Several tests can help your doctor diagnose an arrhythmia (View an animation of arrhythmia). Identifying, or documenting an arrhythmia requires recording the heart's activity using an electrocardiogram (ECG or EKG). Small patches or stickers, called electrodes, are placed on different parts of the body. One is put on each arm and leg and several across the chest. They don't hurt. With various combinations of these electrodes, different tracings of the heart's electrical activity can be made and permanently recorded on paper or in a computer.
Three major waves of electric signals appear on the ECG. Each one shows a different part of the heartbeat.
- The first wave is called the P wave. It records the electrical activity of the atria.
- The second and largest wave is the QRS wave. It records the electrical activity of the ventricles.
- The third wave is the T wave. It records the heart's return to the resting state.
Doctors study the shape and size of the waves, the time between waves and the rate and regularity of beating. This tells a lot about the heart and its rhythm.
This content was last reviewed on 05/30/2012.