Effects of phentolamine on coronary blood flow in patients with recent myocardial infarction.

Abstract

The myocardial clearance of rubidium may be obtained by praecordial counting after intravenous injection of Rb-minus 86 Cl. Eight patients with recent myocardial infarction had this determination performed before and after the infusion of 10 mg phentolamine at a rate of 0.3 mg/minute. The average predrug myocardial clearance of Rb was 89.3 plus or minus 29.9 ml/min per 100 g myocardium. After phentolamine, the average myocardial clearance rose to 117.3 plus or minus 33.3 ml/min per 100 g myocardium (P LESS THAN 0.01). An explanation for this findings is presented as well as its possible clinical applications.

Regional blood flow and oxygenation of the rabbit heart subjected to acute coronary occlusion — effect of phenoxybenzamine

“…It has been shown that many types of vasodilators can produce "coronary steal" from the area of ischemia (5,6,7). In patients with a recent myocardial infarction, phentolamine, an alpha-adrenergic blocking agent, produces no change or a slight fall in coronary blood flow (12), although in one study flow increased markedly (16). Phentolamine, unlike phenoxybenzamine, appears to increase cardiac contractility and heart rate (3,4,13).…”

“…This would reduce afterload and cardiac work (1,11,13,9). Alphaadrenergic blockers have been reported to have both positive and negative effects in myocardial ischemia (1,2,3,4,16,17). Alphaadrenergic blockers have been reported to have both positive and negative effects in myocardial ischemia (1,2,3,4,16,17).…”

Vasodilator treatment for acute and chronic heart failure.

“…Intravenous phentolamine increases overall myocardial blood flow in patients with acute myocardial infarction, despite a fall in blood pressure (Gould et al, 1975). However, this increase in coronary blood flow may be partly the result of an increase in myocardial oxygen demand, as a result of tachycardia.…”