Right Bundle Branch Block-Like Pattern During Uncomplicated Right Ventricular Pacing and the Effect of Pacing Site

Renewed interest in the significance of the tall R wave in ECG lead V1 during right ventricular pacing

“…Tzeis et al [4] found that all their 35 patients with paced RBBB had a transition latest at lead V3, further supporting the clinical utility of this ECG index with a claimed 100% sensitivity. Almehairi et al [2] indicated that in 48 patients that an RV site is present with a transition ≤V3 yielding 96% sensitivity and 100% specificity.…”

“…Almehairi et al [2] cited five patients (from a group of 48 patients) with an axis degree between −90°to -180°and a RBBB-like pattern in the presence of true RV pacing (11%). Tzeis et al [4] reported two cases (5%), Klein et al [9] reported one case with a similar axis degree and Hemminger et al [15] also reported a case. The presence of a right superior axis with a RBBB-like pattern may mimic the pattern of biventricular pacing with the RV lead at the apex.…”

“…In all these studies including that of Tzeis et al [4], fusion was eliminated by standard maneuvers (temporary programming of rate with the shortest AV delay) except those of Refat et al [6] and Almehairi et al [3] which were a retrospective studies. Few details are given regarding the accuracy of ECG lead placement at the V1 site and none is available in retrospective cases.…”

“…The report of Tzeis et al [4] is a secondary analysis of the randomized, prospective, multicenter Septal Positioning of ventricular implantable cardioverter-defibrillator (ICD) Electrodes study. Patients with a standard indication for ICD implantation were randomized to an apical versus midseptal defibrillator lead positioning.…”

“…Several recent articles have renewed interest in the significance of a dominant R wave in ECG lead V1 during right ventricular (RV) pacing [1][2][3][4]. A dominant R wave in V1 (R/ S > 1) during RV pacing is often called a 'right bundle branch block' (RBBB) pattern, but this terminology is potentially misleading because this configuration actually reflects activation moving from the posterior to the anterior part of the heart [5].…”