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Biomedical subjects

Michel Carrier

Publications and source records attributed to Michel Carrier.

72 records · Page 4Linked to original sources
PubMed2003

Improving neurologic outcome in off-pump surgery: the "no touch" technique.

BACKGROUND: As patients referred for cardiac surgery include increasingly older individuals, the prevalence of comorbid factors, such as previous cerebrovascular disease, carotid disease, aortic atherosclerosis, and reoperations, is on the rise. Avoiding manipulation of the ascending aorta in this high-risk subgroup may become a necessity to perform safe coronary artery bypass grafting (CABG) surgery. METHODS: We retrospectively reviewed our database of 640 off-pump CABG patients and identified 84 patients in whom we adopted the "no touch" technique (NTT). Revascularization was carried out with single or bilateral internal thoracic arteries (ITA) and by connecting additional coronary grafts (saphenous vein, radial artery) in a T or Y configuration. The right gastroepiploic artery was used as a conduit in 2 patients. The brachiocephalic artery was used as an alternative inflow site in 3 patients (reoperation). RESULTS: Age, sex, risk factors, functional class, and history of congestive heart failure were comparable in the two groups. In the NTT group, the frequencies were higher for severe atherosclerosis of the aorta (13% versus 0%; P =.00), carotid disease (25% versus 16%; P =.02), and history of previous cerebrovascular accidents (17% versus 8%; P =.04). Complete revascularization was achieved in 96% of the patients in the off-pump CABG group, compared with 90% in the NTT group (P =.17). No differences in the prevalence of postoperative low cardiac output syndrome, intra-aortic balloon pump use, perioperative myocardial infarction, or operative mortality at 30 days were observed between the two groups. In the NTT group, weak trends toward a lower incidence of postoperative delirium (8% versus 15%; P =.12), a lower incidence of stroke (0% versus 1%; P =.85), and a shorter intensive care unit stay (P =.07) were observed. Hospital stay was also shorter in the NTT group (P =.04). CONCLUSION: Avoiding aortic manipulations in patients with severe atherosclerosis of the aorta, carotid disease, and a previous history of cerebrovascular accidents is technically feasible and is associated with a low risk of mortality and good shortterm results. Adopting this practice may reduce the incidence of stroke and improve early outcome in this subset of patients.

Cardiac Output, Low↗
PubMed2003

Randomized trial comparing off-pump to on-pump coronary artery bypass grafting in high-risk patients.

OBJECTIVE: The subset of patients most likely to benefit from off-pump coronary artery bypass grafting (CABG) remains a controversial issue, but the technique has been proposed to decrease postoperative mortality and morbidity. Th e objective of this study was to compare off-pump to onpump CABG in patients with known risk factors for mortality and morbidity. METHODS: Between October 2001 and September 2002, 65 high-risk patients were prospectively randomized to undergo off-pump or o n-pump CABG. Recruited patients had at least 3 of the following criteria: age greater than 65 years, high blood pressure, diabetes, serum creatinine greater than 133 mol/L, left ventricular ejection fraction lower than 45%, chronic pulmonary diseas e, unstable angina, congestive heart failure, repeat CABG, anemia, and carotid atherosclerosis. Hospital mortality and morbidity were the primary end-points of the study. RESULTS: Six patients (9%) crossed over from the original randomized group. Twenty-eight patients averaging 70 +/- 8 years of age underwent 3 +/- 1 grafts off pump, and 37 patients averaging 70 +/- 6 years of age underwent 3.4 +/- 1 grafts on pump. Revascularization was considered complete in 21 (7 5 %) of off-pump patients compared to 33 (89%) of onpump patients (P =.1). There were no hospital deaths in off-pump patients, and 2 patients (5%) undergoing onpump CABG died early following surgery (P =.2). Two offpump (7%) compared to 11 on-pump (30%) of patients presented composite end-points including death, neurological injury, renal failure, respiratory failure, and operative myocardial infarction after CABG (P =.02). CONCLUSION: The present study suggests that off-pump CABG, when technically feasible, significantly reduces morbidity following surgery in a group of high-risk patients.

Aged↗
PubMed2002

Reduced mortality and strokes with off-pump coronary artery bypass grafting surgery in octogenarians.

BACKGROUND: Off-pump coronary artery bypass surgery (OPCAB) has been revived and has gained popularity, although the exact subsets of patients who might benefit most from this technique are unknown. The aim of this retrospective study was to compare the results of coronary artery bypass grafting surgery (CABG) in octogenarians using cardiopulmonary bypass (CPB) or OPCAB techniques. METHODS AND RESULTS: Over a 5-year period (1995-1999), 125 patients older than 80 years of age were operated for isolated myocardial revascularization (63 using CPB and 62 with OPCAB). There was no statistically significant difference in preoperative comorbidities between groups or in mean left ventricular ejection fraction (54.5+/-15.3% in the CPB group and 50.9+/-13.5% in the OPCAB group, respectively). The mean number of distal anastomosis per patient was 2.9 in CPB group and 2.6 in OPCAB group (P=ns). The majority of patients in both groups had unstable angina and were operated on an urgent basis. The operative mortality was 15.9% in the CPB group and 4.8% in the OPCAB group (P=0.04). There were 4 postoperative strokes (6.3%) in the CPB group and none (0%) in the OPCAB group (P=0.04). The percentage of patients transfused was 92.1% in the CPB group and 72.6% in the OPCAB group (P<0.01). Postoperative myocardial infarction occurred in 11.3% in the CPB group and 14.5% in the OPCAB group (P=NS). For all the parameters entered in the multivariate analysis with logistic regression model, the type of surgery (CPB or OPCAB) was an independent predictor of operative mortality and stroke (P=0.0375). The odds ratio (OR) indicates that operative mortality and stroke occur 4 times (OR=4.171) more often in CPB patients than in OPCAB patients. Follow-up showed no significant difference between the 2 groups in terms of cardiac events and mortality. CONCLUSIONS: This retrospective study suggests a benefit of OPCAB in terms of operative mortality and stroke for octogenarian patients when compared with CPB in our institution.

Aged↗
PubMed2002

Long-term results with triple valve surgery.

BACKGROUND: Whether to use biological or mechanical prostheses and whether to repair or replace the tricuspid valve during primary and reoperative triple valve surgery remains controversial. The objective of the present study was to review our experience with primary and reoperative triple valve surgery using CarboMedics (CM) and Carpentier-Edwards (C-E) heart valves. METHODS: All 73 patients undergoing triple valve surgery since 1982 were prospectively followed at the Montreal Heart Institute valve clinic. Aortic valve replacement was performed with CM prostheses (57 patients) and with C-E prostheses (16 patients). Mitral valve replacement was performed with mechanical prostheses (56 patients) and with biological valves (14 patients). Mitral valve repair was done in 3 patients. Tricuspid valve annuloplasty or commissurotomy or both were performed in 66 patients and the tricuspid valve was replaced in 7 patients. Patient survival, complications, and the type of valve procedures were analyzed. RESULTS: Thirty patients averaging 62+/-10 years of age underwent primary triple valve surgery and 43 patients averaging 60+/-10 years of age underwent reoperative triple valve surgery (p = 0.5). Tricuspid repair consisted of annuloplasty with the Bex linear reducer (n = 47), the C-E ring (n = 13), or the De Vega technique (n = 5). Tricuspid valve replacement was done using the C-E pericardial prostheses. The 30-day mortality was 17% and 12% in patients with primary and reoperative surgery, respectively (p = 0.5) and patient survival averaged 80%+/-7%, 75%+/-8%, and 41%+/-15%, and 70%+/-7%, 57%+/-9%, and 50%+/-10%, respectively 1, 5, and 10 years following surgery (p = 0.5). The freedom rate from thromboembolism and from bleeding complications were 87%+/-6% and 95%+/-3% in primary and reoperative patients, respectively, 5 years following surgery. CONCLUSIONS: Triple valve surgery, either as a primary or a reoperative procedure, results in acceptable long-term survival with both mechanical and biological prostheses.

Aged↗
PubMed2002

Cardioplegic arrest with L-arginine improves myocardial protection: results of a prospective randomized clinical trial.

BACKGROUND: Blood cardioplegic arrest remains the method of choice for myocardial protection. L-arginine has been suggested to improve protection through an increase in nitric oxide production. METHODS: A prospective, randomized, double-blinded clinical trial comparing standard blood cardioplegic solution to L-arginine-enriched solution (7.5 g/500 mL) enrolled 200 patients undergoing coronary artery bypass grafting. Clinical data and biochemical markers of ischemia were recorded. Warm blood cardioplegia (33 degrees C) was administered in 74% of patients and cold blood (20 degrees C) was used in 26% of patients. Both groups averaged three grafts per patient. RESULTS: There were two (2%) deaths in both groups. There were four (4%) myocardial infarctions (MI) in the control group and six (6%) infarctions in the L-arginine group (p = 0.5). For the 190 patients without MI, serum levels of troponin T averaged 0.40+/-0.43, 0.38+/-0.42, and 0.39+/-0.50 microg/L in control patients compared with 0.28+/-0.22, 0.24+/-0.18, and 0.27+/-0.20 microg/L in L-arginine patients, respectively, 12, 24 and 48 hours after coronary artery bypass grafting (p = 0.03). The cardiac index averaged 2.7+/-0.8 L x min(-1) x m(-2) in control patients and 2.9+/-0.7 L x min(-1) x m(-2) in arginine patients immediately after surgery (p = 0.09). Intensive care unit and hospital length of stay averaged 3.5+/-5 days and 7.3+/-6 days in control patients compared with 2.5+/-3 days and 6.1+/-4 days in arginine patients (p = 0.09). CONCLUSIONS: L-arginine-supplemented blood cardioplegic solution is associated with reduced release of biochemical markers of myocardial damage, suggesting improved myocardial protection.

Aged↗
PubMed2002

Comparative study of cyclosporine and tacrolimus vs newer immunosuppressants mycophenolate mofetil and rapamycin on coronary endothelial function.

BACKGROUND: Endothelial dysfunction contributes to the development of intimal hyperplasia in transplanted hearts by decreasing the protective effects of endothelial-derived nitric oxide. Immunosuppressive drugs may increase the dysfunction caused by rejection and further accelerate the development of graft coronary vasculopathy. This study compares the effect of cyclosporine and tacrolimus vs two newer immunosuppressive drugs, mycophenolate mofetil and rapamycin, on coronary endothelial function. METHODS: An in vitro model of drug incubation in Krebs-bicarbonate solution (4(o)C, 48 hours) using porcine epicardial coronary arteries was developed. Coronary endothelial function studies were performed in organ chamber experiments after incubation with cyclosporine (10(-4), 10(-7) mol/liter), tacrolimus (10(-4), 10(-7) mol/liter), mycophenolate mofetil (10(-4), 10(-7) mol/liter), rapamycin (10(-7), 10(-11) mol/liter), and their vehicles to assess effects on G-protein-mediated vasorelaxations leading to the release of nitric oxide. RESULTS: Exposure to cyclosporine and mycophenolate mofetil was associated with a dose-dependent decrease in endothelium-dependent relaxations to serotonin (an agonist that binds to 5-HT1D receptors coupled to Gi-protein) but no impairment of relaxations to bradykinin (an agonist that binds to B2 receptors coupled to Gq-proteins). Exposure to tacrolimus and rapamycin caused severe impairment of relaxations to serotonin and a lesser one to bradykinin. We observed alterations of relaxations to the calcium ionophore A23187 after exposure to mycophenolate mofetil and rapamycin. Exposure to rapamycin and mycophenolate mofetil vehicles impaired relaxation to all agonists. CONCLUSIONS: These results suggest that cyclosporine and mycophenolate mofetil induce a dysfunction of the vasorelaxing properties of the endothelium that may lead to a decrease in the protective effects of nitric oxide on the vascular wall but that these drugs still have a more favorable vascular profile than do tacrolimus and rapamycin. Decreased endothelial function after mycophenolate mofetil and rapamycin exposure could be caused by their vehicles.

Animals↗
PubMed2002

Methicillin-resistant Staphylococcus aureus infection in a cardiac surgical unit.

BACKGROUND: Increased antibiotic resistance of common bacteria is attributed in part to the widespread use of various antibiotic agents. Prophylactic and therapeutic antibiotic treatments are routinely used in cardiac surgical units, and it is no surprise that methicillin-resistant Staphylococcus aureus infection is becoming a major cause of surgical infections in cardiac patients. METHODS: We reviewed our experience with patients who underwent cardiac surgery and experienced infection caused by methicillin-resistant Staphylococcus aureus. Between 1992 and 2000 at the Montreal Heart Institute, 39 patients had methicillin-resistant Staphylococcus aureus surgical infections, and 13,199 patients underwent cardiac surgery. The yearly incidence of methicillin-resistant Staphylococcus aureus infection, the relative risk of acute mediastinitis and of superficial wound infections or other types of methicillin-resistant Staphylococcus aureus infection episodes, and the effect of preventive measures were analyzed. RESULTS: The annual incidence of methicillin-resistant Staphylococcus aureus acute mediastinitis decreased from 0.37% (5/1321) of cardiac patients in 1992 and 0.44% (6/1355) in 1993 to 0% between 1994 and 1997, 0.13% (2/1528) in 1999, and 0% (0/1700) in 2000. The total incidence of methicillin-resistant Staphylococcus aureus infection, including mediastinitis, superficial and deep sternal and leg wound infection, and all systemic infection episodes ranged from 0.68% of patients in 1992 and 0.96% of patients in 1993 to 0.46% of patients in 1999 and 0.53% of patients in 2000. The relative risk of severe mediastinal methicillin-resistant Staphylococcus aureus infection to all other methicillin-resistant Staphylococcus aureus infection episodes decreased from 1.65 in 1992 to 0.41 in 1999 and 0 in 2000. Beginning in 1993, all patients given a diagnosis methicillin-resistant Staphylococcus aureus infection and all nasal carriers of methicillin-resistant Staphylococcus aureus were strictly isolated on the surgical unit, and vancomycin was used as the prophylactic antibiotic agent for cardiac surgery in these patients. Moreover, since 1998, all patients admitted in the hospital were screened, and nasal carriers were isolated and treated with topical antibiotic ointment. CONCLUSION: Mediastinal and other infections caused by methicillin-resistant Staphylococcus aureus have a significant morbidity in cardiac surgical patients. After an outbreak of methicillin-resistant Staphylococcus aureus mediastinal infections, several preventive measures to control methicillin-resistant Staphylococcus aureus contamination of surgical patients were implemented (nasal screening, preventive isolation, application of mupirocin, prophylaxis with vancomycin and alcohol gels) and were effective in decreasing the incidence of methicillin-resistant Staphylococcus aureus infection and mediastinitis after cardiac surgery.

Acute Disease↗
PubMed2002

Mitral Doppler indices are superior to two-dimensional echocardiographic and hemodynamic variables in predicting responsiveness of cardiac output to a rapid intravenous infusion of colloid.

UNLABELLED: We hypothesized that mitral flow (MF) Doppler measurements could be used to predict cardiac output (CO) responsiveness to fluid challenge. Fourteen patients with normal systolic and diastolic function, scheduled for coronary artery bypass graft surgery, were evaluated as part of a pilot study in which preload was varied immediately before the beginning of cardiopulmonary bypass. A Validation group of 36 patients with different levels of systolic and diastolic function received a rapid infusion of 500 mL of 10% pentastarch. By use of transesophageal echocardiography, we measured left ventricular end-diastolic area, pulsed Doppler indices of the MF and pulmonary venous flow, and standard hemodynamic variables during acute volemic variations. A baseline measurement was first recorded, followed by measurements taken after a decrease (211 +/- 87 mL) and then an increase (176 +/- 149 mL) in preload (pilot study) and before and after 500 mL of pentastarch (validation study). In the pilot study, we found that a low velocity/time integral (VTI) E wave/A wave (E/A) ratio was associated with a larger increase in CO secondary to an increase in preload (r = 0.64, P < 0.05). Stepwise linear regression identified Doppler measurements of the mitral VTI E/A ratio as the most important variable to predict the increase in CO after fluid infusion. In the validation study, a mitral E/A ratio <1.26 before fluid infusion best predicted a 20% increase in stroke volume (receiver operating characteristic curve, 71%; P < 0.05), whereas no other hemodynamic or echocardiographic variable predicted preload responsiveness. We conclude that the MF Doppler filling pattern is an important factor to predict the increase in CO after intravascular fluid challenge in patients undergoing coronary artery bypass grafting. IMPLICATIONS: In the presence of low cardiac output, the clinician's ability to identify which patients are more likely to benefit from volume administration to improve hemodynamic status while avoiding fluid overload is important. The analysis of Doppler measurement of the mitral flow as an indirect indicator of the individual diastolic pressure/volume relationship may be useful to predict the intravascular volume responsiveness in patients undergoing coronary artery bypass graft surgery.

Adult↗
PubMed2002

Vacuum-assisted venous drainage does not increase the neurological risk.

BACKGROUND: Vacuum-assisted venous drainage (VAVD) with negative pressure applied to integral sealed-hardshell venous reservoir facilitates valvular surgery through minimally invasive approaches. Despite concerns regarding air entrainment from the right atrium, cerebral microemboli of air and neurological complications, VAVD was used in patients who underwent valvular surgery throughout the last two years in our institution. METHODS: We compared the rate of neurological complications in patients who underwent surgery with and without VAVD from June 1997 to July 2001. VAVD was added to solid venous reservoirs with membrane oxygenators and arterial filters. Clinical results were prospectively entered in our valve database and were used for the analysis. RESULTS: Eight hundred twenty-two consecutive patients averaging 65 +/- 11 years of age underwent aortic, mitral and tricuspid valve replacements including 40 redos (40/822, 5%) and 265 associated CABG (265/822, 32%) with VAVD in 1999 to 2001 compared to 723 patients averaging 63 +/- 11 years of age (p = 0.01) who underwent the same procedures with 79 redos (79/723, 11%) and 177 CABG (177/723, 24%) without VAVD in 1997 to 1999. CPB time averaged 117 +/- 50 minutes in VAVD patients compared to 108 +/- 43 minutes in those without VAVD (p = 0.001). Thirty-day mortality averaged 5% (39/822) in patients with VAVD and 4% (30/723) in those without VAVD (p = 0.6). Seven patients of the VAVD group (7/822, 1%) and 11 patients without VAVD (11/723, 1.5%, p = 0.2) suffered from temporary or permanent neurological deficit. CONCLUSION: VAVD is a useful adjunct to modern cardiopulmonary bypass systems. When used with appropriate care, VAVD does not appear to significantly increase air microemboli and is not associated with an increased neurological risk following valvular surgery.

Aged↗
PubMedDate not supplied

Hemodynamic characteristics of a mixed flow pump prototype: progress report of in vitro and acute animal experiments.

A new dual-inlet mixed-flow blood pump was designed and tested in our laboratory. The objective of the present study was to analyze hemodynamic characteristics of the pump prototype in vitro and during acute in vivo experiments. The mixed-flow pump was first tested in vitro and then implanted in 11 pigs and 3 calves. The left ventricular apex was cannulated with the pump and an outflow graft was anastomosed to the descending thoracic aorta. Flow and pressure probes were also implanted. Animals were killed 3 to 12 hours after surgery. In 11 pigs, pump outflow averaged 3.8 +/- 0.4, 4.5 +/- 0.4, 5.2 +/- 0.8, 5.9 +/- 0.3, and 6.5 l/min at 8,000, 9,000, 10,000, 11,000, and 12,000 pump speed in rpm. Differential pressure at the pump averaged 45 +/- 6, 54 +/- 8, 68 +/- 16, 70 +/- 12, and 85 +/- 7 mm Hg at 8,000, 9,000, 10,000, 11,000 and 12,000 rpm. Mean aortic pressure averaged 64 +/- 15 mm Hg throughout the procedures. In 3 calves, mean aortic pressure and left ventricular pressure remained stable during 4, 6, and 9 hours of support at 9,500, 10,000, 10,500, 11,000, and 11,500 rpm. The hemodynamic performance of our mixed-flow pump appears satisfactory during short-term support in animals. It supports similarly to axial-flow blood pumps in clinical trials. Based on these findings, an ameliorated design of this mixed-flow pump running at smaller rotational speed against a similar pressure head is under way.

Anastomosis, Surgical↗
PubMedDate not supplied

Topical effect of various agents on gelatinase activity in the tear film of normal dogs.

OBJECTIVE: To evaluate the topical effect of various agents, currently used in the treatment of melting ulcers, on gelatinase activity present in the tear film of normal dogs. ANIMAL STUDIED: Eight normal adult beagles. PROCEDURES: Each animal received the following agents: cyclosporine A 1%, N-acetylcysteine 10%, ciprofloxacin 0.3%, ethylenediaminetetraacetic acid (EDTA) 1%, doxycycline 0.001%, polysulfated glycosaminoglycans (PSGAG) 5%, autoserum, and artificial tears during a 48-h period following a Latin square design. Tear samples were collected with micro-capillary pipettes following a corneal surface irrigation of each eye with sterile saline on four different occasions. Basal and total gelatinase activities were evaluated by optical density after processing in a commercial gelatinase activity assay. From the optical density ratio, a semi-quantitative measure of gelatinase activity was obtained. Basal and total activities were measured in all samples. RESULTS: The lowest total gelatinase activity, representing a percent decline in the enzyme activity although not significant, was observed 1 h after the last treatment in seven out of the eight ophthalmic agents; EDTA (68%), ciprofloxacin (76%), cyclosporine A (68%), doxycycline (47%), artificial tears (26%), PSGAG (25%), and N-acetylcysteine (20%). However, only the reduction observed with EDTA 6 h after the last treatment was significantly lower compared to the reduction observed with the artificial tears. CONCLUSION: This study indicated that only EDTA was able to significantly reduce the gelatinase activity in a persistent manner in the tear film of normal canine eyes. Further studies will be required to evaluate the effect of EDTA under ulcerative conditions and to more accurately ascertain the potential in vivo effect of the other agents.

Acetylcysteine↗
PubMedDate not supplied

Techniques, complications, and pitfalls of endoscopic saphenectomy for coronary artery bypass grafting surgery.

OBJECTIVES: The purpose of the present paper is to discuss technical features of endoscopic saphenectomy with CO2 insufflation for CABG surgery and to highlight special situations in which to avoid potential pitfalls that may be encountered. METHODS: The initial section describes the approaches used with endoscopic saphenectomy with insufflation of CO2 at the Montreal Heart Institute and the Wausau Heart Institute, which can be used by operators with different levels of experience. The following sections expose numerous intraoperative tricks and maneuvers to facilitate the procedure. Specific situations associated with increased difficulty are reviewed such as the obese patient, venous insufficiency, vein tethered to the dermis, and double venous systems. Complications specific to the technique such as gas embolism, tunnelitis, and hematomas are discussed and preventive measures are proposed to avoid the rare morbidity associated with endoscopic harvesting. Preparation of the patient as well as monitoring during the intervention are also reviewed. RESULTS: Adherence to the comprehensive approach presented in this text should to ensure retrieval of high-quality grafts with a low complication rate providing patients with the full benefits, both cardiac and functional, of this minimally invasive technique of saphenous vein harvesting for CABG.

Age Factors↗
PubMedDate not supplied

Surgical treatment of recurrent dacryocystitis secondary to cystic dilatation of the nasolacrimal duct in a dog.

A 3-year-old, castrated male golden retriever was presented for evaluation of recurrent ocular discharge of 4 months' duration from the left eye. Dacryocystorhinography was performed and demarcated a cystic dilatation of the left nasolacrimal duct with obstruction of the duct distal to the cystic cavity. Surgical exploration of the left maxillary sinus was performed to confirm the diagnosis and reestablish drainage into the nasal cavity. Recovery was uneventful, and the dog has been asymptomatic for >36 months postoperatively. This report documents the third published case of surgical treatment for cystic dilatation of the nasolacrimal duct.

Animals↗