Troubleshooting Part I

1. TroubleshootingPart I

2. Objectives: • Understand the four basic steps used to solve troubleshooting problems • Identify ECG abnormalities that result from pacing system malfunction and pseudomalfunction • Recognize data and resources available to aid in troubleshooting pacing system anomalies • Discern pacemaker functions that can affect patient hemodynamics • Describe the causes of pacemaker system anomalies and propose a potential solution

3. The Steps Used in Troubleshooting Are Simple and Remain the Same for Each Type of Problem • Define the problem • Identify the cause of the problem • Correct the problem • Verify the solution

4. Defining the Problem and Identifying the Cause

5. Potential Problems Identifiable on an ECG Can Generally Be Assigned to Five Categories: • Undersensing • Oversensing • Noncapture • No output • Pseudomalfunction

6. Undersensing • An intrinsic depolarization that is present, yet not seen or sensed by the pacemaker P-wavenot sensed Atrial Undersensing

7. Undersensing May Be Caused By: • Inappropriately programmed sensitivity • Lead dislodgment • Lead failure: • Insulation break; conductor fracture • Lead maturation • Change in the native signal

8. Oversensing • The sensing of an inappropriate signal • Can be physiologic or nonphysiologic ...Though no activity is present Marker channel shows intrinsic activity... Ventricular Oversensing

9. Oversensing May Be Caused By: • Lead failure • Poor connection at connector block • Exposure to interference

10. Noncapture is Exhibited By: • No evidence of depolarization after pacing artifact Loss of capture

11. Noncapture May Be Caused By: • Lead dislodgment • Low output • Lead maturation • Poor connection at connector block • Lead failure

12. Less Common Causes of Noncapture May Include: • Twiddler’s syndrome • Electrolyte abnormalities – e.g., hyperkalemia • Myocardial infarction • Drug therapy • Battery depletion • Exit block

13. No Output • Pacemaker artifacts do not appear on the ECG; rate is less than the lower rate Pacing output delivered; no evidence of pacing spike is seen

14. No Output May Be Caused By: • Poor connection at connector block • Lead failure • Battery depletion • Circuit failure

15. Pseudomalfunctions Pseudomalfunctions are defined as: • Unusual • Unexpected • Eccentric ECG findings that appear to result from pacemaker malfunction but that represent normal pacemaker function

16. Pseudomalfunctions May Be Classified Under the Following Categories: • Rate • AV interval/refractory periods • Mode

17. Rate Changes May Occur Due to Normal Device Operation: • Magnet operation • Timing variations • A-A versus V-V timing • Upper rate behavior • Pseudo-Wenckebach; 2:1 block • Electrical reset • Battery depletion • PMT intervention • Rate response

18. Magnet Operation • Magnet application causes asynchronous pacing at a designated “magnet” rate

19. A to A = 1000 ms A to A = 1000 ms AV = 150 AV = 200 V-A = 850 V-A = 800 A to A = 1000 ms A to A = 950 ms A to A vs. V to V Timing A-A Timing Atrial rate is held constant at 60 ppm AV = 150 AV = 200 V-V Timing V-A = 800 V-A = 800 Atrial rate varies with intrinsic ventricular conduction

20. Upper Rate Behavior • Pseudo-Wenckebach operation will cause a fluctuation in rate

21. Upper Rate Behavior • 2:1 block operation will cause a drastic drop in rate

22. Electrical Reset and Battery Depletion • Reset may occur due to exposure to electromagnetic interference (EMI) – e.g., electrocautery, defibrillation, causing reversion to a “back-up” mode • Rate and mode changes will occur • Device can usually be reprogrammed to former parameters • Elective replacement indicators (ERI) can resemble back-up mode • Interrogating device will indicate ERI (“Replace Pacer”)

23. PMT Intervention • Designed to interrupt a Pacemaker-Mediated Tachycardia

24. Rate Responsive Pacing • An accelerating or decelerating rate may be perceived as anomalous pacemaker behavior VVIR / 60 / 120

25. Rate Changes May Occur Due to Therapy-Specific Device Operation • Hysteresis • Rate drop response • Mode switching • Sleep function

26. Hysteresis • Allows a lower rate between sensed events to occur; paced rate is higher Hysteresis Rate 50 ppm Lower Rate 70 ppm

27. Rate Drop Response • Delivers pacing at high rate when episodic drop in rate occurs • Pacing therapy indicated for patients with neurocardiogenic syncope

28. Mode Switching • Device switches from tracking (DDDR) to nontracking (DDIR) mode

29. Lower Rate Rate Sleep Rate Sleep Function 30 mins. 30 mins. Wake Time Bed Time Time

30. AV Intervals/Refractory Periods May Appear Anomalous Due to: • Safety pacing • Blanking • Rate-adaptive AV delay • Sensor-varied PVARP • PVC response • Noncompetitive atrial pace (NCAP)

31. Ventricular Safety Pace Safety Pacing • Designed to prevent inhibition due to “crosstalk” • Delivers a ventricular pace 110 ms after an atrial paced event

32. Blanking DDDR / 60 / 125 / 200 / 225

33. Rate-Adaptive AV Delay • AV interval shortens as rate increases PAV delay with no activity: 150 ms PAV with activity: 120 ms

34. Sensor-Varied PVARP • PVARP will shorten as rate increases Long PVARP with little activity Shorter PVARP with increased activity

35. PVC Response • PVARP will extend to 400 ms DDD / 60 / 120 PVARP 310 ms

36. Noncompetitive Atrial Pace (NCAP) • Prevents atrial pacing from occurring too close to relative refractory period, which may trigger atrial arrhythmias

37. A Change in Pacing Modes May Be Caused By: • Battery depletion indicators (ERI/EOL) • Electrical reset • Mode switching • Noise reversion

38. Noise Reversion • Sensing occurring during atrial or ventricular refractory periods will restart the refractory period. Continuous refractory sensing is called noise reversion and will: • Cause pacing to occur at the sensor-indicated rate for rate-responsive modes • Cause pacing to occur at the lower rate for non- rate-responsive modes

39. Noise Reversion

40. Note: Adverse patient symptoms may occur as a result of any of the previously mentioned pacing system malfunctions and some pseudomalfunctions.

41. Management of Patient Symptoms May Be Necessary as a Result of: • Muscle stimulation • Palpitations • Pacemaker syndrome • Shortness of breath due to inappropriate rate response settings

42. Muscle Stimulation May Be Caused By: • Inappropriate electrode placement near diaphragm or nerve plexus • Break in lead insulation • Unipolar pacing

43. Palpitations May Manifest From: • Pacemaker syndrome • Pacemaker-Mediated Tachycardia (PMT)

44. Pacemaker Syndrome “An assortment of symptoms related to the adverse hemodynamic impact from the loss of AV synchrony.”

45. Pacemaker Syndrome Symptoms include: • Dizziness • Presyncope • Chest tightness • Shortness of breath • Neck pulsations • Apprehension/malaise • Fatigue

46. Pacemaker Syndrome May Be Caused By: • Loss of capture, sensing • A-V intervals of long duration • Onset of 2:1 block • Single chamber system • Absence of rate increase with exercise

47. Pacemaker-Mediated Tachycardia (PMT) • A rapid paced rhythm that can occur with atrial tracking pacemakers

48. PMT is the Result of: • Retrograde conduction • Tracking fast atrial rates (physiologic or non-physiologic)

49. Retrograde Conduction

50. Retrograde Conduction May Be Caused By: • Loss of A-V synchrony due to: • Loss of sensing/capture • Myopotential sensing • Premature ventricular contraction (PVC) • Magnet application