Rhythm was the first expression of cardiac activity which fell under man's obser vation, and the heart beat has always represented the very essence of life itself as it accelerates or slows during moments of rest, effort, joy and pain until it comes to a halt at the moment of death. Undoubtedly the heart beat was, for a considerable time, the only semiological element by which man could interpret the dysfunctions of the organism. Even after thousands of years, research into the alterations of cardiac rhythm still holds a certain fascination, although modern methods and sophisticated devices...