Echocardiographic left ventricular mass and function in the hypertensive baboon.

Abstract

Nonhuman primates with chronic systemic hypertension provide an ideal model for studying structural and functional alterations associated with compensatory cardiac hypertrophy. Since noninvasive techniques are useful for the longitudinal evaluation of these animals, we sought to critically assess the M-mode echocardiographic estimation of left ventricular mass in the baboon and to characterize estimates of left ventricular size and function in baboons with chronic renal hypertension. In 23 baboons (12 normotensive, 11 chronic hypertensive), M-mode echocardiography-determined left ventricular mass was 73 .+-. 13 (SE) g as compared with the necropsy weight of 69 .+-. 11 g (p = NS), and the correlation was excellent (r = 0.94). When 30 chronically hypertensive baboons being observed longitudinally were compared with 10 normotensive control studied under identical conditions, several differences were noted in measures derived from echocardiography and high fidelity pressure measurements. Left ventricular systolic pressure was considerably higher in the hypertensive baboons (113 .+-. 23 vs 90 .+-. 11 mm Hg; p < 0.001), as was left ventricular mass (148 .+-. 60 vs 103 .+-. 38 g; p < 0.03). However, since the ratio of posterior wall thickness to cavity dimension was larger in the hypertensive baboons (0.52 .+-. 0.17 vs 0.43 .+-. 0.07; p < 0.05), this concentric hypertrophy maintained values for left ventricular meridional stress at the same level as in the control animals. Despite matched heart rate and left ventricular stress, the rates of change in left ventricular dimensions and wall thickness in systole and diastole were all approximately 25% less in the hypertrophied baboons. Therefore, M-mode echocardiography is an accurate technique for estimating left ventricular mass in the baboon and can be used for longitudinal assessment of quantitative left ventricular performance in a nonhuman primate model of pressure-overload hypertrophy. (Hypertension 10: 339-345, 1987).