1. The Electrical Management of Cardiac Rhythm Disorders Tachycardia 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

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

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

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

41. Episodal Pacing Start to Finish

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

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