Digoxin distribution in the dog's left ventricle in the presence of coronary artery ligation

Abstract

Tritiated digoxin was administered intravenously to open-chest dogs 1 h after the left anterior descending coronary artery had been ligated. Myocardium was sampled 1 h later in eight animals and 4 h later in two. Themost severely ischemic area of left ventricle contained 3% to 67% of the digoxin concentration of distant left ventricular muscle, a finding which helps explain the poor clinical and hemo-dynamic response to digitalis when a significant portion of the ventricle is infarcted. No zone of increased digoxin uptake was demonstrated in muscle contiguous with the ischemic area, the concentration residing between that of the maximally ischemic and distant areas. The significant uptake in this boundary zone which is often the site of ectopic impulse formation may, however, explain the additive effects of digitalis and ischemia or infarction in producing ventricular arrhythmias.