A slowed heartbeat, or bradycardia, causes a person to feel fatigued, dizzy, and lightheaded and may trigger fainting spells. Rapid heartbeat, or tachycardia, can also cause inefficient blood circulation. During an episode of tachycardia, a person may feel palpitations, rapid heart action, dizziness, lightheadedness, and may faint. Ventricular arrhythmias . The most severe and life-threatening arrhythmias affect the beating of the ventricles, the main pumping chambers of the heart.
Ventricular tachycardia is a rapid heartbeat arising in the ventricles.
Ventricular fibrillation occurs when the ventricles go out of control, quivering and beating ineffectively, stopping the pumping action. The Power of Electricity to Help the Heart Since the 1800s, pioneering researchers have pondered the use of electricity to stimulate a too-slow heartbeat and worked to find methods to deliver an electrical charge to stop fibrillation . A New York cardiologist, Albert Hyman, MD, invented the first artificial cardiac pacemaker in the 1930s, but its power supply lasted only a few minutes. By 1960, researchers had developed temporary cardiac pacemakers that could be used in hospitals. Today s smaller permanent cardiac pacemakers are widely used.