rate, SAV, and PVARP values that induce
2:1 block at a desired rate (2:1 block rate = 60,000/TARP). Alternatives for controlling
rates in these patients include use of the Mode Switch feature and DDIR mode pacing.

●

When the pacemaker is operating in the DDDR mode, atrial competition may occur if the
Upper Sensor Rate exceeds the 2:1 block rate.

68 Reference Manual

S

P

DDDR

A

V

S

P

S

P

S

P P

R

200 ms

P

Sensor

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

4.7.3 Pacemaker Wenckebach

When the 2:1 block rate exceeds the programmed Upper Tracking Rate, pacemaker
Wenckebach may occur. When the intrinsic rate exceeds the Upper Tracking Rate, a pacing
stimulus at the expiration of the SAV would violate the upper tracking rate. The pacemaker
therefore extends the SAV until the upper tracking rate interval expires. Subsequent SAVs
require greater extension, until an atrial event falls in the PVARP and is not tracked.

●

When the pacemaker is operating in the DDDR, DDD, and VDD modes, the result is
normally a fixed ratio between atrial and ventricular rates (3:2, 4:3, and so forth).

●

When the pacemaker is operating in the DDDR mode, the pacemaker Wenckebach rate
may be smoothed by sensor-driven ventricular pacing, thereby overriding the fixed ratio.

Figure 40 shows how pacemaker Wenckebach operation occurs in the DDDR, DDD, or VDD
modes.

Figure 40. Example of pacemaker Wenckebach operation

1 Upper Tracking Rate interval
2 SAV interval

Parameters: Sensor-Indicated Rate =

PVARP = 300 ms

90 bpm (667 ms)
PAV Interval = 230 ms Upper Tracking Rate = 100 bpm

(600 ms)

SAV Interval = 200 ms

4.7.4 High rate operation in the DDDR mode

Table 3 summarizes how the total atrial refractory period (TARP), the Upper Tracking Rate
(UTR) interval, and the Upper Sensor Rate (USR) interval may interact at high atrial rates
when the pacemaker is operating in the DDDR mode.

Reference Manual 69

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Table 3. Upper rates interaction with TARP

Relationship
Between TARP and
Upper Rate Intervals

TARP > both USR and
UTR intervals

USR interval > TARP >
UTR interval

USR interval > UTR
interval > TARP

UTR interval > both
USR interval and TARP

a

Unless the Non-Competitive Atrial Pacing is On, see Section 6.4, “Non-competitive atrial pacing”, page 123.

Wenckebach Before

2:1 Block

no no yes

no no no

yes yes no

yes yes yes

Achieve Upper Track-

ing Rate

Potential Atrial Com-

petition

a

a

70 Reference Manual

Implant 30 minutes

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

5 Lead/cardiac tissue interface

5.1 Implant Detection

5.1.1 Overview

Implant Detection is a 30 min period, beginning at lead connection, during which the
pacemaker verifies that each lead has been connected by measuring lead impedance. After
30 min of continuous lead connection, the pacemaker completes Implant Detection and
activates the following features (see Figure 41):

●

Operating polarity (automatic configuration occurs during Implant Detection)

●

MVP operations including conduction checks and mode changes

●

Adaptive sensitivity settings (Sensing Assurance)

●

Rate responsive pacing, including adaptive rate profile optimization (Rate Profile
Optimization)

●

Adaptive ventricular output settings for threshold management (Capture Management)

●

Diagnostic data collection

Figure 41. Implant Detection period

1 Lead connection verified
2 Leads connected
3 Lead polarities confirmed, Rate Response enabled, Adaptive features activated, and Data

collection activated

Implant Detection is available in all pacing modes and is turned on at shipment.

Note: Search AV+ initializes 60 min after Implant Detection is complete.

Reference Manual 71

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Note: Automatic polarity configuration does not occur during Implant Detection if the Lead
Monitor parameter is programmed to Monitor Only before implant. Automatic configuration
will take place if Lead Monitor is programmed to Adaptive before implant or remains set to its
shipping setting of Configure.

5.1.2 Verifying lead connection during Implant Detection

At the time of lead connection, the pacemaker begins verifying that each lead is present by
measuring the impedance of each pacing pulse. When a pace is delivered, the pacemaker
determines if the impedance is within the acceptable range, which is programmable
between 200 to 40006 Ω for both bipolar and unipolar configurations.

●

High impedance paces cause Implant Detection to reset.

●

Low impedance paces (and continuous sensing) are considered acceptable for the
purpose of determining lead connection and configuring polarity.

5.2 Automatic polarity configuration

5.2.1 Overview

During Implant Detection, bipolar pacemakers automatically configure pacing and sensing
polarities through the Lead Monitor feature. Bipolar pacemakers are shipped with the Atrial
and Ventricular Lead Monitor set to Configure, enabling automatic polarity determination
shortly after lead connection.

Unipolar-only pacemakers are configured to unipolar pacing and sensing polarity at the time
of manufacture and remain unipolar during the operational life of the pacemaker.

6

The acceptable maximum impedance limit for a valid lead (bipolar or unipolar) can be changed by programming
the Notify If > (Greater Than) parameter, which is part of the Lead Monitor and is found under the programmed
lead polarities. The minimum impedance limit of 200 Ω is nonprogrammable.

72 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

5.2.2 Measuring lead impedance during configuration

Bipolar pacemakers, using either bipolar or unipolar leads, automatically configure pacing
and sensing polarities by measuring the impedance of each pace during the configuration
period. (Lead Monitor must be set to Configure or Adaptive. See Section 5.3, “Lead Monitor”,
page 76.) Impedance measurement during configuration is as follows:

●

The pacemaker issues a bipolar pace and immediately checks the pace for high
impedance.

– If the pace is within range, it is considered an acceptable bipolar pace.

– If high impedance is found, the pacemaker immediately follows the bipolar pace with

a backup unipolar pace.

●

If a unipolar backup pace is issued, the pacemaker checks it for high impedance.

– If the pace is within range, it is considered an acceptable unipolar pace.

– If high impedance is found, the pacemaker assumes a lead is not attached and

restarts Implant Detection.

Notes:

●

During polarity configuration, the pacemaker also detects low impedance paces but
does not follow them with unipolar backup paces. To avoid possible loss-of-capture due
to continuous low impedance pacing, the pacemaker sets unipolar polarity when 3 of 16
paces are detected as low impedance during the first phase of configuration (see “Initial
Configuration Phase”, page 74).

●

If the pacemaker assumes a lead is not present (a high impedance unipolar pace is
detected) in one chamber of a dual chamber pacemaker, Implant Detection will restart.

5.2.3 How polarities are automatically configured

Atrial and ventricular lead polarities are configured independently in dual chamber bipolar
models, with the exception of pacemakers in the VDD Series, which have fixed bipolar atrial
sensing only.

Operating pacing and sensing polarities for bipolar pacemakers are configured
automatically in two phases during Implant Detection. (See Figure 42.) During these phases
the pacemaker continues to measure impedance as described above.

Reference Manual 73

Implant

Leads connected

Implant detection

Initial configuration

phase

Confirmation phase

Lead polarities

configured

Lead polarities

confirmed

30 minutes5 minutes

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 42. Automatic configuration of bipolar models

Initial Configuration Phase – The pacemaker sets lead polarities five minutes after lead

connection unless a high impedance unipolar pace has reset Implant Detection, a
prevalence of low impedance bipolar paces has set unipolar pacing, or if continuous sensing
has occurred.

The pacemaker sets initial polarities as follows:

●

The pacemaker delivers three asynchronous paces at magnet rate.

●

If at least two of the three paces are determined to be bipolar, the pacemaker remains set
to bipolar polarity (with backup unipolar paces) for the Confirmation Phase.

●

If at least two of the three paces are determined to be unipolar, the pacemaker sets
polarity to unipolar. Unipolar polarity becomes the operating polarity for pacing and
sensing, and no Confirmation Phase is required.

Note: If one of the asynchronous paces in a given chamber is a high impedance unipolar
pace, the pacemaker restarts Implant Detection in both chambers. Polarity configuration
restarts only in the affected chamber, however.

Confirmation Phase – Twenty-five minutes after initial configuration, the pacemaker
confirms final operating polarity for leads configured bipolar in the Initial Configuration
Phase. During this 25-minute Confirmation Phase, the pacemaker measures the lead for
high and low impedance paces. If 8 of 16 paces (or the programmed number of paces out of
sixteen) are out of range, the lead will automatically be reconfigured to unipolar polarity.

At the end of twenty-five minutes, operating polarity for leads detected as bipolar during the
Initial Configuration Phase is determined as follows:

74 Reference Manual

●

The pacemaker delivers three asynchronous paces at magnet rate.

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

●

If at least two of the three paces are determined to be bipolar, the pacemaker sets
operating polarity to bipolar (or Adaptive operation if Lead Monitor was programmed to
Adaptive prior to implant). See Section 5.3, “Lead Monitor”, page 76.

●

If at least two of the three paces are determined to be unipolar, the pacemaker sets
operating pace and sense polarities to unipolar.

Note: If a high impedance unipolar pace occurs in a given chamber at any time during
the 25-minute Confirmation Phase, the pacemaker restarts Implant Detection in both
chambers. Polarity configuration restarts only in the affected chamber, however.

Leads configured unipolar during the Initial Configuration Phase continue to operate in the
unipolar configuration. If bipolar polarity switches to unipolar during the Confirmation Phase,
the operating polarity remains unipolar with no additional confirmation through
asynchronous pacing.

Warning: If, at implant, the setscrews, both tip and ring, for a 3.2 mm connector pacemaker
are not properly engaged and all electrical contacts are not sealed, leakage between the tip
and ring contacts may occur. Such leakage may cause the pacemaker to falsely identify a
unipolar lead as bipolar, resulting in a loss of output. The same result could occur for all
bipolar models if the electrical contacts were not properly sealed when using lead extenders
or adaptors.

5.2.4 When automatic configuration is complete

Thirty minutes after lead connection, Implant Detection and automatic configuration are
complete. If, after this time period, the leads are detached and lead polarity type is changed,
automatic configuration and Implant Detection do not restart automatically at reinsertion.
The clinician must reprogram Implant Detection to On/Restart, which automatically resets
Lead Monitor to Configure.

The Lead Monitor feature (see Section 5.3, “Lead Monitor”, page 76) monitors and reports
on lead stability when Implant Detection and automatic configuration are complete. It is
automatically set by the pacemaker as follows:

●

Bipolar models are shipped with Lead Monitor set to Configure. However, after Implant
Detection ends, Lead Monitor is automatically set to Monitor Only for bipolar and
unipolar configurations.

●

Bipolar models with Lead Monitor programmed to Adaptive before implant are set to
Adaptive if polarity was determined to be bipolar. If polarity for these models was
determined to be unipolar, they are set to Monitor Only.

●

Unipolar models are shipped with Lead Monitor set to Monitor Only and continue to
operate at that setting both during and after Implant Detection.

Reference Manual 75

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

5.2.5 Manually setting polarities

To manually program atrial or ventricular lead polarities at implant, the clinician first must
“turn off” the Configure setting under Lead Monitor by choosing the Monitor Only setting
instead. Implant Detection still provides the 30-minute detection period, followed by
automatic feature and diagnostics activation, when the pacemaker is programmed
manually.

5.2.6 Programming interactions

●

Programming Implant Detection to Off /Complete before completion of the 30-minute
automatic polarity configuration period requires the clinician to manually program Lead
Monitor and polarities. The pacemaker’s automatic features are activated when Implant
Detection is turned off.

●

Manually programming Implant Detection to On/Restart restarts lead detection, polarity
configuration (Lead Monitor is set to Configure), and automatic feature activation.

●

Initiating a programming session at any time during Implant Detection causes Implant
Detection to be restarted.

●

If a dual chamber pacemaker is programmed to a single chamber mode, only one lead
is configured. If the mode is reprogrammed to a dual chamber mode, the clinician will
need to change the Lead Monitor from Configure to Monitor Only or Adaptive for the
unconfigured lead, and then program pace and sense polarity for it manually.

5.3 Lead Monitor

5.3.1 Overview

The Lead Monitor feature measures lead impedances during the life of the pacemaker.
When programmed to do so, Lead Monitor also enables the pacemaker to switch bipolar
pacing and sensing to unipolar when bipolar lead integrity is in doubt. It also controls
automatic configuration of lead polarities at implant. Lead Monitor is available in all pacing
modes.

Caution: If the Lead Monitor detects out-of-range lead impedance, investigate lead integrity
more thoroughly.

5.3.2 How lead monitoring works

The Lead Monitor feature monitors lead impedance of paced chambers, as defined by the
mode, by measuring the impedance of each pacing pulse to see if it falls within the
programmed impedance range for a stable lead.

76 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

The three programmable values under Atrial or Ventricular Lead Monitor are as follows:

●

Configure – provides automatic configuration of polarity (see Section 5.2.3, “How
polarities are automatically configured”, page 73).

●

Adaptive

– monitors bipolar paces for high impedance and provides unipolar backup paces

when high impedance is detected.

– switches pacing and sensing polarity from bipolar to unipolar when the pacemaker

detects a prevalence of high or low impedance paces (see Monitor Sensitivity
parameter in Table 4). The Lead Monitor setting changes to Monitor Only when
polarity switches.

– provides automatic polarity configuration when selected prior to implant.

●

Monitor Only – monitors either unipolar or bipolar paces to determine if they are out of
range but does not switch polarity when an out-of-range lead is indicated.

Lead Monitor is activated at lead connection, and it is automatically set to its operating value
of Monitor Only or Adaptive at the end of Implant Detection. See Section 5.2.4, “When
automatic configuration is complete”, page 75.

When Lead Monitor is set to Adaptive or Monitor Only and a lead is determined to be out of
range, the pacemaker issues a lead warning that appears on the programmer screen at the
next interrogation.

Lead Monitor programmable parameters – The programmable parameters for the Lead
Monitor feature are shown below.

Table 4. Programmable parameters for Lead Monitor

General Parameters Meaning

Atrial Lead Monitor Monitors lead impedance in the atrium; option to provide unipolar

backup paces and to switch from bipolar to unipolar polarity for an
out-of-range lead; provides automatic configuration of polarity at
implant.

Ventricular Lead Monitor Monitors lead impedance in the ventricle; option to provide unipolar

backup paces and to switch from bipolar to unipolar polarity for an
out-of-range lead; provides automatic configuration of polarity at
implant.

Notify If < (Less Than) Nonprogrammable minimum boundary for acceptable atrial and ven-

tricular bipolar lead impedance. Fixed at 200 Ω.

Notify If > (Greater Than) Maximum boundary for acceptable atrial and ventricular bipolar lead

impedance.

Monitor Sensitivity Number of high or low impedance paces out of 16 that define an

out-of-range lead on each channel.

Reference Manual 77

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Lead Monitor should not be programmed to Adaptive for patients with implantable
defibrillators. When a prevalence of out-of-range lead impedance paces is detected, the
monitor automatically reprograms the selected lead(s) to unipolar polarity. Pacing in the
unipolar configuration may cause the defibrillator either to provoke inappropriate therapy or
to withhold appropriate therapy.

5.4 Lead impedance data

Lead impedance data is recorded automatically.

5.4.1 Automatic Lead Impedance (Chronic Lead Trend)

The automatic Lead Impedance diagnostic data is based on measurements taken every
three hours for each chamber that is being paced. The maximum, average, and minimum
lead impedances are recorded every seven days for the most recent 14 months.

The following data is continuously updated:

●

Initial impedance (recorded at implant or when Chronic Lead Trend is cleared)

●

Lifetime minimum impedance (recorded since implant)

●

Lifetime maximum impedance (recorded since implant)

●

High impedance paces

●

Low impedance paces

If the maximum number of high impedance paces or low impedance paces is reached, that
value will remain until the data is cleared. All other diagnostic data collection will continue.

Note: To avoid high output pacing, Chronic Lead Trend data collection can be programmed
to Off. The outputs are increased to make lead impedance measurements every 3 hours.

5.4.2 Clearing Lead Impedance data

Automatic (Chronic) Lead Impedance Trend data is retained by the pacemaker unless you
use the Clear Data function on the programmer. Note that the data should be cleared only
when a lead is replaced. Be sure to save the session data or print the trend report before
ending the patient session.

5.4.3 For further information

Refer to the Adapta/Versa/Sensia/Relia Pacemaker Programming Guide for information
about collecting and displaying lead impedance trends.

78 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

5.5 Capture Management and diagnostic

5.5.1 Overview

When Capture Management is enabled, the pacemaker automatically monitors pacing
thresholds at periodic intervals. Once the threshold is determined, the pacemaker
determines a target output based on the programmable safety margin and programmable
minimum amplitude.

●

If programmed to Adaptive, the pacemaker reprograms outputs toward the target.

●

If programmed to Monitor Only, the pacemaker does not reprogram outputs.

Caution: Epicardial leads have not been determined appropriate for use with the Ventricular
Capture Management feature. Program Ventricular Capture Management to Off if implanting
an epicardial lead.

Note: The pacemaker enables Capture Management once Implant Detection is completed.

Note: In the event of partial or complete lead dislodgment, Capture Management may not

prevent loss-of-capture.

5.5.1.1 Ventricular Capture Management (VCM)

At programmable intervals, the pacemaker performs a ventricular pacing threshold search
to determine the ventricular threshold, which is the combination of minimum amplitude and
minimum pulse width that consistently results in capture of the ventricular myocardium.

5.5.1.2 Atrial Capture Management (ACM)

At programmable intervals, the pacemaker performs an atrial pacing threshold search to
determine the atrial amplitude threshold, which is the minimum amplitude that consistently
results in capture of the atrial myocardium.

5.5.1.3 Initiating the pacing threshold search

Scheduling the search – A pacing threshold search is initiated according to the schedule

programmed by the clinician. The Capture Test Frequency parameter under Capture
Management allows the clinician to schedule the search at fixed time intervals. The clinician
can also program the Day At Rest value that allows the pacemaker to determine when to run
the search.

Reference Manual 79

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

If a pacing threshold search is scheduled to occur once per Day At Rest, the pacemaker tries
to initiate the first pacing threshold search 12 hours after Implant Detection is complete. It
then runs subsequent searches at 24-hour intervals from the time of the last successfully
completed search.

If a search cannot be completed, the pacemaker retries after 30 minutes.

5.5.1.4 Programmable Capture Management parameters

Capture Management can be programmed to Adaptive, Monitor Only, or Off. When Capture
Management is programmed to Adaptive, the parameters in Table 5 are used to control
Capture Management operation. They can also be programmed for diagnostic use when
Capture Management is programmed to Monitor Only.

Table 5. Programmable parameters for Capture Management

General parameters Meaning

Amplitude Margin The safety margin applied to the pacing threshold search results for

Amplitude.
Minimum Adapted Amplitude The lower limit to which the operating Amplitude can be adapted.
Capture Test Frequency Determines how often the pacing threshold search will be initiated.
V. Acute Phase Days Remain-

ing

A. Acute Phase Days
Remaining

V. Sensing During Search The polarity used for ventricular sensing during ventricular pacing

Time in days during which output settings can be adapted both

upward and downward, but not below the permanently programmed

ventricular outputs.

Time in days during which output settings can be adapted both

upward and downward, but not below the permanently programmed

atrial outputs.

threshold searches. See page 86.

5.5.2 Ventricular Capture Management (VCM)

Checking for stable rhythm – Before a pacing threshold search can be initiated, the

pacemaker determines if the patient is pacing or sensing at a low rate. A low rate is desirable
during the pacing threshold search to reduce the risk of competition from forced pacing with

80 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

fast intrinsic rhythms. To make the determination, the pacemaker looks for intrinsic or
rate-related events indicating:

●

Out of 8 measured V-V intervals no more than 2 are faster than:

– 100 bpm if the upper sensor rate and upper tracking rate are ≥135 bpm

– 95 bpm if the upper sensor rate and upper tracking rate are ≥125 bpm

– 90 bpm if the upper sensor rate and upper tracking rate are <125 bpm

●

the sensor rate, checked at the end of the 8 intervals, is at or below the ADL rate.

●

in dual chamber modes, at least 1 valid AV interval (AS-VS, AS-VP, AP-VS, AP-VP)
occurred during the 8 measured intervals.

The pacemaker also looks for automatic feature interaction indicating:

●

Rate Drop Response is not in an intervention state.

●

Mode Switch is not changing between a tracking and a nontracking mode.

●

Battery measurements

●

Atrial Preference Pacing

●

Sleep function

If the stable rhythm check is successful, the pacing threshold search is initiated. If any of the
criteria for the stable rhythm check is not met, the pacemaker defers the pacing threshold
search until the next scheduled search period. See “Scheduling the search”, page 79.

5.5.3 The ventricular pacing threshold search

The pacemaker performs the pacing threshold search at a given Amplitude and Pulse Width
setting through a series of support cycles and test paces. Each series has three sets of
support cycles, with each set followed by a test pace and an automatic backup pace (see
Figure 43).

●

The support cycles are pacing cycles at the programmed Amplitude and Pulse Width
that may or may not include ventricular paced events. The pacing threshold search
begins with the support cycles.

●

A test pace follows each set of support cycles and is delivered at a test Amplitude or
Pulse Width. Amplitude and Pulse Width settings above the threshold cause capture of
the myocardium; settings below the threshold result in loss-of-capture.

●

A backup pace automatically follows each test pace regardless of capture or
loss-of-capture for that pace. It is delivered 110 ms after the test pace at the programmed
Amplitude and a 1.0 ms Pulse Width setting.

Reference Manual 81

S S S T

B

S S S T

B

S S S T

B

S = Support cycles
T = Test Paces
B = Backup Paces

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 43. Pacing threshold search

The pacemaker may use one to three of the test paces in a series to determine if a particular
Amplitude or Pulse Width is above or below the patient’s stimulation threshold.

●

When the first of the three test paces indicates capture (CAP), or the last two test paces
indicate capture following loss-of-capture (LOC) on the first pace, the series is
determined to be above the threshold. See Table 6.

●

When two of the three test paces indicate loss-of-capture, the series is determined to be
below the threshold. See Table 6.

Table 6. Above/below threshold determination

Series of 3 test paces Results

a

CAP

Above threshold
LOCb, CAP, CAP Above threshold
LOC, LOC Below threshold
LOC, CAP, LOC Below threshold

a

CAP = capture

b

LOC = loss-of-capture

Not all test paces qualify for use in the determination series. If a test pace meets abort criteria
(see page 86), the pace is ignored, the Amplitude and Pulse Width remain the same, and
the next test pace is used in the determination series instead. For example, if a ventricular
intrinsic sense inhibits the test pace during the test cycle, that intended pace will be ignored
and not evaluated for capture.

If a support pace meets abort criteria, e.g., a ventricular safety pace occurs on a support
pace, the pace is counted in the support/test cycle, but causes the next test pace to be
ignored. The test pace following the ignored test pace remains at the Amplitude and Pulse
Width and is used in the determination series.

Modifying Amplitude and Pulse Width during the search – When modifying first
Amplitude and then Pulse Width during the pacing threshold search, the pacemaker is

82 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

looking for two points that lie on the strength duration curve. These points define the
boundary between settings that capture the myocardium and those that do not.

Amplitude modification operates as follows:

1. The test Amplitude is set at the last Amplitude result from the previous pacing threshold
search or at 0.75 V if no previous search has been done. Pulse Width is set at 0.4 ms.

2. The pacemaker initiates a series of support cycles and test paces to determine whether
the Amplitude setting is above or below the patient’s stimulation threshold.

3. If the test Amplitude is above the patient’s threshold, the pacemaker will reduce it by one
setting and repeat the test series. The process of reducing the Amplitude setting and
retesting continues until a point below the patient’s threshold is found, indicating
loss-of-capture.

4. The pacemaker then increments and retests the Amplitude one setting at a time until
the setting is above the patient’s stimulation threshold for three consecutive test series,
indicating capture is recovered. The setting at which capture is recovered is called the
amplitude threshold.

Pulse Width modification operates as follows:

1. The test Pulse Width is set at the last Pulse Width setting from the previous search or
at 0.21 ms if no previous search has been done. Amplitude is set at two times the
amplitude threshold determined during the Amplitude search. The upper Pulse Width
limit for the test pulse is 0.4 ms.

2. The pacemaker performs the actions detailed in Step 2 through Step 4 for Amplitude
modification above, but for Pulse Width. The Pulse Width setting that is in operation
when capture is recovered at two times the amplitude threshold is designated the pulse
width threshold.

If the clinician uses the in-office Capture Management test, the programmer uses the
amplitude threshold and pulse width threshold to construct a strength duration curve. (See
Figure 44).

Reference Manual 83

Amplitude (V)

1.00.4

13

2

4

3

1

2

4

Loss-of-capture

Starting Amplitude

Amplitude reduced by one setting (2)

Amplitude threshold (4)

Pulse Width reduced by one setting (2)

Pulse Width threshold (4)

Starting Pulse Width (at 2 times the amplitude threshold)

Loss-of-capture

Pulse width (ms)

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 44. Modifying Amplitude and Pulse Width

Pacing therapy during the search – During a pacing threshold search, the pacemaker

must provide ventricular test paces (which may affect normal pacing operation). To ensure
ventricular pacing, if necessary, the pacemaker may adapt timing in both tracking and
nontracking modes.

Note: If an MVP mode is programmed (AAIR<=>DDDR or AAI<=>DDD), Capture
Management sets the pacing mode to DDDR or DDD and suspends MVP mode changes for
the duration of the pacing threshold search.

When operating in tracking modes:

●

The pacemaker shortens the AV interval for each support cycle and test pace based on
calculations using the shortest AV interval measured during the stable rhythm check.

●

The test pace is always followed by a backup pace after 110 ms.

●

PVARP is fixed at 350 ms for support cycles, but PVARP, PVAB, and the ventricular
refractory period are timed from the backup pace on test paces.

●

Ventricular Safety Pacing is disabled on test pace cycles.

84 Reference Manual

110 ms

Atrial pace

Support AV Support AV Support AV (-)15 ms

Support pace Support pace

Atrial pace

Test pace

Atrial pace

Backup pace

110 ms

Support pace

Test pace

Backup pace

Support pace

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 45. Rate modulation in DDD/tracking modes

When operating in nontracking modes:

●

The lower rate is not changed on support cycles.

●

The lower rate on test paces is set to the fastest V-V interval seen on any support cycle
or seen during the stable rhythm check plus 15 bpm or minus 150 ms, whichever results
in a faster rate.

Figure 46. Rate modulation in nontracking modes

Because the pacing threshold search operates as the highest priority feature in control of
pacing cycle parameters, the following pacing features are disabled during the search:

●

Sensing Assurance

●

Rate Drop Response detection

●

AV modulation (Search AV+, Rate Adaptive AV)

●

NCAP operation

●

Lead Monitor

●

Auto PVARP and sensor-varied PVARP operations

●

Ventricular Safety Pacing on test paces

●

Atrial Preference Pacing

●

Sinus Preference

Reference Manual 85

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

When the pacing threshold search aborts – Sometimes the pacing threshold search
cannot be performed as scheduled. The pacemaker ensures that false events will not
influence the determination of capture and loss-of-capture during the search by aborting the
search immediately when the following occur:

●

The sensor rate is greater than the ADL rate.

●

Mode Switch occurs.

The pacemaker allows the following to occur several times before aborting the search:

●

Upper tracking rate extension on a test pace.

●

Nonrefractory ventricular senses in a tracking mode.

●

V-V rate greater than 90 to 100 bpm on support cycles, depending on the value of the
upper sensor rate and upper tracking rate (see “Checking for stable rhythm”, page 80).

●

Ventricular Safety Pacing during the support cycles.

●

Consecutive ventricular refractory events.

Other conditions can also cause the pacing threshold search to abort:

●

Pacemaker RRT/ERI or low battery is detected.

●

Noise reversion is detected.

●

Initiation of a programming or transtelephonic session.

●

Capture is not determined during the entire search, indicating possible high thresholds.

●

Loss-of-capture does not occur during the entire search, indicating a possible lead
problem or undetected intrinsic events.

When a pacing threshold search cannot be completed, the pacemaker will automatically
initiate another search within 30 minutes (or within 15 minutes, if the Capture Test Frequency
parameter is programmed for every 15 minutes). See “Scheduling the search”, page 79. If
four search attempts abort during one test period, however, the pacing threshold test is
suspended until the next test period.

When the pacing threshold search aborts, a message indicating why the search could not be
performed is stored in the Capture Management Detail diagnostic (if enabled).

Preventing undersensing of ventricular evoked response events during the search –

To minimize the likelihood of undersensing of ventricular evoked response events during a
pacing threshold search, the clinician can program the V. Sensing During Search parameter
to Adaptive, if the Ventricular Sense Polarity parameter is set to Bipolar. Then, when an
out-of-range measurement (see Figure 48) occurs, the pacing threshold search will be
automatically repeated, using the Unipolar sensing setting.

86 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

If the second search is successful, the out-of-range measurement is ignored. If the second
search results in another out-of-range measurement, outputs will remain at 5 V and 1 ms.

If the V. Sensing During Search parameter is set to Bipolar or Unipolar, ventricular sensing
during the pacing threshold search will be done at that setting.

5.5.3.1 Automatic ventricular output adaptation

Capture Management can be programmed (Adaptive setting) to provide automatic
adaptation of ventricular Amplitude and Pulse Width based on pacing threshold search
results. Following each search, the pacemaker creates a target output by applying a
programmable safety margin (Amplitude Margin parameter) to the amplitude threshold
determined during the search. The pacemaker’s calculation for the target is always rounded
up to the next programmable setting. The pacemaker then adapts outputs toward this target.

Adaptation can take place only within an output range that is defined by a programmable
lower limit (Minimum Adapted Amplitude parameter) and the upper threshold limit of 5.0 V
and 1.0 ms. The minimum pulse width for ventricular capture management is 0.4 ms.

●

Amplitude is adapted only when a pacing threshold search is successful; otherwise, it
remains as programmed.

●

If the operating Amplitude is below the target, it is immediately adapted to the target.
(See Figure 47.)

Reference Manual 87

P= Pulse width (ms)

A=Amplitude (V)

Output Range

2

1

.2 .4 .6 .8 1.0

3

5

4

P

A

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 47. Adapting outputs upward to the target

1 Target (when 2.0X margins applied)
2 Operating Amplitude and Pulse Width
3 The bottom line indicates the Programmed Minimum Adapted Amplitude

●

If the operating Amplitude is above the target, the pacemaker adapts the Amplitude
downward one programmable setting per successful pacing threshold search. If the
target is below the programmed minimum output limit, the adaptation stops at the
minimum limit.

●

A High Threshold Condition warning is issued if the amplitude threshold is greater than

2.5 V. The pacemaker responds by adapting to an Amplitude of 5.0 V and Pulse Width
of 1.0 ms.

●

If the amplitude threshold multiplied by the safety margin indicates an amplitude target
greater than 5.0 V, the pacemaker responds by adapting to the highest possible Capture
Management settings, an Amplitude of 5.0 V and Pulse Width of 1.0 ms. (See
Figure 48.)

88 Reference Manual

1.2

2

1

.2 .4 .6 .8 1.0

3

5

4

6

Amplitude (V)

Pulse width (ms)

Output Range

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 48. Limiting high thresholds

1 Target (when 3X margin applied)
2 Output adapted to 5.0 V, 1.0 ms limit
3 Operating Amplitude and Pulse Width

5.5.3.2 Considerations when programming parameters

In a small percentage of patients, the following conditions can influence thresholds
measured by Capture Management and can lead to possible symptoms:

Lead fixation – With poor lead fixation, modulations in pacing timing and rate can influence
thresholds.

Reference Manual 89

4 Amplitude threshold
5 The bottom line indicates the Programmed

Minimum Adapted Amplitude

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Intrinsic event rejection – In rare instances, combinations of morphology and rhythm may
result in a low threshold measurement. This may occur if the pacing threshold search is
unable to differentiate between myocardial contractions caused by the pacing pulse and
those caused by physiologic means.

Evoked response detection – In rare instances, the pacemaker may not detect the
electronic waveform created by the contracting myocardium immediately following a pacing
pulse. In such instances, a high threshold measurement may result. See page 86

The Capture Management Threshold Test and manual threshold measurements provide
data that can help in programming the parameters that control outputs (see Section 5.5.1.4,
“Programmable Capture Management parameters”, page 80).

5.5.3.3 Programming interactions

Warning: Capture Management will not program ventricular outputs above 5.0 V or 1.0 ms.

If the patient needs a pacing output higher than 5.0 V or 1.0 ms, program Amplitude and
Pulse Width manually.

The pacemaker must be programmed to a mode that permits pacing and sensing in the
ventricle (but not VVT mode) in order to use the Ventricular Capture Management feature.

5.5.4 Atrial Capture Management (ACM)

Checking for stable rhythm – Before a pacing threshold search can be initiated, the

pacemaker determines if the patient is pacing or sensing at a low rate. A low rate is desirable
during the pacing threshold search to reduce the risk of competition from forced pacing with
fast intrinsic rhythms. A Pacing Threshold Search (PTS) is performed when a stable atrial
rhythm is observed for eight pacing cycles and the sensor rate is less than the ADL rate.

●

ACM does not operate during Mode Switch episodes.

●

ACM operates in DDDR and DDD modes.

●

The sensed atrial rate must not be faster than 87 bpm.

●

The paced atrial rate must be slower than 90 bpm.

7

If the device is programmed to an MVP mode (AAIR<=>DDDR or AAI<=>DDD), the pacemaker changes the
mode to DDDR or DDD during ACM operations.

90 Reference Manual

7

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

5.5.4.1 The atrial pacing threshold search

Conducting the search – The pacemaker performs the pacing threshold search through a

series of support cycles followed by a test pace applied at a slightly faster rate.

●

Beginning at one setting below the last measured value (or at 0.75 V if no previous
search has been done), the amplitude is reduced in one setting decrements at 0.4 ms
pulse width until loss-of-capture is detected. When two of the three test paces indicate
loss-of-capture, the series is determined to be below the threshold.

●

The pacemaker then increments and retests the amplitude one setting at a time until the
setting is above the patient’s stimulation threshold for three consecutive test series,
indicating capture is recovered. The setting at which capture is recovered is called the
amplitude threshold. The threshold criteria are shown in Table 7.

Table 7. Above/below threshold determination for a single test series

Series of up to 3 test paces Results

CAP, CAP
LOCb, CAP, CAP Above threshold
LOC, LOC Below threshold
CAP, LOC, CAP Above threshold
LOC, CAP, LOC Below threshold

a

CAP = capture

b

LOC = loss-of-capture

a

Above threshold

Not all test paces qualify for use in the determination series. If sensed events surrounding the
test pace meet abort criteria, the pace is ignored, the Amplitude remains the same, and the
next test pace is used in the determination series instead. If a support cycle meets abort
criteria, the previous set of support cycles is discarded, and a new set of support cycles is
started.

Atrial Capture Management (ACM) observes the timing of sensed P and R waves (not
evoked response) to evaluate capture.

ACM automatically selects one of two methods for evaluating atrial capture, based on the
patient’s rhythm at the time of the PTS. If the patient has a stable sinus rhythm, the device
selects the Atrial Chamber Reset (ACR) method. Otherwise, the device selects the AV
Conduction (AVC) method.

Reference Manual 91

AS

VP

VP VP VP VP VP VP

VP VP VPVS or VP VP

AS

AS

AS

AS AP

AP

ARAS

AS

AS

AS

AS

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

5.5.4.2 Atrial Chamber Reset (ACR) Method

Atrial Chamber Reset runs during stable sinus rhythm. It evaluates capture by observing the
response of the intrinsic rhythm to the atrial test pace. If the test pace does not capture, the
sinus node is not reset, and an atrial refractory sensed event (AR) is observed after the test
pace. If no AR is observed within the AV interval, ACR concludes that the test pace captured
the myocardium. (See Figure 49.)

Figure 49. Atrial Chamber Reset test method

1 test
2 CAP

3 LOC

5.5.4.3 Atrial-Ventricular Conduction (AVC) Method

Atrial-Ventricular Conduction method runs when stable 1:1 AV conduction is observed with
atrial pacing. The atrial pacing rate is increased by 15 bpm (but no faster than 101 bpm) and
the AV interval is lengthened to try to achieve a stable AP-VS rhythm.

AVC evaluates capture by observing the conducted ventricular response to the atrial test
pace. Each atrial test pace is followed by a backup pace at programmed amplitude and a

1.0 ms pulse width to maintain rhythm stability during the test. If a conducted VS event is
observed at approximately the expected AP-VS interval following the atrial test pace, AVC
concludes that the test pace captured the myocardium. (See Figure 50.)

92 Reference Manual

70 ms

AP AP

VS VS

VP

AP-VS

Scheduled

VP

Overdrive rate interval Overdrive rate interval -

prematurity

Last support AP-VS interval

85 ms

Capture

Loss of Capture

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 50. Atrial-Ventricular Conduction test method

1 Test AP
2 Backup AP

5.5.4.4 Pacing therapy during the search

Because the pacing threshold search operates as the highest priority feature in control of
pacing cycle parameters, the following pacing features are disabled during the search:

●

Sensing Assurance

●

Rate Drop Response detection

●

AV modulation (Search AV+, Rate Adaptive AV)

●

Blanked Flutter Search

●

Lead Monitor

●

Lower rate modulation (APP, Sinus Preference, Conducted AF Response)

Reference Manual 93

3 (Expected VS from Test AP)
4 (Expected VS from Backup AP)

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Note: If an MVP mode is programmed (AAIR<=>DDDR or AAI<=>DDD), the capture
management sets the pacing mode to DDDR or DDD and suspends MVP mode changes for
the duration of the pacing threshold search.

When the pacing threshold search aborts – Sometimes the pacing threshold search
cannot be performed as scheduled. The pacemaker ensures that false events do not
influence the determination of capture and loss-of-capture during the search by aborting the
search immediately when the following occur:

●

Fast atrial rate (>87 bpm with ACR, >100 bpm with AVC)

●

Ventricular pacing (AVC)

●

Undesirable cardiac events (PVCs, PACs)

●

Mode Switch occurs.

The pacemaker allows the following to occur several times before aborting the search:

●

fast or variable intrinsic rate or ectopic events

●

slow intrinsic rate8 and a lack of AV conduction

●

Variable AV conduction time

●

Unexpected sensed events before or after the test pace

●

Ventricular Safety Pacing

Other conditions can also cause the pacing threshold search to abort:

●

Pacemaker RRT/ERI or low battery is detected.

●

Initiation of a programming or transtelephonic session occurs.

●

Capture is not determined during the entire search, indicating possible high thresholds.

●

Loss-of-capture does not occur during the entire search, indicating undetected intrinsic
events.

5.5.4.5 Automatic atrial threshold adaptation

Capture Management can be programmed (Adaptive setting) to provide automatic
adaptation of atrial amplitude based on pacing threshold search results.

8

Turning the Sleep Function to On may allow ACM to run with slower intrinsic rates.

94 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

The pacemaker applies the programmable amplitude safety margin to the amplitude
threshold value measured at a 0.4 ms pulse width to determine the target amplitude. If the
operating amplitude is above the target, the pacemaker adapts the amplitude down toward
the target in one-step decrements. If the operating amplitude is below the target, the
amplitude is immediately adapted to the target.

●

Outputs are not adapted below the programmable minimum amplitude. During the
programmable Acute Phase following implant detection, outputs are not adapted below
the programmed outputs or the default shipping settings (3.5 V, 0.4 ms).

●

A High Threshold Warning is issued if the amplitude threshold is greater than 2.5 V. The
pacemaker responds by adapting to an Amplitude of 5.0 V and Pulse Width of 1.0 ms.

●

A High Threshold warning is issued if the target amplitude is greater than 5.0 V and
outputs are adapted to 5.0 V and 1.0 ms (See Figure 51).

Reference Manual 95

1.2

2

1

.2 .4 .6 .8 1.0

3

5

4

6

Amplitude (V)

Pulse width (ms)

Output Range

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 51. Limiting high atrial thresholds

1 Target (when 3X margin applied)
2 Output adapted to 5.0 V, 1.0 ms limit
3 Operating Amplitude and Pulse Width

5.5.4.6 Programming interactions

Warning: Capture Management will not program atrial outputs above 5.0 V or 1.0 ms. If the

patient needs a pacing output higher than 5.0 V or 1.0 ms, program Amplitude and Pulse
Width manually.

96 Reference Manual

4 Amplitude Threshold
5 The bottom line indicates the Programmed

Minimum Adapted Amplitude

0

1

2

3

4

5

11/16 12/16 01/15 02/14 03/16 04/15 05/15 06/14

Average to max. threshold

Amplitude (V @ 0.4ms)

Date (Month/Day)

Monitor only "What if"

Max. adapted

Threshold > 2.5V

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

The pacemaker must be programmed to DDDR, DDD, AAIR<=>DDDR, or AAI<=>DDD
mode in order to use the Atrial Capture Management feature.

5.5.5 Recording Capture Management data

Programming Capture Management also initiates automatic data collection. In addition, you
may collect detailed information about every Capture Management search.

5.5.5.1 Summary Capture Management data

The automatic Capture Management trend records pacing threshold history. Every 7 days,
the pacemaker collects the following Capture Management data automatically for 14
months:

●

Maximum Threshold

●

Average Threshold

●

Maximum Amplitude

●

Type of Capture Management search (Adaptive or Monitor Only)

Figure 52 shows a typical summary Capture Management trend.

Figure 52. Summary Capture Management data

Reference Manual 97

0

1

2

3

4

5

09/04/0308/03/03

Amplitude (V)

Date

Threshold

Monitor only "What if"

Adapted

Aborted search

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

5.5.5.2 Detail Capture Management data

Capture Management Detail data provides a record of the pacing threshold, pulse width, and
amplitude in the selected chamber. For the most recent 668 ventricular or 359 atrial Capture
Management searches, the pacemaker records the following information for the selected
chamber:

●

Date and Time

●

Threshold Amplitude

●

Threshold Pulse Width (VCM only)

●

Method of Search (ACM only)

●

Adapted or Monitor Only (suggested) Amplitude (with programmed margin applied)

●

Adapted or Monitor Only (suggested) Ventricular Pulse Width

A beat-to-beat trend for the most recent Capture Management search is available.
Recording stops if more than 1000 events occur during the search. Clinicians have the option
to record an EGM (atrial, ventricular, or summed EGM). Figure 53 shows an example of a
detailed Capture Management trend.

Figure 53. Detail Capture Management trend

The data collected can be displayed or printed from the Data icon.

5.5.5.3 Clearing Capture Management data

Automatic Capture Management Trend data can be cleared from the Clear Data screen by
selecting the option to clear lead impedance trend data for the respective chamber.
However, the clinician-selected Capture Management Detail data is cleared automatically
one hour after the end of a programming session.

98 Reference Manual

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Also, you can select the option to clear data immediately. Be sure to save the session data
or print the report before ending the patient session.

5.5.5.4 For further information

Refer to the Adapta/Versa/Sensia/Relia Pacemaker Programming Guide for information
about collecting and displaying Capture Management data.

5.6 Sensing Assurance and diagnostic

5.6.1 Overview

The Sensing Assurance feature automatically adjusts atrial and ventricular sensitivities
within defined limits. At the completion of Implant Detection, the pacemaker enables
Sensing Assurance and begins monitoring the peak amplitude of sensed signals. In
response to monitoring, the pacemaker automatically increases or decreases Sensitivity to
maintain an adequate sensing margin with respect to the patient’s sensed P and R waves.

5.6.2 Monitoring sensitivity thresholds

The pacemaker monitors each nonrefractory sensed event (AS or VS) by measuring the ratio
of the peak amplitude of the P or R wave to the Sensitivity setting. The pacemaker then
compares the measured sensing margin to a target sensing margin.

Sensing Assurance provides the following target sensing margins:

●

Atrial bipolar sensing: 4:1 ratio to 5.6:1 ratio

●

Atrial unipolar sensing: 2.8:1 ratio to 4:1 ratio

●

Ventricular (unipolar or bipolar) sensing: 2.8:1 ratio to 4:1 ratio

Reference Manual 99

2.8 mV

4 mV

1 mV

Atrial Unipolar Sensing

Medtronic ADAPTA® / VERSA® / SENSIA® / RELIA™

Figure 54. Maintaining a sensing margin of 3:1

1 Target sensing margin
2 Sensitivity setting

5.6.3 Qualifying sensed events

When monitoring nonrefractory sensed events, the pacemaker checks each event to see if
it qualifies for use in determining Sensitivity threshold adjustments. Events are disqualified
when:

●

The pacemaker is monitoring a high level of continuous interference

●

A second event occurs in either chamber within 40 ms after a sensed event

5.6.4 Adjusting sensing thresholds

To adjust sensing thresholds, the pacemaker keeps a record of many sensed events.
Non-PVC, nonrefractory senses that fall below the target sensing margin (low events) are
assigned a negative value, and those that are above the target sensing margin (high events)
are assigned a positive value. When the accumulated value of the events exceeds the upper
or lower limits of a counter, the pacemaker will adjust the sensitivity by one setting:

●

Many low events indicate an adjustment of one setting to a more sensitive (smaller
numerical) setting.

●

Many high events indicate an adjustment of one setting to a less sensitive (larger
numerical) setting.

At least 17 low events are required to cause an adjustment to the next more sensitive setting,
and 36 high events are required to cause an adjustment to the next less sensitive setting.

Adjustments occur more gradually if a mixture of low and high events are occurring or if
paced events are intermingled with sensed events. If fewer than 60% of events are high (or
low), or if the pace to sense ratio is greater than 5:1, no sensitivity adjustment is made.

100 Reference Manual