When should we diagnose incomplete right bundle branch block?

Abstract

An rSr' pattern with QRS duration of less than 0.12 s in the right precordial leads can be due to incomplete right bundle branch block (which may progress to complete right bundle branch block) or can be a normal electrophysiological variant. To identify other ECG features that may help to distinguish between these two possibilities, ECGs of 15 patients who progressed from normal to complete right bundle branch block through an intermediate rSr' pattern of incomplete right bundle branch block were analysed. The following features in the right precordial leads (V1, V2) that preceded or accompanied the appearance of the rSr' were identified: diminution of the S wave depth (100%), inversion of ratio of the S wave depth to SV1 > SV2 (93%), slurring of the downstroke or upstroke of the S wave (27%) and prolongation of the QRS duration to > or = 0.10 s (73%). When a further 79 subjects with rSr' pattern in the right precordial leads and QRS duration of < 0.12 s were divided into those with SV1/SV2 ratio > 1.0 and those with SV1/SV2 < 1.0, compared with the latter the subjects with SV1/SV2 ratio > 1.0 were found to be significantly older (59.8 +/- 18.4 years vs 32.8 +/- 18.1 years, P < 0.001), to exclusively show S wave slurring (37% vs 0%), and to more likely have a QRS duration > or = 0.10 s (74% vs 7%).(ABSTRACT TRUNCATED AT 250 WORDS)

Striking Similarities in Systemic Factors Contributing to Decreased Exercise Capacity in Patients With Severe Chronic Heart Failure or COPD

“…A substantial part of the patients with COPD had some degree of right ventricular conduction delay, which is a common phenomenon in progressive COPD 28 and can also be a normal electrophysiological variant. 29,30 Since the literature is controversial with respect to the interdependency of left and right ventricular dysfunction, 28,31 some degree of left ventricular dysfunction cannot be excluded in this study. Five patients with COPD had abnormal ECG findings, but none of them had signs of heart failure on physical examination nor used cardiac medication.…”

Differential Diagnosis of rSr’ Pattern in Leads V1-V2. Comprehensive Review and Proposed Algorithm

“…Similarly to the normal variant, in partial RBBB the r’ is of fast inscription, the ST‐segment presents a descending slope without ST‐segment ascent and there is not mismatch between the right and left precordial leads duration. Some electrocardiographic features to differentiate partial RBBB from a normal ECG variant have been described . These may predict progression to advanced RBBB and include: (1) progressive decrease of the S‐wave voltage; (2) slurring of the ascending slope of the S wave (Fig.…”

“…This “normal” rSr’ pattern is more frequent in younger subjects, with male preponderance and by definition is not a precursor of complete (proximal) RBBB. The r’ is of fast ascent/descent inscription and the mechanism is a peripheral conduction delay with late activation of the pulmonary conus and posterobasal portion of the left ventricle …”

“…These may predict progression to advanced RBBB and include: (1) progressive decrease of the S‐wave voltage; (2) slurring of the ascending slope of the S wave (Fig. ); (3) inversion of the ratio of the S‐wave depth to SV1 > SV2; and (4) prolongation of the QRS duration to ≥0.10 second . However, in an isolated tracing with rSr’ (Fig.…”