Dwight Reynolds MD

1
Pacemaker Diagnostics

• Dwight Reynolds MD
• University of Oklahoma
• Health Sciences Center

2
Pacemaker Diagnostics

• The Goals of Diagnostics
• More and better information
• Faster follow-up
• Less face-to-face follow-up

3
Pacemaker Diagnostics

• Device Information
• Device-Patient Interface Information
• Patient Information

(A discussion based on currently available
technology)
4
Pacemaker Diagnostics

• Device Information
• Device Identification / Implant Date
• Program Settings
• Device Longevity Estimate
• Lead Monitoring

5
Pacemaker DiagnosticsDevice Identification and
Implant Date

• This data can be very important, especially in
  patients who are not geographically stable and
  who are not maintained in consistent follow-up

6
Pacemaker DiagnosticsProgram Settings

• This data can be viewed in this format or in more
  detail on another screen

7
Pacemaker DiagnosticsDevice Longevity Estimate

• Device longevity estimate appears on this initial
  interrogation and on another screen
• Based on remaining battery voltage / battery
  impedance and percent pacing

8
Pacemaker DiagnosticsDevice Longevity Estimate

• The Elective Replacement Indicator warning
  automatically appears in the Significant Events
  window on this screen

The remaining longevity estimate is also on this
screen
9
Pacemaker DiagnosticsLead Monitoring

• Automatically included on this initial
  interrogation report

Measured Data includes Lead Impedances Lead
Status
10
Pacemaker DiagnosticsLead Monitoring

• Chronic lead impedance trends can be accessed via
  links on the Quick Look screen

Automatic Lifetime Lead Impedance Trends
11
Pacemaker DiagnosticsLead Monitoring

• The Chronic Lead Monitor and Polarity Switch can
  automatically reprogram the pacemaker to unipolar
  if out of range impedance(s) are detected - A and
  V leads

• Polarity switch noted on
• Initial Interrogation lead status
• Chronic lead impedance trend
• Switch is date and time stamped

12
Pacemaker Diagnostics

• Device-Patient Interface Information
• Atrial/Ventricular Sensing/Pacing time
• Sensing Thresholds
• Pacing Thresholds
• Mode Switching s and time

13
Pacemaker Diagnostics Atrial/Ventricular
Sensing/Pacing Time

• This important information is part of the
  initial interrogation information and appears on
  the Quick Look screen

14
Pacemaker Diagnostics Sensing Thresholds

• While sensing can be evaluated at the time of
  follow-up, some current devices can do this
  automatically and adapt automatically
• Measure intrinsic P and R wave
• Adapt sensitivity based on target safety margins
• Designed to automatically provide safe sensing
  margins
• Designed to increase the sensitivity of Mode
  Switch detection

15
Pacemaker Diagnostics Sensing Thresholds

• Safety Margins

Safety Margins
Chamber and Sensing Polarity
4.0-5.6 times programmed value
Atrial Bipolar
2.8-4.0 times programmed value
Atrial Unipolar Ventricular Unipolar/Bipolar
16
Pacemaker Diagnostics Sensing Thresholds

• Diagnostic Information
• P and R-Wave amplitudes
• Atrial and Ventricular sensitivity
• Data recorded every 7 days (can be set to as
  often as every 2 hours)

17
Pacemaker DiagnosticsRole of Pacing Thresholds
in Maximizing Longevity
Example of one devices longevity estimates at
different output settings
18
Pacemaker DiagnosticsPacing Thresholds

• While we can measure thresholds manually at
  the time of follow-up and adjust outputs, some
  devices can do this automatically and provide
  diagnostic information
• Automatically measure ventricular thresholds
• Automatically reprogram ventricular outputs using
  an appropriate safety margin
• Optimize device longevity
• Use with a wide variety of leads
• Provide diagnostics to verify performance

19
Pacemaker DiagnosticsPacing Thresholds -
Automatic

• Automated threshold measurements rely on sensing
  the evoked response to the pacing pulse
• The characteristics of this sensed response is
  how the pacemaker determines if the pulse has
  captured the myocardium
• Evoked response sensing can be affected by
• Lead tissue interface (acute vs. chronic lead)
• Lead Polarization
• Tip-to-Ring spacing
• Lead tip design
• Other factors

20
Pacemaker DiagnosticsPacing Thresholds -
Automatic

• Pacing Threshold Search
• Amplitude threshold determined at 0.4 ms pulse
  width
• Threshold voltage reported at 0.4 ms pulse width
• Minimum programmable pulse width 0.4 ms
• Acute period
• Thresholds tested, outputs may remain unchanged
  or increased
• Chronic period
• Outputs may increase, remain unchanged or decrease

21
Pacemaker DiagnosticsPacing Thresholds -
Automatic
1.50 V
2 X Amplitude Threshold
1.25 V
1.0 V
0.75 V
Amplitude Threshold
0.5 V
LOC
0.4ms
1.0 ms
Establishing Amplitude Threshold
22
Pacemaker DiagnosticsPacing Thresholds -
Automatic
Loss of capture
1.50 V
2X Amplitude Threshold
Pulse Width Threshold
1.25 V
1.0 V
0.75 V
0.5 V
1.0 ms
0.4ms
0.21 ms
0.12 ms
Pulse Width Threshold Search
23
Pacemaker DiagnosticsPacing Thresholds -
Automatic
Pulse Width Threshold
1.50 V
2X Amplitude Threshold
1.25 V
1.0 V
0.75 V
0.5 V
1.0 ms
0.4ms
0.21 ms
0.12 ms
Drawing the Threshold Curve
24
Pacemaker DiagnosticsPacing Thresholds -
Automatic
Recommended amplitude with a 2.0V minimum output
selected
2X Amplitude Safety Margin Curve
25
Pacemaker DiagnosticsPacing Thresholds -
Automatic

• Designed to enhance capture management
  performance with a wider variety of leads
• If pacing threshold search results in an
  amplitude threshold of gt 2.5 V
• Ventricular sensing polarity changes (only for
  the duration of the test, pacing
  polarity unaffected)
• The pacing threshold search is repeated
• If threshold is acceptable, all subsequent PTS
  repeated in this polarity
• May improve evoked response sensing by increasing
  the tip- to-ring spacing for the test (for
  example Bipolar to Unipolar)
• Designed to further increase the reliability of
  Capture Management

26
Pacemaker DiagnosticsPacing Thresholds -
Automatic

• Select V.Sensing During Search
• Select
• Adaptive (N)
• Bipolar or Unipolar permanently programs the
  sensing polarity for the pacing threshold search
  only

27
Pacemaker DiagnosticsPacing Thresholds -
Automatic

• Simple to program-choose only the amplitude
  safety margin and minimum amplitude
• Minimum adapted pulse width 0.4ms
• Choose when to do the test

28
Pacemaker DiagnosticsPacing Thresholds -
Automatic

• Capture Management Trend
• Lifetime trend data
• Data reported every 30 days (can be as often as
  every search - maximum 668)
• EGM of last search

29
Pacemaker DiagnosticsMode Switching - Automatic

• Mode Switching Goals
• Accurate detection of SVTs
• Fast switching to a non-P wave tracking mode
  designed to avoid symptoms

30
Pacemaker Diagnostics

• Patient Information
• Demographics
• Sensor Information
• AV Conduction Information
• Arrhythmia Information

31
Pacemaker DiagnosticsArrhythmia Monitoring

• Continuous monitoring and diagnostics
• Automatically accessed with initial interrogation

32
Pacemaker DiagnosticsArrhythmia Monitoring

• What types of arrhythmias are present?

Arrhythmia Log
Up to 48 seconds of EGM collection triggered by
either atrial or ventricular high rates
33
Pacemaker DiagnosticsArrhythmia Monitoring

• What types of arrhythmias are present?

EGMs
Triggered by Atrial and/or Ventricular high
rates Duration delay to specify episode
persistence before an EGM is collected
Episode Duration(seconds)
TriggerAlignment
Number of Episodes
Rolling
Frozen
1 2 4 8
24 16 8 4
Up to 48 seconds of EGMs triggered by either AHR
or VHR episodes Marker/Interval data on 40 pre,
20 post detection, and 10 termination events, for
16 episodes per trigger
48 24 12 6
All Pre orHalf Half
1 2 4 8
48 24 12 6
48 24 12 6
All Post
34
Pacemaker DiagnosticsArrhythmia Monitoring

• What is the atrial arrhythmia burden?

Arrhythmia Trend-Cardiac Compass
A 6-month rolling trend providing hours/day
patient is in atrial arrhythmia
35
Pacemaker DiagnosticsArrhythmia Monitoring

• What is the ventricular rate during atrial
  arrhythmias?

Episode Log
Provides the Maximum atrial and ventricular,
average ventricular, and sensor rates during
arrhythmias
36
Pacemaker DiagnosticsArrhythmia Monitoring

• What is the ventricular rate during atrial
  arrhythmias?

Ventricular Rate during Atrial Arrhythmia
Histogram
Information on ventricular response to SVTs,
Divided into Paced and Sensed Events
37
Pacemaker DiagnosticsArrhythmia Monitoring

• What is the frequency/duration of the arrhythmia?

Episode Log
Displays time in atrial high rates, average
hours/day and episode durations
38
Pacemaker DiagnosticsArrhythmia Monitoring

• What is the frequency/duration of the arrhythmia?

Atrial Arrhythmia Durations
Atrial Arrhythmia Trend Cardiac
Compass