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Troubleshooting Part I

Troubleshooting Part I. 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

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Troubleshooting Part I

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  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

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