How serious is bundle branch block?

Ask the doctor

Published: August, 2020

Q. A recent electrocardiogram showed that I have a right bundle branch block. My doctor says it's fairly common and nothing to worry about, but I'm a bit concerned. What is it, exactly? And what specifically can cause this problem?

A. Bundle branch block refers to a small glitch in the heart's electrical conduction system. The term "bundle" refers to a collection of nerve fibers that receive the "contract now" signal from the atrioventricular node and relay it to the ventricles, the heart's lower chambers (see illustration).

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