HYPERTROPHIC REMODELING - GENDER DIFFERENCES IN THE EARLY RESPONSE TOLEFT-VENTRICULAR PRESSURE-OVERLOAD

Objectives. To identify gender differences in left ventricular remodel ing, hypertrophy, and function in response to pressure overload due to ascending aortic banding in rats. Background. Gender may influence th e adaptation to pressure overload, as women with aortic stenosis have greater degrees of left ventricular hypertrophy and better left ventri cular function than men. Methods. Fifty-two,weanling rats underwent as cending aortic banding (16 males, 18 females), or sham surgery (9 male s, 9 females). At 6 and 20 weeks, rats underwent transthoracic echo Do ppler studies, and closed chest left ventricular pressures with direct left ventricular puncture. Perfusion-fixed tissues from eight rats we re examined morphometrically for myocyte cross sectional area and perc ent collagen volume. Results. At 6 weeks after aortic banding, left ve ntricular remodeling, extent of hypertrophy, and function appeared sim ilar in male and female rats. At 20 weeks, male but not female rats sh owed an early transition to heart failure, with onset of cavity dilata tion (left ventricular diameter = 155% vs. 121% of same-sex: sham), lo ss of concentric remodeling (relative wall thickness = 102% vs. 139% o f sham), elevated wall stress (systolic stress = 266% vs. 154% of sham ), and diastolic dysfunction (deceleration of rapid filling = 251% vs. 190% of sham). Left ventricular systolic pressures were higher in fem ale compared with male rats (186 +/- 20 vs. 139 +/- 13 mm Hg), while d iastolic pressures tended to be lower (14 +/- 4 vs. 17 +/- 4 mm Bg). C onclusions. Gender significantly influences the evolution of the early response to pressure overload, including the transition to heart fail ure in rats with aortic stenosis, (C) 1998 by the American College of Cardiology.