[Evaluation of coronary vasomotricity by intracoronary ultrasonography]

Coronary vasomotion dependent on the endothelium and on the smooth muscle has been intensively studied by quantitative angiography and intracoronary Doppler. Intracoronary ultrasound is a new imaging technique which allows precise measurement of the section of the coronary artery. This study was undertaken to assess the value of intracoronary ultrasound in the investigation of epicardial coronary artery vasomotion. Twenty hypercholesterolaemic patients with irregularity of the arterial lumen on angiography and 6 normo-cholesterolaemic subjects with normal coronary angiogram (control group) were included. An intracoronary ultrasonic catheter with a rotating mirror (4.3 French, CVIS) emitting at 30 MHz was positioned in the proximal segment of a coronary artery. Endothelial function was studied during sympathetic stimulation by a cold pressor test and during increased coronary flow by local injection of papaverine. The intima of the coronary arteries of the patient group was significantly thicker than that of the control group. The cold test induced significant paradoxical vasoconstriction of the atheromatous coronary arteries and a significant vasodilatation of the coronary arteries of the control group. The increased coronary flow tended to constrict the ateromatous arteries but significantly dilated the normal arteries. Administration of Linsidomine (SIN-1) induced vasodilatation by direct relaxation of the smooth muscle in both groups. No correlation was observed between the thickness of the intima measured by intracoronary ultrasound and the abnormal vasomotor response to the vasomotion different stimuli. The results of this study concord with those of studies of coronary by quantitative angiography. Intracoronary ultrasound provides an accurate method of studying coronary endothelial function and the vasomotor tone of the epicardial coronary arteries.