Biomedical subjects

Laurent Belhassen

Publications and source records attributed to Laurent Belhassen.

3 recordsLinked to original sources

PubMed2003

Improved endothelial function by the thromboxane A2 receptor antagonist S 18886 in patients with coronary artery disease treated with aspirin.

OBJECTIVES: In this study, we evaluated the effect of S 18886, a specific thromboxane A(2) receptor antagonist, on endothelial function in patients with coronary artery disease (CAD). BACKGROUND: Impaired release of endothelial vasodilator substances and increased release of vasoconstrictor prostanoids both contribute to endothelial dysfunction in atherosclerosis. One unresolved question is whether vasoconstrictor prostanoids are still produced and affect vascular tone or alter endothelium-dependent vasodilation in patients treated with aspirin. METHODS: Twenty patients with stable CAD treated with 100 mg/day aspirin were evaluated in a randomized, double-blinded, placebo-controlled study. Twelve patients received a single oral dose of 10 mg S 18886, and eight patients received placebo. Before and 60 min after a single oral dose of S 18886 or placebo, flow-mediated vasodilation (FMD) was evaluated using an echo-tracking device. Venous occlusion plethysmography was used to evaluate the effects on forearm blood flow (FBF) of a brachial artery infusion of acetylcholine (ACh), sodium nitroprusside (SNP), or norepinephrine before and after treatment. RESULTS: Baseline FBF was not affected by S 18886 or placebo. The vasodilator response to ACh was significantly potentiated by S 18886 as compared with placebo (p = 0.03 by analysis of co-variance), whereas the effects of norepinephrine and SNP were unchanged. Flow-mediated dilation increased from 2.50 +/- 1.14% to 3.84 +/- 1.80% (p < 0.01) after S 18886, but was unchanged after placebo. CONCLUSIONS: Single administration of S 18886 improved FMD and ACh-induced vasodilation in aspirin-treated patients with CAD. These results suggest that release of endogenous agonists of TP receptors may contribute to endothelial dysfunction, despite aspirin treatment, in patients with atherosclerosis.

Acetylcholine↗

PubMed2002

Evaluation of carotid artery and aortic intima-media thickness measurements for exclusion of significant coronary atherosclerosis in patients scheduled for heart valve surgery.

OBJECTIVES: We assessed the value of carotid intima-media thickness (CIMT) and thoracic aorta intima-media thickness (AoIMT) in ruling out significant coronary artery disease (CAD) in patients scheduled for heart valve surgery. BACKGROUND: Evaluation of CAD is needed in most patients undergoing heart valve surgery because of the high surgical morbidity in patients with significant CAD, raising the need for sensitive tests to exclude CAD. Coronary angiography is the reference standard, but this invasive procedure is not cost-effective, because more than two-thirds of these patients do not have significant CAD. METHODS: In a pilot study, CIMT and AoIMT cutoff values separating low- from high-risk groups were determined in 96 patients by using receiver-operating characteristic curves. Then, a prospective study was conducted in 152 patients to determine the statistical power of these cutoff values used alone or in combination. In both studies, carotid artery ultrasonography and transesophageal echocardiography were performed before coronary angiography and valve surgery. RESULTS: In the pilot study, CIMT < 0.55 mm and AoIMT < 3 mm were excellent predictors of the absence of CAD. In the prospective study, CIMT and AoIMT criteria were independent predictors of significant CAD in these patients, as assessed by logistic regression analysis. Carotid IMT criterion had 100% sensitivity and 100% negative predictive value. For the AoIMT criterion, sensitivity was 98%, and negative predictive value 99%. Combining the two criteria did not change sensitivity and negative predictive value but increased specificity to 78%. CONCLUSIONS: Measurements of CIMT and AoIMT may be useful in selecting patients who do not require coronary angiography before heart valve surgery.

Aged↗

PubMed2002

Characterization of peripheral arterial wall motion by Doppler tissue echography: a validation study.

Doppler tissue echography (DTE) has been proposed for arterial wall-motion analysis. However, it is not known if DTE gives precise measurements of arterial displacement. Therefore, we used a pig aorta, in vitro model to study arterial wall velocities. High resolution color B-mode DTE acquisitions gave accurate estimations of velocities as compared with those obtained by a referenced wall-tracking system, with a slight underestimation of values calculated from DTE (14.4 +/- 0.1 for DTE vs 16.1 +/- 0.2 at 5 L/min output, P >.05). Excellent correlations were obtained between both methods (r(2) = 0.94, P <.001), and Bland-Altman analysis revealed no significant differences between measurements. We also compared common carotid arterial wall velocities obtained in 16 healthy volunteers by DTE and a wall-tracking system, which gave similar wave profiles. As expected, arterial distensions calculated from DTE were lower than those from a wall-tracking system (6.8 +/- 1.7% vs 7.4 +/- 2.1%, respectively, P =.02). These results indicate that DTE may be used to study arterial wall displacement.

Adult↗