CARDIAC MORPHOLOGY AND FUNCTION IN SENESCENT RATS - GENDER-RELATED DIFFERENCES

Objectives. We sought to better understand the effects of aging and ge nder on left ventricular (LV) structure and function. Background. Card iovascular disease in older persons is associated with increased morta lity and morbidity, The influence of gender on age-related cardiac cha nges is incompletely characterized. Methods. We studied 34 senescent, male and female, normotensive Fischer rats viith transthoracic Doppler echocardiography and morphometric and histopathologic analyses. Resul ts. Male rats were larger (396 +/- 31 g vs. 282 +/- 35 g), and LV mass in males was greater (1.04 +/- 0.22 g vs. 0.67 +/- 0.13 g). However, wall and chamber dimensions normalized to body weight revealed proport ionately thicker anterior and posterior walls in females, Relative wal l thickness ratio (2[Diastolic posterior wall thickness]/Diastolic LV internal chamber diameter) was greater in females, but abnormal fracti onal shortening and diastolic filling (E/A ratio) patterns were more c ommon in males, Significant mitral regurgitation (MR) was sevenfold mo re common among males (88% vs. 12%, p < 0.001). Histopathologic analys is showed that the cardiac myocytes were larger, and there was greater LV fibrosis in males (both p < 0.001). Conclusions. Gender-related mo rphologic and functional differences are important to consider in card iovascular assessment, Very old rats show significant gender differenc es in LV size and function, Male rat hearts are larger, thinner and mo re fibrotic and have indexes of diminished performance, The high preva lence of MR in male rats may play a crucial role in these gender diffe rences. (C) 1997 by the American College of Cardiology.