The Role of Necrosis in the Origin of Electrocardiographic Alterations Characteristic of Myocardial Infarction

Action of Necrotic Tissue on the Intact Myocardium and the Method of Study T HE METHOD of monophasic or unipolar leads is used in all the diverse fields of electrophysiology: one electrode is placed on an altered section of the myocardium, nerve, or muscle. However, the reason for the registration of unipolar or monophasic waves by this method has yet to be explained. Injured tissue is a good physical conductor and therefore should, it seems, be in itself a continuance of the registering electrode and thus insure the registration of the action potential from the intact tissue, neighboring the altered region. The injured tissue also does not have rectifier properties. It is therefore impossible to explain the "indifference" of the electrode placed on the injured tissue by the physiologic properties of the latter. We therefore decided to try to explain this phenomena of unipolar leads by the action of the necrotic tissue on the adjacent intact myocardial structures. To study this problem in simple and easily controllable experimental conditions we decided against employing the usual method of forming a section of necrotic tissue by injuring the myocardial structures. Instead a strip of necrotic tissue was placed on the surface of the intact myocardium. This strip of tissue was originally taken from a skeletal muscle or from the ventricle and they were permanently injured beforehand. One of the registering electrodes was placed on the sur-