Pacemaker Malfunction Differential Diagnoses

Updated: Sep 19, 2016
  • Author: Chakri Yarlagadda, MD, FACC, FSCAI, FASNC, CCDS; Chief Editor: Jeffrey N Rottman, MD  more...
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Diagnostic Considerations


In pseudomalfunction of the pacemaker, although an apparent pacing system malfunction is suggested clinically, the apparent malfunction is a normal programmed pacer function. This is partly due to new algorithms to preserve intrinsic conduction and more physiologic pacing.

Examples of pseudomalfunction include the following:

  • Functional undersense with magnet application, safety pacing, triggered mode, fusion and pseudofusion beats, and blanking period

  • Functional oversense with short ventricular blanking period

  • Inappropriate rate with rate hysteresis, rate-drop response, rate smoothing, rate-responsive mode, programmed rest/sleep rate, and mode switch

  • Inappropriate mode with magnet application and mode switch

Manufacturers' advisories: Manufacturer recall or advisories due to unanticipated device malfunction after its release may require replacement of pulse generator, lead, or both. A decision analysis model by Amin et al warrant device replacement in pacemaker-dependent patients if a manufacturer advisory device failure rate is >0.3%. [4]

Differential Diagnoses