SECTION OF ELECTROPHYSIOLOGY AND PACING

www.clevelandclinic.org/heartcenter Appointments: (216) 444-6697

© The Cleveland Clinic Foundation 2005 182488 Rev. 5/05

THE HEART’S ELECTRICAL SYSTEM

Sinoatrial (SA)NodeThe electrical impulsebegins at the SA node,located in the rightatrium. The electricalactivity spreads throughthe walls of the atria andcauses them to contract.

The atria andventricles work

together, alternatelycontracting and

relaxing to pump bloodthrough the heart. The

electrical system ofthe heart is the powersource that makes this

possible.

AV NodeThe AV node is located betweenthe atria and ventricles and actslike a gate that slows the electricalsignal before it enters the ven-tricles. This delay gives the atriatime to contract before the ven-tricles do.

Aorta

Pulmonary artery

His-Purkinje NetworkThis pathway of fibers sends theimpulse into the muscular walls ofthe ventricles and causes them tocontract.

Pulmonaryveins