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SA node and AV node

Electrical pulses in the heart are controlled by special groups of cells called nodes. The SA (sinoatrial) node generates an electrical signal that causes the upper heart chambers (atria) to contract; the signal then passes through the AV (atrioventricular) node to the lower heart chambers (ventricles), causing them to contract, or pump.

The SA node is considered the pacemaker of the heart. Its electrical signals normally cause the atria to contract at a rate of 60 to 100 times per minute.

Disturbance anywhere along this electrical pathway can cause irregular heartbeats (arrhythmia).

Author Robin Parks, MS
Editor Kathleen M. Ariss, MS
Associate Editor Pat Truman, MATC
Primary Medical Reviewer Caroline S. Rhoads, MD - Internal Medicine
Specialist Medical Reviewer Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
Last Updated September 17, 2008

WebMD Medical Reference from Healthwise

Last Updated: September 17, 2008
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