Structural changes of large arteries in sustained essential hypertension.

The physical properties of intact superficial arteries can be studied in humans by using original pulsed Doppler systems. Measurements of the diameter, blood flow velocity, volumic flow, and compliance of the brachial artery can be obtained in hypertensive humans in comparison with controls of the same age. In sustained essential hypertension, arterial compliance is decreased, in a manner that is not related exclusively to age and to the level of blood pressure. On the basis of pharmacological studies, the predominant role of activation of the autonomic nervous system can be excluded. As observed in isolated systolic hypertension and in arteriosclerosis obliterans of the lower limbs, the reduction in arterial compliance is probably due to structural alterations of the arterial wall, which produce a disproportionate increase in systolic pressure. Nitroglycerine is able to reverse both the decreased compliance and the increased systolic pressure. The conclusion follows that adaptive changes of large arteries participate in the structural autoregulation of blood flow in hypertension and lead to a predominant elevation of systolic pressure in older subjects.