Effects of dilazep on regional myocardial blood flow during selective coronary hypotension

Effects of 1,4-bis-[3-(3,4,5-trimethoxybenzoyloxy)-propyl]-perhydro-1,4-diazepine (dilazep), a powerful coronary dilator via adenosine potentiation, on regional blood flow during acute selective coronary hypotension were studied in the canine heart under anesthesia and thoracotomy. The proximal left circumflex coronary artery (LCX) was partially obstructed and mean LCX pressure distal to obstruction was reduced to 40-45 mmHg and two different doses of dilazep were given i.v. The left ventricular free wall and interventricular septum were divided into normally perfused, borderline ischemic, moderately ischemic and severely ischemic area according to the level of regional myocardial blood flow measured by tracer microspheres. 50 microgram dilazep/kg b.w. increased myocardial flow in the normally perfused and borderline ischemic areas without a significant alteration of blood flow to the moderately and severely ischemic areas. The fall of aortic pressure was more striking in dogs receiving 100 microgram dilazep/kg b.w. than in animals with 50 microgram dilazep. 100 microgram dilazep increased flow in the normally perfused area, but increased the number of segments in the moderately and severely ischemic area. These results indicate that an appropriate dose of dilazep causing a slight reduction of aortic pressure increased flow to the borderline ischemic as well as normally perfused myocardium in selective coronary hypotension.