4.3 Impact of Age and Gender on the Haemodynamic Determinants of Blood Pressure Across the Adult Age-Span

Background Systolic and diastolic blood pressure (BP) oscillate around the mean arterial pressure (MAP), which is determined, physiologically, by the cardiac output (CO) and peripheral vascular resistance (PVR). Although data describing the influence of age and gender on BP are widely available, few studies have examined the normal age-related changes in CO and PVR and the impact of gender on these changes, in a sufficiently large cohort of healthy individuals. Methods Detailed haemodynamic data including blood pressure (BP), CO and PVR were available in 5580 individuals (2518 males), aged between 18–92 years. Data were stratified according to gender and decade of age. Results As expected, MAP increased progressively with age in both males and females (P<0.001 for both). PVR was significantly higher in females at all ages and increased significantly with age in both sexes (P<0.001 for both). In contrast, CO was significantly higher in males at all ages and declined significantly with age in both sexes (P<0.001 for both). The decline in CO was due to a decline in stroke volume (SV) (P<0.001 for both), since there was no effect of age on heart rate. Adjusting CO and SV for body size abolished the gender-related differences but the age-related differences remained. Conclusion These data indicate that the physiological determinants of blood pressure vary between genders and with ageing, supporting the need for differential approaches in understanding, and treating high BP across the adult age-span.