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Biomedical subjects

S Doucet

Publications and source records attributed to S Doucet.

At least 19 recordsLinked to original sources
PubMed2001

Stent placement to prevent restenosis after angioplasty in small coronary arteries.

BACKGROUND: Lesions in small-diameter vessels (<3 mm) define a group with distinct clinical and morphological characteristics. There is an inverse relationship between vessel size and angiographic restenosis rate. This study assessed whether stents reduce angiographic restenosis in small coronary arteries compared with standard balloon angioplasty. METHODS AND RESULTS: We randomly assigned 351 symptomatic patients needing dilatation of 1 native coronary vessel between 2.3 and 2.9 mm in size to angioplasty alone (n=182) or stent implantation (n=169). The primary end point was angiographic restenosis at 6 months. Secondary end points included death, myocardial infarction, bypass surgery, and target vessel revascularization in hospital and at 6 months. There were no significant differences between groups in terms of major in-hospital complications. There was a trend toward fewer in-hospital events in the stent group (3% versus 7.1% in angioplasty group, P=0.076). Crossovers to stent occurred in 37 patients (20.3%). Repeat angiography at 6-month follow-up was performed in 85.3% of patients. Angiographic restenosis occurred in 28% of the stent group and 32.9% of the angioplasty group (P=0.36). Target vessel revascularization was required in 17.8% versus 20.3% of patients (P=0.54), respectively. CONCLUSIONS: Stenting and standard coronary angioplasty are associated with equal restenosis rate in small coronary arteries. With a lower in-hospital complication rate, stenting may be a superior strategy in small vessels.

Angioplasty, Balloon, Coronary↗
PubMed2001

Complications of cardiac catheterization in the current era: a single-center experience.

Consecutive cardiac catheterization procedures done over a 2-yr period (April 1996 to March 1998) were prospectively analyzed to determine and characterize procedure-related complications (in-hospital and 1-mo follow-up), as they occur at present. During the study period, 11,821 procedures (7,953 diagnostic and 3,868 therapeutic) were performed. The majority of procedures (> 60%) were done in high-risk patients. Stents were implanted in 33% of patients, and adjunctive abciximab was used in 6.6% of therapeutic procedures. The overall complication rate was 8% (3.6% of diagnostic procedures and 15.1% of therapeutic procedures). The procedure-related mortality rates were 0.2%, 0.1%, and 0.5% for total, diagnostic, and therapeutic procedures, respectively. Cardiac complications were seen in 3.9% (1.5% of diagnostic and 9% of therapeutic procedures). Emergency cardiac surgery was required in 0.05% of the diagnostic procedure group and 0.3% of the therapeutic procedure group (total, 0.1%). Despite marked changes in patient population and practice, the complication rates of cardiac catheterization remain very low.

Abciximab↗
PubMed2001

Intravascular ultrasound assessment of pulmonary vascular disease in patients with pulmonary hypertension.

BACKGROUND: Measurements of pulmonary pressure and resistance are still considered to be the "gold standard" in the evaluation of pulmonary hypertension (PH), despite their limitations in predicting irreversible disease. Hemodynamic assessment also only provides a global evaluation of the pulmonary vascular bed, whereas PH is an inhomogeneous disease of the vessel wall. METHODS AND RESULTS: We assessed the value of intravascular ultrasound (IVUS) in 30 patients with suspected PH and correlated the structural changes in distal pulmonary arteries found on IVUS with conventional hemodynamic data. Plasma endothelin (ET)-1 levels and pulmonary ET-1 extraction also were measured as markers of the severity of PH. The anatomic abnormalities revealed by IVUS were more severe in the lower lobes than in the upper lobes, as evidenced by the greater percentage of wall thickness (WT), the smaller lumen diameter/WT and lumen area/total vessel area (p < 0.05 for each). IVUS anatomic indexes correlated directly with hemodynamic data (eg, with pulmonary arterial systolic pressure; r = 0.56; p < 0.001) and ET-1 levels but inversely with pulmonary ET-1 extraction. CONCLUSION: Patients with PH have greater pulmonary arterial WT that is more severe in the lower lobes than in the upper lobes. The severity of structural abnormalities found on IVUS is directly correlated with hemodynamic findings and ET-1 levels. IVUS may provide useful additional information in the assessment of patients with PH.

Adult↗
PubMed2001

Impact of residual plaque burden after balloon angioplasty in the MultiVitamins and Probucol (MVP) trial.

BACKGROUND: It has been shown in the MultiVitamins and Probucol (MVP) trial that probucol reduces angiographic lumen loss by 68% after percutaneous transluminal coronary angioplasty (PTCA). Restenosis occurred in 40% of patients not treated with probucol and in 20% of those in the probucol alone group. OBJECTIVE: To determine the morphological predictors of restenosis in patients treated with probucol. PATIENTS AND METHODS: Beginning 30 days before angioplasty, 317 patients were randomly assigned to receive probucol, multivitamins, the combined treatment or placebo. Patients were then treated for six months after angioplasty. Intravascular ultrasound (IVUS) examination was performed immediately after angioplasty and at follow-up in 94 patients (108 segments). The angioplasty operator was blinded to the IVUS results. The cross-section selected for serial analysis was the one at the angioplasty site with the smallest lumen area at follow-up. Receiver operating characteristic curves were used to determine the performance of criteria to predict angiographic restenosis at follow-up. RESULTS: In probucol-treated patients, the cross-sectional area (CSA) narrowing of 67.6% or less was the best IVUS predictor for the absence of restenosis (P=0.03). Diameter stenosis of 35% or less almost reached significance as a predictor in these patients (P=0.056). The restenosis rate when either of these predictors was met was less than 13%. Rates of repeat PTCA in patients treated with probucol were 9.7% when CSA narrowing was 67.6% or less on IVUS and 3.1% with a post-PTCA stenosis of 35% or less on quantitative coronary angiography (QCA). No predictor of the absence of restenosis in patients not treated with probucol was identified. CONCLUSIONS: The presence after balloon angioplasty of a CSA narrowing of 67.6% or less on IVUS or a diameter stenosis of 35% or less on QCA is associated, in patients treated with probucol, with extremely low rates of coronary restenosis and repeat angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed2001

[Influence of the type of breech presentation on delivery in selected primiparous women at term].

OBJECTIVE: Study the effect of the type of breech presentation on the prognosis of delivery in selected primiparous women at term. PATIENTS AND METHODS: We reviewed retrospectively 146 breech presentations seen between January 1, 1993 and December 12, 1999 in our unit. We limited our study to primiparous mothers at term (> or = 37 weeks gestation) who had had a normal single fetus pregnancy and who had accepted a trial of labor. We analyzed the mode of labor termination, and maternal, fetal, ovular, obstetrical and neonatal features by type of breech presentation and by type of delivery. We collected data by manual search of the patients' registered files (AUDIPOG). The chi-squared and Fisher's tests were used as appropriate for statistical analysis. RESULTS: Spontaneous vaginal delivery was achieved in 10.3% of the cases and non-spontaneous vaginal delivery in 56.2%. Cesarean section during labor was required in 33.5%. There was no significant difference between frank breech presentation (27.4%) and incomplete breech presentation (72.6%). Maternal, fetal, ovular, obstetrical and neonatal features were not significantly different. CONCLUSIONS: Unlike data reported by others, our series did not demonstrate any significant feature predictive of obstetrical and neonatal prognosis irrespective of the type of breech presentation in selected primiparous women at term who had had a normal pregnancy.

Adult↗
PubMed2000

Randomized trial comparing intravenous nitroglycerin and heparin for treatment of unstable angina secondary to restenosis after coronary artery angioplasty.

BACKGROUND: The treatment of unstable angina targets the specific pathophysiological thrombotic process at the site of the active culprit lesion. In unstable angina due to a restenotic lesion, smooth muscle cell proliferation and increased vasoreactivity may play a more important role than thrombus formation. Therefore, the relative benefits of nitroglycerin and heparin might differ in unstable angina associated with restenosis compared with classic unstable angina. METHODS AND RESULTS: We randomized 200 patients hospitalized for unstable angina within 6 months after angioplasty (excluding those with intracoronary stents) to double-blind administration of intravenous nitroglycerin, heparin, their combination, or placebo for 63+/-30 hours. Recurrent angina occurred in 75% of patients in the placebo and heparin-alone groups, compared with 42.6% of patients in the nitroglycerin-alone group and 41.7% of patients in the nitroglycerin-plus-heparin group (P<0.003). Refractory angina requiring angiography occurred in 22.9%, 29.2%, 4. 3%, and 4.2% of patients, respectively (P<0.002). The odds ratios for being event free were 0.24 (95% CI, -0.13 to 0.45, P=0.0001) for nitroglycerin versus no nitroglycerin and 0.98 (95% CI, -0.55 to 1. 73, P=NS) for heparin versus no heparin. No patient died or suffered myocardial infarction. CONCLUSIONS: Intravenous nitroglycerin is highly effective in preventing adverse ischemic events (recurrent or refractory angina) in patients with unstable angina secondary to restenosis, whereas heparin has no effect.

Aged↗
PubMed1999

Physical interaction of the bHLH LYL1 protein and NF-kappaB1 p105.

The LYL1 gene was first identified upon the molecular characterization of the t(7;9)(q35;p13) translocation associated with some human T-cell acute leukemias (T-ALLs). In adult tissues, LYL1 expression is restricted to hematopoietic cells with the notable exclusion of the T cell lineage. LYL1 encodes a basic helix-loop-helix (bHLH) protein highly related to TAL-1, whose activation is also associated with a high proportion of human T-ALLs. A yeast two-hybrid system was used to identify proteins that specifically interact with LYL1 and might mediate its activities. We found that p105, the precursor of NF-kappaB1 p50, was the major LYL1-interacting protein in this system. The association between LYL1 and p105 was confirmed both in vitro and in vivo in mammalian cells. Biochemical studies indicated that the interaction was mediated by the bHLH motif of LYL1 and the ankyrin-like motifs of p105. Ectopic expression of LYL1 in a human T cell line caused a significant decrease in NF-kappaB-dependent transcription, associated with a reduced level of NF-kappaB1 proteins.

Basic Helix-Loop-Helix Proteins↗
PubMed1998

Prevention of restenosis after angioplasty in small coronary arteries with probucol.

BACKGROUND: Restenosis remains the major limitation of coronary angioplasty. Coronary stents have reduced the incidence of restenosis in selected patients with relatively large vessels. No strategies to date have demonstrated a beneficial effect in vessels < 3.0 mm in diameter. We have shown in the MultiVitamins and Probucol (MVP) Trial that probucol, a potent antioxidant, reduces restenosis after balloon angioplasty. The purpose of this study was to determine whether the benefit of probucol therapy is maintained in the subgroup of patients with smaller coronary vessels. METHODS AND RESULTS: We studied a subgroup of 189 patients included in the MVP trial who underwent successful balloon angioplasty of at least one coronary segment with a reference diameter < 3.0 mm. One month before angioplasty, patients were randomly assigned to one of four treatments: placebo, probucol (500 mg), multivitamins (beta-carotene 30000 IU, vitamin C 500 mg, and vitamin E 700 IU), or probucol plus multivitamins twice daily. The treatment was maintained until follow-up angiography was performed at 6 months. The mean reference diameter of this study population was 2.49+/-0.34 mm. Lumen loss was 0.12+/-0.34 mm for probucol, 0.25+/-0.43 mm for the combined treatment, 0.35+/-0.56 mm for vitamins, and 0.38+/-0.51 mm for placebo (P=.005 for probucol). Restenosis rates per segment were 20.0% for probucol, 28.6% for the combined treatment, 45.1% for vitamins, and 37.3% for placebo (P=.006 for probucol). CONCLUSIONS: Probucol reduces lumen loss and restenosis rate after balloon angioplasty in small coronary arteries.

Aged↗
PubMed1998

Comparison of ionic and nonionic low osmolar contrast media in relation to thrombotic complications of angioplasty in patients with unstable angina.

BACKGROUND: Acute complications of percutaneous transluminal coronary angioplasty (PTCA) are more common in patients with unstable coronary syndromes. The objective of this study was to prospectively determine the differences between ionic and nonionic low osmolar contrast media (LOCM) on potential risk of acute complications, particularly abrupt vessel closure, in patients with unstable angina undergoing PTCA. METHODS: A total of 210 patients with 278 lesions were randomized to receive either ionic or nonionic LOCM during PTCA. Quantitative coronary angiographic measurements and assessment of filling defects were made by experienced observers who were blinded to the type of contrast media used. RESULTS: The baseline clinical and angiographic characteristics, the immediate postangioplasty results, and clinical outcome were similar in both groups. Subacute recoil, defined as the difference between minimal luminal diameter (in millimeters) at 0 and 15 minutes after angioplasty, was significantly greater in patients receiving nonionic LOCM (0.17 +/- 0.36 mm vs 0.07 +/- 0.18 mm, p = 0.004). A filling defect abnormality attributable to dissection, thrombus, or a combination of the two was noted in similar proportions of the two groups. Although nonsignificant, more thrombus was noted in the nonionic group (21 of 129 vs 15 of 141, p = NS). The abrupt vessel closure rate was similar in the two groups and was only 1.9% in the first 24 hours. However, 17 (8.3%) patients had a repeat PTCA at 15 minutes (9 ionic vs 8 nonionic). CONCLUSION: In patients with unstable angina the choice of ionic or nonionic LOCM does not appear to significantly affect the clinical outcome of PTCA.

Adult↗
PubMed1998

Intravascular ultrasound-guided optimized stent deployment. Immediate and 6 months clinical and angiographic results from the Multicenter Ultrasound Stenting in Coronaries Study (MUSIC Study)

OBJECTIVES: A study was set up to validate the safety and feasibility of intravascular ultrasound-guided stenting without subsequent anticoagulation, and its impact on the 6 months restenosis rate. METHODS: The study was designed to be multicentred, prospective, and observational. RESULTS: One hundred and sixty-one patients with stable angina and a de novo coronary artery lesion were enrolled. In four patients, the implantation of a Palmaz-Schatz (with spiral bridge) stent had failed. One of these four patients died 3 days following bypass surgery. In two other patients, intravascular ultrasound assessment was not performed. One hundred and twenty-five of the remaining 155 patients (81%) were treated with aspirin (100 mg x day(-1)), because all three criteria for optimized stent expansion were met. Twenty-two of the remaining 38 patients (25%), in whom at least one criterion was not met were treated with aspirin and acenocoumarol (3 months, INR 2.5-3.5), while 16 patients only received aspirin. Stent thrombosis was documented in two patients (1.3%) for which repeat angioplasty was performed. During the hospital stay, there were no deaths or Q-wave myocardial infarctions. Five patients (3.2%) sustained a non-Q-wave myocardial infarction. During the follow-up period (198+/-38 days, complete for all patients, except one), one patient (0.6%) sustained a Q-wave myocardial infarction, one (0.6%) underwent bypass surgery, and repeat angioplasty was performed in nine patients (5.7%). In two of the nine patients, repeat angioplasty involved another lesion. Therefore, the target lesion revascularization rate during follow-up was 4.5% (seven patients). At quantitative coronary angiography, the minimal lumen diameter (mean+/-SD) increased from 1.12+/-0.34 mm before to 2.89+/-0.35 mm after stenting. Repeat angiography at 6 months was performed in 144 patients (92%). The minimal lumen diameter at follow-up was 2.12+/-0.67 mm. Restenosis (diameter stenosis of 50% or more) was documented in 12 patients or 8.3%. When the two patients with documented stent thrombosis are included, the restenosis rate amounts to 97%. CONCLUSIONS: These data confirm that, in selected patients, stents can safely be implanted without the use of systemic anticoagulation, provided optimal stent expansion is achieved. The exact role of intravascular ultrasound in the achievement of these results needs to be established by appropriately designed studies. In the meantime, intravascular ultrasound coupled with the Palmaz-Schatz stent incorporating a spiral bridge, may have contributed considerably to the immediate angiographic outcome, which in turn may explain the favourable clinical and angiographic outcome at 6 months.

Aged↗
PubMed1997

Probucol and multivitamins in the prevention of restenosis after coronary angioplasty. Multivitamins and Probucol Study Group.

BACKGROUND: Oxidizing metabolites generated at the site of coronary angioplasty can induce chain reactions that may lead to restenosis. Antioxidants may counter oxidative stress and modify neointimal formation and vascular remodeling. Experimental data and small clinical studies have suggested that antioxidants may prevent restenosis after angioplasty. In a double-blind, randomized trial, we studied whether drugs with antioxidant properties decrease the incidence and severity of restenosis after angioplasty. METHODS: One month before angioplasty, 317 patients were randomly assigned to receive one of four treatments: placebo, probucol (500 mg), multivitamins (30,000 IU of beta carotene, 500 mg of vitamin C, and 700 IU of vitamin E), or both probucol and multivitamins-all given twice daily. Patients were treated for four weeks before and six months after angioplasty. Patients received an extra 1000 mg of probucol, 2000 IU of vitamin E, both probucol and vitamin E, or placebo 12 hours before angioplasty, according to their treatment assignments. Base-line and follow-up angiograms were interpreted by blinded investigators using a quantitative approach. RESULTS: The mean (+/-SD) reduction in luminal diameter six months after angioplasty was 0.12 +/- 0.41 mm in the probucol group, 0.22 +/- 0.46 mm in the combined-treatment group, 0.33 +/- 0.51 in the multivitamin group, and 0.38 +/- 0.50 mm in the placebo group (P = 0.006 for those receiving vs. those not receiving probucol, and P = 0.70 for those receiving vs. those not receiving vitamins. Restenosis rates per segment were 20.7 percent in the probucol group, 28.9 percent in the combined-treatment group, 40.3 percent in the multivitamin group, and 38.9 percent in the placebo group (P = 0.003 for probucol vs. no probucol). The rates of repeat angioplasty were 11.2 percent. 16.2 percent, 24.4 percent, and 26.6 percent, respectively (P = 0.009 for probucol vs. no probucol). CONCLUSIONS: The antioxidant probucol is effective in reducing the rate of restenosis after balloon coronary angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1996

Changes in segment mass and mass distribution during pregnancy.

The purpose of the study was to evaluate the rates of change in the estimated masses and principal moments of inertia of the body segments during the second and third trimesters of pregnancy. Fifteen subjects, on average 15.1 weeks pregnant, were tested monthly until term. The body was modelled as 16 segments consisting of 2 cm stacked elliptical cylinders sectioned in the transverse plane. Linear regressions were fitted to the segment inertias and regression coefficients determined for the individual growth curves. The mean rate of increase for the lower trunk mass was 0.29 kg per week and 0.0069 kg m2 per week for the transverse axis principal moment. Differences between the means of the segments for rates of change of mass and the three principal moments were then tested. All four ANOVAs used to test the differences were significant. The post hoc analysis established that over the second and third trimesters the lower trunk inertias increased at a greater rate than all other segments and there were no significant differences between the remaining segments. The effect of such changes in the trunk segment masses and principal moments was illustrated by an analysis of intersegmental dynamics during a sit to stand of one pregnant subject whose lower trunk mass increased from 21.6 kg to 28.4 kg. A knowledge of the differences in an individual's segment inertias should lead to a better understanding of how movements are affected during pregnancy.

Abdomen↗
PubMed1996

Intravascular ultrasound for diagnosis of left main coronary artery stenosis.

Coronary angiography has many limitations for the assessment of coronary artery disease. Intracoronary ultrasound imaging may overcome some of these limitations by providing direct visualization of the luminal area. This report describes a case where intracoronary ultrasound imaging was useful for correct assessment of left main coronary artery disease which enabled avoidance of coronary artery bypass grafting in this patient. Intravascular ultrasound may be a good complement to coronary angiography in selected cases of left main coronary artery lesion.

Aged↗
PubMed1991

Application of circular statistics to the study of neuronal discharge during locomotion.

An application of circular statistics is described which permits one to readily and efficiently describe neuronal discharge patterns recorded during locomotion. The method can be adapted to any data which are normally plotted as post-event histograms (PEHs) and can also be used to describe the pattern of electromyographic (EMG) activity during the step cycle. Data can be objectively classified with respect to both the mean direction and amplitude of their discharge, as well as to the variability (angular deviation) of that discharge. In addition, the Rayleigh test for directionality can be used to determine whether cells are modulated or unmodulated. Finally, the ability to describe each cell's discharge as a single vector allows the data from several different neurones to be displayed on a single figure and provides an efficient method for comparing the discharge of a population of cells under two or more different conditions.

Action Potentials↗
PubMed1990

Late coronary aneurysm formation following coronary angioplasty.

In a 38-year-old man with recurrent chest pain 14 months following percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending coronary artery, two aneurysms were noted at previous PTCA sites without evidence of restenosis. Although the precise mechanism of formation of these aneurysms is not known, it is possible that medial dissection and weakening of the artery provoked aneurysm formation.

Adult↗