In This Report

More Features

Electrocardiogram - ECG - recording

An ECG represents a composite recording of all the action potentials generated by all cardiac muscle cells during each heartbeat. To record an ECG, 12 metal electrodes are positioned on the arms, legs, and chest. These electrodes detect the heart electric activity and transmit it to the electrocardiograph, which amplifies and records the signals.

The twelve electrodes, or leads, are placed on the body to obtain 6 limb leads and 6 chest leads. Together, these leads provide a 3-dimensional representation of the heart electric activity. Each lead is analogous to a video camera recording the same event, atrial and ventricular depolarization, and repolarization from a different angle. Therefore, each limb or chest lead record slightly different electric activity of the heart. This results in the electrocardiograph producing 12 different tracings.

By comparing these recordings with one another, and with normal tracings, physicians can detect heart abnormalities, including the presence of arrhythmia, enlargement of left ventricle, abnormalities in the cardiac conduction system, and damage to certain regions of the heart.


Review Date: 7/3/2013
Reviewed By:
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
© 1997- adam.comAll rights reserved.