Safe and effective clinical application of new interventional therapies may require more precise imaging of atherosclerotic coronary arteries. To determine the reliability of catheter-based intravascular ultrasound as an imaging modality, a miniaturized prototype ultrasound system(1-mm transducer; center frequency, 25 MHz) was used to acquire two-dimensional, crosssectional images in 21 human coronary arteries from 13 patients studied at necropsy who had moderate-to-severe atherosclerosis. Fifty-four atherosclerotic sites imaged by ultrasound were compared with formalin-fixed and fresh histological sections of the coronary arteries with a digital video planimetry system. Ultrasound and histological measurements correlated significantly (all p<0.0001) for coronary artery cross-sectional area (r=0.94), residual lumen cross-sectional area (r=0.85), percent cross-sectional area narrowing (r=0.84), and linear wall thickness (plaque and media) measured at 00, 90°, 1800, and 2700 (r=0.92). Moreover, ultrasound accurately predicted histological plaque composition in 96% of cases. Anatomic features of the coronary arteries that were easily discernible were the lumen-plaque and media-adventitia interfaces, very bright echoes casting acoustic shadows in calcified plaques, bright and homogeneous echoes in fibrous plaques, and relatively echo-lucent images in lipid-filled lesions. These data indicate that intravascular ultrasound provides accurate image characterization of the artery lumen and wall geometry as well as the presence, distribution, and histological type of atherosclerotic plaque. Thus, ultrasound imaging appears to have great potential application for enhanced diagnosis of coronary atherosclerosis and may serve to guide new catheter-based techniques in the treatment of coronary artery disease. (Circulation 1990;81:1575-1585

Rotational atherectomy causes atheroablation with only moderate evidence of barotrauma in heavily calcified arteries, even after adjunct balloon angioplasty. The lumen is cylindrical, especially in areas of calcified plaque, and somewhat larger than the largest burr tip used.

Intravascular ultrasound is more sensitive than angiography for identifying arterial calcium and dissection at the site of angioplasty. At the site of angioplasty, arterial dissection occurred more frequently in calcified plaques whereas arterial expansion occurred more frequently in noncalcified plaques. Successful angioplasty causes a continuum of arterial responses that vary importantly with plaque composition.

On exercise thallium-201 scintigraphy, it has been noted that the size of the left ventricle is sometimes larger on the immediate poststress image than on the 4 hour redistribution image; this phenomenon has been termed transient ischemic dilation of the left ventricle. The angiographic correlates of this finding were assessed in 89 consecutive patients who underwent both stress-redistribution thallium-201 scintigraphy and coronary arteriography. A transient dilation ratio was determined by dividing the computer-derived left ventricular area of the immediate postexercise anterior image by the area of the 4 hour redistribution image. In patients with a normal coronary arteriogram or nonsignificant coronary stenoses (less than 50%), the transient dilation ratio was 1.02 +/- 0.05 and, therefore, an abnormal transient dilation ratio was defined as greater than 1.12 (mean + 2SD). The transient dilation ratio was insignificantly elevated in patients with noncritical coronary artery disease (50 to 89% stenosis) (1.05 +/- 0.05) and in patients with critical stenosis (greater than or equal to 90%) of only one coronary artery (1.05 +/- 0.05). In contrast, in patients with critical stenoses in two or three vessels, the transient dilation ratio was significantly elevated (1.12 +/- 0.08 and 1.17 +/- 0.09, respectively; p less than 0.05 compared with all other patient groups). An abnormal transient dilation ratio had a sensitivity of 60% and a specificity of 95% for identifying patients with multivessel critical stenosis and was more specific (p less than 0.05) than were other known markers of severe and extensive coronary artery disease, such as the presence of multiple perfusion defects or washout abnormalities, or both.(ABSTRACT TRUNCATED AT 250 WORDS)