Modification of Myocardial Infarct Volume

An experimental model was developed to study the direct effect of propranolol hydrochloride on myocardial infarct volume as produced by a standard coronary artery ligation. A ligature was placed around the left anterior descending coronary artery at the bifurcation of the apical branch in 21 dogs with normal coronary artery distribution. Propranolol hydrochloride (1 mg/kg) was administered intravenously to nine of the dogs one hour after ligation. Six hours after ligation, the left ventricle was sliced and incubated in nitro blue tetrazolium solution. The nonstained muscle was excised and weighed. In this model, the use of a β-adrenergic blocking agent decreased the myocardial infarct volume by 34%. Such an agent may have a place in the treatment of certain patients with myocardial infarction in order to decrease the extent of muscle damage.