INTRAVASCULAR ULTRASOUND EVALUATION OF PLAQUE DISTRIBUTION AT CURVED CORONARY SEGMENTS

Although the distribution of atherosclerosis at the curved coronary si gments has implications for atherogenesis and interventional procedure s, few data exist regarding the plaque distribution in these sites. Th erefore, we prospectively analyzed the intravascular ultrasound images of 55 coronary sites from 37 patients where the atherosclerotic plaqu e and pericardium were simultaneously demonstrated by intravascular ul trasound. The pericardial images were defined as a high-intensity line ar echo image moving during cardiac cycles outside the vessel wall. By the line that was parallel to the pericardial image, the vessel area was divided into 2 semicircles with the same area, namely myocardial a nd pericardial sides. In each side, the maximal thickness, area, and p ercent area of plaque were measured. The plaque thickness and area of the myocardial side were significantly greater (1.5 +/- 0.5 mm, 4.9 +/ - 2.1 mm(2) or 66%, mean +/- SD) than those of the pericardial side (1 .1 +/- 0.4 mm, 3.5 +/- 2.1 mm(2) or 45%, p <0.01). The maximal plaque thickness was positioned at the point with a mean angle of 139 +/- 37 degrees from the point just facing the pericardial image, indicating t hat atherosclerosis was eccentrically located on the opposite side of the pericardium in these coronary segments, and suggesting that the si de of the pericardial image represents the outer curvature of the coro nary artery. These results indicate that the pericardial images can be seen by intravascular ultrasound, facilitating the recognition of the disease distribution in situ. The eccentric plaque located on the inn er wall at the curved coronary segments, probably due to uneven local shear stress, may have implications for the interventional procedures for these segments. (C) 1998 by Excerpta Medica, Inc.