Arterial alterations with aging and high blood pressure. A noninvasive study of carotid and femoral arteries

Abstract

Noninvasive in situ evaluations of pulsatile changes of blood pressure and arterial diameter were performed at the sites of the common carotid and femoral arteries in a population of 78 untreated normotensive and hypertensive subjects. Arterial segments were studied by using an original echotracking technique for internal diameter and validated applanation tonometry for local pulse pressure measurements. Whereas mean arterial pressure is known to be identical in all parts of the arterial tree, pulse pressure was significantly lower in the carotid (52.7 ± 2.2 mm Hg) than in the brachial (62.0±2.0 mm Hg) or femoral (62.5 ± 2.5 mm Hg) arteries. Despite a higher pulse pressure and diastolic diameter, the femoral artery had a lower pulsatile change in diameter (3.47±0.18% versus 6.07±0.28%;p<0.0001) and distensibility coefficient (9.36±0.58 versus 21.60±1.75×10-3 kPa-1) than the carotid artery. Local cross-sectional compliance of the carotid artery was higher than that of the femoral artery (7.42±0.46 versus 6.20±0.28 m2·kPa-1 · 10-7;p<0.05). Whereas age was strongly correlated with arterial parameters at the site of the carotid artery (pulse pressure: r=0.54,p<0.0001; pulsatile change in arterial diameter: r=-0.62, p<0.0001; distensibility coefficient: r=-0.70, p<0.0001), no significant correlation was observed at the femoral artery. Mean blood pressure was the second factor of carotid artery alterations: the higher the mean blood pressure, the lower the distensibility of this artery (r=-0.36, p<0.01). Since no atherosclerotic lesions were detected in the studied subjects, it is suggested that, for the same mean arterial pressure 1) the common carotid artery is exposed to lower pulse pressure than the common femoral artery, 2) the common carotid artery is a highly compliant artery with a strong alteration of its viscoelastic properties with age, and 3) the common femoral artery has smaller mechanical "buffering" properties than the carotid artery, with little influence by aging. This study provides evidence that the effects of aging and elevated blood pressure differ substantially in the different portions of the arterial tree.