Biomedical subjects

A Benetos

Publications and source records attributed to A Benetos.

135 records · Page 8Linked to original sources

PubMedDate not supplied

Carotid artery pulsatility during parabolic flights.

In cardio-vascular hemodynamic, the arterial pulsatility, represented by the arterial pulse pressure (PP= systolic blood pressure-diastolic blood pressure), is different from one site to another, in opposite with the mean blood pressure almost identical in the whole body in supine position (or in microgravity). This is due to the arterial tree geometry and regional differences in the distensibility properties of the arterial wall. As the level of blood pressure opposed to the cardiac left ventricle work is the central pressure, on one hand and as the arterial pulsatility at the site of arterial baro-receptors (located on aortic arch and carotid arteries' bifurcation) regulates the sympathetic and vagal control of heart and peripheral resistances on the other hand, to determine the evolution of this central pulse pressure is of major importance in the knowledge of cardio-vascular hemodynamic during hyper or hypogravity as observed during parabolic flights. The aim of this study was to evaluate noninvasively the carotid artery pulsatility and mechanic properties during parabolic flights.

Adult↗

PubMedDate not supplied

Action of vasodilating drugs on small and large arteries of hypertensive patients.

We studied blood pressure, arterial diameter, and blood flow of the brachial artery in patients with sustained essential hypertension before and after administration of the vasodilating drugs nitroglycerin, captopril, dihydralazine, diltiazem, and isosorbide dinitrate (ISDN). The diameter and the blood flow of the brachial artery were measured with a pulsed Doppler device which allowed the angle between the ultrasound beam and the vessel axis to be determined with a precision better than 2%. Nitroglycerin and captopril decreased blood pressure slightly but increased arterial diameter markedly. Dihydralazine, diltiazem, and ISDN decreased blood pressure similarly and significantly and also reduced forearm vascular resistance. Dihydralazine reduced arterial diameter (p less than 0.001), but did not change brachial blood flow. Diltiazem and ISDN increased the arterial diameter markedly (p less than 0.001 and p less than 0.01, respectively), but only the former increased brachial blood flow. We conclude that antihypertensive drugs that dilate small arteries can either reduce (dihydralazine) or increase (nitroglycerin, captopril, diltiazem, ISDN) the caliber of large peripheral arteries and thus have different effects on peripheral blood flow.

Adult↗

PubMedDate not supplied

Blockade of angiotensin II type 1 receptors: effect on carotid and radial artery structure and function in hypertensive humans.

Converting-enzyme inhibition reduces cardiovascular hypertrophy in hypertensive subjects. Whether the blockade of angiotensin II type 1 (AT(1)) receptors reduces arterial hypertrophy has never been investigated. In a double-blind study versus placebo in subjects with essential hypertension, the effect of the AT(1) blocker irbesartan (150 mg/day for 8 weeks) on blood pressure, wall thickness, diameter and stiffness of the common carotid and radial arteries was studied, using echotracking techniques of high resolution. With irbesartan, mean blood pressure decreased significantly and proportionally to the baseline levels of active renin, and angiotensin I and II. There was a significant decrease in radial artery wall thickness. The percent change from baseline (+/- SEM) was -10.51 +/- 3.42 versus 6.18 +/- 4.77. There was no significant change in diameter or distensibility. This effect was correlated neither to blood pressure changes nor to hormonal baseline levels of the renin-angiotensin system. Carotid wall thickness and diameter were unchanged. Thus a 2-month treatment with an AT(1) antagonist significantly reduced radial but not carotid artery wall thickness. Blood pressure reduction could be explained on the basis of circulating renin-angiotensin activity. On the contrary, radial artery wall thickness reduction was independent of the baseline circulating renin-angiotensin activity and was not correlated with the effects of AT(1) blockade on blood pressure, thus implying the involvement of local hemodynamic and/or cellular mechanisms.

Adult↗

PubMedDate not supplied

Dose-related changes in the mechanical properties of the carotid artery in WKY rats and SHR following relaxation of arterial smooth muscle.

Acute converting enzyme inhibition relaxes arterial smooth muscle and increases arterial compliance in several models of animal and human hypertension. However, it is unknown whether the doses needed for the relaxation of large arteries are similar to those inducing arteriolar relaxation and blood pressure (BP) decrease. To answer this question, we used a previously described model of the in situ carotid artery to determine the pressure-volume relationship over a range of transmural pressures from 25 to 200 mm Hg in normotensive rats (WKY) and spontaneously hypertensive rats (SHR). The pressure-volume relation was determined after an acute single oral administration of either a placebo or the converting enzyme inhibitor quinapril given at two different doses (0.3 or 3 mg/kg). At the end of each experiment, the total relaxation of arterial smooth muscle was achieved after a local administration of potassium cyanide (KCN). In the WKY placebo group, from 25 to 100-125 mm Hg transmural pressure, carotid compliance increased and reached a maximum value at 100-125 mm Hg (i.e. close to the operating range of systemic mean BP of the animals), and decreased thereafter. In the SHR placebo group, carotid compliance was significantly lower than in the WKY placebo group for transmural pressure up to 125 mm Hg, and thereafter was equal or even higher; the maximum value of compliance was reached at 125-150 mm Hg transmural pressure, i.e. substantially less than the operating range of the systemic mean BP of the SHR placebo (180 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Pulsed Doppler: an evaluation of diameter, blood velocity and blood flow of the common carotid artery in patients with isolated unilateral stenosis of the internal carotid artery.

Arterial diameter, blood velocity and blood flow of both common carotid arteries were studied in 24 patients with isolated unilateral internal carotid artery stenosis, without any other significant lesion of the carotid system. The methodology used a pulsed Doppler system with two original characteristics: an adjustable range-gated system and a double transducer probe enabling both the arterial diameter and blood velocity to be evaluated. On the involved side, the diameter, the blood velocity and the blood flow were significantly reduced (p less than 0.001) in comparison with the opposite side. The degree of the internal carotid artery stenosis judged on arteriography was negatively correlated with (i) the blood flow of the common carotid artery homolateral to the stenosis (r = -0.78, p less than 0.001); and (ii) the ratio of the common carotid artery blood flow between the involved and the opposite side (r = -0.80, p less than 0.001). The proposed quantitative evaluation can be suitable for the detection and for the follow up of patients with stenosis of the internal carotid artery who do not have any other lesion of the carotid system.

Aged↗

PubMedDate not supplied

[Comparison of central pulse pressure estimated from pulse wave propagation velocity and carotid pulse pressure measured by applantation tonometry].

BACKGROUND: Pulse pressure (PP) corresponds to the difference between arterial systolic blood pressure and diastolic blood pressure. Central PP seems to be a stronger coronary risk marker than brachial PP. Central PP can be estimated by aortic PP measured non invasively by aplanation tonometry of the carotid artery. The aim of this study was to compare 2 methods of estimation of aortic PP: estimation from Pulse Wave Velocities (PWV) and by aplanation tonometry of the carotid artery. Estimation from PWV is based on the non uniform transmission of the PP i.e. the amplification of PP from the aorta to brachial artery, through arteries of increasing impedance. METHODS: One hundred and fifty one subjects were included, 111 hemodialysis patients and 40 subjects free of cardiovascular treatment or cardiovascular organ damage, recruited in a preventive medicine setting. Central PP was measured by aplanation tonometry of the carotid artery. The following formula was used for the relationship between PP and PWV in the two arterial segments considered for pulse wave travel (waterhammer formula): [formula: see text] Where measurement of brachial PP (PPBr) and PWV at aortic (PWVAo) and brachial (PWVBr) gives an estimation of aortic PP (PPAo estimated). Carotid-femoral PWV was used for PWVAo and carotid-radial PWV was used for PWVBr. The two methods were compared by t-test and according to Bland and Altman's method. RESULTS: In the hemodialysis group (73 males, 44 +/- 12 years old), brachial PP was 56 +/- 15 mm Hg and central PP as measured at the carotid level was 47 +/- 15 mmHg. In the healthy group (29 males, 46 +/- 11 years old), these values were 46 +/- 10 mmHg and 35 +/- 10 mmHg respectively. Compared to carotid artery aplanation tonometry, PPAo estimated was larger than central PP by 2.9 +/- 6.3 mmHg in hemodialysis patients and by 5.4 +/- 6.6 mmHg in the healthy group. The difference was significantly larger in healthy subjects than in hemodialysis patients (p = 0.031). CONCLUSION: The PWV estimated PP is larger than the central PP measured at the carotid level by aplanation tonometry. The difference is larger in cardiovascular event free subjects than in patients on hemodialysis.

Adult↗

PubMedDate not supplied

Management of heart failure in the elderly: recommendations from the French Society of Cardiology (SFC) and the French Society of Gerontology and Geriatrics (SFGG).

Heart failure, a frequent disease in the elderly, has a pejorative prognosis. Clinical diagnosis is complicated by atypical or difficult-to-interpret symptoms and by the concomitant presence of other diseases, particularly cognitive impairment, neurological disorders and diseases of the musculoskeletal system. Among the additional investigations, echocardiography remains underused. Impairment of diastolic left ventricular function is frequent. The usual laboratory tests must include calculation of the creatinine clearance, which is indispensable for dosage adjustment of certain drugs (ACE inhibitors, digoxin, spironolactone). The value of plasma natriuretic peptide assays as diagnostic tools has not been determined in elderly or very elderly populations and the plasma B-type natriuretic peptide increases with age. Comprehensive geriatric assessment is essential in order to screen for concomitant diseases and determine the patient's degree of dependence. The general objectives of treatment remain applicable to the elderly subject: improvement in the quality of life, reduction of mortality and the number and duration of hospitalisations, and slowing disease progression. In the frail elderly subject, symptom alleviation is to be the primary objective. In the absence of specific studies on elderly or very elderly subjects, most of the recommendations have been extrapolated from the data based on the evidence generated in younger populations. The dietary rules are to be more flexible than those used for younger subjects, particularly in order to prevent the risk of denutrition induced by strict salt-free diets. Special precautions for the use of heart failure drugs are due to comorbidities and the pharmacokinetic and pharmacodynamic changes related to aging. Drugs dosage increase is to be cautious and carefully monitored for adverse reactions. The therapeutic programmes in which multidisciplinary teams are involved reduce the number and duration of hospitalisations and the costs generated by the disease.

Aged↗

PubMedDate not supplied

[Antihypertensive efficacy of the combination of captopril 50mg and hydrochlorothiazide 25mg evaluated by ambulatory blood pressure measurement].

The anti-hypertensive effects of the captopril-hydrochlorothiazide combination administered during three months as one single morning dose were evaluated in 51 patients with moderate essential hypertension by means of ambulatory blood pressure recording. At the end of the study, the mean values of arterial blood pressure recorded over 24 hours were significantly lowered: systolic pressure was reduced from 145 +/- 11 to 131 +/- 10 mmHg (P less than 0.001), and diastolic pressure from 88 +/- 5 mmHg to 81 +/- 4 mmHg (P less than 0.001). The same results were recorded during the day (07.00 to 22.00 hours) and during the night (23.00 to 06.00 hours). No change in heart rate was observed.

Adult↗

PubMedDate not supplied

[Comparison between the effects of angiotensin-converting enzyme inhibitors and angiotensin II antagonists].

The renin-angiotensin-aldosterone system (RAAS) plays an important role in blood pressure regulation and fluid and electrolyte homeostasis. Angiotensin converting enzyme inhibitors (ACEI) were the first of the RAAS blocking agents to be widely used in the treatment of hypertension and congestive heart failure. Angiotensin II receptor antagonists, another class of pharmacological blockers of the RAAS, have more recently been shown to be safe and useful in hypertension and perhaps also in heart failure. This review deals with the similarities and differences between these two classes of drugs with particular emphasis on the effects of the drugs on the heart, the blood vessels, the kidney (role of the drugs as nephroprotective), the brain, the hormonal profile and finally the potential adverse effects. The place of angiotensin II antagonists in congestive heart failure remains to be more precisely defined.

Angiotensin II↗