Biomedical subjects

Louis-Mathieu Stevens

Publications and source records attributed to Louis-Mathieu Stevens.

8 recordsLinked to original sources

PubMed2007

Effect of intravenous N-acetylcysteine on outcomes after coronary artery bypass surgery: a randomized, double-blind, placebo-controlled clinical trial.

OBJECTIVE: N-acetylcysteine, a potent anti-inflammatory and antioxidant agent, is known to decrease the production of reactive oxygen species after cardiac surgery. The objective of this study was to evaluate the effects of intravenous N-acetylcysteine on clinical and biochemical outcomes after coronary artery bypass surgery with cardiopulmonary bypass. METHODS: One hundred patients (mean age 60.5 years, range 43-78 years, 89% male) undergoing coronary artery bypass grafting at the Montreal Heart Institute were randomized to receive either N-acetylcysteine (600 mg orally the day before and the morning of the operation, a bolus of 150 mg/kg of intravenous N-acetylcysteine before skin incision, followed by perfusion at 12.5 mg x kg(-1) x h(-1) over 24 hours; n = 50) or placebo (n = 50). The patients and clinical team were blinded to group assignments. Preoperative characteristics were similar between the two groups. Postoperative clinical data (death, myocardial infarction, low-output syndromes, arrhythmias, bleeding, transfusion requirements, and intensive care unit and hospital lengths of stay) and biochemical markers (creatine kinase MB, troponin T, creatinine, hemoglobin, and platelet levels) were evaluated serially over 4 days. RESULTS: Clinical outcomes were not significantly different between the two groups with regard to the incidence of death, myocardial infarction, bleeding, transfusion requirements, intubation time, and hospital length of stay. No differences were found in postoperative biochemical markers (troponin T, creatine kinase MB, creatinine, hemoglobin, and platelets) between the groups. No differences were observed between the groups in interleukin-6 production (P = not significant). CONCLUSIONS: Prophylactic use of N-acetylcysteine in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass does not lead to improvement in clinical results or biochemical markers. Further strategies to decrease reperfusion injury should be devised.

Acetylcysteine↗

PubMed2006

Effect of tetrahydrobiopterin on selective endothelial dysfunction of epicardial porcine coronary arteries induced by cardiopulmonary bypass.

BACKGROUND: We hypothesized that cardiopulmonary bypass induces a selective alteration of the coronary arterial endothelial cell signal transduction which could be explained by a state of depletion and/or decreased activity of endogenous tetrahydrobiopterin (BH(4)). The aim of this study was to assess the effects of cardiopulmonary bypass and BH(4) on the endothelial function of epicardial coronary arteries in a swine model of cardiopulmonary bypass. METHODS: Swine underwent 90 min of cardiopulmonary bypass alone (N=19) or in association with a brief cardioplegic arrest with (N = 6) or without (N = 5) in vivo BH(4) administration, followed by a 60-min period following weaning from cardiopulmonary bypass and were compared to a control group (N = 7). Endothelium-dependent relaxations of epicardial coronary artery rings were studied using standard organ chamber experiments in the presence or absence of in vitro BH(4) or superoxide dismutase (SOD) and catalase. RESULTS: Cardiopulmonary bypass caused a statistically significant reduction of endothelium-dependent relaxations to serotonin (p < 0.0001), bradykinin (p < 0.001), UK14304 (p < 0.0001) and calcium ionophore (p < 0.01) in epicardial porcine coronary arteries. In vitro and in vivo BH(4) supplementation improved endothelium-dependent relaxations to serotonin and bradykinin, which were left unchanged by SOD-catalase administration. Cardiopulmonary bypass was associated with a decrease in nitric oxide availability (p = 0.002) and increased oxidative stress (p < 0.001), which were both restored by in vivo BH(4) administration (p < 0.001). CONCLUSION: Treatment with BH(4) improves the endothelial dysfunction of porcine epicardial coronary arteries, restores nitric oxide availability and reduces the oxidative stress associated with cardiopulmonary bypass.

Animals↗

PubMed2006

Alternative to sternotomy: aortic valve replacement through right thoracotomy.

Many minimally invasive alternatives to aortic valve replacement through full sternotomy have been described. We report an approach through a right thoracotomy that has been planified in 2 patients with contraindication to standard thoracotomy. Exposure was excellent, and valve replacement could be performed safely.

Aortic Valve Stenosis↗

PubMed2005

Aspergillus endocarditis after cardiac surgery.

Aspergillus species infections are an increasingly common occurrence in hospital wards. Aspergillus endocarditis constitutes one of the manifestations of the disease, which bears a poor prognosis in cardiac surgery patients. A review of the literature on fungal and Aspergillus endocarditis was undertaken. Valvular risk factors, indwelling intravenous catheters, prolonged antibiotics, malignancy, and intravenous drug use increase the risk. Clinical presentation is insidious, with embolic complications often representing the first manifestation of the disease. Blood cultures are typically negative. The mortality rate is almost 100%. Amphotericin B represents the mainstay of medical therapy with several possible adjuncts. Surgery is an essential part of therapy in Aspergillus endocarditis after cardiac surgery and should be undertaken as soon as the diagnosis is made. Aspergillus endocarditis is an ominous complication after cardiac surgery. A high suspicion index, early administration of appropriate antibiotics, and prompt surgical intervention should improve the prognosis, which remains dismal.

Adult↗

PubMed2005

Injury of the coronary endothelium at implantation increases endothelial dysfunction and intimal hyperplasia after heart transplantation.

BACKGROUND: Coronary endothelial dysfunction occurs early after heart transplantation and predicts the development of intimal thickening characteristic of cardiac allograft vasculopathy. OBJECTIVES: To assess the effects of removal of the endothelium by balloon injury of coronary arteries of allografts without rupture of the internal elastic lamina at the time of implantation and on coronary endothelial dysfunction, and to assess the development of accelerated atherosclerosis after heart transplantation. METHODS: A porcine model of heterotopic heart transplantation with preoperative immunologic typing, enabling progressive rejection without immunosuppression, was used to study the effect of endothelial removal on these 2 end points. Endothelium-dependent relaxations of epicardial coronary arteries from allografts submitted to endothelial denudation after harvest, arteries from allografts not undergoing denudation, and native coronary arteries were compared 30 days after graft implantation by using standard organ chamber experiments. Intimal thickening was measured by light microscopy with a semiquantitative scale (0 to 4+ grading). RESULTS: Relaxations to serotonin and to bradykinin were significantly decreased in denuded arteries compared with nondenuded allograft arteries. There was a significant increase in the incidence of severe intimal hyperplasia in denuded arteries compared with nondenuded arteries, which were both significantly increased compared to native coronary arteries. CONCLUSIONS: Endothelial injury at implantation worsens the endothelial dysfunction as a result of rejection after heart transplantation and compounds the intimal thickening leading to cardic allograft vasculopathy. All efforts should be deployed to maintain a morphologically intact and functional endothelium at the time of graft implantation.

Animals↗

PubMed2005

Incidence and prognosis of cancer following heart transplantation using RATG induction therapy.

Cancer limits survival following heart transplantation. The study's objectives were to evaluate the incidence and risk factors for cancers after heart transplantation and to assess the association between i.v. thymoglobuline induction therapy [rabbit antithymocyte immunoglobulin, (RATG)] and neoplasia. From 1982 to 2002, prospective data were gathered for 207 heart transplant recipients. Except from 1982 to 1987, all patients received a 3-day course of i.v. RATG following transplantation. Forty-three malignant neoplasms (21%) were diagnosed. The most common were: skin (42%), lung (12%), prostate (9%), genitourinary (9%) and lymphoma (5%). Mean length of follow-up after transplantation was 99 +/- 57 months. Mean survival after diagnosis was 52 +/- 44 months. Multivariate analysis showed no significant increase in the incidence of cancer with recipient age, sex, number of rejection episodes, the type of immunosuppression or the use of RATG. Patients receiving RATG developed their malignancies significantly earlier after transplantation (P =0.007) and succumbed faster after the diagnosis (P = 0.06). Cancer is a limiting event for long-term survival after heart transplantation. No individual risk factors allow predicting its development. In the present cohort, RATG does not have carcinogenic effects following transplantation, but is associated with a more precocious development of malignancies.

Adolescent↗

PubMed2004

Continuous renal replacement therapy after heart transplantation.

BACKGROUND: Renal failure following heart transplantation carries a poor prognosis. The objectives of this study were to determine risk factors for renal failure requiring continuous renal replacement therapy (CRRT), to describe the management strategies regarding immunosuppressive therapy and to examine the short-term prognosis. METHODS: Fifty-six patients who underwent heart transplantation from 1998 to 2002 at the Montreal Heart Institute were retrospectively analyzed. RESULTS: Six of 56 patients (11%) underwent CRRT after heart transplantation. Patients who underwent CRRT had lower preoperative creatinine clearance than those who did not (median 44 versus 59 mL/min, P=0.04) and lower first two-week postoperative creatinine clearance (median 23 versus 42 mL/min, P<0.01) compared with patients without CRRT. The total duration of CRRT ranged between two and 60 days (median 15 days). Cyclosporine was withheld for 12 days versus two days (P<0.01) and the time to achieve therapeutic levels of cyclosporine averaged 18 days versus nine days (P=0.01) among CRRT versus non-CRRT patients. Patients were administered thymoglobulin or basiliximab during cyclosporine withholding. The time to discharge from hospital after transplantation was longer in patients with CRRT (median 47 days versus 17 days, P<0.01). There was no mortality at three months in the CRRT group. CONCLUSION: Creatinine clearance is an important predictor of renal failure requiring renal replacement therapy. Although renal failure remains a serious complication after transplantation, the use of CRRT and antilymphocyte agents during cyclosporine A withholding is associated with a favourable short-term prognosis following heart transplantation.

Acute Kidney Injury↗

PubMed2004

A cluster of cases of Aspergillus endocarditis after cardiac surgery.

Aspergillus endocarditis is an ominous condition whose prevalence is increasing in the hospital population. Despite the life-threatening nature of the disease, detection of the source, establishment of the diagnosis, and treatment remain highly challenging. A cluster of three cases of Aspergillus endocarditis recently encountered at the Montreal Heart Institute are presented.

Adult↗