For example, if a main artery becomes blocked, blood flow is stopped to part of the heart. The heart loses its synchrony because all parts of it no longer function properly and arrhythmia occurs. Arrhythmias can cause the heart to beat either slower or faster than the normal rate of 60 to 100 beats per minute. This situation can lead to a potentially fatal condition called ventricular fibrillation, in which the heart quivers rapidly instead of pumping blood. If left untreated, the patient could die within minutes.
Treatments vary for each type of arrhythmia.
Excessive slowing of the heart often requires the implantation of an electronic pacemaker under the skin. Arrhythmias that result in an accelerated heart rate can be classified as either atrial or ventricular fibrillation. According to the American Heart Association in Dallas, atrial fibrillation causes about 15 percent of strokes per year when blood clots develop in the atria and move to an artery in the brain. This type of fibrillation is often treated with medication to prevent clotting. Ventricular fibrillation, the most serious type of fibrillation, is involved in a large number of the 250,000 sudden cardiac deaths in the United States each year.