Estimating Collateral Circulation

losses as well as nitroglycerin and digitalis glycosides were applied with favorable effect to cardiovascular risk patients during the perioperative period.1 3 Frequency of myocardial infarctions and of heart failure during the early postoperative period suggest that in coronary artery disease adrenergic overactivity induces myocardial necrosis and augments the surrounding or preceding "twilight zone"4 of failing, but not yet irreversibly damaged myocardium. Therefore in a pilot study practolol was applied before and after major surgical interventions to patients with high cardiovascular risk, characterized by hypertension . 160/95 mm Hg and/or old myocardial infarction and/or combined coronary artery, cerebrovascular and arterial occlusive disease.' Doses ranged between 100 and 300 mg orally and 10 to 15 mg intravenously per day. In the practolol treated group no myocardial infarction occurred during treatment. In one patient an infarction led to death six days after omitting the drug. Another patient, who was operated on for a second time without practolol treatment, died two days after operation from an acute myocardial infarction. Incidence of heart failure and mortality rate were lower and no adverse reactions were noted. In a recently published study6 Dr. H. S. Mueller and coworkers report similar results using propranolol after acute myocardial infarction. It is concluded that betareceptor blockade probably protects high risk patients against hypoxemic heart failure, progression of necrosis and cardiogenic shock by reduction of an extremely high and long lasting elevation of oxygen demand following stressful operations. ERICH VORMIITTAG, M. D. I. Chir. Universitatsklinik Vienna, Austria