An electrocardiogram, also know as an EKG or ECG, is used to measure the electrical activity of the heart. The electrocardiogram produces a continuous drawing on graph paper. The waves and intervals of the EKG relate to stages of electrical activity during a heartbeat. The parts of an EKG reading include the heart rate, sinus rhythm, QRS axis, P waves, PR interval, QRS complex, ST segments, T waves, and U waves.
To perform an EKG, leads that detect electrical activity are placed at various places on the body including the chest, arms and legs. During a typical EKG, you are lying down and the test lasts for only a few minutes.
An EKG may be performed as a routine screening procedure or in response to symptoms such as angina (chest pain).
An EKG is also used as part of the exercise stress test. During an exercise stress test, the individual is hooked up to the EKG machine and then proceeds with exercise, usually walking on a treadmill.
Monitoring the EKG during increased levels of exercise allows the doctor to see how the heart is working during times of increased work. During the exercise stress test, your blood pressure is often monitored and you may be asked to blow air into a tube to measure lung function.
Like the typical EKG, the exercise stress test helps doctors identify potential coronary artery disease, problems with blood flow, and diagnose the cause of symptoms such as chest pain. The exercise stress test also lets doctors determine how much exercise an individual can safely perform.