Opposing effects of ageing on distal and proximal large arteries in hypertensives

Abstract

Hypertension has been reported to accelerate the alterations in large arteries induced by ageing. Distal large arteries have been poorly investigated in contrast to proximal large arteries. The objectives of this cross-sectional study were (1) to compare the storage capacity of different arterial sites in normotensive subjects or hypertensive patients; and (2) to compare the different arterial sites with respect to the effects of ageing on storage capacity, in normotensives and in hypertensives. Two recently developed ultrasonic echo-tracking devices, offering a high resolution for the assessment of internal arterial diameter and its systolo-diastolic variations, were used to measure end-diastolic diameter, absolute (change at end-systole minus change at end-diastole) and relative (absolute change divided by change at end-diastole) changes in diameter with stroke and the absolute change in cross-sectional area (3.14 x the end-diastolic diameter x half the absolute stroke change in diameter) at the site of the common carotid artery, the abdominal aorta, the common femoral artery, the brachial artery and the radial artery in 50 untreated essential hypertensive patients and 32 normotensive subjects. In both groups, the end-diastolic diameter increased with age for the common carotid artery and the abdominal aorta but not for the common femoral, brachial or radial arteries. In the normotensives, the relative stroke change in diameter was negatively correlated with age for the common carotid artery (P < 0.001) and the abdominal aorta (P < 0.001), and not correlated for the common femoral, brachial and radial arteries. In hypertensives, the relative stroke change in diameter was negatively correlated with age for the common carotid artery (P < 0.05) and the abdominal aorta (P < 0.05), positively correlated with age for the common femoral (P < 0.05) and the radial arteries (P < 0.05) and not correlated for the brachial artery. Similar results were observed for the relationships between the absolute change in cross-sectional area and age. In hypertensives, enlargement of the proximal large arteries offsets the decrease in the relative stroke change in diameter and maintains an adequate storage capacity. It thus appears that ageing exerts opposing effects on central elastic large arteries and distal muscular medium-sized arteries.