title: Impact of nitroglycerin and verapamil on coronary arterial distensibility as assessed by intravascular ultrasound.
abstract: 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.
authors.affiliation: Cedars-Sinai Medical Center, Los Angeles, California 90048, USA.
authors.forename: Takashi
authors.initials: T
authors.lastname: Akima
authors.forename: Rajendra
authors.initials: R
authors.lastname: Makkar
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nishioka
authors.forename: Suhail
authors.initials: S
authors.lastname: Dohad
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Iida
authors.forename: Sorel
authors.initials: S
authors.lastname: Goland
authors.forename: Saibal
authors.initials: S
authors.lastname: Kar
authors.forename: Huai
authors.initials: H
authors.lastname: Luo
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Siegel