Ventricular tachycardia is an abnormally fast heart rate. The abnormal heart rate originates in one of the heart's lower chambers (ventricles). It is diagnosed when there are three or more beats in succession originating from a ventricle. The heart beats at a rate greater than 100 beats per minute, but less than 200 beats per minute.

Heart Chambers and Valves

The ventricles are the large lower chambers of the heart. They are responsible for moving blood to the organs and tissues of the body. In ventricular fibrillation, the heart’s ventricles contract in a rapid and chaotic manner. As a result, little or no blood is pumped from the heart. Unless emergency medical help is provided immediately, ventricular fibrillation will lead to cardiovascular collapse and sudden death.