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Biomedical subjects

M Safar

Publications and source records attributed to M Safar.

At least 235 records · Page 13Linked to original sources
PubMed1987

[Index of arterial and venous compliance and echocardiographic parameters in essential permanent arterial hypertension].

Forearm venous tone (FVT), carotido-femoral pulse wave velocity (PWV), and left ventricular end diastolic diameter (LVD), left ventricular posterior wall thickness (LVPWT), myocardiac mass (MM), measured by echography were evaluated on 25 subjects with sustained essential hypertension and 30 normotensive subjects with same age and same sex. For the overall population, FVT is positively correlated with LVD (r = 0.45, p less than 0.001), with LVPWT (r = 0.37, p less than 0.01) and with MM (r = 0.55, p less than 0.001). PWV is not correlated with LVD but is positively correlated with LVPWT (r = 0.48, p less than 0.001) and with MM (r = 0.40, p less than 0.01). Stroke volume is positively correlated with FVT (r = 0.42, p less than 0.01), but not with PWV. This study shows that in a population of normals and sustained essential hypertensive subjects: i) indexes of venous compliance are correlated with myocardial thickness, myocardiac mass, left ventricular diameter and stroke volume, while ii) indexes of arterial compliance are only correlated with myocardial thickness. Thus, the modifications of arterial and venous compliance observed in sustained essential hypertension influence cardiac structure and function.

Adult↗
PubMed1987

[Prevention trials and role of vascular factors in moderate arterial hypertension].

Epidemiological studies on the treatment of moderate arterial hypertension show little change in the frequency of coronary disease despite a significant lowering of arterial pressure. This phenomenon reflects the causative role played by alterations of the main arteries in the cardiovascular morbidity and mortality of treated hypertensive patients. These alterations may be of different natures, notably haemodynamic (increased arterial rigidity) or biochemical (especially changes in lipid profile). Seen from that angle, involvement of the main arteries reflects either an arterial wall pathology specific to the hypertensive disease, or an associated atherosclerosis, or the effect of certain drugs. The role of each of these factors is described.

Antihypertensive Agents↗
PubMed1987

[Hyperreactivity of the humeral artery to noradrenaline in essential hypertension patients].

The hyperresponsiveness of small arteries to norepinephrine is well documented in essential hypertensive patients. Our objective was to investigate in situ the reactivity to norepinephrine of the diameter of large arteries which are involved in the arterial disease of hypertension as well as small arteries. Brachial artery diameter, blood flow velocity, local volumic blood flow and local vascular resistances were determined non invasively using a pulsed Doppler system in 19 patients with essential hypertension and 9 normotensive subjects, before and after placebo (glucose) or increasing doses of norepinephrine (10, 20 and 40 ng/kg/min; i.v.) given in a single blind fashion. In hypertensive patients, norepinephrine (40 ng/kg/min) induced (i) a significant decrease in brachial artery diameter, local blood velocity, volumic flow and conductance and (ii) a small increase in mean arterial pressure. These hemodynamic changes did not occurred in the placebo group and were significantly greater in hypertensive patients than in normotensive subjects although plasma norepinephrine increased to the same extent in both groups. We conclude that in hypertensive patients, the increase in vascular reactivity to norepinephrine involves not only the resistive vessels, but also the large arteries thus decreasing their conducting and buffering function.

Adult↗
PubMed1987

[Comparison between the ambulatory and occasional determination of the blood pressure].

In this study, we have attempted to determine the link between the occasional measurement of the blood pressure with an Hg sphygmomanometer and the ambulatory pressure, considering different recording periods during the nyctemer. The mean values of the period 8-10 A.M. and more generally of the diurnal period (7 am-10 pm) are close to the values occasionally observed, contrary to the night values and the values of the entire 24 hours. The heart frequency is always well correlated to the mean ambulatory frequency, for the entire period studied. The systolic and mean arterial pressure are also well correlated. On the contrary, there is no meaning when the diurnal period (7 am-10 pm) is reduced to the period of diurnal activity (7 am-7 pm). There is a very strong correlation between the values of the systolic, diastolic, and mean pressures observed during 24 hours and the morning period (8-10 am), giving the impression that this period could be a good reflection of the ambulatory blood pressure of the 24 h.

Adult↗
PubMed1986

Extracellular and interstitial fluid volume in obesity with and without associated systemic hypertension.

Fluid volumes and cardiac and renal hemodynamics were investigated in 44 obese men, 22 with normal blood pressure and 22 with sustained essential hypertension. For the same degree of obesity hypertensive patients had a higher value in extracellular (p less than 0.05) and interstitial fluid (p less than 0.01) volumes than normotensive subjects, while plasma volume, total body water, body cellular water, cardiac output, renal blood flow and glomerular filtration rate were similar. For the same level of blood pressure, the expansion of extracellular and interstitial fluid volume paralleled the degree of obesity. Thus, obese patients with hypertension have an absolute increase in extracellular and interstitial fluid volumes. The increase was related both to the degree of overweight and to the mechanisms of hypertension.

Adult↗
PubMed1986

[Non-invasive study of the role of carotid distension in the baroreflex response to the arteriolar vasodilator cadralazine in essential hypertension].

Using pulsed Doppler methods, hemodynamics of the common carotid and the brachial arteries were measured in 10 patients with essential hypertension. After vasodilatation due to Cadralazine, a Dihydralazine-like substance, mean arterial pressure significantly decreased and heart rate increased. Change in PRA was significantly and positively correlated with the change in heart rate. In the brachial artery circulation, diameter and vascular resistance decreased while blood flow velocity and volumic blood flow did not increase significantly. In the common carotid artery circulation, diameter, mean blood flow did not change. However, vascular resistance and tangential tension decreased slightly. The increase in heart rate was strongly and negatively correlated (r = 0.82 p less than 0.01) with the change in the carotid artery tangential tension (measured as the product between mean arterial pressure and arterial radius) while no comparable correlation was observed with the change in blood pressure or arterial radius alone. The study suggested that in essential hypertensives, modifications in the carotid artery tangential tension secondary to arteriolar vasodilatation contribute actively to the baroreflex response.

Adult↗
PubMed1985

Pulsed Doppler evaluation of diameter, blood velocity and blood flow of common carotid artery in sustained essential hypertension.

Diameter, blood flow velocity, and volumic flow of the common carotid artery were measured in 38 patients with sustained essential hypertension and compared with those of 38 age-matched normal subjects. Both hypertensive and control subjects were classified according to age into those younger and those older than 45 years. For the determinations, a pulsed Doppler velocimeter with an adjustable range-gated time system and a double transducer probe was used. In the younger group, the diameter of the common carotid artery had a similar value in hypertensive patients (0.639 +/- 0.014 cm) and in controls (0.651 +/- 0.015). The same level of blood flow velocity in hypertensive patients (19.7 +/- 0.9 cm/s) and in controls (21.2 +/- 0.9 cm/s) was observed. Therefore, the volumic flow was equal in the common carotid artery of the hypertensive patients (385 +/- 20 ml/min) and of the normotensive subjects (410 +/- 23 ml/min). In the older group, blood flow velocity was reduced in the common carotid artery of the hypertensive patients (19.4 +/- 1.0 cm/s vs. 15.6 +/- 0.6 cm/s; p less than 0.01), but the diameter was unchanged (0.653 +/- 0.018 cm in hypertensive patients and 0.665 +/- 0.018 cm in controls). Thus, there was a significant reduction of volumic blood flow in common carotid artery of the hypertensive patients over 45 years (321 +/- 14 ml/min). A negative relationship was observed between common carotid artery blood flow and age in elderly hypertensive patients (r = -0.42; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[The renin-angiotensin system and large arteries in the hypertensive patient].

The large arteries are impaired in uncomplicated, permanent, essential arterial hypertension. The peripheral arteries such as the humeral artery or the common carotid artery have a normal or increased diameter, reduced blood flow and, especially, reduced compliance. Reduction of the arterial compliance reflects an impairment peculiar to the large blood vessels, independent of the pressure. Antihypertensive medicines, for a given drop in pressure, may increase, diminish or not change arterial compliance. This is an important point to be taken into account in relation to cardiovascular morbidity and mortality of treated hypertensives. It has been particularly well studied in the context of inhibitors of the renin-angiotensin system.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1985

[Effect of arterial hypertension on pulse wave velocity and the diameter and compliance of the brachial artery in man].

The non invasive investigation of the brachial artery was performed in 51 mild to moderate essential hypertensive patients and 23 normal subjects of similar age. It included quantitative evaluation of arterial diameter (pulsed Doppler velocimetry), pulse wave velocity (strain gauge mechanography) and arterial compliance deduced from the former indices. Hypertensive patients exhibited higher pulse wave velocity (Pw 0.001) and arterial diameter (p less than 0.01) than normal controls. The strong correlation found in normal subjects between pulse wave velocity and the product of age and diastolic pressure (r = 0.88, p less than 0.001) was used as a nomogram for the analysis of those hypertensive arterial changes. Accordingly the projection of patients on this nomogram enables to distinguish two groups according to that pulse wave velocity was inside (Group 1) (37 patients) or above (Group II) (34 patients) the upper limit of the nomogram. The comparison of these two groups of hypertensive patients showed that despite a similar level of age and pressure, arterial compliance was lower and pulse pressure higher in Group II than in Group I. These results demonstrate that early alterations of brachial artery occur in hypertension: these arterial changes can be attributed in most of the patient to the exclusive effect of aging and pressure elevation; however, in some patients additional degenerative process, perhaps atherosclerotic in nature, is responsible for profound decrease in arterial compliance and increase in pulse pressure so that such patients may appear as especially predisposed to systolic hypertension and degenerative arterial complications.

Adult↗
PubMed1984

Adipose tissue cellularity and hemodynamic indexes in obese patients with hypertension.

Fat-cell weight, fat-cell number, and hemodynamic indexes were determined in 25 obese men with sustained elevation of BP. Fat-cell weight (and not fat-cell number) was positively correlated with overweight (r = .51) and mean arterial pressure (MAP) (r = .57) in basal conditions. After body weight reduction, BP decreased significantly through a decrease in cardiac index due to a predominant decrease in heart rate. Simultaneously, fat-cell weight decreased significantly. The ratio between the change in BP and the change in body weight, ie, the ability to decrease pressure per unit weight loss, was positively related to the level of initial BP (r = .80) and reached a plateau above 120 mm Hg of the initial MAP. We suggest that, in patients with obesity and hypertension, high BP is associated with hypertrophic obesity, and after body weight reduction, the simultaneous decrease in BP, heart rate, and fat-cell weight could be mediated by neurogenic mechanisms.

Adipose Tissue↗
PubMed1983

[Systolic arterial hypertension in patients amputated for injury].

The blood pressure of 106 men who had undergone amputation of one limb on account of war injury was compared with that of 184 male controls of the same ages. All subjects with a diastolic pressure above 90 mmHg were excluded from the study. The diastolic pressure was statistically equivalent in both groups, but the amputees had a significantly higher systolic pressure. Changes in the visco-elastic properties of the arterial system related to amputation might be responsible for this rise in systolic pressure.

Adult↗
PubMed1983

Intravascular volume, extracellular fluid volume, and total body water in obese and nonobese hypertensive patients.

Intraarterial blood pressure, plasma volume, extracellular and interstitial (IFV) fluid volumes, and total and intracellular (IBV) body water were evaluated in 50 men: 16 obese hypertensive patients, 16 nonobese hypertensive patients, and 18 normal subjects of similar age. In obese hypertensive subjects, the IBW/IFV ratio was significantly increased (p less than 0.01) in comparison with both control subjects and nonobese hypertensive patients. After body weight reduction, blood pressure (p less than 0.01), heart rate (p less than 0.05), and the IBW/IFV ratio (p less than 0.01) significantly decreased. The decrease in the ratio was due to an absolute increase in the interstitial fluid volume, related to a shift of fluid volume from the intracellular to the interstitial space. Thus, obese hypertensive patients have an increased water cell content, causing an altered partition between the intracellular and the interstitial spaces.

Adult↗
PubMed1983

Circadian changes in heart rate in unanesthetized normotensive and spontaneously hypertensive rats.

Circadian changes in heart rate and heart rate variability were measured in spontaneously hypertensive (SHR) and normotensive (WKY) rats. Electrocardiograms (ECG) were continuously recorded, over a 24 hour period from freely moving conscious rats via three small metallic subcutaneous electrodes which were positioned a week before the recording period. The findings reported here show: 1/ Mean heart rate calculated over 24 hours were lower in both strains than previously reported. This difference probably reflects the lack of anesthesia and minimal stress in the present study. 2/ The timing of the circadian variations in both strains were the same, suggesting that were both entrained to the light-dark cycle. 3/ The 24 hours mean heart rate variability was significantly higher in SHR than in WKY but in each strain it was similar throughout the 24 hours. This suggests that the vagal tone in SHR was higher by a fairly constant amount throughout the light-dark cycle.

Animals↗
PubMed1983

Thromboxane B2 in borderline and essential hypertensive patients.

Thromboxane B2 (TxB2) was measured in the venous and arterial plasma and in the urine of 15 borderline and 15 sustained essential hypertensive patients, and in the plasma and urine of 12 control normotensive age-matched subjects. Plasma and urine thromboxane B2 were significantly higher in both the borderline and sustained hypertensives than in the control normotensives. There was a significant positive correlation between urinary (i.e. renal)TxB2 excretion and the glomerular filtration rate, and between urinary TxB2 excretion and sodium excretion in the hypertensive but not in the normotensive subjects. Thromboxane A2 participates in pressure natriuresis.

Adolescent↗
PubMed1983

Comparative effects of beta-adrenergic blockade in systolic hypertension according to age.

Hemodynamic variables were measured in 34 patients with isolated systolic hypertension before and after acute administration of propranolol. The patients were separated into two groups, those younger than and those older than 45 years of age, respectively. After drug administration, systolic pressure decreased significantly (P less than 0.001) in younger subjects with a concomitant increase in rapid ejection time (P less than 0.001). In the older patients, cardiac and peripheral factors determining systolic pressure were each altered after beta-adrenergic blockade. The most striking result was the reduction in systemic arterial compliance (P less than 0.01) probably due to unmasked alpha-adrenergic vasoconstriction. This arterial effect explains the lack of systolic pressure reduction despite a decrease in cardiac performance.

Adrenergic beta-Antagonists↗