Hemodynamics of the carotid artery after vasodilation in essential hypertension.

Abstract

SUMMARYWe performed simultaneous noninvasive measurements of common carotid artery and brachial artery hemodynamics in nine normal subjects and 10 subjects with sustained essential hypertension. In hypertensive subjects, brachial artery blood flow and forearm vascular resistance were in the normal range while carotid artery blood flow and carotid artery resistance were decreased and increased, respectively. The most important findings were the changes in the internal caliber of large arteries. Although the brachial and carotid artery diameters of hypertensive subjects were measured for the same level of mean arterial pressure, brachial artery diameter was significantly increased and carotid artery diameter was strictly normal as compared with values found in normal subjects. To assess whether carotid artery circulation could influence the baroreceptor reflex response to arteriolar vasodilation, carotid artery and brachial artery hemodynamics were measured in immediate succession in normotensive and hypertensive subjects before and after oral administration of cadralazine, a dihydralazine derivative. After cadralazine treatment, carotid artery tangential tension decreased in hypertensive subjects, and the changes were significantly correlated to the Increase in heart rate. A similar correlation was found in normal subjects, but it was reset toward higher heart rates. These results indicate that the carotid artery does not behave like the brachial artery in response to a chronic increase in blood pressure. This behavior indicates intrinsic alterations of the arterial wall and might be involved in the resetting of the carotid baroreceptor reflex. Carotid artery circulation could play a role in hypertension by modulating the carotid baroreceptor mechanisms involved in the response to drug-induced arteriolar vasodilation. Whether these findings represent a primary or a secondary event remains to be determined. (CCA) and the brachial artery (BA) to a chronic elevation of blood pressure may differ according to the regional circulation. Using a noninvasive pulsed Doppler system, we evaluated arterial diameter and blood flow of the straight superficial arteries. We measured simultaneously CCA and BA hemodynamics in normal and hypertensive subjects to assess the effect of essential hypertension on circulation in these arteries.The decrease in blood pressure and vascular resistance observed after treatment with dihydralazine or its derivative, cadralazine, was related to the dilation of small arteries, as has been shown extensively for dihyFrom the Diagnosis Center and the Hypertension Research Center, Broussais Hospital, Paris, France.Address for reprints: Prof. M. Safar, Centre de Diagnostic, H6pi-tal Broussais,

Influence of acetylator status on the haemodynamic effects and pharmacokinetics of cadralazine in healthy subjects.

“…The increase in heart rate despite any reduction in mean arterial pressure is probably due to sympathetic stimulation or parasympathetic withdrawal. In the present study there was no detectable decrease in the diameter of the humeral artery, which contrasts with the reduction observed in hypertensive patients after a single 20 mg dose of cadralazine (Laurent et al, 1988). Moreover absence of a change in diameter at unaltered pressure despite stimulation of the sympathetic nervous system and the renin-angiotensin system might indicate a direct vasodilator effect of the drug on the humeral artery.…”

Risk Factors for Stiffness of the Wall of the Thoracic Aorta in Patients With Mild Atherosis.

“…Diffuse intimal thickening may represent an early preplaque stage of atherosclerosis and current studies have shown a highly significant agerelated increase in intimal thickness of the thoracic aorta, similar to findings in the carotid artery. [17][18][19][20] Although the presence of aortic plaque was observed more frequently in the older group, the IMT in that group was not significantly different from the younger group, so in the present study atherosis of the aortic wall was relatively mild even in the older subjects.…”

Large artery function in patients with chronic heart failure. Studies of brachial artery diameter and hemodynamics.

“…Abnormalities in the aorta7 and carotid baroreceptor5 have been documented in patients with heart failure and throughout the arterial tree in both proximal and more distal arteries in animal models of failure.6 In hypertension, abnormalities in large artery compliance have been observed in both the carotid and brachial arteries by using the same methodology as described in our current study. 24 Whether diffuse changes are seen throughout the large arterial tree in heart failure in humans awaits confirmation in further studies. Increased stiffness in the peripheral arteries could cause the reflected pressure wave to return earlier to the heart, possibly before aortic valve closure.…”

“…24 Since the specific technique used is noninvasive, measurements are limited to those conductance arteries that are close to the skin surface. Other noninvasive techniques have been used to examine other large conductance vessels such as the aorta.…”