High resolution miniature trans-esophageal echocardiography is useful to evaluate atherosclerosis and the effects of alacepril in hyper-cholesterol rabbits.

Abstract

This study tested the efficacy of high resolution miniature transesophageal echocardiography (m-TEE; 3.5 mm-diameter probe, 7.5 MHz, axial resolution of 0.25 mm) in the evaluation of atherosclerotic lesions of the thoracic aorta rabbits exposed to a high cholesterol diet. The effects of the ACE inhibitor Alacepril (90 mg/kg) on atherosclerosis were also assessed in normotensive, high cholesterol-diet rabbits by m-TEE, both in situ and in vitro. Oral treatment with Alacepril was begun on confirmation of atherosclerosis after a three month high cholesterol diet (group AL). Ultrasound examination reliably distinguished the lesions of atherosclerosis in situ. A three month course of Alacepril treatment decreased the systolic and diastolic blood pressures by approximately 20 and 5 mmHg, produced a regression of atherosclerosis and significantly decreased the intimal plus medial thickness compared with hyperlipidemic-controls (group HC) (1.0 + 0.3 vs 1.6 + 0.4 mm, p < 0.02). The intimal surface involvement area in group AL was marginally smaller than in group HC (57 + 23 vs 76 + 23%, p = 0.06). The high dose of Alacepril in this study did not affect the serum levels of t-cholesterol, HDL-C, LDL-C, triglycerides, or apoproteins A-I and B. These results suggest that Alacepril can produce regression of atherosclerosis, without changing circulating lipoprotein or apoprotein levels. Further miniature TEE offers high repeatability and is useful both in situ and in vitro for determining changes in arterial wall thickness and the severity of atherosclerosis.