Abstract
We investigated the vasodilative effects of various doses of intracoronary diltiazem on coronary resistance vessels. Nine patients with normal angiograms were studied. A coronary Doppler guide wire was inserted into the left anterior descending coronary artery. Diltiazem, in doses of 0.1 mg, 0.5 mg, 1.0 mg, 2.0 mg and 4.0 mg, was injected into the left coronary artery at 10 min intervals and coronary blood flow velocity was measured. The coronary artery was pretreated with intracoronary nitroglycerin to avoid changes in the cross-sectional area. As a measure of the change in coronary vascular resistance, a coronary vascular resistance index (CVRI) was calculated as mean aortic pressure/coronary blood flow velocity. An injection of diltiazem into the left coronary artery caused a significant dose-dependent decrease in CVRI. A dose of 2.0 mg was the lowest dose on the plateau of the dose-response curve. In conclusion, the injection of diltiazem into the left coronary artery causes a dose-dependent dilatation of coronary resistance vessels, and the maximal effect can be produced with a dose of 2.0 mg.
