Left ventricular (LV) hemodynamics, LV muscle mass, and LV geometry of 28 spontaneously hypertensive rats (SHR) treated for 20, 40, and 60 weeks with nifedipine (30 mg/kg/day) were compared with those of 29 age-matched untreated SHR. LV Pressure (PLV), systolic wall stress (Tsyst), ejection fraction (EF), cardiac index (CI), the ratio of LV muscle mass to body weight (LV/BW) and the ratio of LV muscle mass to end-diastolic volume (M/V) were determined. Myocardial contractility was analyzed through studies of the isolated LV papillary muscle. After 60 weeks of nifedipine treatment, PLV was 32.2% and Tsyst 22.9% lower in the treated group compared to the untreated control group (PLV 116 vs 171 mm Hg; Tsyst 165 vs 214 10(3)dyn/cm2). The degree of LV hypertrophy as indicated by LV/BW (-14%) and M/V (-21%) was less after treatment. LV pumping performance was considerably improved (EF = from 54% to 61%; Cl = from 175 to 220 ml/kg), whereas myocardial contractility indices such as maximum isotonic shortening velocity and isometric tension development remained unchanged. Thus, nifedipine reduced cardiac hypertrophy and improved LV function. These effects seem to result from a reduction in LV afterload.
- Copyright © 1983 by American Heart Association