Impact of nitroglycerin and verapamil on coronary arterial distensibility as assessed by intravascular ultrasound.
OBJECTIVE
To examine the effects of coronary artery vasodilators on coronary arterial distensibility using intravascular coronary ultrasound (IVUS).


BACKGROUND
There is limited information on the effect of coronary artery vasodilators on coronary arterial distensibility.


METHODS
We studied 20 patients using IVUS. Patients received 100 microg of nitroglycerin (10 patients) or 1 mg of verapamil (10 patients) intravenously. We measured coronary arterial elasticity, the distensibility index, compliance and stiffness index. There were no differences in patient characteristics, lesion characteristics or baseline coronary arterial distensibility between the two groups.


RESULTS
Systolic and diastolic blood pressure decreased in both groups (p < 0.05). Maximal coronary arterial cross-sectional luminal area (LA) during the cardiac cycle showed similar dilation in both groups. Nitroglycerin increased maximal LA by 5%, and verapamil increased it by 4% (p < 0.05; p < 0.0001, respectively). However, the degree of dilation of the minimal LA during the cardiac cycle showed a different pattern. Nitroglycerin dilated the minimal LA by 8%, while verapamil dilated the minimal LA by 2% (p < 0.001, p < 0.05, respectively). Consequently, the degree of expansion of LA during each cardiac cycle increased in the verapamil group and decreased in the nitroglycerin group. Thus, nitroglycerin decreased elasticity by 31% (p < 0.001), with no change in compliance, stiffness index or distensibility index. While, verapamil increased elasticity by 37%, the distensibility index by 48% and compliance by 53%, and decreased the stiffness index by 27% (all, p < 0.0001).


CONCLUSIONS
While both drugs acutely dilate the coronary arteries, nitroglycerin reduced local coronary arterial distensibility; however, verapamil increased local coronary arterial distensibility.
Akima
Takashi
T
Cedars-Sinai Medical Center, Los Angeles, California 90048, USA.
Makkar
Rajendra
R
Nishioka
Toshihiko
T
Dohad
Suhail
S
Iida
Kiyoshi
K
Goland
Sorel
S
Kar
Saibal
S
Luo
Huai
H
Siegel
Robert J
RJ