Haemodynamic basis of early modifications of the large arteries in borderline hypertension.

Quantitative evaluation of brachial artery diameter, blood velocity and flow (pulsed Doppler velocimetry) and of forearm arterial compliance (FAC)--mathematical analysis of the simultaneous diastolic pressure and flow according to a first-order arterial model--was carried out in 10 normotensive controls, and in 23 borderline hypertensive patients, of the same age. Using a value of 2 standard deviations above the average cardiac index of 20 normotensive subjects, enabled us to classify 12 patients as having a normal cardiac output and 11 patients as having a high cardiac output. Each group was of similar age and pressure. FAC was lower in patients with a normal cardiac output than in normal controls (P less than 0.01) and also lower than in patients with high output (P less than 0.01). Brachial artery diameter and flow were higher in patients with high output than in normal controls (P less than 0.01, P less than 0.001) and also higher than in patients with a normal output (P less than 0.001). A positive correlation (r = 0.55; P less than 0.01) was found between heart rate and brachial artery diameter in the 23 patients. These results demonstrate a non-homogenous pattern of brachial artery characteristics of patients with borderline hypertension. Patients with normal cardiac output exhibited a clear reduction of the distensibility of the forearm arteries while patients with high cardiac output had strong dilation of the brachial artery.