Search

We measured coronary sinus blood flow by continuous thermodilution technique and aortic pressure after administration of diltiazem to 23 patients with coronary artery disease. In one group of patients (n = 12) the drug was infused at a rate of 0.15 mg/kg during 2 min followed by an infusion of 0.05 mg/kg during 8 min. Heart rate was unchanged except at 5 min when it decreased slightly. Aortic pressure was significantly (p less than 0.01) decreased, while coronary sinus flow increased slightly and transiently. A second group of patients (n = 5) received an intracoronary injection of 0.15 mg/kg of diltiazem into the left coronary artery. In a third group of patients (n = 7) 0.05 mg/kg of diltiazem was injected into the left coronary artery. In both these two groups the drug induced a marked increase of coronary sinus flow and a decrease of aortic pressure, while myocardial oxygen consumption was unchanged. This effect was dose related, since the rise in coronary flow was 47% with an injection of 0.15 mg/kg but only 23% with a dose of 0.05 mg-kg. These changes were short-lasting with values returning to normal within 10 min after the injection. We conclude that diltiazem is a potent dilator of coronary arteries.

This study determines, with quantitative variables, if propranolol is detrimental in patients with documented coronary arterial spasm and if this drug can be used in combination with calcium antagonists. Eleven patients with documented coronary spasm were entered prospectively in a study with 4 phases of 2 days each: (1) control, (2) diltiazem or propranolol (mean 225 +/- 75 mg/day), (3) propranolol or diltiazem (360 mg/day), (4) propranolol and diltiazem. The effects of the drugs were assessed by the detection of ischemic electrocardiographic episodes (24-hour electrocardiographic monitoring) and provocative tests with ergonovine. During the period of treatment with propranolol, the number and the duration of attacks increased and provocative tests had positive results in all patients. Diltiazem completely abolished spontaneous episodes, but 6 of 11 patients remained sensitive to the administration of ergonovine. The association of the 2 drugs led to a disappearance of ischemic episodes. In conclusion, propranolol is ineffective in patients with coronary artery spasm. It can be used in combination with diltiazem, but without any advantage over diltiazem alone.