Peripheral conduction disease in left ventricular dysfunction

Abstract

Several studies have correlated conduction abnormalities on the 12-lead electrocardiogram (ECG) with echocardiographic findings.1–3 Echocardiographic studies on left bundle branch block (LBBB) produce variable findings that are related to the underlying cardiac pathophysiology. However, paradoxical septal motion on echocardiography is seen in most and is presumed secondary to abnormal septal activation related to a proximal conduction abnormality. We have previously reported that nonspecific widening of the QRS complex in the absence of typical electrocardiographic criteria for right bundle branch block (RBBB) or LBBB is associated with evidence of left ventricular (LV) dysfunction.4 Although the mechanism of QRS widening was unknown, it was hypothesized that increased LV fibrosis in the presence of LV dysfunction led to an intraventricular conduction delay (IVCD), suggesting the presence of peripheral conduction disease. The present report has 3 purposes: (1) to support the existence of peripheral conduction disease by evaluating upper septal motion on echocardiography in patients with typical electrocardiographic criteria for either an IVCD or LBBB—peripheral conduction block was presumed in the presence of normal upper septal motion (no paradoxical septal motion) using echocardiography; (2) to compare LBBB versus IVCD in relation to echocardiographic findings of LV dysfunction; and (3) to compare the LV echocardiographic systolic function in patients with LBBB and paradoxical septal motion in comparison with normal septal motion.