Cardioversion: Electrical system of the heart

Picture of the heart's electrical system

In the normal heart, electrical impulses pace the rhythm at which the heart contracts and relaxes. The sinoatrial (SA) node triggers the electrical impulse, causing the upper chambers (atria) to contract. The signal travels through the atrioventricular (AV) node to the atrioventricular bundle, which divides into the Purkinje fibers that carry the signal and cause the lower chambers (ventricles) to contract. The electrocardiogram (EKG, ECG) tracing above reflects this normal electrical activity.

Last Updated: December 18, 2008

Medical Review: Caroline S. Rhoads, MD - Internal Medicine & John M. Miller, MD - Electrophysiology

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