VALIDATION OF AN ECHOCARDIOGRAPHIC ASSESSMENT OF CARDIAC FUNCTION FOLLOWING MODERATE SIZE MYOCARDIAL INFARCTION IN THE RAT

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Abstract
1. The present study determined whether two dimensional guided M-mode echocardiography could assess left ventricular (LV) geometry and function following a moderate size myocardial infarction in the rat. 2. Myocardial infarction (MI) was induced by left coronary artery ligation and rats were studied 4 weeks later. Infarct rats showed increased LV internal diastolic diameter (7.33 ± 0.8 vs 5.91 ± 0.6 mm; P > 0.001), LV systolic diameter (3.73 ± 1.2 vs 1.87 ± 0.6 mm; P > 0.001) and thickening of the noninfarcted posterior wall compared with sham operated rats (1.81 ± 0.2 vs 1.47 ± 0.3; P > 0.001; n= 10/group; mean ± s.d.). Systolic function was impaired in infarct rats who showed reduced fractional shortening (50 ± 12 vs 68 ± 9%; P > 0.001) and fractional area change (41 ± 14 vs 78 ± 5%; P > 0.001). Infarct size measured echocardiographically was comparable to that measured by quantitative histological examination (29 ± 10 vs 28 ± 5%; NS). 3. The present study indicates that postinfarction remodelling leading to LV cavity dilation, hypertrophy of surviving myocardium and impaired systolic function is apparent 4 weeks following moderate size MI in the rat. 4. Transthoracic echocardiography is a noninvasive technique that may be used to assess serially the efficacy of therapeutic interventions designed to prevent remodelling in moderate size MI in the rat.