A 63-year-old man underwent implantation of an Adapta dual chamber pacemaker for management of syncopal events due to paroxysmal AV block; at a routine device interrogation, an episode of rapid ventricular rate was stored in the device memory.
Tracing 9a: graph and episode data:
Tracing 9b: tracing coinciding with the episode:
This tracing illustrates the recording of a 50 Hz source of noise by the pacemaker instead of a ventricular rhythm disorder, which can be ascertained by examination of the ventricular EGM; the event markers and intervals are also highly suggestive, particularly the very short, non-physiologic ventricular cycles. It is, therefore, mandatory to verify systematically all episodes stored in memory. An erroneous diagnosis made by the device might be rectified by analysing the EGM.
This patient was not pacemaker-dependent and the sensing of noise was not associated with bradycardia. Older pacemakers were considerably more subject to this type of interference, as they operated in unipolar configurations. In these circumstances, triggered modes were used to prevent all pauses.
