bundle branch block
Delay or blockage in electrical conduction through the heart's bundle branches.
Full Definition
Bundle branch block refers to a delay or interruption in electrical conduction through either the right bundle branch (RBBB) or left bundle branch (LBBB) of the cardiac conduction system. This results in asynchronous ventricular activation, with the affected ventricle being activated later through muscle-to-muscle conduction rather than through the specialized conduction system. On ECG, bundle branch blocks appear as widened QRS complexes (≥120 ms) with characteristic morphologies. LBBB often indicates underlying structural heart disease and may warrant cardiac resynchronization therapy, while RBBB can occur in healthy individuals but may also indicate pulmonary or right heart disease.
Usage
Usage note: Specify left or right; distinguish from AV blocks and fascicular blocks.
In Context
- "The ECG demonstrated new left bundle branch block concerning for acute coronary syndrome." — Emergency assessment
- "Right bundle branch block was noted as an incidental finding on routine ECG." — Screening examination