Incidence and electrocardiographic localization of safe XXXX during permanent ventricular pacing.

@entity1 @entity2270 @entity714
The usual morphology for paced events originating from the right ventricle has a @entity714 (BBB) pattern. However, in a few @entity1 , right BBB configurations are identified. It is important to differentiate safe right BBB patterns from those caused by septal or free wall perforation. Paced electrocardiograms were examined in 179 consecutive @entity1 who underwent pacemaker placement. Fourteen @entity1 (8%) were identified with right BBB configurations. Posteroanterior and lateral chest radiographs and echocardiograms were evaluated specifically to identify the pacing lead location in this group. In addition, 152 paced episodes from published reports were combined with our population to create an electrocardiographic algorithm differentiating right ventricular septum, right ventricular apex, coronary venous, and left ventricular pacing. Chest radiographs and echocardiographic lead locations correlated perfectly in the 11 @entity1 available for echocardiograms. With use of a left superior @entity2270 and precordial transition by lead V3, right ventricular right BBB morphologies were correctly detected in 18 of 21 @entity1 (86% sensitivity, 99% specificity) and appropriately separated from left ventricular pacing in 18 of 19 @entity1 (95% positive predictive value). Therefore, 12-lead electrocardiograms are a rapid, reliable means of separating right and left ventricular right BBB pacing morphologies. Prudent use of these criteria will help eliminate unnecessary echocardiography, anticoagulation, and lead revision.
