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Biomedical subjects

R Cartier

Publications and source records attributed to R Cartier.

At least 19 recordsLinked to original sources
PubMed2002

Early reoperation for iatrogenic left main stenosis after aortic valve replacement: a perilous situation.

BACKGROUND: Iatrogenic left main coronary artery (LMCA) stenosis secondary to direct ostial cannulation during aortic valve replacement still occurs and is a morbid situation due to the difficulties of early reoperation and in providing adequate myocardial protection. METHODS: A retrospective analysis was performed and identified seven patients with an iatrogenic LMCA stenosis, after 2158 aortic valve replacements (AVR) (0.3%) in our institution since 1987. RESULTS: All patients with LMCA stenosis after AVR had undergone direct ostial cannulation with self-inflating balloon cannulas at the time of AVR. At reoperation for LMCA stenosis, severe ischemia developed in one patient and injury to cardiac structures occurred in four patients. Four patients suffered a perioperative myocardial infarction and congestive heart failure developed in two patients at late follow-up. CONCLUSIONS: LMCA stenosis following coronary ostial cannulation at the time of AVR is a rare yet morbid complication. Reoperation for this condition is fraught with a high operative morbidity rate and poor long-term outcome. Prevention of this complication is quintessential, avoiding ostial cannulation with self-inflating balloons.

Adult↗
PubMed2002

Utilization of synthetic peptides containing nuclear localization signals for nonviral gene transfer systems.

The ability of nonviral gene delivery systems to overcome extracellular and intracellular barriers is a critical issue for future clinical applications. In recent years, several efforts were focused on the elucidation of the gene transfer mechanisms and on the development of multicomponent systems in order to improve both targeted gene delivery and transfection efficiency. The transport of the therapeutic DNA from the cytoplasm into the nucleus is an inefficient process and is considered as the major limiting step in nondividing cells. One of the strategies to improve nuclear uptake of DNA is taking advantage of the cellular nuclear import machinery. Synthetic peptides containing a nuclear localization signal (NLS) are bound to the DNA so that the resulting DNA-NLS complex can be recognized as a nuclear import substrate by specific intracellular receptor proteins. In this review, we critically summarize recent studies applying this approach with a particular focus on NLS-sequence specificity. Implications of the observed results are also discussed in regards to future developments of this technology.

Active Transport, Cell Nucleus↗
PubMed2001

Coronary artery endothelial dysfunction after ischemia-reperfusion and acute untreated rejection in a canine heterotopic heart transplantation model.

BACKGROUND: Acute rejection is a common problem in heart transplantation and may contribute to the development of cardiac allograft vasculopathy. This study was designed to evaluate the mechanisms of coronary endothelial dysfunction associated with ischemia-reperfusion and acute untreated rejection. METHODS: Two groups of mongrel dogs (n=7 per group) underwent heterotopic cervical heart transplantation without immunosuppression. Allografts were harvested on posttransplant day 1 (group 1) and day 5 (group 2). A third group of unoperated dogs served as control (group 3). After harvesting, epicardial coronary arteries were studied in organ chamber for endothelium-dependent and independent reactivity. RESULTS: Group 1 displayed multifocal ischemic damage without any rejection while hearts from group 2 reached grade IV rejection. Immunohistochemical studies for von Willebrand factor showed expression on coronary endothelial cells in all animals with scattered areas of denudation in transplanted groups. Endothelium-dependent responses to acetylcholine, calcium ionophore A23147, and bradykinin were unaffected in groups 1 and 2. Endothelial relaxations to sodium fluoride (Gi-protein activator) was significantly reduced in group 1 and significantly increased in group 2 compared with control. Responses to serotonin and UK14304 (receptors linked to Gi-protein) were significantly increased in group 2. Responses to thrombin were decreased in both groups. Endothelium-independent responses were unaffected. CONCLUSIONS: In the canine model of heterotopic heart transplantation, the early (24 hr) endothelial dysfunction seen after transplantation is specific to the thrombin receptor and the Gi-protein signaling pathway. Acute untreated rejection did not modify the alteration in endothelial reactivity to thrombin but enhanced the sensibility of the Gi-protein signaling pathways.

Animals↗
PubMed2001

Increased incidence of acute ascending aortic dissection with off-pump aortocoronary bypass surgery?

BACKGROUND: An apparent increase in the incidence of acute ascending aortic dissection following off-pump coronary artery bypass grafting (OPCAB) led us to assess retrospectively the rate and circumstances of this complication in our institution on a consecutive series of patients undergoing aortocoronary bypass performed with and without extracorporeal circulation (ECC). METHODS: A retrospective analysis of acute ascending aortic dissections complicating coronary artery bypass grafting surgery in 3,031 patients in our institution since April 1, 1995, was performed using the database of the Montreal Heart Institute. RESULTS: There was a greater frequency of hypertension in the OPCAB group. Iatrogenic acute aortic dissection occurred in 3 patients among 308 operated on without ECC (0.97%) and 1 patient among 2,723 operated on under ECC (0.04%). This difference was statistically significant (p < 0.00001). CONCLUSIONS: The risk of aortic dissection may be increased in OPCAB. Careful manipulation of the aorta with a single side-clamping and a control of the arterial pressure should be used to minimize aortic trauma. High-risk patients should undergo CABG without side-clamping of the aorta or CABG with ECC to prevent this redoubtable complication of myocardial revascularization.

Aged↗
PubMed2001

Experience with the 19-mm Carpentier-Edwards pericardial bioprosthesis in the elderly.

BACKGROUND: Valve replacement in small aortic root remains a surgical challenge. The objective of this study was to compare results of the 19-mm bioprosthesis with those of larger prostheses in the elderly. METHODS: The 443 patients, 70 years of age and older, who underwent aortic valve replacement with Carpentier-Edwards pericardial bioprostheses were reviewed. RESULTS: There were 93 patients with a mean age of 76+/-4 years with implantation of 19-mm prostheses and 350 patients with a mean age of 75+/-4 years with larger bioprostheses. Associated aortoplasty was performed in 10 patients (11%) with 19-mm bioprostheses and in 8 patients (2%) with larger bioprostheses (p = 0.001). There were 11 deaths (12%) within 30 days of surgery in patients with 19-mm prostheses and 22 deaths (6%) among those with larger prostheses (p = 0.1). The 7-year survival rate averaged 61%+/-7% in patients with 19-mm prostheses and 67%+/-4% in those with larger prostheses (p = 0.8). The 7-year freedom rates from all valve-related events averaged 96%+/-2% and 93%+/-2%, respectively (p = 0.6). CONCLUSIONS: Aortic valve replacement with the 19-mm Carpentier-Edwards pericardial bioprosthesis offers excellent midterm results in the elderly.

Actuarial Analysis↗
PubMed2001

Aortic valve replacement with mechanical and biologic prosthesis in middle-aged patients.

BACKGROUND: Mechanical prostheses are used in young patients and bioprostheses in the elderly because of the higher rate of structural failure of bioprostheses. The objective of the present study was to compare results after aortic valve replacement with mechanical (Carbo-Medics) and biologic (Carpentier-Edwards pericardial) in middle-aged patients. METHODS: Five hundred twenty-one patients, aged between 55 and 65 years, who underwent aortic valve replacement with mechanical (n = 363) or biologic (n = 158) prostheses were reviewed. RESULTS: The 10-year actuarial survival rate averaged 66%+/-6% in patients implanted with mechanical valves compared with 75%+/-4% in patients implanted with biologic valves (p = 0.2). The 10-year freedom rate from thromboembolism, hemorrhage, and endocarditis averaged 92%+/-7%, 97%+/-2%, and 99%+/-1%, respectively, in patients with mechanical valves compared with 91%+/-3% (p = 0.03), 99%+/-1% (p = 0.4), and 95%+/-2% (p = 0.01), respectively, in those with biologic valves. The 10-year freedom rate from all valve-related complications averaged 90%+/-7% and 83%+/-4%, respectively (p = 0.01). CONCLUSIONS: The freedom rate from all valve-related complications was higher among patients with mechanical valves compared with biologic valves 10 years after aortic valve replacement in middle-aged patients.

Actuarial Analysis↗
PubMed2001

Multivessel off-pump coronary artery bypass surgery in the elderly.

OBJECTIVE: Coronary artery bypass grafting in the elderly patient is associated with increased perioperative morbidity and mortality. The avoidance of cardiopulmonary bypass (CPB) in this population is potentially beneficial. We examined our initial experience with off-pump multivessel coronary artery revascularization in patients aged 70 years and older. METHODS: In a consecutive series of 300 off-pump coronary artery bypass (OPCAB) operations performed by a single surgeon between 1996 and 1999, 98 patients were aged 70 years and older. These patients were compared with a consecutive cohort of 497 patients aged 70 years and older operated on with CPB in the same institution from 1995 to 1996, period where OPCAB surgery was not performed in our institution. RESULTS: Patients in the beating heart group were older (75+/-4 vs. 74+/-3 years; P=0.001). Gender distribution and other preoperative risk factors were comparable for the two groups. On average, 3.0+/-0.8 and 2.8+/-0.7 grafts per patient were completed in the OPCAB and the CPB groups, respectively (P=0.007). Perioperative mortality rates (OPCAB group, 3.1%; CPB group, 3.6%), perioperative myocardial infarction (OPCAB, 2.0%; CPB, 5.1%) and neurologic events (OPCAB, 1.0%; CPB, 3.2%) were comparable for the two groups. The incidence of postoperative atrial fibrillation was lower in the OPCAB group (42 vs. 54%; P=0.05). The need for allogenic blood transfusions was significantly less in the OPCAB group (53 vs. 82%; P=0.001). CONCLUSIONS: In patients aged 70 years and older, multivessel OPCAB surgery is associated with lower rates of postoperative atrial fibrillation and reduced transfusion requirements. Multivessel OPCAB in the elderly patient is an acceptable alternative to procedures performed with CPB.

Age Factors↗
PubMed2001

Pulmonary metabolism of endothelin 1 during on-pump and beating heart coronary artery bypass operations.

BACKGROUND: Coronary artery bypass operations are associated with increased circulating levels of the powerful vasoconstrictor endothelin 1. The pulmonary circulation is an important site for both production and clearance of endothelin 1. Lung endothelial injury resulting from cardiopulmonary bypass could modify pulmonary endothelin 1 metabolism through an increase in production, a reduction in removal, or a combination of both. METHODS: Pulmonary endothelin 1 kinetics were quantified by using the indicator-dilution technique in patients undergoing coronary artery bypass grafting with (n = 11) or without cardiopulmonary bypass (ie, beating heart; n = 10). Mixed venous endothelin 1 levels were also measured in samples from the pulmonary artery, and systemic levels were obtained from the radial artery. RESULTS: Pulmonary artery endothelin 1 levels were similar before and after cardiopulmonary bypass, with means of 1.59 +/- 0.37 pg/mL and 1.33 +/- 0.15 pg/mL (P =.45), respectively. Systemic endothelin 1 levels, however, increased after bypass from 1.64 +/- 0.22 pg/mL to 2.07 +/- 0.16 pg/mL (P =.01). In the beating heart group, endothelin 1 levels before and after the operation were similar in the pulmonary artery (1.25 +/- 0.27 pg/mL and 1.45 +/- 0.31 pg/mL, respectively; P =.38), as well as in the radial artery (1.70 +/- 0.26 pg/mL and 1.73 +/- 0.35 pg/mL, respectively; P =.92). The capacity to clear endothelin 1 from the pulmonary circulation, as computed from the permeability-surface area product for endothelin 1, was not affected by cardiopulmonary bypass before and after the operation (25.19 +/- 2.67 mL/s and 23.12 +/- 4.39 mL/s, respectively; P =.49). It was similar and also unaffected in the beating heart group. CONCLUSION: Coronary artery bypass grafting with cardiopulmonary bypass is associated with an increase in systemic endothelin 1 levels. The mechanism involved is not related to a decreased pulmonary clearance of endothelin 1 from the systemic circulation but rather to an increased endothelin 1 release by the lungs.

Aged↗
PubMed2001

Thrombotic complications in beating heart operations.

BACKGROUND: Off-pump coronary artery operations have recently gained popularity among the community of cardiac surgeons. Because the use of cardiopulmonary bypass is avoided, full anticoagulation is generally not sought to decrease perioperative blood loss and transfusion needs. Traditionally, patients undergoing coronary artery bypass operations with cardiopulmonary bypass are not considered at risk of having venous or arterial thromboembolic complications, and prophylaxis is generally not recommended. METHODS AND RESULTS: We have reviewed our experience with off-pump coronary bypass operations, focusing on thromboembolic complications with clinical manifestations, and compared these findings with our experience with cardiopulmonary bypass operations. In our series of 500 off-pump cases, thromboembolic complications occurred in 1%, causing death in 1 patient, whereas in a contemporary cohort of 1476 patients operated on with cardiopulmonary bypass, thromboembolic complications resulted in stroke in 0.5% of the cases. This difference did not reach statistical significance. CONCLUSIONS: Thromboembolic complications in off-pump coronary bypass operations are comparable with those in cardiopulmonary bypass operations. Although the prevalence of this complication remains low, the associated morbidity should lead to reconsideration of prophylactic measures.

Anticoagulants↗
PubMed2001

Results following valve replacement for ischemic mitral regurgitation.

BACKGROUND: Although several authors have favoured mitral repair in ischemic mitral regurgitation (IMR), mitral valve replacement is a valuable option and most often a necessity in patients with structural IMR. OBJECTIVE: To review the authors' experience with valve replacement for patients with acute and chronic IMR. The effect of preserving the valve leaflets and the subvalvular apparatus during replacement was also evaluated. PATIENTS AND METHODS: The authors' experience with mitral valve replacement for IMR between 1990 and 1999 was retrospectively analyzed at the Montreal Heart Institute, Montreal, Quebec. Results obtained with mitral valve replacement due to degenerative disease were used for comparative purposes. RESULTS: Ninety-two patients with IMR and 213 patients with degenerative mitral regurgitation underwent valve replacement with mechanical prostheses (262 of 305 [86%]) or biological prostheses (43 of 305 [14%]). Fifteen patients (15 of 92 [16%]) died within 30 days of mitral valve replacement among IMR patients compared with eight (eight of 213 [4%)] among patients with degenerative mitral valve disease (P=0.01). The seven-year survival average following mitral valve replacement was 66+/-7% in patients with ischemic disease compared with 72+/-4% in patients with degenerative disease (P=0.07). Cardiopulmonary bypass time (odds ratio [OR] 1.01) and emergency operation (OR 2.5) were correlated with the 30-day mortality; the patient's age (OR 1.04) was the only risk factor correlated with the seven-year mortality after valve replacement. The five-year survival of patients with papillary muscle rupture averaged 59+/-12% compared with 78+/-7% in those with functional IMR. CONCLUSIONS: Preoperative risk factors and higher early mortality in patients with mitral valve replacement for ischemic disease contribute to a lower seven-year survival than with mitral valve surgery for degenerative disease. The short and long term survival of the patients in the acute structural mitral disease subgroup was significantly worse.

Aged↗
PubMed2001

Predictive value of Candida colonization index in 131 patients undergoing two different cardiovascular surgical procedures.

BACKGROUND: Nosocomial candidemia is an important infection because of its increasing incidence and its high fatality rate. Candidiasis involves multiple risk factors. In this work, we study the degree of Candida colonization in cardiovascular surgical patients by taking into account the number of sites colonized and the density of growth. METHODS: Eleven (11) selected variables (age, sex, weight, diabetes, number of antibiotics, duration of antibiotics, length of hospitalization, length of stay in surgical intensive care unit, duration of surgery, temperature during surgery, and number of bypass) were considered to predict the perioperative variation of the colonization index (CI) by Candida in 131 cardiovascular surgical patients. These patients were divided into two groups: group A, coronary artery bypass grafting with extracorporeal circulation (72 patients) and group B, coronary artery bypass grafting without extracorporeal circulation (59 patients). RESULTS: One thousand and forty-eight fungal cultures were obtained from four different body sites and 162 isolated were identified. Candida albicans accounted for 74% of the strains in group A and 97% in group B. The statistical analysis (two-way anova) shows that group A patients with an increased CI have received significantly more antibiotics than those with a stable CI (1.50+/-0.83 vs 1.08+/- 0.40, p=0.0055). CONCLUSIONS: Epidemiological data obtained from this study show that coronary artery bypass grafting with extracorporeal circulation procedure is associated with an increase in the use of antibiotics and subsequently a higher risk a Candida colonization-infection.

Aged↗
PubMed2000

Bolus endovascular PDGFR-beta antisense treatment suppressed intimal hyperplasia in a rat carotid injury model.

BACKGROUND: Intimal thickening in accelerated arteriopathies relies on the migration of medial vascular smooth muscle cells (VSMCs) and their proliferation within the neointima. Activation of platelet-derived growth factor receptor-beta (PDGFR-beta) expressed in injured VSMCs is responsible for the migration of medial VSMCs to the intima. In the present study, we wanted to assess whether a single local endovascular delivery of antisense PDGFR-beta in injured rat carotid arteries would be sufficient to prevent intimal hyperplasia and how it might contribute to the vascular healing process. METHODS AND RESULTS: A bolus of antisense PDGFR-beta delivered into injured rat carotid arteries reduced PDGFR-beta protein overexpression by >90% from day 3 to 28 after injury. At day 28 after injury, compared with injured untreated carotids, treatment with antisense PDGFR-beta reduced intimal hyperplasia by 58% and medial VSMC migration by 49% and improved vascular reendothelialization by 100% and vascular reactivity (EC(50)) to acetylcholine by 5-fold. CONCLUSIONS: A single-bolus luminal delivery of antisense PDGFR-beta to injured rat carotids reduced intimal hyperplasia, improved the reendothelialization process, and led to the recovery of endothelium-dependent regulation of vascular tone.

Animals↗
PubMed2000

Torsades de pointes secondary to intravenous haloperidol after coronary bypass grafting surgery.

PURPOSE: Postoperative delirium occurs in about 2% of patients undergoing major cardiac surgery including coronary artery bypass grafting surgery (CABG). Haloperidol (Sabex, Boucherville, Canada) is a drug commonly used in the intensive care unit for the treatment of delirium and is usually considered safe even at high doses and is rarely implicated in the development of malignant ventricular arrhythmias such as torsades de pointes. The purpose of this study is to report such a complication of use of haloperidol after myocardial revascularization. CLINICAL FEATURES: The patient reported underwent uneventful triple bypass surgery. Administration of large intravenous doses of haloperidol was necessary for control of psychomotor agitation due to delirium. Torsades de pointes occurred in the absence of QT prolongation on the third postoperative day following use of the drug with no other obvious etiological factor. CONCLUSION: Awareness of this rare complication is key to judicious use of this drug in the post CABG patient in whom such an arrhythmia may have very deleterious consequences because of the underlying cardiac condition.

Anti-Dyskinesia Agents↗