70 years old man implanted with a triple chamber defibrillator Viva XT CRT-D for severe ischemic cardiomyopathy and left bundle branch block; good response to the resynchronization therapy; However he presented two endocarditis requiring the complete removal of the system (first implanted on the left side, then on the right side); complete surgical re-implantation of a defibrillator with 2 coils, a bipolar atrial and RV lead and a bipolar LV lead ; routine follow-up ;
The loss of the right ventricular capture due to a lead displacement or the elevation of the RV threshold is uncommon, because the right ventricular lead is screwed into the endocardium. In this patient, the right ventricular lead was implanted surgically. The two electrodes were sewn on the epicardium and were relatively distant from each other, which explains the increase in threshold (epicardial thresholds are often higher) but also the double aspect of QRS. The thresholds are usually high immediately after a surgical epicardial implantation, however they tend to quickly improve during the first 3 months, a phenomenon encouraged by the elution of steroids (4968 leads)
The right ventricular loss of capture is accompanied by a pure left ventricular capture without any changes in the refractory periods and without any adaptation of the post-ventricular pacing ventricular blanking period. A pure left ventricular pacing is often associated with an increased QRS width and the double counting of the paced QRS (detected by the right ventricular lead). In this patient, a left ventricular pacing was favored by programming a long post-ventricular pacing ventricular blanking period of 220 ms. This long blanking period may delay the initial detection in FV, but then, remains optimal since the post-ventricular blanking period after a sensed event remains much shorter.
