Pacemaker troubleshooting-single chamber pacemakers

1. Pacemaker troubleshooting-single chamber pacemakers

2. Reasons for evaluation • Patient symptomatic • Palpitation • Syncope • presyncope • Pacemaker malfunction suspected • ECG • Telemetry • Ambulatory ECG • Routine pacemaker follow up

3. Patient details • Indication for pacing • Implant operative note • Diagnosis • Medication –can alter pacing tresholds • DC ,MRI,electrocautery • Trauma,electrical current exposure • Concurrent medical problems-CRF,hyperkalemia • Prior ECG,CXR

4. Pacemaker system • manufacturer • Model • current programming • date of implant • special features • Sensing and pacing tresholds • impedance

5. Lead system • manufacturer • model • polarity • Fixation • insulation and date

6. Causes of pacemaker malfunction • Pacing stimuli present with failure to capture • Pacing stimuli present with failure to sense • Pacing stimuli absent • Oversensing • No output • Pseudomalfunction

7. Failure to capture • No evidence of depolarization after pacing artifact Loss of capture

11. Early post device implantation • CXR abnormal • Lead dislodgement • Downward migration of PG • Failure to secure anchoring sleeves properly • Too little or too much slack • Lead perforation • Elevated impedance • Loose set screw • failure to seat lead pin properly in header • Normal CXR,normal impedance • Micro lead dislodgement • Inflammatory response

12. Late post device implantation • Battery depletion • Twiddler s syndrome • Abnormal myocardium • Insulation failure • Conductor failure • Mechanical stress on lead • Anchoring sleeve • Interaction with generator in pocket • b/w clavicle and first rib

13. Increase the energy in the output pulse • Run a capture threshold test • Adjust the output parameters, if necessary • Pulse amplitude (V) • Pulse width or duration (ms) • It is generally more efficient to increase the pulse amplitude • Investigate possible lead problems • Reprogram device polarity

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

15. Undersensing occurs when the pacemaker does not detect intrinsic activity that really is there • Undersensing causes the pacemaker to pace more than it should

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

20. Adjust the sensitivity setting • Run a sensing threshold test • Measure the intrinsic signals • Adjust the sensitivity appropriately • To increase sensitivity, decrease the mV setting • Make all changes to sensitivity settings in small steps since large changes may only introduce new sensing problems

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

23. Oversensing occurs when the pacemaker inappropriately “thinks” that it sees intrinsic activity that is not there • Oversensing causes the pacemaker to inhibit the pacing output pulse, even though the device should be pacing

26. Myopotentials • Pectoralis,rectusabdominis,diaphragm • Bipolar leads are less susceptible • Oversensing of normal intracardiac signals • Reduce sensitivity of affected lead to eliminate oversensing • EMI • Provocative maneuvers may be needed if intermittent symptoms • Magnet eliminates pauses-oversensing

27. Reprogram the sensitivity • Conduct a sensing threshold test • Adjust the sensitivity by making the device less sensitive (increase the mV setting) • Make only small changes • Extend the refractory period

28. 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

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

31. Steps to take for possible loss of output • Verify all lead connections • Check lead integrity • Evaluate battery status • Contact the device manufacturer • Loss of output may require the replacement of all or part of the pacing system

32. Pseudomalfunctions Pseudomalfunctions are defined as: Unusual,UnexpectedECG findings that appearto result from pacemaker malfunction but that represent normal pacemaker function

33. Hysteresis • Magnet rate • rate responsive pacing • Noise reversion • Rate drop response • Sleep rate algorithm

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

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

36. Threshold Margin Test (TMT) • Three beats at 100 bpm, followed by a magnet rate of 85 • Third beat has an automatic pulse width decrement of 25% • Elective replacement indicators-change the rate from 85 to 65 • Extended TMT. • TMT is performed at 100 ppm • Pulse width reduced by 25% on 3rd , 50% on 5th , and 75% on 7th

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

38. Electrical Reset and Battery Depletion • Reset may occur due to exposure to EMI 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”)

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

40. 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

41. Noise reversion VT in a patient with VVI-pacing occurs at lower rate due to noise reversion

42. Rate drop response Delivers pacing at high rate when episodic drop in rate occurs

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

44. Flouro diagnosis

49. 1.ECG shows A.Failure to sense B.Failure to capture C.Hysteresis D.Oversensing

50. 2.ECG shows A.Failure to sense B.Failure to capture C.Hysteresis D.Oversensing