GENDER RELATED DIFFERENCES IN LARGE ARTERY MECHANICAL PROPERTIES
T.K. Waddell*, C.D. Gatzka, J.D. Cameron, A.M. Dart, B.A. Kingwell.
Alfred and Baker Medical Unit, Baker Medical Research Institute, Prahran, Victoria.
Arterial mechanical properties influence both cardiac afterload and coronary perfusion. Gender differences in these properties may contribute to the cardioprotective effects of female gender. Sixteen males (mean±SD, 26±44 years) and 16 females (23±5 years) were compared. Subjects were healthy, sedentary, non-smokers, with normal plasma lipids. Systemic arterial compliance (SAC) and aortic input impedance were measured using carotid applanation tonometry and Doppler velocimetry of the ascending aorta. SAC was higher in males compared with females (mean±SEM, 0.65±0.04 vs 0.53±0.04 arbitrary compliance units, ACU; p=0.05). However, distensibility (compliance normalised for aortic size) was greater in females (0.16±0.01 vs 0.21±0.02 ACU .cm-2; p=0.02). Aortic area was greater in males (4.00±0.15 vs 2.57±0.10; p<0.001). Aortic input impedance (1.63±0.10 vs 1.25± 0.10 mmHg.s.cm-1; p=0.01) and characteristic impedance (1.20±0.08 vs 0.89±0.07 mmHg.s.cm-1; p=0.007) were significantly higher in males. Resting brachial systolic (115±2 vs 106±3; p=0.01) and pulse pressure (51±2 vs 41±2; p=0.001) and pulse pressure (45±3 vs 30±2; p,0.001) were greater in males. Mean arterial pressure, diastolic pressure and heart rate did not differ between groups. These data indicate that while females have a lower arterial compliance, this effect is balanced by smaller aortic area. Thus distensibility is higher and aortic input impedance and both peripheral and central systolic and pulse pressure are lower in young healthy females.
