Intraventricular Conduction Abnormalities

An intraventricular conduction abnormality refers to a conduction disturbance in either the right or left bundle branch or in 1 of the 2 divisions (fascicles) of the left bundle branch. A delay in conduction or block in either the right or left bundle is commonly referred to as a bundle-branch block (BBB; right or left). A delay in conduction through one of the fascicles associated with the left bundle is referred to as a hemiblock or fascicular block. This column will describe the anatomy of the intraventricular conduction system, with a focus on etiologies of bundle-branch blocks and the electrocardiographic criteria associated with each.