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Brady Pacing in the ICD. Bradycardia pacing is part of ICD therapyWhen clinicians talk about single-chamber or dual-chamber ICDs, they're actually talking about the brady component of the deviceICDs today incorporate full-featured bradycardia pacemakersICD patients may require up to three differe
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1. The Electrical Management of Cardiac Rhythm DisordersTachycardiaBrady Therapy The Electrical Management of Cardiac Rhythm Disorders, Tachycardia, Slide Presentation 12 Brady TherapyThe Electrical Management of Cardiac Rhythm Disorders, Tachycardia, Slide Presentation 12 Brady Therapy
2. Brady Pacing in the ICD Bradycardia pacing is part of ICD therapy
When clinicians talk about single-chamber or dual-chamber ICDs, they’re actually talking about the brady component of the device
ICDs today incorporate full-featured bradycardia pacemakers
ICD patients may require up to three different kinds of brady therapy
Brady therapy outside of a tachy episode (conventional pacing)
Brady therapy during a tachy episode (episodal pacing)
Brady therapy after a tachy episode, especially after therapy delivery (post-shock pacing)
3. Programming Pacing Parameters
4. Conventional Pacing Parameters Mode and basic timing parameters
Mode
Rate
AV delays
Pacing output settings
Pulse amplitude
Pulse width
Refractory periods
Rate-responsive parameters
Extended parameters
AMS
PMT and PVC options
5. Mode Programming Considerations Permanent mode should be most appropriate for patient’s condition and pacing prescription
Asynchronous modes (DOO, VOO) are not recommended
Most ICDs will not allow more than temporary programming to such modes
No sensing
Can provoke ventricular tachyarrhythmias
If patients has high-rate intrinsic atrial activity
Program to a non-tracking mode (DDI, DDIR, VVI, VVIR)
Program AMS on
Use AF Suppression™ algorithm, if appropriate
6. Basic Rate and Maximum Tracking Rate Defines how many pulses per minute the device will pace in the absence of intrinsic activity
If the device allows for atrial tracking (DDD, DDDR mode), it will try to pace the ventricle to keep up with the intrinsic atrial rate, even if the intrinsic atrial rate exceeds the basic rate
Atrial tracking was designed to encourage 1:1 AV synchrony
Atrial tracking may cause high-rate ventricular pacing
The Maximum Tracking Rate (MTR) sets the limit as to how fast the ventricle can be paced in response to high-rate intrinsic atrial activity
7. Paced and Sensed AV Delays The AV Delay is the time lag between an atrial beat and a ventricular beat
AV Delays can be programmed independently depending on whether they follow a
Paced atrial event = paced AV Delay
Sensed atrial event = sensed AV Delay
The sensed AV Delay should be programmed a bit shorter than the paced AV Delay (~ 25 ms)
8. Rate-Responsive and Shortest AV Delay Rate-responsive AV delay (RRAVD) automatically shortens the AV delay setting as the patient’s rate increases
It has nothing to do with sensor-based rate response
Shortest AV Delay is the minimum value the AV Delay can achieve, even in the presence of high-rate activity
9. Programming Considerations The higher the basic rate, the more likely the patient will be paced
DDD(R) mode is very comprehensive but it allows for atrial tracking
Even if the patient has no known atrial tachyarrhythmias, program a reasonable Maximum Tracking Rate
If the patient has high-rate intrinsic atrial activity, set up AMS as well
Program independent values of sensed and paced AV delays
Patients who are likely to achieve higher-than-base-rate activity should have RRAVD on
10. Rate Hysteresis with Search In an ICD without hysteresis, the patient’s intrinsic rate must equal or exceed the base rate to inhibit pacing
With hysteresis, the clinician can program a “hysteresis rate” that will inhibit pacing
If the patient’s rate meets or exceeds the hysteresis rate, pacing is inhibited
If the patient’s rate fails to meet the hysteresis rate, pacing begins at the programmed basic rate
The search function “searches” for intrinsic activity at programmable intervals
Typical settings
Basic rate 60 ppm
Hysteresis rate 50 bpm
11. Programming Considerations Hysteresis is particularly appropriate for patients with a good underlying rhythm and/or intermittent bradycardia
Can reduce unnecessary pacing
May save battery energy
Hysteresis allows the patient’s own rhythm the maximum opportunity to inhibit the device
The hysteresis rate should always be slightly less than the basic rate (~ 10 bpm difference)
Hysteresis is incompatible with biventricular or CRT pacing
12. Ventricular Intrinsic Preference™ The goal of Ventricular Intrinsic Preference™ or VIP pacing is to reduce ventricular pacing without compromising pacing support
Based on proven AutoIntrinsic Conduction Search (AICS) technology
Automatically extends AV delay at programmable intervals to offer intrinsic ventricular activity maximum opportunity to “break through” and inhibit pacing
This algorithm is particularly suitable for patients with a good underlying rhythm or who have only intermittent bradycardia
13. Temporary Pacing Sometimes unusual parameter settings are required
During threshold tests
While taking real-time measurements of the ICD
Acquiring or updating a template for the Morphology Discrimination
Temporary pacing allows the clinician the opportunity to set up special settings for a specific short-term situation
Parameters available for temporary pacing
Mode
Basic rate
Sensed and paced AV Delays
PVARP
Pulse amplitude, pulse width
14. Programming Considerations Detection is not active whenever temporary pacing is active
Temporary pacing is intended for very short-term use in specific situations
For example, may have to increase the pacing rate to run a capture test
The advantage of temporary pacing is that the device will revert quickly (one-button) to the previously programmed parameters
If you permanently program such test settings, it takes longer to restore the original values
15. Pacing Output Output defines total energy delivered to the heart in order to pace it
Pulse amplitude (in Volts)
Pulse width (in ms)
Pacing output is governed by threshold value plus the safety margin (2:1, 3:1)
Atrium and ventricle will quite likely have different output settings
Capture testing (to verify or adjust output) should be performed regularly
16. Refractory Periods Post-ventricular atrial refractory period (PVARP) is a refractory period on the atrial channel that is initiated whenever a ventricular event occurs
Designed to help prevent the atrial channel from sensing ventricular activity and inappropriately “seeing” it as atrial activity
PVARP adjustments can help prevent pacemaker-mediated tachycardia (PMT)
Ventricular refractory period
Absolute blanking period (no signals are “seen” at all)
Relative refractory period (device “sees” and can count signals but will not respond to them)
17. Rate-Responsive and Shortest Refractory The healthy heart decreases its refractory period at higher rates
This automatic algorithm does the same (for sensed activity)
Shortest refractory establishes the minimum value that the refractory period can be in the presence of high-rate intrinsic activity
18. Programming Considerations When adjusting output settings, it is more efficient to increase pulse amplitude (V) than pulse width (ms) to increase energy
Extending the PVARP can help prevent pacemaker-mediated tachycardias (PMT)
Essentially how PMT prevention algorithms work
Refractory periods have an absolute and relative phase
These may not be directly programmable
Use caution with Rate-Responsive Refractory and Shortest Refractory Period in patients with heart failure
19. Sensor Parameters ON, OFF, PASSIVE
PASSIVE allows you to test how sensor drive would have worked without the sensor being in control
Maximum Sensor Rate
Threshold
Slope
Reaction Time
Recovery Time
20. Maximum Sensor Rate (MSR) MSR is the fastest rate the device will pace in response to sensor input
Program a higher MSR for active patients than for sedentary patients
MTR and MSR can be different values
MTR governs ventricular pacing in response to atrial tracking (high-rate intrinsic atrial activity must be present)
MSR governs response to the sensor (sensor must be in control)
21. Other Sensor Parameters Threshold governs how much activity must occur to activate rate response
Slope defines how much rate response is delivered
The higher the slope, the faster the rate-responsive pacing
Reaction time determines how much time it will take for the device to go from basic rate to the sensor-controlled rate
Recovery time sets how fast the device goes from sensor-controlled rate back to the basic rate
22. Programming Considerations Rate response benefits patients who are active and need pacing support to vary in response to their levels of exertion
Nominal settings are appropriate for most patients
Athletic, fit, and very active patients need more aggressive rate response
Sedentary, bed-ridden, or extremely inactive patients should have only slight rate response
Make sure the patient can tolerate pacing at sensor-driven rates
PASSIVE is a great way to “test drive” rate response
23. Extended Parameters Auto Mode Switch
Goal: Avoid high-rate ventricular pacing in response to atrial tracking
PVC Options
Goal: Minimize the impact of PVCs on the patient’s rhythm or pacing
PMT Options
Goal: Prevent PMTs and terminate them if they do occur
Noise Reversion
Goal: Provide patient safety in the presence of overwhelming interference
24. Programming Extended Parameters
25. Auto Mode Switch (AMS) In DDD(R) mode, the device will try to provide 1:1 AV synchrony, even in the presence of high-rate intrinsic atrial activity (atrial tracking)
Atrial tracking can result in ventricular pacing at rates well above the programmed base rate
Patient may not tolerate such fast ventricular pacing
Uncomfortable, may even produce symptoms
AMS “turns off” atrial tracking
Mode changes (DDD to DDI or VVI) with or without rate response
Automatic
26. PVC Options PVCs happen and they can trigger a reentry tachycardia
A PACE ON PVC can be programmed on
Automatically extends the PVARP to 475 ms when a PVC is detected
If a retrograde P-wave occurs in that extended PVARP,
1. The PVARP is terminated
2. The ventricular output is inhibited
3. The device delivers an atrial output pulse (A PACE) 330 ms after the detected retrograde P-wave
27. A PACE ON PVC in Action Point out:
The circled event is the PVC (defined by the device as a ventricular event without a preceding atrial event)
When it was detected, the algorithm automatically extended the PVARP—that means the device would not respond to an atrial event
A retrograde P-wave occurs and falls in the extended PVARP (the PVARP’s relative refractory period can see the atrial event but will not respond to it)
The algorithm now delivers an atrial output pulse 330 ms following the sensed P-wave
This breaks the potential PMT before it can start and restores normal paced behavior in the next beatPoint out:
The circled event is the PVC (defined by the device as a ventricular event without a preceding atrial event)
When it was detected, the algorithm automatically extended the PVARP—that means the device would not respond to an atrial event
A retrograde P-wave occurs and falls in the extended PVARP (the PVARP’s relative refractory period can see the atrial event but will not respond to it)
The algorithm now delivers an atrial output pulse 330 ms following the sensed P-wave
This breaks the potential PMT before it can start and restores normal paced behavior in the next beat
28. PMT Options A PMT is a reentry tachycardia that incorporates the device to form the endless loop
Programmable options
A PACE ON PMT
PASSIVE
OFF
Parameter settings
PMT Detection Rate (nominal: 90 ppm)
The device looks at V-P timing (VP-AS events)
Timing (is it fast?)
Stability (is the V-P interval stable?)
29. A PACE ON PMT in Action Point out:
When the PMT Detection Rate is met, the device starts to analyze VP-AS events and their relationship, looking at how fast the intervals are and how stable they are
Fast, stable intervals suggest a PMT
Once the algorithm diagnoses PMT, it withholds the next ventricular output and delivers an atrial output (A PACE) 330 ms after the detected retrograde P-wave (AS event)
This breaks the cycle that creates a PMTPoint out:
When the PMT Detection Rate is met, the device starts to analyze VP-AS events and their relationship, looking at how fast the intervals are and how stable they are
Fast, stable intervals suggest a PMT
Once the algorithm diagnoses PMT, it withholds the next ventricular output and delivers an atrial output (A PACE) 330 ms after the detected retrograde P-wave (AS event)
This breaks the cycle that creates a PMT
30. Noise Reversion Noise is defined as anything 50 Hz or greater
These signals can interfere with pacing function
Device response is unpredictable
Consequences can be very serious
Noise can occur in the presence of
Electromagnetic interference
Stray signals
Certain industrial environments
Sometimes investigation is required to ascertain the source of interference
31. Noise Reversion Ventricular noise reversion
DDD(R) goes to DOO mode or OFF
VVI(R) goes to VOO mode or OFF
Tachycardia detection is suspended
If charging was in progress, charge aborts
EGM is automatically stored
Atrial noise reversion
If an atrial mode was selected, it becomes asynchronous
Tachycardia detection continues but if Rate Branch is selected, it will always indicate V>A
No mode switching
32. Ventricular Safety Standby (VSS) Crosstalk occurs when the device inappropriately senses an atrial output pulse for an intrinsic ventricular event
This causes oversensing (counting ventricular events that did not really happen) which leads to ventricular under-pacing
VSS monitors the ventricular channel right after an atrial output pulse and the simultaneous ventricular blanking period
Helps prevent crosstalk
Crosstalk could cause inappropriate inhibition of ventricular pacing
33. Conventional Pacing Summary If the ICD patient has a standard pacing indication, program brady therapy to accommodate the patient’s condition
Sick sinus syndrome
AV block
Many ICD patients do not have a standard pacing indication
Program “backup pacing” only
Use a low rate (~ 40 ppm) and simple mode (VVI)
This offers pacing support if the patient truly needs it but will not unnecessarily pace the patient
34. Conventional Pacing Summary If the patient has some LV impairment and RV pacing should be minimized (but pacing is still required)
Program the pacemaker appropriately for the patient’s pacing condition
Use VIP™ pacing to search out intrinsic ventricular activity (with the goal of inhibiting RV pacing as much as possible)
Optimize the AV delay
Echo
QuickOpt™ algorithm
Optimizing the AV delay helps avoid unnecessary RV pacing while enhancing hemodynamics and providing patients the safety of pacing support
35. Episodal Pacing For the ICD, a tach or fib episode
Begins when the very first tach or fib interval is binned
Ends when the device determines “Return to Sinus” (RS)
The patient may require pacing while an episode is in progress
Pacing during a real or suspected tachyarrhythmia can expose the patient to possible risk
For that reason, special pacing parameters go into place for pacing during an episode
Episodal pacing has special settings and cannot be programmed OFF
36. Programming Episodal Pacing Episodal pacing cannot be programmed OFF but it may be possible to program the mode
Extended Parameters screen
Mode must be non-tracking mode
DDI
VVI
37. Episodal Pacing Function Once three intervals are binned as tach or fib, the device will launch episodal pacing
Mode switches to the episodal mode (non-tracking but not asynchronous)
Desired mode may be programmable (limited choices)
If the sensor was ON, it switches to PASSIVE
DDDR becomes DDI, for example
Ventricular safety standby or VSS (crosstalk protection) is turned off
Rate-responsive AV delay (RRAVD) is turned off
38. Episodal Pacing in Action Point out:
Episodal pacing begins on the fourth beat that is binned as tach or fib
Look at the annotation line and find the F; these are fib intervals
Episodal pacing begins on the fourth F and the changed mode is indicated at the top; in this example, the episodal pacing mode is VVI
Fib detection continues; episodal pacing has no bearing on that
Episodal pacing is not really obvious on the tracing beyond the mode change, but certain features (RRAVD, VSS, sensor) have been turned off or to passive settingsPoint out:
Episodal pacing begins on the fourth beat that is binned as tach or fib
Look at the annotation line and find the F; these are fib intervals
Episodal pacing begins on the fourth F and the changed mode is indicated at the top; in this example, the episodal pacing mode is VVI
Fib detection continues; episodal pacing has no bearing on that
Episodal pacing is not really obvious on the tracing beyond the mode change, but certain features (RRAVD, VSS, sensor) have been turned off or to passive settings
39. Episodal Pacing Episodal pacing remains in effect
Through arrhythmia detection
Through therapy delivery
Until post-shock pacing goes into effect
Episodal pacing occurs right after a shock
Since episodal pacing disables VSS, it is possible for crosstalk to occur in the post-shock period of the episodal mode is DDI
May be prudent to program VVI as episodal pacing mode
Crosstalk is not possible in VVI mode
40. Crosstalk During Episodal Pacing Point out:
Episodal pacing goes into effect on the fourth binned fib interval (see top strip, about the middle)
A vertical line indicates the change of mode with the start of episodal pacing—in this case it’s DDI
Fib detection continues and leads to the delivery of high-voltage therapy (second strip, vertical line, marked HV)
The shock immediately breaks the arrhythmia; there is a pause and some slow intrinsic activity
The circle shows annotations for one atrial paced event (AP) and two ventricular sensed events (VS)
However, if you look at the actual tracing, there is one atrial event and one ventricular event
The atrial paced event (AP) is actually sensed twice—once appropriately on the atrial channel which calls it an AP and once inappropriately on the ventricular channel, which calls it a VS
This strip provides good support for choosing VVI as the episodal pacing mode since crosstalk cannot occur in VVI mode (and this crosstalk would not have occurred if VSS had been active—but VSS is not allowed in episodal pacing)Point out:
Episodal pacing goes into effect on the fourth binned fib interval (see top strip, about the middle)
A vertical line indicates the change of mode with the start of episodal pacing—in this case it’s DDI
Fib detection continues and leads to the delivery of high-voltage therapy (second strip, vertical line, marked HV)
The shock immediately breaks the arrhythmia; there is a pause and some slow intrinsic activity
The circle shows annotations for one atrial paced event (AP) and two ventricular sensed events (VS)
However, if you look at the actual tracing, there is one atrial event and one ventricular event
The atrial paced event (AP) is actually sensed twice—once appropriately on the atrial channel which calls it an AP and once inappropriately on the ventricular channel, which calls it a VS
This strip provides good support for choosing VVI as the episodal pacing mode since crosstalk cannot occur in VVI mode (and this crosstalk would not have occurred if VSS had been active—but VSS is not allowed in episodal pacing)
41. Episodal Pacing Start to Finish Point out:
Episodal pacing is launched with the fourth binned fib event
The vertical line shows the point at which the mode changes (here to VVI) and episodal pacing goes into effect
Episodal pacing is not really very evident on the tracing beyond the mode change, but the sensor is off, and RRAVD and VSS are off
Fib detection continues, fibrillation is diagnosed, and the device delivers a high-voltage shock (middle strip, first third, evident as shock icon
Following the shock, there is a pause and then intrinsic activity resumes; there is a run of slow AS and VS beats (and one stray fib interval)
The ICD determines that sinus rhythm has been restored (third strip, red circle)
On the next beat after the return to sinus, episodal pacing discontinuesPoint out:
Episodal pacing is launched with the fourth binned fib event
The vertical line shows the point at which the mode changes (here to VVI) and episodal pacing goes into effect
Episodal pacing is not really very evident on the tracing beyond the mode change, but the sensor is off, and RRAVD and VSS are off
Fib detection continues, fibrillation is diagnosed, and the device delivers a high-voltage shock (middle strip, first third, evident as shock icon
Following the shock, there is a pause and then intrinsic activity resumes; there is a run of slow AS and VS beats (and one stray fib interval)
The ICD determines that sinus rhythm has been restored (third strip, red circle)
On the next beat after the return to sinus, episodal pacing discontinues
42. Post-Shock Pacing (PSP) When the myocardium is shocked, there are some immediate but temporary changes
The cardiac tissue may be vulnerable for a few seconds
Needs a few seconds to recover
Easy to provoke an arrhythmia during this vulnerable phase
The capture threshold may be temporarily elevated
Patient’s blood pressure may decrease during shock
Post-shock pacing (PSP) allows for temporary parameters to be set up to allow for pacing support during this crucial period
43. Programming PSP
44. PSP Parameters Pause
The pause gives the myocardium a short period to recover
Programmable from 1 to 7 sec
Post-shock base rate
Consider patient: there is no one-size-fits-all
Post-shock output parameters
Typically higher than normal
PSP duration
Programmable from 30 sec to 10 min
Post-shock mode
Choices are DDD, DDI, VVI, AAI
No rate response
45. PSP Pause The goal of the pause is to give the just-shocked myocardial tissue some time to recover
Pacing or applying any electrical stimulus to this vulnerable tissue may provoke a new arrhythmia
Programmable from 1 to 7 sec
The timer for the PSP begins with the delivery of the shock itself
Pause can allow post-shock intrinsic activity to emerge
46. Post-Shock Base Rate HIGHER than normal rate
Compensates for drop in blood pressure that may occur with therapy delivery
Increased heart rate increases cardiac output
May help compensate for temporary hypotension
LOWER than normal rate
Allows stressed myocardial tissue more time to recover
Gives intrinsic activity more opportunity to break through
Consider the patient’s condition and his response to shock (if known)
47. Post-Shock Output Parameters & Duration Most patients experience an immediate but very short-term increase in pacing thresholds
It is recommended to increase output parameters
Pulse amplitude
Pulse width
Nominal settings are 7.5 V and 1.5 ms
PSP duration can be programmed from 30 sec to 10 min
When PSP ends, the normal programmed parameters resume
48. PSP in Action Point out:
When this strip starts, episodal pacing is already in force
Therapy is delivered in the first third of the upper strip (see shock icon)
The PS timer launches with the therapy delivery and times out; during that time there is no pacing at all
The PS duration timer also launches with the therapy delivery
Pacing at the PS rate and PS output starts as soon as the PS timer times out—however, the episodal pacing mode remains in effect until there is a return to sinus. In this example, the episodal pacing mode is VVI.
After shock, the device paces in the episodal mode at the PS rate and output settings until the device determines there is a return to sinus. That is called out toward the left in the bottom strip.
Once Return to Sinus is confirmed episodal pacing ends. The device now continues in PSP until the PS Duration times out. This may mean a change in mode.
In this case, the new mode is circled as PSP takes over. It happens to be VVI which in this instance is the same as the episodal mode. However, had the modes been different, the mode change would have occurred where shown.
PSP continues until the timer expires.Point out:
When this strip starts, episodal pacing is already in force
Therapy is delivered in the first third of the upper strip (see shock icon)
The PS timer launches with the therapy delivery and times out; during that time there is no pacing at all
The PS duration timer also launches with the therapy delivery
Pacing at the PS rate and PS output starts as soon as the PS timer times out—however, the episodal pacing mode remains in effect until there is a return to sinus. In this example, the episodal pacing mode is VVI.
After shock, the device paces in the episodal mode at the PS rate and output settings until the device determines there is a return to sinus. That is called out toward the left in the bottom strip.
Once Return to Sinus is confirmed episodal pacing ends. The device now continues in PSP until the PS Duration times out. This may mean a change in mode.
In this case, the new mode is circled as PSP takes over. It happens to be VVI which in this instance is the same as the episodal mode. However, had the modes been different, the mode change would have occurred where shown.
PSP continues until the timer expires.
49. Conclusion Brady therapy in an ICD invovles
Pacing outside of a tachy epsiode (conventional pacing)
Pacing during an episode (episodal pacing)
Pacing following a tachy episode (post-shock pacing)
Conventional pacing should be set up in accordance to the patient’s pacing indication (and if there is none, then only backup pacing should be provided)
Episodal pacing should avoid competitive pacing or pacing into the tachyarrhythmia
Post-shock pacing should not stress vulnerable shocked tissue while still providing necessary pacing support