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

1. The present study determined whether two dimensional guided hi-mode echocardiography could assess left ventricular (LV) geometry and func tion following a moderate size myocardial infarction in the rat. 2. My ocardial 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 opera ted 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 red uced fractional shortening (50 +/- 12 vs 68 +/- 9%; P<0.001) and fract ional area change (41 +/- 14 vs 78 +/- 5%; P<0.001). Infarct size meas ured echocardiographically was comparable to that measured by quantita tive histological examination (29 +/- 10 vs 28 +/- 5%; NS). 3. The pre sent study indicates that postinfarction remodelling leading to LV cav ity dilation, hypertrophy of surviving myocardium and impaired systoli c 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 d esigned to prevent remodelling in moderate size MI in the rat.