The effect of gender and age on hemodynamics, blood volume and cardiac size in healthy humans

Abstract

We compared age and gender associated differences in hemodynamics, blood volume, and left ventricle size and function at rest in healthy sedentary adults. Ten young men [32 ±10 (SD) yrs] and 10 young women (30 ±8 yrs) as well as 12 older men (69 ±4 yrs) and 12 older women (70 ±5 yrs) volunteered for the study. Supine resting blood pressure (BP, Suntech), heart rate (HR, ECG) and cardiac output (Qc, C2H2) were measured. Stroke volume (SV=Qc/HR) and total peripheral resistance (TPR = mean BP/Qc) were calculated. Blood/plasma volume (BV/PV) was measured using a carbon monoxide rebreathing method. Cardiac size and function was assessed by MRI and later analyzed for left ventricular mass (LVM), left ventricle end diastolic volume (LVEDV) and ejection fraction (EF). BP and TPR increased, and normalized Qc, SV, BV, PV, LVM and LVEDV were significantly decreased in the older groups (all P<0.05). Females for both age groups had higher HR and TPR, lower BP, and lower normalized LVM and LVDEV than their respective male counterparts (all P<0.05). Normalized BV and PV were also lower in the female groups (both P<0.05). With age EF increased (P<0.05) but there was no gender effect on EF. This study shows both age and gender affect resting hemodynamics, blood volume, and cardiac size/function in humans, but the effect of gender is consistent with increasing chronological age.