Arrhythmias or dysrhythmias are abnormal heart rhythms. They can cause the heart to pump less effectively. Normally the heartbeat starts in the right atrium when a special group of cells sends an electrical signal. The A-V node connects to a group of fibers in the ventricles that conduct the electric signal. This exact route must be followed for the heart to pump properly.
Cardiac arrhythmia is the leading cause of death in the Western world.
Every minute a person in the United States dies instantly and unexpectedly, such that, in the United States alone, as many as 400,000 people die suddenly each year. Although approximately seventy-five percent of sudden death victims have a history of heart disease or damage, arrhythmias may strike young and apparently healthy men and women. In addition, among those who have heart disease, it is usually an acute lethal arrhythmia rather than sudden deterioration of the heart that kills. Under some conditions almost all heart tissue can start a heartbeat. In other words, another part of the heart can become the pacemaker.