Right bundle branch block: varying electrocardiographic patterns.

Abstract

Ten dissimilar electrocardiographic (ECG) patterns associated with right bundle branch block (RBBB) are presented. Electrophysiologic basis of the changes is discussed and possible causes for such diversity outlined. We have not found any aetiological association to this variation. The morphological diversity in RBBB patterns is likely to be related to multiple factors — site of block, nature of defect (functional, necrosis, fibrosis), degree of conduction delay, and associated pathologies with their own ECG patterns. Distinguishing RBBB from a normal ECG-variant like rsr′ is particularly important when associated with left hemiblocks as the latter situation warrants extensive cardiac evaluation.

Introduction

Right bundle branch block (RBBB) refers to an electrocardiographic (ECG) pattern resulting from a block or delay in conduction of cardiac impulse through the right branch of the Bundle of His. Depending on the degree of conduction delay, RBBB can be complete (CRBBB) or incomplete (ICRBBB). Definite criteria (Table 1) have been laid down to identify this conduction defect [1], [2]. ECG patterns that meet these criteria often look considerably dissimilar morphologically from one another. Although previously documented, current literature lacks the compilation of these variations to show them side by side. This has formed the basis of the present report. An aetiological correlation to this variation is also explored, electrophysiology outlined and literature reviewed.