Gender-specific cardiovascular adaptation due to circadian blood pressure variations in essential hypertension

To determine the effects of circadian variation in arterial pressure on early hypertensive target organ disease, we examined systemic hemodynamics (cardiac output by indocyanine green dye dilution), renal hemodynamics (renal plasma flow by iodine-131 para-aminohippuric acid clearance), left ventricular structure and function (2D-guided M-mode echocardiogram), and 24-h ambulatory blood pressure in 20 women and 46 men with untreated essential hypertension. Both gender groups were subdivided into ''dippers'' and ''nondippers'' according to the physiologic nocturnal decrease in mean arterial pressure by 10% of daytime values. Systemic and renal hemodynamics, neurohumoral findings (norepinephrine, epinephrine, dopamine, plasma renin activity), casual blood pressure values, duration of hypertension, and body weight did not differ between the two groups. In contrast, left ventricular mass and mass index was higher in female nondippers than dippers (255 +/- 68 v 184 +/- 81 g, and 137 +/- 30 v 102 +/- 39 g/m(2), P <.05, respectively), while in men no significant differences were found (234 +/- 48 v 240 +/- 54 g, and 119 +/- 27 v 121 +/- 13 g/m(2), P = NS, respectively). Relative wall thickness (0.45 +/- 0.06 v 0.39 +/- 0.06, P <.05) and posterior wall thickness (1.1 +/- 0.1 v 0.89 +/- 0.2 mm, P <.05) were also found to be greater in female nondippers than in dippers, whereas no significant differences were obtained in men. Thus, the degree of left ventricular hypertrophy correlated with the circadian blood pressure variations in women only, which indicates that left ventricular structure may be more load-dependent in women than in men with essential hypertension.