Experimental coronary artery occlusion: Ventricular fibrillation and survival as affected by selected drugs and ionic alterations

The effect of drugs and ions upon the normal heart and upon isolated myocardium has been thoroughly investigated and adequately documented. Increased interest in the application of these substances in a manner which approaches the abnormal clinical situation-that is, following coronary artery occlusion and in various arrythmias-has been demonstrated during the past few years. The stimulus for this recent investigative trend has come primarily from three sources: (1) Fibrillation following coronary artery occlusion and the efforts to devise means of permanently increasing collateral blood supply to the myocardium; (2) Cardiac arrest or ventricular fibrillation during surgery; and (3) Ventricular fibrillation during hypothermia. This report concerns experimental myocardial ischemia produced by acute coronary artery occlusion, the influence of drugs and inorganic ions on survival rates and early fibrillation and the influence on certain ions upon other ions. Materials and Methods Adult mongrel dogs were used as the experimental animals. Following anesthetization with intravenous nembutal, endotracheal intubation was accomplished and the chest opened by an incision in the fourth inter-space. The left coronary, circumflex coronary, and left anterior descending coronary arteries were carefully demonstrated. A heavy silk ligature was placed beneath the anterior descending branch immediately adjacent to its origin. The loose ligature was threaded through a small plastic tube which was anchored to the pericardium at one end and brought out through the chest wall at the other end. Following closure of the chest wall, the ligature ends and plastic tube were placed subcutaneously, the animal was given penicillin and returned to his cage.