M. Ishihara et al., EFFECTS OF VARIOUS DOSES OF INTRACORONARY VERAPAMIL ON CORONARY RESISTANCE VESSELS IN HUMANS, Japanese Circulation Journal, 61(9), 1997, pp. 755-761
To investigate the vasodilatory effect of various doses of intracorona
ry verapamil on coronary resistance vessels, we studied 13 patients wi
th normal angiograms. A coronary Doppler guide wire was inserted into
the left anterior descending coronary artery, and coronary blood flow
velocity (CBFV) was measured. Verapamil was injected into the left cor
onary artery at doses of 0.1 mg, 0.5 mg, 1.0 mg, and 2.0 mg at 10-min
intervals. Nitroglycerin was also injected into the same artery to avo
id changes in cross-sectional area. As a measure of coronary vascular
resistance, coronary vascular resistance index (CVRI) was calculated a
s the quotient of mean aortic pressure/CBFV. An injection of verapamil
produced a dose-dependent increase in CBFV: 79+/-38% with 0.1 mg, 131
+/-56% with 0.5 m.g, 143+/-46% with 1.0 mg, and 128+/-47% with 2.0 mg
of verapamil. The percent peak decreases in CVRI were dose dependent:
-42+/-13% with 0.1 mg, -50+/-17% with 0.5 mg, -62+/-14% with 1.0 mg, a
nd -60+/-9% with 2.0 mg of verapamil. Thus, intracoronary verapamil pr
oduces a dose-dependent dilation of coronary resistance vessels, and t
he optimal effect is produced with an injection of verapamil at a dose
of 1.0 m.g into the left coronary artery. At this dose, verapamil did
not affect atrioventricular conduction.