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Special Timing Functions PMT PVC Crosstalk Auto Ventricular Blanking

Special Timing Functions PMT PVC Crosstalk Auto Ventricular Blanking. Pacemaker - Mediated Tachycardia Initiation Prevention Detection Therapy. PMT – Endless Loop Tachycardia. PMT – Endless Loop Tachycardia. PMT – Endless Loop Tachycardia. PMT - Conditions to be fulfilled. Initiator

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Special Timing Functions PMT PVC Crosstalk Auto Ventricular Blanking

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  1. Special Timing Functions • PMT • PVC • Crosstalk • Auto Ventricular Blanking

  2. Pacemaker - Mediated Tachycardia • Initiation • Prevention • Detection • Therapy

  3. PMT – Endless Loop Tachycardia

  4. PMT – Endless Loop Tachycardia

  5. PMT – Endless Loop Tachycardia

  6. PMT - Conditions to be fulfilled • Initiator • Retrograde (VA) conduction • VDD or DDD Pacemaker

  7. PMT – Cycle Length • PMT cycle time • = • VA conduction time • + • programmed AV delay • (or Maximum Tracking Rate interval)

  8. PMT – Endless Loop Tachycardia • Initiation • PVC • Atrial undersensing • Atrial oversensing • Atrial noncapture • Long AV delay

  9. AS AP AS AP AS AS AS AS AS VP VP VP VP VP VP VS VP VP VP PMT – Initiation by PVC PVC Surface ECG Retrograde P-waves Esophageal ECG

  10. PMT – Initiation by PVC

  11. PMT – Initiation Atrial noncapture causes ventricular stimulation without the AV node being blocked by anterograde event Atrial oversense Inhibits atrial output: causes ventricular stimulation without the AV node being blocked by anterograde event

  12. AP AS AS AS AP AS AP AP AS AS VP VP VP VP VP VP VP VP VP VP PMT – Initiation by loss of atrial capture Surface ECG Retrograde P-waves Esophageal ECG

  13. PMT – Initiation Atrial undersense Results in a long AV interval, allowing the AV node time to recover and conduct retrograde Long AVI Allows the AV node time to recover

  14. PMT – Initiation by loss of atrial sensing AS AP AS AS AS AS AS AS AS AS VP VP VP VP VP VP VP VP VP VP Surface ECG Retrograde P-waves Esophageal ECG

  15. PMT – Endless Loop Tachycardia • Prevention (not SJM specific) • PVARP • PVARP extension after PVC • Differential atrial sensing; anterograde / retrograde p-wave morphology comparison • Rate adaptive PVARP • High max tracking rate – retrograde fatigue

  16. PMT – Endless Loop Tachycardia • Detection • P tracking at upper rate limit • P tracking at intermediate rate • AV interval modulation • Discrepancy between sensed atrial rate and sensor indicated rate

  17. PMT Options SJM • Off (nominal for Identity and Integrity) • 10 Beats > PMT • Auto detect (nominal for Zephyr and Victory) • No PMT options during AMS or Magnet Application

  18. PMT Options SJM - 10 Beats > PMT • Detection • 10 consecutive AS-VP events at a rate > PMT Detection Rate • PMT Detection Rate: 90 – 150 bpm, nominal 110 • Response • Reset of PVARP to 480 ms for a single cycle • After PVARP extension • PMT detection is suspended for 256 cycles • the atrial alert period is 330 ms

  19. 10 Beats > PMT PVARP: 480ms Atrial Alert Period 330ms

  20. PMT Options SJM – Auto Detect • Detection • Rapid stable VP – AS interval • Rapid: atrial rate > PMT Detection Rate • Stable: compares average of 8 VP – AS intervals to average of all cycles. If all VP - AS intervals are with 16 ms of average  stable • On the 9th cycle the AS – VP delay is • Shortened 50 ms if AS – VP  100 ms • Lengthened 50 ms if AS – VP < 100 ms • If VP – AS cycle is within 16 ms of average VP – AS cycle  PMT. Else  Sinus Tachycardia

  21. (VP-AS)1 (VP-AS)2 PMT Options SJM – Auto Detect (VP-AS)1 (VP-AS)2 (VP-AS)1  (VP-AS)2 therefore: sinus tachycardia AS - VP AS - VP (AS-VP) -  (VP-AS)1 = (VP-AS)2 therefore: PMT AS - VP AS - VP (AS-VP) - 

  22. PMT Options SJM – Auto Detect

  23. PMT – Endless Loop Tachycardia • Termination • PVARP extension • Withhold of ventricular output • Withhold of ventricular output with early atrial pace

  24. PMT Options SJM – Auto Detect and Response • Response • After 9th interval no ventricular response • Atrial pulse 330 ms after retrograde P-wave

  25. PMT Option Auto Detect AVI: +50ms

  26. Special Timing Functions • PMT • PVC • Crosstalk • Auto Ventricular Blanking

  27. PVC Options • To distinguish between a premature ventricular contraction (PVC) and a conducted R-wave in DDD(R) or VDD(R) mode • A response to a PVC to prevent the evolution into a PMT

  28. PVC Detection • A PVC is confirmed if • An R-wave is not preceded by an atrial event Or • A P-wave is detected in the relative portion of the PVARP but is not followed by an R-wave within 280ms of the atrial event

  29. PVC Options: + PVARP on PVC • After PVC Detection • PVARP extension to 480 ms • Followed by atrial alert period of 330 ms

  30. PVC Options: Atrial Pace on PVC • After PVC Detection • PVARP extension to 480 ms • If retrograde P-wave is detected PVARP is terminated • No ventricular output • Atrial Escape Interval 330 ms

  31. Atrial Pace on PVC DDD 60 330ms Extension of PVARP to 480 Atrial Alert Period of 330ms

  32. Special Timing Functions • PMT • PVC • Crosstalk • Auto Ventricular Blanking

  33. What’s up Doc?

  34. Crosstalk • Sensing of an atrial output in the ventricular channel resulting in inhibition of the ventricular pulse • Clinical manifestation: atrial pacing with no ventricular output. Can be overcome with Ventricular Safety Standby • Crosstalk can occurs with • High atrial pulse amplitude • High ventricular sensitivity • Short ventricular blanking • Rapid pacing rates • Unipolar pacing and sensing

  35. Crosstalk • Decrease atrial output? • Decrease ventricular sensitivity? • Prolong ventricular blanking? • Enable Ventricular Safety Standby!

  36. Crosstalk Detection Window Blanking Period Ventricular Safety Standby 64ms

  37. sensitivity V EGM Ventricular Safety Standby Crosstalk Ventricular Safety Pacingafter 120 ms

  38. Ventricular Safety Standby

  39. Is Ventricular Safety Standby Pacing Present In This Panel?

  40. Ventricular Safety Standby Sensing in Crosstalk Detection Window Ventricular Safety Pacing after 120 ms

  41. Ventricular Safety Standby Blanking Period - No sensingVentricular Pacing after programmed AV Interval

  42. Blanking period undersensing can be dangerous at long AV intervals

  43. Crosstalk – Ventricular Safety Standby

  44. Special Timing Functions • PMT • PVC • Crosstalk • Auto Ventricular Blanking

  45. Auto Ventricular Blanking • Maximizes the ventricular alert window. • Minimizes inappropriate inhibition due to crosstalk. • When crosstalk is present, ventricular blanking period automatically lengthens • In the absence of crosstalk, ventricular blanking period remains short

  46. Auto Ventricular Blanking - Programmability Auto Ventricular Blanking - Zephyr

  47. Auto Ventricular Blanking - Zephyr • Programmable values • Shipped setting is Auto

  48. AP Absolute v. Blanking 52 ms 12 ms time 64 ms Maximum ventricular blanking interval Auto Ventricular Blanking - Zephyr • AP - a 12 ms absolute blanking window begins. • If ventricular activity (crosstalk) is sensed, • a retriggerable 12 ms relative refractory window • begins and can retrigger to a maximum of • 52 ms. • If no ventricular activity is sensed the • ventricular channel enters an alert period.

  49. AP VP 170 ms No Sensed Ventricular Event Ventricular Crosstalk No Crosstalk Detection Window R R Alert 12 ms 40 ms time 52 ms 64 ms Auto Ventricular Blanking - Zephyr • Crosstalk ends before 52 ms. • No need for crosstalk detection window. • Ventricular channel enters an alert period.

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