Intra-venous bevacizumab in hereditary hemorrhagic telangiectasia (HHT): A retrospective study of 46 patients

Background

Bevacizumab, an anti-VEGF monoclonal antibody, has recently emerged as a new option for severe forms of hereditary hemorrhagic telangiectasia (HHT). Its utilization in this orphan disease has rapidly spread despite the lack of randomized trials and international guidelines. The objective of this study is to report the main clinical data (baseline characteristics, dose schedule, efficacy, adverse events and deaths) of HHT patients treated by intravenous bevacizumab in France.

Methods

Retrospective observational study of HHT patients treated with bevacizumab for a severe form of the disease in the 14 centers of the French HHT network.

Results

Forty-six patients (median age: 68 years) were treated between March 2009 and May 2015. Ten patients were treated for high output cardiac failure, 20 patients for severe hemorrhages and 16 for both indications. The standard protocol (6 infusions of 5mg/kg every 2 weeks) was initially used in 89% of the cases but diverse strategies were subsequently applied. A clinical improvement was noted by the referent physician for 74% of the patients with a median effect’s duration of 6 months. Wound healing complications led to 2 amputations. Arthralgia/arthritis and arterial hypertension occurred in 5 patients each. One third of the patients were dead at the time of the final update, coherently with age and the poor prognosis of these highly symptomatic patients.

Conclusion

Intravenous bevacizumab seems to provide a clinical benefice in severe HHT patients. Precautions concerning wound healing and vascular pathologies must be respected. Prospective double blinded versus placebo trials are needed.

Pulmonary hypertension subtypes associated with hereditary haemorrhagic telangiectasia: Haemodynamic profiles and survival probability

BACKGROUND

Different pulmonary hypertension (PH) mechanisms are associated with hereditary haemorrhagic telangiectasia (HHT).

METHODS AND RESULTS

We conducted a retrospective study of all suspected cases of PH (echocardiographically estimated systolic pulmonary artery pressure [sPAP] ≥ 40 mmHg) in patients with definite HHT recorded in the French National Reference Centre for HHT database. When right heart catheterization (RHC) was performed, PH cases were confirmed and classified among the PH groups according to the European guidelines. Among 2,598 patients in the database, 110 (4.2%) had suspected PH. Forty-seven of these 110 patients had RHC: 38/47 (81%) had a confirmed diagnosis of PH. The majority of these had isolated post-capillary PH (n = 20). We identified for the first time other haemodynamic profiles: pre-capillary pulmonary arterial hypertension (PAH) cases (n = 3) with slightly raised pulmonary vascular resistances (PVR), and combined post- and pre-capillary PH cases (n = 4). Compared to controls, survival probability was lower in patients with PAH.

CONCLUSION

This study revealed the diversity of PH mechanisms in HHT. The description of combined post- and pre-capillary PH with/or without high cardiac output (CO) suggests either a continuum between the pre- and post-capillary haemodynamic profiles or a different course in response to high CO.

Central hemodynamics and cardiac output control in essential hypertensive patients

Central hemodynamics were determined in 202 men including 101 normotensive and 101 permanent essential hypertensive patients of the same age. Cardiac output was identical in the two groups while blood pressure and total peripheral resistance were significantly different. Strong differences between the two groups are revealed by a systematic correlation study: (i) correlations of blood pressure (with respectively heart rate and total blood volume) were significant in the normotensive group but not in the hypertensive group; (ii) correlations of cardiac output (with respectively heart rate and total blood volume) were significant in both groups; (iii) correlations of renal blood flow (with respectively cardiac output and blood pressure) were significant in the hypertensive group but not in the normo tensive group. This study provided evidence that the volume and neural pressure controls are impaired in hypertensive patients while the cardiac output control is maintained and, suggested the existence of adaptive mechanisms involving the kidney in the maintenance of normal cardiac output in permanent essential hypertensive patients.

Hand hygiene, the crusade of the infection control specialist. Alcohol-based handrub: the solution!

Hands of healthcare workers are the main route of transmission of microorganisms responsible for nosocomial infections. Compliance with hand hygiene procedures however is still grossly insufficient. Rubbing hands with alcohol-based solutions in order to decontaminate hands instead of handwashing, as proposed in new recommendations is one way of solving the problem. Alcohol is more efficient and faster acting than antiseptic soaps and takes care of the real or perceived constraints of healthcare workers against hand hygiene. The pocketsize bottle version of the alcohol-based solution significantly improves doctors' compliance with hand hygiene.

In vitro generation of endothelial microparticles and possible prothrombotic activity in patients with lupus anticoagulant

Microparticles (MPs) resulting from vesiculation of platelets and other blood cells have been extensively documented in vitro and have been found in increased numbers in several vascular diseases, but little is known about MPs of endothelial origin. The aim of this study was to analyze morphological, immunological, and functional characteristics of MPs derived from human umbilical vein endothelial cells (HUVECs) stimulated by TNF, and to investigate whether these MPs are detectable in healthy individuals and in patients with a prothrombotic coagulation abnormality. Electron microscopy evidenced bleb formation on the membrane of TNF-stimulated HUVECs, leading to increased numbers of MPs released in the supernatant. These endothelial microparticles (EMPs) expressed the same antigenic determinants as the corresponding cell surface, both in resting and activated conditions. MPs derived from TNF-stimulated cells induced coagulation in vitro, via a tissue factor/factor VII-dependent pathway. The expression of E-selectin, ICAM-1, alphavbeta3, and PECAM-1 suggests that MPs have an adhesion potential in addition to their procoagulant activity. In patients, labeling with alphavbeta3 was selected to discriminate EMPs from those of other origins. We provide evidence that endothelial-derived MPs are detectable in normal human blood and are increased in patients with a coagulation abnormality characterized by the presence of lupus anticoagulant. Thus, MPs can be induced by TNF in vitro, and may participate in vivo in the dissemination of proadhesive and procoagulant activities in thrombotic disorders.

Influence of HDL subfractions on erythrocyte aggregation in hypercholesterolemic men. PCVMETRA Group

Recent studies have suggested that rheological mechanisms may be involved in the pathogenesis of ischemic syndromes in hyperlipidemias. We investigated the association between erythrocyte aggregation and components of lipoproteins in the blood of 60 normotensive, hypercholesterolemic men aged 45 +/- 8 years. The rheological parameters assessed were aggregation index (AI) and disaggregation shear rate threshold (gamma t) as determined by laser reflectometry, plasma fibrinogen, total serum protein, and hematocrit. The lipoprotein variables included total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol and its subfractions HDL2 cholesterol and HDL3 cholesterol, apolipoprotein (apo) B, apoA-I, HDL particles containing apoA-I without apoA-II (LpA-I), and HDL particles containing both apoA-I and apoA-II (LpA-I/A-II). Covariables considered for possible confounding effects were age, body mass index, and smoking behavior. Fibrinogen, total serum protein, and both aggregation parameters (AI and gamma t) were elevated in this hypercholesterolemic population. Univariate analysis showed that both AI and gamma t correlated positively with fibrinogen (P < .001) and total serum protein (P < .01) and negatively with HDL2 cholesterol (P < .01) and LpA-I (P < .01); gamma t also provided a positive correlation with LpA-I/A-II (P < .05). A multivariate model analysis demonstrated that HDL2 cholesterol, LpA-I, and LpA-I/A-II also emerged as significant factors influencing erythrocyte aggregation; 60% to 68% of the variance of AI and 47% to 64% of the variance of gamma t could be explained by these factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Development and implementation of a microcomputer-based multi-user MEDLINE system

The Health Sciences Libraries Consortium, a group of health sciences libraries based in Philadelphia, PA, has implemented a MEDLINE database retrieval system based on the CD Plus PlusNet2 system. The system provides access to the entire MEDLINE database file through three centralized servers and four distributed servers, and is accessible over the HSLC wide-area network linking all of its members. This article describes the implementation process, from selection of the system to future development.

Physiopharmacological approach to mechanical factors of hypertension in the atherosclerotic process

Hypertension may influence the atherosclerotic process of large arteries via pressure and shear forces. The pressure force dilates and stiffens arteries because of the non-linear elastic behaviour of arterial walls. This partly explains the increased diameter and decreased compliance of the brachial artery in hypertensive subjects compared with normotensive controls. However, pressure lowering by antihypertensive drugs does not always reverse large artery alterations indicating that other mechanisms are involved. Reversal of low compliance obtained with certain antihypertensive drugs is generally concomitant with large artery vasodilation, suggesting that smooth muscle relaxation plays a major role in the compliance response to drugs. Atherosclerosis associated with hypertension also causes additional loss of compliance and creates a vicious circle of sclerosis development by accelerating the biophysical fatigue of bioelastomers. Hypertension may contribute to atherogenesis by means of wall shear stress which is the frictional force exerted by the circulating blood column on the intima of arteries. Since it is likely that atherosis lesions may develop preferentially in low shear conditions, hypertension may promote the haemodynamic conditions of atherogenesis at the blood-wall interface. The response of wall shear to antihypertensive treatment is not unequivocal. For example, the beta-blocker, atenolol, does not change shear whereas carteolol increases shear rate and stress and these effects are closely related to change in platelet-free calcium concentration. This finding is consistent with the effect of shear forces on cell permeability to calcium demonstrated in vitro and points to the crucial role of wall shear as a biophysical signal capable of modifying the endothelial structure and function of arteries.

Risk factors and early extracoronary atherosclerotic plaques detected by three-site ultrasound imaging in hypercholesterolemic men. Prévention Cardio-vasculaire en Médecine du Travail METRA Group

Ultrasonic detection of atherosclerotic plaque of carotid abdominal aortic and femoral arteries and evaluation of risk factors were performed in 208 hypercholesterolemic men without cardiovascular disease. Twenty-six percent of them had no plaque. Plaque at the carotid, aortic, and femoral sites was found in 37%, 48%, and 53% of subjects, respectively. Plaque was associated (1) in carotid arteries with increased total and low-density lipoprotein cholesterol; (2) in the aorta with increased age, pressure, glycemia, and smoking; and (3) in femoral arteries with increased age, systolic pressure, low-density lipoprotein cholesterol, and smoking. Multiple regression analysis showed correlations between carotid plaque and low-density lipoprotein cholesterol; aortic plaque and age, smoking, glycemia, and pressure; femoral plaque and age, smoking, and pressure. This suggests that multiple risk factors influence lesions, and risk profile differs according to atherosis site.

Non-invasive evaluation of segmental pressure drop and resistance in large arteries in humans based on a Poiseuille model of intra-arterial velocity distribution

STUDY OBJECTIVE

The aim of the study was to evaluate in hypertensive subjects the longitudinal pressure drop and segmental resistance in a large artery in relation to shearing forces of the circulating blood column at the arterial wall.

DESIGN

Arterial diameter, blood velocity, and flow were measured in the brachial artery using pulsed Doppler apparatus. Blood viscosity was measured at 96 s-1 with a low shear viscometer. Segmental resistance per unit arterial length was calculated using the basic Poiseuille resistance expression from the ratio between blood viscosity and the fourth power of arterial diameter. Longitudinal pressure drop was deduced as the product between segmental resistance and blood flow. The Poiseuille model of velocity distribution also enabled wall shear rate and stress to be calculated from the ratio between blood velocity and arterial diameter and from the product between shear rate and blood viscosity respectively.

PATIENTS

19 ambulatory male patients with mild to moderate hypertension and 11 normotensive male controls of similar age were studied.

RESULTS

Compared to controls, hypertensive patients had higher arterial diameter (p less than 0.001) lower blood velocity (p less than 0.05), higher blood viscosity (p less than 0.01), lower segmental resistance and pressure drop (p less than 0.001, p less than 0.01) and lower shear rate and stress (p less than 0.01, p less than 0.05). A negative correlation existed in the overall normotensive and hypertensive population between pressure drop and mean blood pressure (r = -0.55, p less than 0.01).

CONCLUSION

The hypertensive state is associated with a clear reduction in large artery segmental resistance and longitudinal pressure drop concomitantly with a decrease in shear conditions at the arterial wall. The mechanisms of reduced resistance and pressure drop are related to decreased wall shear and increased diameter of the artery, both of which reduce the frictional forces at the blood-arterial wall interface.

Pulsatile flow and oscillating wall shear stress in the brachial artery of normotensive and hypertensive subjects

STUDY OBJECTIVE - The aim of the study was to examine oscillating arterial wall shear stress in hypertension. DESIGN - Pulsatile flow and oscillating wall shear stress were measured in brachial artery in hypertensive v normotensive subjects using pulsed Doppler apparatus. Methods were tested in four subjects using a micrometric procedure of Doppler probe displacement providing instantaneous real time velocity profiles. SUBJECTS - 19 ambulatory male patients with mild to moderate hypertension (diastolic blood pressure 95-114 mm Hg) and 11 normotensive male controls of similar age were studied. All were non-smokers. MEASUREMENTS and RESULTS - Arterial diameter and pulsatile centreline blood velocity were determined with pulsed Doppler, and blood viscosity was measured with a coaxial cylinder viscometer. Shear rates corresponding to maximum (gamma Vmax), minimum (gamma Vmin), and pulse (gamma Vpulse) velocities were evaluated with a simplified method of computation of Womersley equations. Corresponding shear stresses (tau Vmax, tau Vmin, tau Vpulse) were calculated as the product between shear rate and viscosity. The differences in wall shear rates obtained with the Womersley method and with the micrometric procedure were less than 10%. Compared to normotensives, hypertensives had greater arterial diameter [0.508(SEM0.006) v 0.446(0.014), p less than 0.001], lower maximum velocity [36.2(1.5) v 46.3(2.4) cm.s-1, p less than 0.001], lower absolute value of minimum velocity [-8.3(1.2) v -14.3(2.3) cm.s-1, p less than 0.01], lower pulse velocity [44.5(2.2) v 61.2(3.9) cm.s-1, p less than 0.001], and higher blood viscosity [4.77(0.08) v 4.28(0.09) mPa.s, p less than 0.001]. gamma and tau Vmax, Vmin and Vpulse were all lower in absolute value in hypertensives. Overall mean blood pressure in all subjects was negatively correlated to gamma Vmax (r = -0.65), tau Vmax (r = -0.46), gamma Vmin (r = -0.45), tau Vmin (r = -0.37), gamma Vpulse (r = -0.63), and tau Vpulse (r = -0.48). In hypertensives, age was correlated negatively to gamma Vmax (r = -0.44), tau Vmax (r = -0.46), gamma Vmin (r = -0.57), tau Vmin (r = -0.57), gamma Vpulse (r = -0.58), and tau Vpulse (r = -0.58). In normotensives, age was not correlated with shear parameters, except for tau Vmax (r = -0.60) and tau Vpulse (r = -0.66). CONCLUSIONS - The hypertensive state is associated with a reduction in oscillating wall shear in large arteries despite an increase in blood viscosity. Age in combination with hypertension also decreases wall shear conditions.

Abnormal wall shear conditions in the brachial artery of hypertensive patients

Brachial artery wall shear phenomena were studied in 20 untreated essential hypertensive patients and in 11 normotensive controls of similar age. A pulsed-Doppler velocimeter was used to measure brachial artery internal diameter and mean cross-sectional and systolic centreline blood velocities. A coaxial-cylinder viscometer was used to measure blood viscosity at a shear rate of 96 s-1. A Poiseuille model of velocity distribution across the arterial lumen was used to determine wall shear rate and stress from, respectively, the ratio of blood velocity to arterial diameter and the product of shear rate and blood viscosity. Mean and systolic shear rates and stresses were calculated using, respectively, mean cross-sectional and systolic centreline blood velocities. Hypertensive patients had larger brachial artery diameters (P less than 0.001), lower systolic centreline and mean cross-sectional blood velocities (P less than 0.001, P less than 0.05), higher blood viscosity (P less than 0.001), lower mean and systolic wall shear rates (P less than 0.01, P less than 0.001) and lower systolic wall shear stress (P less than 0.05) than normotensive controls. In all subjects, mean blood pressure was negatively correlated both with mean and systolic shear rates (r = -0.38, P less than 0.05;r = -0.45, P less than 0.01). Thus the hypertensive state was associated with decreases in both mean and systolic wall shear rates, and in systolic wall shear stress. These shear abnormalities merit attention because of the atherogenic effect of low-shear conditions.

Effects of nicorandil on arterial and venous vessels of the forearm in systemic hypertension

The effects of a single oral dose of 20 mg of nicorandil were evaluated in 12 untreated patients with mild to moderate essential hypertension. Serial measurements of arterial pressures were obtained by means of an automatic device (Dynamap) up to 120 minutes after drug administration. Forearm hemodynamics were determined with a pulsed Doppler velocimeter, or strain gauge mecanography and plethysmography enabling measurement of the diameter, velocity and flow of the brachial artery as well as the arterial pulse wave velocity and forearm venous tone. In addition, local vascular resistance, compliance and impedance were deduced. Nicorandil administration produced a significant decrease in systolic and diastolic blood pressure, from 18 minutes after dosing which lasted up to the end of the study (i.e., 120 minutes after drug administration) (p less than 0.01). This decrease in blood pressure was not associated with reflex tachycardia. The brachial artery diameter increased significantly (p less than 0.01) with no change in brachial artery blood flow. A decrease in brachial-radial pulse wave velocity and arterial impedance (p less than 0.01) and an increase in arterial compliance were observed. Thus, this study demonstrated an antihypertensive activity of a single oral administration of nicorandil without baroreflex activation. This decrease in blood pressure was associated with a dilation of peripheral large arteries leading to an increase in arterial compliance. Thus, clinical testing to evaluate the antianginal activity of nicorandil, especially in hypertensive patients with coronary heart disease, should be encouraged.

Comparative haemodynamic effects of ketanserin and ritanserin in the proximal and distal upper limb circulations of hypertensive patients

The effects of ketanserin (40 mg p.o.) on blood pressure and brachial haemodynamics (brachial artery diameter, brachial blood velocity and blood flow) have been compared in a double-blind study with those of ritanserin (10 mg p.o.) and placebo. Haemodynamic parameters were measured before and 1 h after treatment. Patients with mild to moderate essential hypertension participated in this study, 6 each on ketanserin, ritanserin and placebo. Placebo significantly reduced heart rate and did not modify the other parameters. Compared to placebo, ketanserin significantly reduced systolic and diastolic blood pressure, increased brachial blood velocity and flow, and decreased forearm vascular resistance. Compared to placebo, ritanserin slightly decreased blood pressure and slightly increased blood flow, but neither effect was significant. When blood circulation to the hand was excluded, neither ketanserin nor ritanserin modified the proximal arterial resistance or blood flow. It is concluded that the actions of ketanserin and ritanserin essentially occurred in the distal part of the upper limb, and alpha 1-receptor blockade is probably involved.

Aortic pulsatile pressure and diameter response to intravenous perfusions of angiotensin, norepinephrine, and epinephrine in conscious dogs

The aortic elastic behavior has been studied in conscious dogs chronically instrumented with a pressure microtransducer and two ultrasonic crystals. Pressure and diameter measurements were analyzed in terms of their mean values and systolic-diastolic variations, enabling calculation of Peterson elastic modulus, and were displayed in the x-y form to obtain pressure diameter hysteresis loops. After recovery from surgery and under autonomic blockade, intravenous perfusions of angiotensin, norepinephrine, and epinephrine were made at incremental steps of doses until steady-state pressure-diameter changes were achieved. The slopes of the positive pressure-diameter correlations obtained at each dose of the same vasoactive substance were higher for angiotensin than norepinephrine (p less than 0.01) and epinephrine (p less than 0.001) and were higher for norepinephrine than epinephrine (p less than 0.05). Similarly, the slopes of the elastic modulus to mean pressure relation were significantly lower for angiotensin than for norepinephrine (p less than 0.05) and epinephrine (p less than 0.001) and were significantly lower for norepinephrine than epinephrine (p less than 0.001). Thus, at the same transmural pressure, the distension and stiffness of the aorta were lower and higher with epinephrine than with norepinephrine, respectively, and with norepinephrine than with angiotensin suggesting different potencies of these drugs in terms of smooth muscle activation in the aorta.

[Effect of age on brachial and carotid circulation in human arterial hypertension]

Right brachial artery and common carotid artery haemodynamic parameters were studied using pulsed Doppler velocimetry enabling non invasive measurements of their internal diameters and blood velocities in 74 untreated essential hypertensive patients subdivided in two groups of younger than (33 patients) and older than 45 years (41 patients). There were no significant differences in the haemodynamic parameters of brachial artery (i.e. diameter and blood velocity) between the two groups of patients. In the patients older than 45, there were no changes in the diameter of common carotid artery, but there was a decrease in carotid artery blood velocity as compared with patients younger than 45 (p less than 0.001). In the patients younger than 45, there were no correlations between the haemodynamic parameters of both circulations; in contrast, in patient older than 45 significant relationship were found between the common carotid artery diameter and the brachial artery diameter (r = 0.45, p less than 0.01) and between the blood velocity in the common carotid artery and in the brachial artery (r = 0.55, p less than 0.001). Thus, in these hypertensive patients, brachial artery circulation was not affected by age; but age older than 45 was associated with a decrease in common carotid blood flow, with no change in common carotid artery diameter. However, the existence of strong correlations between brachial and carotid artery diameters and blood velocities in patients older than 45, suggests that age might interfere, in hypertensive patients, with the specific regulatory adjustments of the brachial and carotid circulations.

Combined effects of gender and hypertension on the geometric design of large arteries. Sexual differences in normal and hypertensive forearm arteries

The effects of sex, hypertension, morphologic status, and heart rate were assessed on the large arteries of 46 normotensive subjects (23 men and 23 women) and 50 hypertensive patients (25 men and 25 women) by means of pulsed Doppler determination of diameter and blood velocity of the brachial artery. Compared to men, women had lower height, weight, and forearm volume (P less than 0.001), higher heart rate (P less than 0.001), and lower brachial artery diameter (P less than 0.001) both in the normotensive and hypertensive groups. Compared to normotensives, hypertensives of the same sex showed an increase in brachial artery diameter, only significant in men (P less than 0.001), and an increase in heart rate, only significant in women (P less than 0.001). The multiple regression analysis of brachial artery diameter showed significant coefficients for sex and hypertension (P less than 0.001), and for age and heart rate (P less than 0.05); the multiple regression analysis of blood velocity showed that only the coefficient of hypertension was significant (P less than 0.05). The study of first-order interactions between the independent variables revealed that effect of sex on arterial diameter did not depend on the other variables. In contrast the effects of age and heart rate were influenced by the presence or the absence of hypertension, and arterial caliber was positively related to age in normotensive subjects (P less than 0.05) but not in hypertensive patients, and negatively related to heart rate in hypertensive patients (P less than 0.001) but not in normotensive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Brachial artery hemodynamic response to acute converting enzyme inhibition by enalaprilat in essential hypertension

To assess the vascular involvement of renin-angiotensin system inhibition in human hypertension, acute effects of intravenous enalaprilat on brachial artery diameter, blood flow, and blood velocity were investigated in hypertensive patients by pulsed Doppler technique and compared with effects of saline vehicle. Compared with saline vehicle, enalaprilat reduced blood pressure (P less than 0.001) and increased brachial arterial diameter (P less than 0.01) and brachial blood flow (P less than 0.01). Enalaprilat effect on arterial pulse pressure was dependent on preinjection pulse pressure (r = -0.76; P less than 0.001), but its effect on mean blood pressure was not dependent on preinjection mean blood pressure. On the other hand, enalaprilat effect on arterial blood flow was negatively correlated with preinjection blood pressure (r = -0.64; P less than 0.02). The findings point to different responses of large and small arteries to intravenous enalaprilat.

Combined effects of sex and hypertension on the geometrical design of large arteries. Sexual differences in normal and hypertensive forearm arteries

The effects of sex, hypertension, morphological status, and heart rate were assessed on the large arteries of 46 normotensive subjects (23 men and 23 women) and 50 hypertensive patients (25 men and 25 women) by means of pulsed Doppler determination of diameter and blood velocity of the brachial artery. Compared with men, women had lower height, weight, and forearm volume (p less than 0.001), higher heart rate (p less than 0.001), and lower brachial artery diameter (p less than 0.001), both in the normotensive and hypertensive groups. Compared with normotensive subjects, hypertensive patients of the same sex showed an increase in brachial artery diameter (only significant in men [p less than 0.001]) and an increase in heart rate (only significant in women [p less than 0.001]). The multiple regression analysis of brachial artery diameter showed significant coefficients for sex and hypertension (p less than 0.001) and for age and heart rate (p less than 0.05); the multiple regression analysis of blood velocity showed that only coefficient of hypertension was significant (p less than 0.05). The study of first-order interactions between the independent variables revealed that effect of sex on arterial diameter did not depend on the other variables. In contrast, the effects of age and heart rate were influenced by the presence or the absence of hypertension, and arterial caliber was positively related to age in normotensive subjects (p less than 0.05) but not in hypertensive patients and negatively related to heart rate in hypertensive patients (p less than 0.01) but not in normotensive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Cigarette smoking and hypertension. Factors independently associated with blood hyperviscosity and arterial rigidity

The effects of cigarette smoking and hypertension on hemorheological variables (blood viscosity over a wide range of shear rates, plasma viscosity, microhematocrit, and plasma protein concentration) and on arterial stiffness (pulse wave velocity) were investigated in 33 normotensive men and 81 mild to moderately hypertensive men. Of these, 22 normotensive and 24 hypertensive subjects were cigarette smokers. Cigarette smoking and hypertension were independently associated with higher blood viscosity at all studied shear rates (from 0.2 to 241 sec-1) as well as with higher plasma viscosity, hematocrit, and pulse wave velocity. At constant hematocrit levels, hypertension remained associated with a higher blood viscosity, while the association with cigarette smoking disappeared. Normotensive smokers had the same increase of blood and plasma viscosity and pulse wave velocity as hypertensive nonsmokers. No interactive effects of hypertension or cigarette smoking on blood or arterial variables were observed, suggesting that the effect of these two factors on blood and vascular rheology are cumulative. Smoking and hypertension may change the flow properties of the blood and the behavior of the arterial wall and this may explain the arterial damage observed in cigarette smokers and hypertensive patients.

[Early changes in the circulation of the humeral artery in borderline arterial hypertension]

The brachial artery diameter and blood flow rate were measured by pulsed Doppler velocimetry in 9 healthy subjects and 24 patients of the same age group with borderline hypertension. To evaluate the results, the patients were divided into two groups according to their cardiac output: high cardiac output group (i.e. patients whose cardiac output was superior to the mean +/- 2 S.D. value in the control population), and normal cardiac output group (i.e. cardiac output lower than that value). Patients in both groups were of the same age and had the same level of blood pressure. The brachial artery diameter and blood flow rate values were the same in the normal cardiac output group and in the control population. However, these values were significantly higher in patients with high cardiac output than in controls (P less than 0.05 and P less than 0.001) and in patients with normal cardiac output (P less than 0.01). These results suggest that the haemodynamic profile in the brachial artery is not the same in all patients with borderline hypertension: there was a tendency to vasoconstriction in patients with normal cardiac output, whereas the brachial artery was clearly dilated in patients with high cardiac output.

[Effect of smoking on blood viscosity and arterial rigidity in normal and hypertensive subjects]

The purpose of the study was to assess whether cigarettes smoking could induce blood hyperviscosity and arterial rigidity in 30 normotensive and 70 hypertensive men aged from 24 to 65 years. Of those, 20 normotensive and 20 hypertensive were cigarettes smokers, while the remaining subjects were non smokers. Age and weight were similar in the 4 groups of subjects. A couette viscometer with coaxial cylinders allowed the measurements of blood viscosity over a wide range of shear rates (0.033 to 241 sec-1) mimicking the flow condition of the circulation, and two strain gauge transducers permitted the measurements of the brachial to radial pulse wave velocity as an index of arterial wall distensibility. In normotensive subjects cigarettes smoking increased pulse wave velocity from 7.1 + 1 to 9.2 + 0.6 m/sec. (P less than 0.05) as well as blood viscosity, which increased both at higher shear rates (+10% from 52 to 241 sec-1, P less than 0.05) and lower shear rates (+20% from 11.2 to 0.2 sec-1, P less than 0.02). In hypertensives, cigarettes smoking increased pulse wave velocity (9.8 + 0.3 to 11.3 + 0.4; P less than 0.05) and blood viscosity (4% at higher shear rate P less than 0.05 and 10% at lower shear rates P less than 0.02). Although hypertensive patients had increased pulse wave velocity and blood viscosity compared to normotensive controls, these variables were not significantly different when hypertensive non smokers were compared to normotensive. The present study demonstrated that cigarettes smoking produced in normotensive and hypertensive men significant rheological disturbances of flow and wall arteries.2

Heterogeneity of the atherosclerotic process in systemic hypertension poorly controlled by drug treatment

A cross-sectional study of 85 patients with poorly controlled treated hypertension was performed to detect, by means of aortic pulse wave velocity measurement and ultrasonic examinations, subclinical alterations of arteries. Pulse wave velocity was related to the product of age and diastolic blood pressure (BP) according to a nomogram obtained from normotensive subjects, and was found inside the nomogram in 37 patients (group I) and outside in 48 (group II). Group II had higher systolic and pulse BP (p less than 0.01), lower diastolic BP (p less than 0.01), higher proportion of cigarette smokers (p less than 0.05) and higher blood glucose levels (p less than 0.02) than group I. In group II a positive correlation existed between blood glucose and pulse wave velocity (p less than 0.01). Group II had a higher frequency of carotid artery stenosis (p less than 0.05) and a trend toward increased frequency of aortic and lower limb atherosclerotic lesions. The results indicate a heterogeneous pattern of arterial alterations in which systolic BP, cigarette smoking and blood glucose level are implicated.

The efficacy of a transdermal formulation of clonidine in mild to moderate hypertension and its effects on the arterial and venous vasculature of the forearm

We have studied the efficacy of clonidine hydrochloride administered transdermally once a week for 9 to 15 weeks in 12 patients with mild to moderate hypertension. Clonidine reduced both supine and standing blood pressures on average, but only 8 subjects were responders, i.e. had a decrease in supine diastolic blood pressure to below 90 mm Hg or more than 10% from baseline. Supine heart rate was unchanged, but in the responders the orthostatic increase in heart rate was reduced by clonidine from baseline (p less than 0.05). Moreover, in all the patients the change in the orthostatic increase in heart rate was correlated with the change in supine diastolic pressure (p less than 0.05). Brachial artery blood flow, forearm arterial compliance, vascular resistance, and venous tone were not affected by clonidine. Thus, transdermal clonidine reduced blood pressure, probably by a baroreflex-mediated effect, but did not affect the vasculature of the forearm.

Arterial dynamics, cardiac hypertrophy, and antihypertensive treatment

The relationship between cardiac hypertrophy, ventricular function, and aortic volume distensibility was studied in men with sustained essential hypertension by echocardiography and determination of pulse-wave velocity. The more reduced the aortic distensibility, the higher was the blood pressure response to exercise and the greater were the degree of cardiac hypertrophy and the modifications in systolic time intervals. Changes in cardiac performance as determined by vasodilators equipotent in relation to blood pressure reduction were found to have markedly different effects on aortic distensibility; volume distensibility was unchanged by cadralazine but was improved by calcium entry blockers and isosorbide dinitrate. Our findings suggest that alterations in the buffering function of the large arteries, as indicated by decreased volume distensibility, participate in the increased afterload in patients with essential hypertension and thus influence the degree of cardiac hypertrophy and changes in cardiac function and selective use of antihypertensive drugs may influence cardiovascular morbidity and mortality by their differential effect on large-vessel distensibility.

Large arteries in hypertension: heterogeneous haemodynamic response to beta-adrenoceptor antagonists with and without intrinsic sympathomimetic activity

1. Hypertension is associated with a distension of the large arteries and consequently a marked reduction in arterial compliance, which does not result merely from the mechanical effects of elevated arterial pressure but also from early functional and/or structural changes in the arterial walls. This suggests that one of the aims of antihypertensive therapy should be to reverse these arterial abnormalities in the hope of protecting the patient from the atherosclerotic complications of hypertension. 2. Studies have been carried out to compare the effects of equieffective antihypertensive doses of pindolol and propranolol on the arterial circulation in patients suffering from essential hypertension. After 3 months therapy pindolol produced a dilatation of the brachial artery with an increase in arterial compliance and blood flow. In contrast, propranolol, despite comparable antihypertensive effects, did not influence brachial artery circulation. 3. These different effects on the arterial circulation presumably reflect the differing pharmacological properties of the two beta-adrenoceptor antagonists and suggest that the intrinsic sympathomimetic activity of pindolol may be responsible for the qualitative differences in the arterial responses to the two drugs. 4. The results reviewed here reveal that even when two drugs of the same class are used to treat patients with essential hypertension the effects of these agents on arterial haemodynamics can vary greatly and are unrelated to the degree of blood pressure lowering. Thus, pindolol, in contrast to propranolol, not only lowers blood pressure but also reverses some of the changes in arterial haemodynamics which are characteristic of hypertensive disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Isosorbide dinitrate: relationship between pharmacokinetics and brachial artery hemodynamics in essential hypertension

Pharmacokinetics of isosorbide dinitrate (ISDN) and brachial arterial hemodynamics have been studied in 15 patients with sustained essential hypertension. The hemodynamic study was performed by using a pulsed Doppler device enabling evaluation of the diameter of the brachial artery with an error of less than 10%. After intravenous administration until plateau concentrations were reached, the ISDN infusion was stopped in order to study the disappearance curve of the drug and the pharmacokinetic parameters. ISDN caused a significant decrease in systolic pressure, a significant increase in arterial diameter, and no change in heart rate. Brachial hemodynamics were not correlated with the plasma concentration in the steady state or the area under the disappearance curve. In contrast, the changes in arterial diameter during perfusion were significantly correlated with the apparent distribution volume, a finding that might indirectly reflect the affinity of ISDN for vascular tissues.

Chronic effects of pindolol on the arterioles, large arteries, and veins of the forearm in mild to moderate essential hypertension

The effects of pindolol were studied on the large arteries, arterioles, and veins of the forearm in 13 patients with essential hypertension after 12 weeks of dosing. The methods used were pulsed Doppler velocimetry of the brachial artery and strain gauge mercury-in-silicone rubber plethysmography of the forearm. Compared with placebo baseline values, chronic pindolol significantly decreased systolic and diastolic blood pressure (P less than 0.001), pulse pressure (P less than 0.001), and pulse rate (P less than 0.05). A significant increase was observed in brachial artery diameter (P less than 0.01), brachial artery blood flow and velocity (P less than 0.001), and forearm arterial flow (P less than 0.001). Forearm vascular resistance and venous tone were decreased (P less than 0.001 and P less than 0.05, respectively), whereas forearm arterial compliance was increased (P less than 0.001). These results demonstrate a dilatory effect on large and small peripheral arteries and on veins of pindolol after chronic dosing, which leads to improvement in the conduction and buffering arterial function of the forearm.

Haemodynamic effects of vasodilating drugs on the common carotid and brachial circulations of patients with essential hypertension

The haemodynamic pattern of the common carotid artery was studied in men with sustained essential hypertension using pulsed Doppler methods before and after administration of vasodilating drugs. Captopril produced both a fall in vascular resistance and an increase in arterial diameter of the common carotid artery. Isosorbide dinitrate increased markedly the arterial diameter but did not change vascular resistance. Nitrendipine decreased vascular resistance with no change in the arterial diameter. In the common carotid circulation of patients with essential hypertension, vasodilating drugs may either dilate small arteries (nitrendipine), large arteries (isosorbide dinitrate), or both (captopril).

Comparative effects of propranolol and pindolol on small and large arteries and veins of the forearm circulation in hypertensive man

Brachial artery diameter (pulsed Doppler method), forearm vascular resistance, and venous tone (plethysmographic method) were studied in 18 patients with sustained essential hypertension. Hemodynamic parameters were reevaluated after 3 months of treatment by propranolol (9 patients) or pindolol (9 patients). For the same decrease in pressure, propranolol decreased heart rate significantly while pindolol did not, indicating the role of intrinsic sympathomimetic activity. After pindolol, forearm vascular resistance and venous tone significantly decreased while brachial artery cross-sectional area significantly increased. After propranolol, forearm vascular resistance and brachial artery cross-sectional area did not change significantly, while forearm venous tone increased markedly. The study shows that, in the long term, pindolol dilates small and large arteries and veins of the forearm circulation whereas Propranolol apparently does not.

Effects of beta-adrenergic blockade on the arterial vasculature in essential hypertension

The effect of beta-blockade was studied in 3 different kinds of human hypertension: borderline, sustained and isolated systolic hypertension. Young patients with borderline hypertension had a similar decrease in cardiac output with both nonselective and selective beta-blockade. Only nonselective beta-blockade decreased brachial artery blood flow and increased forearm vascular resistance. In patients with sustained essential hypertension, chronic administration of 2 nonselective beta-blockers, propranolol and pindolol, caused a similar significant decrease in blood pressure with different effects on forearm circulation. Pindolol produced a significant vasodilation of both large and small arteries of the forearm while propranolol did not. In patients with isolated systolic hypertension, short-term beta-adrenergic blockade with propranolol had different effects according to age. In younger patients, propranolol significantly decreased systolic pressure with a concomitant increase in rapid ventricular ejection. In older patients, a lack of systolic pressure reduction was observed with an increase in total peripheral resistance and a decrease in systemic arterial compliance. The results suggested that beta-adrenergic blockade in hypertension may affect blood vessels with different effects, according to age, to the characteristics of hypertension and to the specific properties of the beta-blocking agent. The vascular effects involve not only resistive vessels but also large arteries.

Evidence of early changes of the brachial artery circulation in borderline hypertension

Quantitative evaluation of brachial artery diameter and blood flow (pulsed Doppler velocimetry) was carried out in nine normal subjects and 24 borderline hypertensive patients of the same age. The analysis of patients according to their value of cardiac index compared with the normal mean value plus 2 SD (standard deviation) enabled us to subdivide the patients into those with normal cardiac output and those with high cardiac output of similar age and pressure. Brachial artery diameter and flow were not different in patients with normal output and in normal controls, but were higher in patients with high output than in normal controls (p less than 0.05; p less than 0.01) and lower in patients with normal output than those with high output (p less than 0.01). These results demonstrate a nonhomogeneous pattern of the brachial artery of patients with borderline hypertension. Patients with normal cardiac output exhibited a trend to vasoconstriction, while patients with high cardiac output had a strong dilatation of the brachial artery.

Effect of cadralazine on brachial artery hemodynamics and forearm venous tone in essential hypertension

Forearm venous tone and brachial artery hemodynamics, including determinations of the arterial diameter and compliance by the use of pulsed Doppler systems, were measured in 16 patients with sustained essential hypertension before and after acute oral cadralazine dosing. Systolic and diastolic blood pressures significantly decreased, whereas heart rate increased. Brachial artery diameter and vascular resistance decreased, respectively, from 0.501 +/- 0.015 to 0.485 +/- 0.015 cm (P less than 0.001) and from 124.8 +/- 13.8 to 99.3 +/- 11.9 mm Hg/ml . sec (P less than 0.01). Blood flow velocity increased (P less than 0.05) but volumic flow, pulse wave velocity, and brachial artery compliance did not change. Forearm venous tone increased but the increase was inversely related to the degree of arteriolar vasodilatation. Our results indicate that, with cadralazine, forearm vascular resistance decreased while forearm blood flow was unchanged, the dilatation of small arteries contrasted with a significant reduction in the diameter of the large brachial artery, and the decrease in blood pressure was associated with a lack of increase in arterial compliance and changes in venous tone. This suggests an overriding influence of the activation of the autonomic nervous system on the action of cadralazine on large arteries and veins.

[Central and peripheral hemodynamic effects of nifedipine administered orally and sublingually in essential arterial hypertension]

The central and peripheral haemodynamic effects of the administration of 10 mg nifedipine sublingually in 6 patients with essential hypertension were compared with those observed after the administration of one 20 mg slow release tablet of nifedipine in 7 other hypertensive patients of the same age. The circulatory effects in the forearm were studied by pulsed Doppler velocimetry which allowed simultaneous measurement of the diameter of the brachial artery and of the velocity of blood flow. Both forms of administration significantly reduced the blood pressure by a significant reduction in total peripheral resistance. This reduction in total peripheral resistance was more significant (p less than 0.001 vs p less than 0.01) and more rapid with sublingual administration and was associated with a greater increase in heart rate and cardiac output. Both forms of administration induced an increase in brachial arterial blood flow due to a simultaneous increase in vessel calibre and velocity of blood flow. The results of this study show that both forms of administration act directly on the vessel wall of the arterioles and great arteries leading to a fall in blood pressure associated with an increase in peripheral blood flow. Sublingual nifedipine would seem to be the drug of choice for the treatment of hypertensive crises, whilst the slow release preparation with its lesser baroreflex stimulation would appear better suited for the long-germ treatment of essential hypertension.

Evidence of early degenerative changes in large arteries in human essential hypertension

Noninvasive evaluation of brachial artery diameter (pulsed Doppler velocimetry) and pulse wave velocity (strain gauge mechanography) was performed in 23 normal subjects and 49 patients with uncomplicated essential hypertension. Pulsatile arterial function was described in terms of derived characteristic impedance and arterial compliance. Compared with normal controls, hypertensive patients had greater arterial diameter (p less than 0.01) and pulse wave velocity (p less than 0.001). Two nomograms obtained from normal subjects relating the product of age and diastolic pressure to diameter and pulse wave velocity were used for analysis of the hypertensive group; 35 patients were inside the 95% confidence limits of the diameter and pulse wave velocity nomograms (Group 1), while 14 patients were outside the pulse wave velocity nomogram (Group 2). Age and mean pressure were similar, but pulse wave velocity was higher (p less than 0.001), arterial compliance lower (p less than 0.001), and characteristic impedance higher (p less than 0.001) in Group 2 than in Group 1. The amplitude of pulse pressure was higher in Group 2 than in Group 1 (p less than 0.001), and a negative correlation was found between pulse pressure and arterial compliance in Group 2, but not in Group 1. Thus, in the majority of hypertensive patients, arterial modifications could be related to the normal influence of age and pressure. In contrast, other patients exhibited features suggesting excessive arterial stiffness, manifested by abnormally high pulse wave velocity, decreased arterial compliance, and increased characteristic impedance.

Blood pressure in the 'low-pressure system' and cardiac performance in essential hypertension

Determinations of central venous pressure, cardiac haemodynamics and rapid volume expansion using iso-oncotic dextran were made in 49 men with sustained, uncomplicated essential hypertension and compared with those in 27 normotensive subjects of the same age and sex. In the hypertensives, central venous pressure was significantly increased in basal conditions while the cardiac index was normal and total blood volume was reduced. There was a positive and significant correlation of central venous pressure with age, arterial pressure and pulmonary wedge pressure. After rapid volume expansion, the slope of the curve relating cardiac output to central venous pressure was within the normal range, while the slope of the curve relating blood volume to central venous pressure was significantly reduced. The study provided evidence that in hypertensives: central venous pressure as well as arterial pressure is increased, the elevated central venous pressure is not due to an alteration in the cardiac 'pump function' or to hypervolaemia but rather to a decrease in the compliance of the venous bed or the left ventricle or both, and the strong correlation with age of the venous disturbances is similar to that found for the arterial side of the circulation.

Cardiac hypertrophy and arterial distensibility in essential hypertension

Echocardiographic determinations, left ventricular mass-volume ratio (M/V), left ventricular end-systolic stress (ESS), carotidofemoral pulse wave velocity (PWV), and brachial artery compliance (BAC), deduced from pulsed Doppler measurements and from the Bramwell-Hill equation, were evaluated in 20 patients with sustained essential hypertension in comparison with 20 control subjects of the same age and sex. In hypertensive patients, M/V ratio, ESS, and PWV were significantly increased while BAC was reduced. In the overall population, ESS was directly correlated with PWV (r = 0.73), and M/V ratio was significantly correlated with PWV (r = 0.60), BAC (r = -0.70), and systolic arterial pressure (r = 0.71). No comparable results were observed with diastolic arterial pressure. PWV was unchanged after cadralazine, a dihydralazine-like substance, and was decreased with the same blood pressure reduction following nitrendipine, a new calcium-blocking agent. These results suggest that: (1) the distensibility of large arteries plays an important role in the maintenance of cardiac hypertrophy in hypertension, and (2) antihypertensive drugs may act differently on arterial distensibility with possible consequences on ESS and reversion of left ventricular hypertrophy.

Elevation of brachial arterial blood velocity and volumic flow mediated by peripheral beta-adrenoreceptors in patients with borderline hypertension

Simultaneous determinations of cardiac output and brachial arterial blood flow were performed in patients with hypertension and high cardiac output in comparison with normal subjects of the same age. Brachial arterial blood flow was measured with a previously described pulsed Doppler apparatus that permitted the noninvasive determination of arterial diameter and blood flow velocity. In patients with borderline hypertension, brachial blood flow was significantly increased (136 +/- 11 vs 72 +/- 8 ml/min; p less than .001). After short-term administration of indomethacin, cardiac output decreased while brachial blood flow remained constant. After short-term administration of a selective beta 1-receptor antagonist (primidolol) and nonselective blocker (propranolol), cardiac output decreased significantly in both cases but the decrease in brachial blood flow was significant only after the administration of the nonselective beta-blocking agent. The study strongly suggested that in patients with borderline hypertension, the increased cardiac output is related to a prostaglandin and beta 1-adrenergic mechanisms whereas the increased brachial blood flow depends mainly on beta 2-adrenergic mechanisms.

Effects of acute and chronic angiotensin-converting enzyme inhibition on large arteries in human hypertension

The effects of angiotensin-converting enzyme inhibition on large arteries have been examined in uncomplicated essential hypertensive patients (grade 1-2 WHO). These effects were determined from (a) changes in arterial compliance as measured from the slope of the decline in arterial pressure during diastole and (b) alterations in diameter of the brachial artery and blood flow velocity within its lumen, as assessed by pulsed Doppler velocimetry. Both acute and chronic ACE inhibition were accompanied by a significant increase in arterial compliance and a dilation of the brachial artery. This response might be related to changes in plasma and/or intraarterial angiotensin and/or to changes in plasma potassium. Whatever their mechanism, the arterial dilatation and increase in compliance would improve the buffering and the conducting functions of the large arteries, and these in turn may, if persistent, prove beneficial in possibly preventing arterial complications of hypertension.

Regional compliance of brachial artery and saline infusion in patients with arteriosclerosis obliterans

Simultaneous brachial artery pressure and blood flow measurements were made in 15 patients with arteriosclerosis of the lower limbs (AOLL) and in controls of the same age and sex. Blood flow was evaluated by a pulsed Doppler device with a double-transducer probe. From analysis of the pressure-flow curves during diastole, regional arterial compliance (RAC) was determined by using as a model of the forearm arterial tree a system of tubes, each with a storage capacity, in series with the arteriolar resistance vessels. In AOLL patients, RAC was significantly reduced (102 +/- 13 vs 173 +/- 14.10(-4) ml/mm Hg, p less than 0.01), and systolic pressure was significantly increased. After saline infusion, systolic pressure continued to increase and arterial compliance, to decrease; brachial blood flow did not change. Study of the baroreflex sensitivity in AOLL patients under basal conditions indicated that a higher pulse pressure was required to obtain the same heart rate as in the controls. The study provided evidence that in AOLL patients: 1) compliance was reduced in the brachial artery (a regional circulation with no clinical evidence of arterial occlusion); 2) an increase in systolic pressure resulted from the decreased arterial compliance; and 3) saline infusion exaggerated the observed reduction in arterial compliance and increase in systolic pressure.

The effect of acute and chronic nicardipine therapy on forearm arterial haemodynamics in essential hypertension

By using simultaneous recording curves obtained with pulsed Doppler velocimetry and strain gauge mechanography, forearm arterial haemodynamics were studied in 26 patients with mild to moderate essential hypertension. Fifteen patients received a single oral dose of nicardipine 40 mg, and 11 patients were treated with nicardipine 30 mg three times daily for 3 months. In both groups of patients there was a similar and significant (P less than 0.001) reduction in mean, systolic, and diastolic pressures. There was a slight increase in heart rate (P less than 0.05) after the single dose, but no change after 3 months of treatment. The diameter, blood velocity, and blood flow of the brachial artery increased significantly in both treatment groups. The decrease in forearm vascular resistance was significant for both treatment groups. Brachial artery compliance increased (P less than 0.01) and characteristic impedance decreased (P less than 0.01) after both single-dose and long-term therapy with nicardipine. In patients who received nicardipine for 3 months, there were close correlations between the baseline serum calcium level and the percent change in vascular resistance (r = -0.73, P less than 0.01), blood flow (r = 0.89, P less than 0.001), and blood velocity (r = 0.91. P less than 0.001) of the forearm. No correlation was found between the baseline serum calcium and the change in arterial pressure. This study provided evidence that the blood-pressure-lowering effect of nicardipine was accompanied by a direct vasodilatory action in the small and large arteries of the forearm. An increase in peripheral blood flow with concomitant improvement of arterial compliance are the consequences of these arterial actions.

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.

Peripheral hemodynamic effects of short-term nadolol administration in essential hypertension

A study of forearm arterial and venous hemodynamics by pulsed Doppler velocimetry and plethysmography was performed in 21 patients with essential hypertension, aged 16 to 54 years, before and after short-term nadolol administration at a dose of 0.05 mg/kg. Because of a large intersubject variability in the responses of the hemodynamic parameters to nadolol, an unconventional statistic approach was used to divide the overall population of patients into two homogeneous groups. The first included nine patients (group 1) and the second 12 patients (group 2). In patients of group 1, nadolol significantly decreased the systolic blood pressure (p less than 0.001), venous tone (p less than 0.01), and brachial artery flow (p less than 0.05). In patients of group 2, nadolol did not affect any forearm parameters. Each group of patients was compared to an age- and pressure-matched group of patients receiving propranolol at equiblocking doses. Contrary to nadolol, propranolol was found to increase significantly the forearm vascular resistance in patients of groups 1 and 2 (90 +/- 19%, p less than 0.001; 63 +/- 10%, p less than 0.001, respectively). Thus the hemodynamic beta-blocking effects of nadolol in the forearm were less marked than those of propranolol, suggesting that the effects of acute beta blockade by nadolol could be offset by other effects, such as a peripheral partial-agonist effect.

Systemic compliance, renal hemodynamics, and sodium excretion in hypertension

Extracellular fluid volume (ECF), plasma volume (PV), glomerular filtration rate (GFR), renal plasma flow (RPF), efferent arteriolar oncotic pressure (pi E), sodium output (UNaV), and sodium clearance (CNa) were determined in 150 men including 50 normal controls (NC) and 100 sustained essential hypertensive patients (EH). Total effective vascular compliance (TEVC) and central venous pressure (CVP) were measured in 17 normotensives and 24 EH. EH had a decreased RPF and TEVC (P less than 0.001), while CVP and pi E were higher than in NC (P less than 0.001). ECF, GFR, UNaV, and CNa were identical in EH and NC. A positive correlation between RPF and CNa (P less than 0.01) and a negative correlation between pi E and CNa existed in both groups with a significant reset of the curve in EH: For any given RPF or pi E the CNa was higher in EH. In the overall population TEVC was negatively correlated with CVP (P less than 0.01) and pi E (P less than 0.01); CVP was positively correlated with pi E (P less than 0.01). The results suggest that physical properties of the low pressure system could participate in the natriuretic adaptation of the kidney in EH man.

Renal and systemic hemodynamics in sustained essential hypertension

Cardiac output (CO), renal blood flow (RBF), calf blood flow (CBF), and hepatic blood flow (HBF), glomerular filtration rate (GFR), and dopamine beta hydroxylase (D beta H) activity were studied in 198 men (67 normotensive controls and 131 hypertensive patients) of the same age with sustained uncomplicated essential hypertension. In the hypertensive men, the RBF and the RBF/CO ratio were significantly decreased (p less than 0.001). The RBF and RBF/CO ratio were negatively correlated with age (p less than 0.01), blood pressure (p less than 0.01), and D beta H activity (p less than 0.01). None of these relationships were observed with CBF and HBF. The observed decreases in RBF and the RBF/CO ratio in hypertensive men were reversed after administration of clonidine and alpha-methyldopa (p less than 0.01), but not after administration of propranolol. The study provides evidence that the reduction of renal perfusion in essential hypertension is partly reversible and related to an abnormality in the adrenergic system control.

Forearm arterial compliance: the validation of a plethysmographic technique for the measurement of arterial compliance

Arterial compliance was determined in eight normal subjects and 23 patients with hypertension and vascular disease by two independent techniques: (a) with a plethysmographic strain gauge (to measure pulsatile forearm volume changes as representing intra-arterial volume changes) and an automated sphygmomanometric system (to measure pulse pressure) and (b) calculation from the local pulse wave velocity and dimension of the brachial artery measured by pulsed wave Doppler ultrasound. Arterial compliance measured both by the plethysmographic technique and calculated from the pulse wave velocity was reduced in subjects with hypertension and vascular disease as compared with normal subjects. The regression equation between the compliance determined by the plethysmographic technique (x) and that calculated (y) from the pulse wave velocity and brachial arterial diameter was y = 3. 35x + 1.53, r = 0.77, P less than 0.001. The good correlation appears to validate the plethysmographic technique as a method of determining arterial compliance.

Captopril-induced changes in large arteries in essential hypertension

The effect on large arteries of the converting enzyme inhibitor captopril was studied in men with sustained essential hypertension with two different hemodynamic parameters: (1) systemic arterial compliance and (2) brachial artery diameter. After captopril administration, a 20 percent increase in arterial compliance was observed. The same increase was obtained with a 5 percent (acute experiment) and a 15 percent (short-term experiment) decrease in blood pressure, indicating that the decrease in pressure could not explain exclusively the increase in compliance. This assumption was studied with determinations of brachial artery diameter using original pulsed Doppler systems. After captopril administration, brachial artery diameter increased markedly despite the decrease in blood pressure. In addition to its effect on small arteries, the converting enzyme inhibitor captopril also has a special effect on the large arteries of patients with essential hypertension.

Comparison of oral MK 421 and propranolol in mild to moderate essential hypertension and their effects on arterial and venous vessels of the forearm

The efficacy of MK 421 and propranolol was compared in 48 patients with mild to moderate hypertension. Each patient was randomly assigned to receive 1 of the drugs for 12 weeks. Additionally, a subgroup of 28 patients underwent studies of forearm arterial and venous circulation by means of pulsed Doppler and mercury-in-silastic plethysmography. Both drugs reduced supine and standing blood pressure (BP) (p less than 0.001). Propranolol reduced heart rate (p less than 0.001), while MK 421 did not change it. Brachial artery diameter, blood velocity and flow increased after MK 421 (p less than 0.001), but were not changed after propranolol therapy. Forearm vascular resistance decreased after MK 421 (p less than 0.001) and after propranolol (p less than 0.05). Forearm venous tone was unaffected on MK 421, but increased after propranolol (p less than 0.01). Thus, in moderate hypertension, 3 months of treatment with MK 421 or propranolol similarly decrease BP, but affect the forearm circulation differently: MK 421 dilates both the brachial artery and the arterioles of the forearm, but does not affect the venous vessels, and propranolol causes little arterial change but increases the forearm venous tone.