Differential effects of age on large artery stiffness and minimal vascular resistance in normotensive and mildly hypertensive individuals.

Large artery stiffness and small artery structural changes are both cardiovascular risk factors. Arterial stiffness increases with age and blood pressure (BP), but it is unclear in which way large artery pulse wave velocity (PWV) and peripheral vascular resistance are related and whether age has any influence. In a cross-sectional study, PWV and forearm minimum vascular resistance (Rmin ) was compared with emphasis on the impact of age. Normotensive (n = 53) and untreated hypertensive (n = 23) subjects were included based on 24-h BP measurements. Age ranged from 21 to 79 years with an even distribution from each age decade. PWV was assessed using tonometry. Forearm Rmin was measured by venous occlusion plethysmography at maximal vasodilatation induced by 10 min of ischaemia in combination with skin heating and hand grip exercise. In both normotensive and hypertensive subjects, PWV correlated significantly with age and BP. Based on median age, both groups were assigned into two equally large subgroups. Normotensive older (66 ± 7 years) and younger (35 ± 10 years) persons had different carotid-femoral PWV (7.9 ± 1.8 versus 5.7 ± 0.9 m/s, P<0.01), but similar Rmin values (3.7 ± 0.9 versus 3.6 ± 1.2 mmHg/ml/min/100 ml). Hypertensive older (63 ± 6 years) and younger (40 ± 10 years) also had different PWV (8.0 ± 1.5 versus 6.7 ± 1.1 m/s, P<0.05), but the older had lower Rmin (3.1 ± 0.8 versus 4.7 ± 2.2 mmHg/ml/min/100 ml, P<0.05). In a regression analysis adjusting for age, BP, gender and heart rate, no correlation was seen between PWV and Rmin . The data suggest that age differentially affects PWV and Rmin and that BP can increase in older persons without affecting Rmin .