Benjamin N. Potkin

Coronary artery imaging with intravascular high-frequency ultrasound.

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, cross-sectional images in 21 human coronary arteries from 13 patients studied at necropsy who had moderate-to-severe atherosclerosis. Fifty-four atherosclerotic sites imagined 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 less than 0.0001) for coronary artery cross-sectional area (r = 0.94), residual lumen cross-sectional area (r = 0.85), percent cross-sectional area (r = 0.84), and linear wall thickness (plaque and media) measured at 0 degrees, 90 degrees, 180 degrees, and 270 degrees (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.

Transient ischemic dilation of the left ventricle on stress thallium-201 scintigraphy: a marker of severe and extensive coronary artery disease.

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)

Effects of percutaneous transluminal coronary angioplasty on atherosclerotic plaques and relation of plaque composition and arterial size to outcome

To delineate their relation to outcome of percutaneous transluminal coronary angioplasty (PTCA), the atherosclerotic plaque composition and coronary artery size in 82 five-mm long segments at 28 PTCA sites were determined in 26 patients having PTCA. The 26 patients were subdivided into 3 groups according to the degree of angiographic patency at the end of the PTCA procedure and to the duration of survival after PTCA (less than or equal to 30 or greater than 30 days): early success (13 patients, 16 PTCA sites and 49 five-mm segments); early failure (4 patients, 4 PTCA sites and 16 five-mm segments) and late success (9 patients, 8 PTCA sites and 17 five-mm segments). The mean percent of plaque comprised of fibrous tissue among the 3 groups was 80 +/- 18%, 71 +/- 23% and 82 +/- 16% (difference not significant); the mean percent of plaque comprised of lipid was 17 +/- 16%, 21 +/- 24% and 16 +/- 15% (difference not significant); and of calcium it was 3 +/- 4%, 8 +/- 10% and 2 +/- 3% (p = 0.01). The mean coronary arterial internal diameter was 3.3 +/- 0.6, 3.9 +/- 1.2 and 3.2 +/- 0.7 mm (p less than 0.02). Plaque tear was present in 1 or more histologic sections in 25 of the 26 patients and the 1 patient without it had the longest interval (nearly 3 years) between PTCA and death. Plaque tear extending from intima into media with dissection was observed only in the early and late success groups (p = 0.03). Hemorrhage into plaque was present in 16 (80%) of 20 PTCA sites in the 2 early groups and in 3 (37%) of 8 sites in the late group (p less than 0.03). Occlusive thrombus (5 of 16, 1 of 4 and 1 of 8) and plaque debris (7 of 16, 1 of 4 and 2 of 8) in residual lumens were insignificantly different among the 3 groups and their 82 five-mm segments. Plaques that had greater than 25% lipid content, however, had an increased frequency of hemorrhage into plaque (p less than 0.004), occlusive thrombus (p = 0.0001) and plaque debris in residual lumens (p less than 0.05). These findings suggest that coronary arterial size and plaque composition are strong determinants of PTCA outcome. The ideal coronary arterial atherosclerotic narrowing for both technically and clinically successful PTCA appears to be a small (less than 3.3 mm in internal diameter) artery in which the plaque contains relatively little calcium and lipid.

Mode of death, frequency of healed and acute myocardial infarction, number of major epicardial coronary arteries severely narrowed by atherosclerotic plaque, and heart weight in fatal atherosclerotic coronary artery disease: analysis of 889 patients studied at necropsy

Mode of death, frequency of a healed or an acute myocardial infarct, or both, number of major epicardial coronary arteries severely narrowed by atherosclerotic plaque, and heart weight were studied at necropsy in 889 patients 30 years of age or older with fatal atherosclerotic coronary artery disease. No patient had had a coronary bypass operation or coronary angioplasty. The 889 patients were classified into four major groups and each major group was classified into two subgroups: 1) acute myocardial infarct without (306 patients) or with (119 patients) a healed myocardial infarct; 2) sudden out of hospital death without (121 patients) or with (118 patients) a healed myocardial infarct; 3) chronic congestive heart failure with a healed myocardial infarct without (137 patients) or with (33 patients) a left ventricular aneurysm; and 4) sudden in-hospital death without (20 patients) or with (35 patients) unstable angina pectoris. The mean age of the 687 men (77%) was 60 +/- 11 years, and of the 202 women (23%), 68 +/- 13 years (p = 0.0001). Although men included 77% of all patients, they made up approximately 90% of the out of hospital (nonangina) sudden death group. The frequency of systemic hypertension and angina pectoris was similar in each of the four major groups. The frequency of diabetes mellitus was least in the sudden out of hospital death group and similar in the other three major groups. The mean heart weight and the percent of patients with a heart of increased weight were highest in the chronic congestive heart failure group; values were lower and similar in the other three major groups.(ABSTRACT TRUNCATED AT 250 WORDS)

An in vivo feasibility study of intravascular ultrasound imaging

Increasingly complex vascular reconstructions and emerging endovascular therapeutic modalities have stimulated the need for improved vascular imaging. To determine the feasibility of in vivo intravascular ultrasound, a miniature probe 1 mm in diameter with a 25 MHz center frequency was used to obtain two-dimensional, 360-degree cross-sectional images. In sheep, 14 superficial femoral arteries were imaged at different sites, and a portion of each vessel was resected for immediate in vitro imaging and histologic examination. In vivo images clearly showed the intima, media, and adventitia of the vessel wall as well as the lumen-intima and media-adventitia interfaces. There was a significant correlation in measured lumen area between resected artery ultrasound images and histologic sections. We conclude that intravascular ultrasound can produce high-resolution dynamic images that demonstrate vessel wall architecture and allow precise calculation of lumen area.

Size of coronary sinus at necropsy in subjects without cardiac disease and in patients with various cardiac conditions

Abstract We and others have noted the coronary sinus (CS) to be enlarged in some patients with chronic congestive heart failure and in virtually all patients with drainage of a left superior vena cava into the CS. 1 The CS is receiving increasing attention because of its potential usefulness as a route for retrograde delivery to ventricular myocardium of cardioplegic solutions during cardiopulmonary bypass, of various antiarrhythmic agents during electrophysiologic testing and of blood and blood substitutes for symptomatic myocardial ischemia. In 1984, an entire symposium was devoted to myocardial protection through the CS, and the proceedings from it were published. 2 Despite the increasing interest in the CS, little anatomic information is available in subjects with normal hearts and in patients with abnormal hearts. To fill this void, we measured the circumference of the CS in 50 normal human hearts and in 234 hearts with various cardiac diseases unassociated with intercirculatory shunts.

Aneurysmal coronary artery disease in cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX), first described by van Bogaert et al in 1937,1 is a rare (<100 cases reported), autosomal recessive disease characterized by accumulation of cholesterol and cholestanol in tissues. Its clinical features can include tendon xanthomas, cataracts, neurologic dysfunction (dementia, ataxia, paresis and peripheral neuropathy) and accelerated arterial atherosclerosis. CTX results from a deficiency of a hepatic microsomal enzyme necessary for primary bile acid synthesis from cholesterol. Because bile acid synthesis is impaired, chenodeoxycholic acid in bile is reduced or absent, biliary cholesterol secretion is reduced, and, for reasons uncertain, the hepatic conversion of cholesterol to cholestanol is markedly increased and blood, biliary and tissue cholestanol levels are markedly elevated (Figure 1).2,3 Cholestanol appears to be highly atherogenic and has been demonstrated in most tissues, including the coronary arteries.3 Although accelerated coronary atherosclerosis is believed to be characteristic of this lipid disorder, coronary angiographic findings have not been reported in CTX. Herein, we describe such findings.

Location of an acute myocardial infarct in patients with a healed myocardial infarct: Analysis of 129 patients studied at necropsy

To determine the relation of a single healed myocardial infarct to a fatal acute myocardial infarct, 129 patients with 1 grossly visible healed and 1 grossly visible acute infarct were studied at necropsy. It was determined whether the acute infarct was opposite to or adjacent to the healed infarct or if 1 infarct was so large that it was both opposite to and adjacent to the other infarct. In 74 (57%) of the 129 patients, the 2 infarcts were opposite one another, in 40 (31%) they were adjacent and in 15 (12%) they were both opposite and adjacent. The age, sex, mean size of the healed infarct and heart weight were similar among the 3 groups. Acute myocardial infarcts were larger in the group that had both opposite and adjacent infarcts than either of the other 2 groups (p less than 0.001). Information regarding whether the infarcts were clinically recognized or not was available in 108 patients: both infarcts were recognized in 41 (38%), neither infarct was recognized in 15 (14%) and 1 infarct was recognized and the other was not in 52 (48%). The number of the 4 major epicardial coronary arteries narrowed at some point greater than 75% in cross-sectional area by atherosclerotic plaque was similar in patients with recognized and in those with unrecognized infarcts. Similar numbers of narrowed major epicardial coronary arteries also were found in each of the 3 infarct groups (opposite, adjacent or both).

Delayed Clinical Evidence of Coronary Arterial Disruption After Presumably Successful Percutaneous Transluminal Coronary Angioplasty for Angina Pectoris

1. Griintzig A, Riedhammer HH, Turina M, Rutishauser W. Eine neue Methode zur perkm42:282-285. 2. Griintzig A, Myler R, Hanna LE, Turina M. Transfuminol ongiopfasty of coronary artery stenosis. CircuJation 1977;84:suppJ ll:II-55-11-56. 3. Simpson JB, Bairn DS, Robert EW, Harrison DC. A new catheter system for coronary angiopfasty. Am 1 Cardiol 1982;49:1216-1222. 4. Kaltenbach M. The long wire technique-a new technique for steerable balloon catheter dilatation of coronary artery stenosis. Eur Heart [ 1384; 5:1004-1009. 5. Meier B, Grhntzig AR, King SB III, Douglas JS, Hollman J, Ischinger T, Aueron F, Galan K. Risk of side branch occlusion during coronary angioplasty. Am J Cardiol 1984;53:10-14. 6. Vetrovec GW. Cowlev Ml. Wolfeane TC. Ducev KF. Effects of PTCA on Jesion associate2 brane10:433-443: 8. McAulev Bl. Sheehan DI. Simuson TB. Coronarv annionlastv of stenoses at major bifa7O:suppJ IJ:IJ-108.