Loss of cardiac resynchronization therapy in a patient with a biventricular implantable cardioverter‐defibrillator

Figures

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  Fig. 1. Left- ECG shows wide QRS complexes with LBBB pattern morphology and bipolar pacing spike in front of each QRS complex without obvious P-waves compatible with right ventricular pacing during atrial fibrillation rhythm. Right- Marker channels and intracardiac signals from the atrium (A), far field (FF), RV, and LV shows atrial fibrillation with RV paced and LV sensed events.

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  Fig. 2. Left- ECG shows narrower QRS complexes with right bundle branch block pattern morphology and unipolar pacing spike in front of each QRS complex without obvious P-waves compatible with biventricular pacing during atrial fibrillation rhythm. Right- Marker channels and intracardiac signals from the atrium (A), far field (FF), RV, and LV shows atrial fibrillation with biventricular pacing (RV paced and LV paced events).

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  Fig. 3. Initiation of LVURI lock-in after loss of capture in the LV (arrow). LV pacing (LVp) cannot capture LV, but it starts a LVURI. RV pacing (RVp) captures the RV and after IVD and conduction to the left ventricle, the LV signal is sensed (LVs) and restarts LVURI. The RVp is released without an accompanying LVp because the LVp falls into an ongoing LVURI. The inhibited LVp restarts another LVURI and, again after RVp and conduction to the LV, the LVs resets the LVURI, and the cycle will continue.