Key result
Repetitive activation of the automatic postventricular atrial refractory period extension, initiated by a PVC or needle contact, caused a DDD pacemaker to fail to track P waves in two cases.
Case Report (n=2)
Repetitive automatic PVARP extension can cause P wave undersensing in DDD pacemakers, which can be triggered by PVCs or external interference like needle contact.
May cause P-wave undersensing in DDD pacemakers; case reports leave open need for algorithm refinements.
WILSON, J.H., et al.: Undersensing of P Waves in the Presence of an Adequate P Wave Due to Automatic Postventricular Atrial Refractory Period Extension Two cases in which a DDD pacemaker failed to track P waves due to repetitive activation of the automatic postventricular atrial refractory period (PVARP) extension are reported. In one case, the cycle was initiated by a premature ventricular contraction (PVC); in the other, by touching the unipolar pacemaker with a needle while suturing. We demonstrated that chest wall stimulation can be used to induce cycles of repetitive automatic PVARP extension and failure to track P waves. We demonstrated in vitro that touching a unipolar pacemaker with a needle can generate a signal suffiicient to mimic a QRS complex, and initiate a cycle of repetitive P wave undersensing.
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Wilson et al. (1989) conducted a case report in DDD pacemaker failure to track P waves (n=2). Automatic postventricular atrial refractory period (PVARP) extension was evaluated on Failure to track P waves. Repetitive activation of the automatic postventricular atrial refractory period extension, initiated by a PVC or needle contact, caused a DDD pacemaker to fail to track P waves in two cases.
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