The pharmacology of the normal and diseased heart in relation to cardiac surgery.

Recent advances in the treatment of arrhythmias have stemmed from careful observation and monitoring in postoperative intensive care areas and from the renewed interest of physicians in the arrhythmias after myocardial infarction. The basic treatment of arrhythmias is the same whenever they occur. Although a knowledge of the electrophysiological changes leading to arrhythmias (Hoffman and Cranefield, 1964; Hoffman, Cranefield and Wallace, 1966) is helpful, it is seldom possible to define precisely what the mechanism is in a particular case. Much is known about the pharmacological properties of anti-arrhythmic drugs and their action on myocardial cells (Singer and Ten Eick, 1969) and this has led to some rationalization of therapy, but there are still wide gaps in our knowledge between the basic causes of arrhythmias and the ways in which drugs act to influence them. Therapy is still largely based on clinical experience. Anti-arrhythmic drugs can be divided into four main groups.