A Case of Ventricular Undersensing in the DDI Mode: Cause and Correction

Abstract

A case is presented that demonstrates a confusing problem of ventricular undersensing in the DDI pacing mode. Electrocardiographic monitoring of the patient after pacemaker implantation revealed intermittent ventricular channel outputs which appeared to be inappropriate. These occurred a period of time after the intrinsic R wave, equal to the programmed AV interval. This problem was caused by ventricular lead undersensing, which resulted when the patient's intrinsic rate was such that the intrinsic ventricular complex occurred during the ventricular blanking period. The problem was corrected by reprogramming the blanking period.

ICD Proarrhythmia as a Consequence of an Interaction with an Algorithm to Prevent Atrial Arrhythmias

“…Reprogramming the ventricular blanking period could also correct this problem, 5 but not in the case under discussion. Finally, we can inactivate the APP algorithm to avoid new episodes of induced proarrhythmia.…”

Implantable Cardioverter Defibrillator Proarrhythmia Due to an Interaction with “Noncompetitive Atrial Pacing”: An Algorithm to Prevent Atrial Arrhythmias

“…6 Reprogramming the ventricular blanking period can correct this problem and thus, could have prevented the last step of the observed proarrhythmic cascade. 7 A further component involved in this episode was the NCAP algorithm. This feature is nominally activated with an NCAP interval of 300 ms. As discussed above, the episode was initiated by inappropriate mode switching to a ventricular-based DDIR mode.…”

Pacemaker Troubleshooting and Follow-up

“…[73][74][75][76][77][78][79] Any of these may affect the observed behavior and help guide further evaluation of the system, as well as any parameter adjustments. It is also important to know if any special considerations apply to the device.…”