Arrhythmias Following Acute Myocardial Infarction

Abstract

The coronary circulation is unique in that the heart is responsible for generating the arterial pressure that is required to perfuse the sys¬temic circulation and yet, at the same time, has its own perfusion impeded during the systolic portion of the cardiac cycle. Because myocardial contraction is closely connected to coronary flow and oxygen delivery, the balance between oxygen supply and demand is a critical determinant of the normal beat-to-beat function of the heart. When this relation is acutely disrupted by diseases affecting coronary blood flow the resulting imbalance can immediately precipitate a vicious cycle and myocardial ischemia. Diseases affecting the coronary blood flow include; coronary artery disease, hypertension and heart failure. The electrophysiological properties of cardiac cells are important in understanding cardiac arrhythmias and their management. Cardiac cells undergo cyclical depolarization and repolarisation to form an action potential. The shape and duration of each action potential are determined by the activity of ion channel protein complexes on the myocyte surface.