Electrocardiogram (EKG, ECG) tracing

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Electrocardiogram (EKG, ECG) tracing

Electrocardiography (EKG, ECG) tracings show a characteristic pattern of electrical impulses that are generated by the heart. The different parts of an EKG tracing of a heartbeat are called the P wave, the QRS complex, the ST segment, and the T wave.

See a picture of EKG components and intervals .

The P wave is a record of the movement of electrical activity through the upper heart chambers (the atria) and is recorded when they contract.
The QRS complex is a record of the movement of electrical impulses through the lower heart chambers (the ventricles) and is recorded when they contract.
The ST segment appears as a straight, level line between the QRS complex and the T wave. Elevated or lowered ST segments may mean the heart muscle is damaged or not receiving enough blood.
The T wave corresponds to the period when the lower heart chambers are relaxing and preparing for their next muscle contraction.

Credits

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Author	Robin Parks, MS
Editor	Kathleen M. Ariss, MS
Editor	Marianne Flagg
Associate Editor	Pat Truman, MATC
Associate Editor	Terrina Vail
Primary Medical Reviewer	Caroline S. Rhoads, MD - Internal Medicine
Specialist Medical Reviewer	Robert A. Kloner, MD, PhD - Cardiology
Last Updated	August 25, 2008

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Last updated:	August 25, 2008
Author:	Robin Parks, MS
Reviewed By:	Caroline S. Rhoads, MD - Internal Medicine, Robert A. Kloner, MD, PhD - Cardiology
Editors:	Marianne Flagg, Terrina Vail

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