ECG (EKG) (electrocardiogram)
A record of the electrical impulses that immediately precede contraction of the heart muscle. The waves produced are known as the P,Q,R,S and T waves. An ECG is a useful means of diagnosing disorders of the heart, many of which produce deviations from normal electrical patterns. Electrocardiography causes no discomfort. Electrodes connected to a recording machine are applied to the chest, wrists, and ankles. The machine displays the electrical activity in the heart as a trace on a moving graph or on a screen. An ECG can be taken at home; a 24-hour record can be obtained from a tape recorder worn by the patient.