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R Cartier

Publications and source records attributed to R Cartier.

At least 73 records · Page 4Linked to original sources
PubMed1998

[The vasoconstrictor effect of cyclosporine on the pulmonary vein is mediated by its vehicle: the cremophor].

OBJECT: Cyclosporin A (CyA) induced vasoconstriction and impaired relaxation to agonists has been related in some models to its vehicle: the cremophor (CRE). There is no data concerning the effect of CyA and its vehicle CRE on the pulmonary veins. Therefore, the present study was designed to characterize the effect of CyA and CRE on isolated pulmonary veins. MATERIAL AND METHODS: Third-order canine pulmonary veins (n = 6) were suspended in organ chambers for measurement of isometric force. Segments were exposed to cumulative doses (10(-9) to 10(-4) M) of CyA in its vehicle CRE, and to CRE alone. RESULTS: CyA induced an ehdothelium-independent vaasoconstriction similar to CRE, maximal constriction (Emax) were: 1.8 +/- 0.3 g versus 2.1 +/- 0.4 g respectively (p = NS). This vasoconstriction observed with CRE was not affected by indomethacine (a cyclooxygenase inhibitor), and by pinane thromboxane (a thromboxane antagonist). However, the vasoconstriction was decreased by diltiazem (10(-5) M), a calcium channel blocker, Emax were: 2.1 +/- 0.4 g and 0.8 +/- 0.04 g respectively for CRE and CRE with diltiazem (p < 0.05). CONCLUSION: CyA vehicle CRE induces an endothelium-independent vasoconstriction in isolated third order pulmonary veins in the dog. This vasoconstriction is not related to a cyclooxygenase product, but is partially mediated by a calcium channel activation in vascular smooth muscle.

Animals↗
PubMed1998

[The beneficial effect of natural antioxidants on the endothelial function of regenerated endothelium].

HYPOTHESIS: Lipid peroxidation and LDL oxidation have been implicated in intimal hyperplasia and endothelial dysfunction following direct arterial trauma. OBJECTIVES: The aim of this study was to evaluate the effects of megadose of natural antioxidant vitamin E (VE) combined to vitamin C (VC) on the regenerated endothelial dysfunction. METHOD: A first group of rats (VE and C) (n = 10) was pretreated with VE (500 IU/kg/day) and VC (1200 mg/kg/day) for 4 weeks before aortic (thoracic) endothelial denudation with a Fogarty catheter. Rats were then fed with the same vitamin supplemented diet for 2 months. A second group (n = 10) was similarly denuded and treated with soya oil (SO), VE vehicle, for the same period; a third group (n = 10) was denuded only (DN); and a fourth group was maintained on a regular diet (CL) without denudation. Endothelial-dependent and independent relaxation was assessed in organ chambers. RESULTS: Vascular relaxation to nitric oxide analogue sodium nitroprusside was not affected either by the regenerative process or the vitamin supplementation. However, endothelial-dependent relaxation to acetylcholine, was significantly preserved in VE and C (p < 0.01) treated animals compared to DN group. CONCLUSION: These results suggest that, in this model, dietary megadose of antioxidants vitamin initiated 4 weeks before denudation can improve the post-regenerative endothelial dysfunction and could contribute to the prevention of the atherosclerotic process.

Acetylcholine↗
PubMed1997

Calcium-channel blockers preserve coronary endothelial reactivity after ischemia-reperfusion.

BACKGROUND: Calcium-channel blockers have been reported to improve myocardial recovery after ischemia-reperfusion, but their effects on coronary blood flow regulation remain to be defined. Experiments were designed to evaluate the effects of calcium antagonists on coronary artery vasoregulation exposed to ischemia-reperfusion. METHODS: Three groups of hearts (n = 6) were pretreated with a 10-minute infusion of either diltiazem, verapamil, or nifedipine at concentrations of 10(-9) mol/L to 10(-6) mol/L and exposed to 30 minutes of no-flow ischemia and 45 minutes of reperfusion. Another group (n = 6) received no pretreatment and was used as control. Endothelium-dependent and -independent relaxations were tested by assessing coronary flow increase to 5-hydroxytryptamine (10(-6) mol/L) and sodium nitroprusside (10(-5) mol/L) infusion, respectively. Left ventricular pressure, its first derivative, and coronary basal flow were recorded before and after ischemia as well as during calcium antagonist infusion. RESULTS: Endothelium-dependent relaxation after ischemia was significantly improved with all three drugs in a dose-dependent fashion; nifedipine was found to be the more potent. Endothelium-independent relaxation was also significantly preserved with calcium antagonists regardless of the type, whereas left ventricular hemodynamics were not. During perfusion, nifedipine was found to have the most negative inotropic effect and to be the most potent vasodilator on the coronary circulation. Diltiazem was the less effective drug on both left ventricular hemodynamics and coronary circulation. CONCLUSIONS: This study indicates that preischemic infusion of calcium antagonists enhance endothelium-dependent and -independent coronary artery relaxation in the isolated rat heart model in a dose- and drug-dependent fashion. This can be achieved at low doses without affecting left ventricular hemodynamics and should contribute to preserve coronary artery autoregulation.

Animals↗
PubMed1997

Vascular effects of cyclosporin A and acute rejection in canine heart transplantation.

BACKGROUND: Alteration of coronary vascular regulation during acute rejection may induce graft dysfunction and promote the occurrence of coronary atherosclerosis in transplant recipients. We studied the effects of treated and untreated acute rejection on coronary vascular regulation. METHODS: Two groups of mongrel dogs (n = 7) underwent heterotopic heart transplantation (cervical position) and received either no treatment (group 1) or cyclosporin A (CyA), 10 mg.kg-1.day-1 (group 2). On day 7, recipient native and transplanted hearts were harvested and studied in organ chambers for coronary vascular reactivity. RESULTS: Transplanted hearts from group 1 displayed grade IV histologic rejection, whereas those from group 2 displayed grade IIIA to IV rejection. Intimal hyperplasia was found in the coronary arteries of both groups. Immunoperoxidase staining revealed the presence of factor VIII and of immunoglobulin M and G antibodies on the endothelium of both groups. Coronary relaxation to thrombin was impaired in transplanted hearts compared with native hearts (p < 0.05), and this was not influenced by CyA treatment. Conversely, endothelium-dependent relaxation to 5-hydroxytryptamine was enhanced in both CyA-treated (p < 0.01) and untreated groups (p < 0.05). A facilitating effect of CyA on 5-hydroxytryptamine also was seen in transplanted hearts in group 1 versus group 2 (p < 0.05), suggesting an intrinsic effect of CyA. Endothelium-independent relaxation to sodium nitroprusside and the contractile response to prostaglandin F2 alpha were not affected. CONCLUSIONS: In our model, acute rejection did not specifically impair cyclic guanosine monophosphate-mediated relaxation, but it did affect, in a receptor-specific manner, endothelium-dependent relaxation. Cyclosporin A appeared to enhance coronary endothelial sensitivity to 5-hydroxytryptamine.

Acetylcholine↗
PubMed1997

Mycotic aneurysm of the palmar arch after endocarditis.

Mycotic pseudoaneurysms of upper extremities are an infrequent complication of endocarditis. We describe a case of mycotic pseudoaneurysm of the superficial palmar arch in a patient who had acute bacterial endocarditis. We discuss operative and pathologic findings and briefly review the literature on the subject.

Aged↗
PubMed1997

[Clinical results of peroperative transesophageal echography in peri-valvular leaks of heart prosthesis].

Perivalvular leaks following prosthetic valve replacement are associated with significant morbidity. Management has classically consisted of valve replacement or blind surgical repair. Our study examines the results of intraoperative transesophageal echo-guided repair of perivalvular leaks (ITEGR). Between November 24, 1987 and January 1st, 1996, 23 patients (10 men, 13 women) at the Montreal Heart Institute underwent ITEGR. Ninety percent were NYHA class III-IV preoperatively. Seventy to 85% had significant cardiac insufficiency preoperatively. Eighty-six percent of the leaks were in the mitral valve location, 90% of which were mechanic prosthesis. Eighty-nine percent of patients had hemolysis with an average LDH of 720. Mean bypass time was 125 minutes with a mean clamp time of 77 minutes. Most patients were undergoing a third operation at the time of repair. Operative mortality was 8%, all due to biventricular failure. A mean follow-up of 67 months showed a late death of 10%. Of the 19 survivors, 77% were NYHA class I-II. Overall mortality was 20%. In our institution valve re-replacement in similar circumstances was associated with an operative and long-term mortality of 7% and 26% respectively. We conclude that intraoperative transesophageal echo-guided repair is an excellent management alternative in patients with perivalvular leaks with decreased late and overall mortality.

Adult↗
PubMed1997

[Influence of carotid atheroma on the neurologic status after myocardial revascularization].

Surgical management of the carotid disease remains controversial in patients affected with coronary artery atheromatous disease. We report the Montreal Heart Institute experience on the influence of carotid disease on postoperative neurologic events of 501 consecutive patients operated on for coronary revascularization during the period from January 1994 to December 1994. There were 381 men and 114 women averaging 62 +/- 9 years old. Major risk factors were high blood pressure (35%), and smoking habit (48%). Fifty-nine patients presented clinical signs of carotid atheromatosis and among them 21 had significant carotid stenosis (> 80% decrease of cross sectional area). During surgery, the mean duration of extracorporeal circulation (ECC) was 76 +/- 31 minutes and the mean perfusion pressure (MPP) was 70 +/- 11 mmHg. The use of inotropic drugs was mandatory in 26% of the cases and the mean arterial lactate (AL) dosage during ECG was 3.07 +/- 1.35 mM/L. During the perioperative period, 13 (2.5%) patients sustained neurologic disturbances of which 5 (1%) were lateralized. Among them, 8 completely recovered whereas 3 of the 5 with permanent damage died. None of the patients with preoperative stigmata of carotid disease experienced lateralized neurologic deficit. Multivariate regression analysis identified the use of vasopressor drugs and perioperative increase of AL as predictive factors. We conclude that in our series, the incidence of neurologic complications was low. The presence of carotid atheromatosis did not increase the postsurgical risk of cerebrovascular accident, however, the increased incidence of neurologic events associated with inotropic drugs and increased AL suggests a direct link with a systemic oxygen debt. Consequently, we do no recommend concurrent prophylactic surgery during coronary artery revascularization.

Adult↗
PubMed1997

[Effects of chronic administration of captopril on vascular reactivity of the rat aorta].

UNLABELLED: The vascular endothelial function is altered in certain vascular pathology such as arterial hypertension. However, the endothelial effect of the pharmacologic treatment of this pathology with angiotensin converting enzyme (ACE) inhibitor is poorly understood. To evaluate the effects of long-term treatment of captopril on the rat aortic vascular reactivity, 2 groups of spontaneously hypertensive rats (SHR) (n = 6) were studied for 12 weeks: the first group was treated with captopril (CAP) (2 g/l of water) while group 2 (OCAP) received no treatment. A third group without hypertension was considered as control group (CTL). At the end of the experiments, isolated aortic rings were studied in organ chambers for endothelial and smooth muscle vascular reactivity. The endothelial-dependent relaxations (EDR) to cumulative doses of acetylcholine, histamine or adenosine diphosphate were significantly decreased in the aortic segments of CTL compared to CAP (p < 0.05). Aortic segments from OCAP group demonstrated intermediate EDR responses between CAP and CTL groups. Smooth muscle relaxation to sodium nitroprusside was comparable among the 3 groups. Maximal smooth muscle contraction to progressive doses of norepinephrine was significantly higher in the CTL group compared to the hypertensive groups. CONCLUSION: Spontaneously hypertensive rats have an increased basal vascular tone. The increased EDR observed with hypertension partially compensates this hypercontractility. Chronic hypertension treatment with captopril partially normalizes EDR responses in the rat aorta suggesting the lost of the endothelial compensatory mechanism by ACE inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

[Revascularization of the circumflex artery with mechanical stabilization: initial experience].

OBJECTIVES: To evaluate the short-term result of the coronary artery revascularization without cardiopulmonary bypass for triple vessel disease, including the circumflex territory performed on the stabilized beating heart. METHODS: Prospective study conducted on the first 35 consecutive patients with triple vessel disease operated upon without cardiopulmonary bypass by a single surgeon (RC) at the Montreal Heart Institute between October 1996 and March 1997. RESULTS: Mean age of patients was 64 +/-1.6 years and the majority were men (30). Most common risk factors were hypercholesterolemia (65%) and familial history (55%) of ischemic heart disease. Main surgical indication was unstable angina (74%) and mean preoperative left ventricular ejection fraction was 53 +/- 3%. Hundred and twelve bypass were constructed averaging 3.2 +/- 0.1 grafts/patients of which 39 were made on branches of the circumflex artery. Average ischemic time was 34.17 +/- 2.17 minutes. The internal thoracic artery, saphenous vein, and radial artery were used as a vascular conduit in 44, 67, and 1 occasions respectively. There was one operative mortality, and one non Q perioperative myocardial infarction (CK-MB: 89 U/L). No patient required aortic counterpulsation balloon assistance. The average postoperative CK-MB (U/L) were 12.2 +/- 1.9, 15.2 +/- 3.2, and 10.3 +/- 1.7 at 1, 24 and 48 hours respectively. During the post-operative period 26% (9) of the patients presented atrial fibrillation, 6.5% (2) early reexploration for bleeding, and 63% (22) did not require transfusion. Average stay in hospital was 6.1 +/- 45 days. Coronary grafts were angiographically assessed in the first 10 patients and at the postmortem exam in one and displayed a 100% patency with 93.5% (29/31) adequate runoff. CONCLUSION: Triple vessel coronary artery disease revascularization is feasible on the beating heart without cardiopulmonary bypass with excellent short-term clinical and angiographic results.

Aged↗
PubMed1997

[Cyclosporine A prevents ischemia-reperfusion induced myocardial dysfunction in the isolated heart of the rat].

Cyclosporin A (CyA) has been shown to prevent mitochondrial injury following ischemia-reperfusion injury. Therefore, the present study was designed to investigate the effect of CyA on ischemia-reperfusion injury in the isolated rat heart preparation. Hearts from Sprague-Dawley rats were perfused in the Langerdorffmode at constant pressure (80 cm H2O) and paced (270 beats/min). After equilibration, hearts were treated with CyA (10(-5) mol/l) (n = 8) or its vehicle, cremophor (Cr) (n = 8) for 10 minutes before exposure to 30 minutes of global ischemia and 60 minutes of reperfusion. Hemodynamic variable vascular reactivity, and oxygen consumption (MVO2) were tested at baseline and at selected points during reperfusion Hemodynamic variables were significantly improved in the CyA group. The maximal mean percentage of preservation for left ventricular developed pressure (PDVG) was -14.9 +/- 10.7% and +31.5 +/- 23.6% respectively for Cr and CyA group (p<0.05) The maximal mean percentage of preservation for dp/dt was -11.7 +/- 11.4% and +28.3 +/- 29.9% respectively for Cr and CyA group (p < 0.05): the compliance, -dP/dt was also preserved, maximal mean preservation was -25.9 +/- 9.2% and +53.1 + 30.1% respectively in Cr and CyA group (p < 0.01). Oxygen debt was decreased at 30 minutes of reperfusion in the CyA-treated hearts: 0.06 x 10(-2) +/- 0.23 x 10(-2) cc/min/g compared to Cr-treated hearts: 0.61 x 10(-2) +/- 0.37 x 10(-2) cc/min/g (p = 0.05). The coronary endothelial dependent and independent responses were similarly decreased in both groups during reperfusion. Thus, in the isolated rat heart preparation, CyA preserves myocardial function (hemodynamic variables) and oxygen consumption without affecting the coronary vascular function during ischemia-reperfusion injury.

Animals↗
PubMed1996

Clinical trial of retrograde warm blood reperfusion versus standard cold topical irrigation of transplanted hearts.

BACKGROUND: A prospective, randomized clinical study involving 34 patients undergoing heart transplantation compared myocardial preservation of donor hearts maintained with continuous reperfusion with retrograde warm blood cardioplegia during surgical implantation versus the standard cold topical irrigation. METHODS: Hearts in both groups were arrested with a standard crystalloid solution and maintained in a cold saline solution during transportation. In the retrograde group, cardioplegia was administered through a catheter in the coronary sinus during surgical implantation. An average of 471 +/- 30 mL of hyperkalemic crystalloid solution diluted 1:4 in warm blood from the oxygenator was infused. In the standard group, the heart was kept cold by topical irrigation of cold saline solution and was reperfused only when the ascending aorta was unclamped. RESULTS: Preoperative characteristics of donors and recipients were similar in the two cohorts. Ischemic time average 139 +/- 12 minutes in the retrograde group compared with 130 +/- 11 minutes in the standard group (p = 0.57). Cardiopulmonary bypass time averaged 89 +/- 4 minutes in the retrograde group and 110 +/- 12 minutes in the standard group (p = 0.12). Defibrillation at reperfusion was performed in 4 patients (4/17, 24%) in the retrograde group and 12 patients (12/18, 67%) in the standard group (p = 0.01). There were no deaths in the retrograde group (0/17), whereas in the standard group, 3 patients (3/17) died of early graft failure (p = 0.11). Four early graft failures occurred in the standard group (p = 0.06). Two patients (2/17, 12%) were weaned from bypass with ventricular assist devices in the standard group. The number of subendocardial necrotic cells in the first two weekly endomyocardial biopsy specimens averaged 2.7 +/- 0.8 cells/mm2 in the retrograde group and 5.9 +/- 2.4 cells/mm2 in the standard group (p = 0.12). CONCLUSIONS: Retrograde warm blood reperfusion appears to improve the initial recovery of transplanted hearts. The technique is easy to use and may be a useful approach to graft protection during surgical implantation.

Adult↗
PubMed1996

Changing flow pattern of the internal thoracic artery undergoing coronary bypass grafting: continuous-wave Doppler assessment.

Surgeons have limited ability to evaluate intraoperatively the patency of internal thoracic artery graft as a bypass for coronary artery revascularization. We used continuous-wave Doppler ultrasonography to study the velocity of the internal thoracic artery before harvesting and after grafting (scanning probe, 8 MHz). Systolic and diastolic frequency shift (in kilohertz) and systolic frequency/diastolic frequency index were analyzed. Twenty four internal thoracic artery grafts in 15 patients were studied. Fourteen internal thoracic artery grafts were anastomosed to the left anterior descending artery, one to a diagonal artery, and nine to the circumflex artery. The mean systolic frequency before harvesting was 1.19 +/- 0.40 KHz and no significant differences were found between the right and the left internal thoracic artery (right, 1.17 +/- 0.37; left, 1.19 +/- 0.42 KHz). There was a 40% drop in systolic frequency related to the harvesting. Mean systolic frequency decreased after grafting (1.19 +/- 0.40 versus 0.87 +/- 0.32 KHz; p < 0.01) whereas mean diastolic frequency doubled (0.32 +/- 0.12 versus 0.83 +/- 0.4 KHz; p < 0.001) and mean diastolic frequency/systolic frequency index increased from 28% +/- 11% to 101% +/- 39% (p < 0.001), indicating an increased myocardial vascularization during diastole. No significant difference was found between grafted arteries (left anterior descending versus circumflex). All patients had an uneventful postoperative course and no perioperative myocardial infarction was reported. Doppler flow quantification of internal thoracic artery bypasses may give the surgeon an opportunity to evaluate intraoperatively the physiologic features and patency of the internal thoracic artery before and after coronary artery bypasses.

Aged↗
PubMed1996

Receptor-specific effects of acute rejection after heart transplantation on endothelium-dependent coronary relaxation in dogs.

To establish the effects of acute rejection on coronary artery endothelial reactivity in a canine model of heart transplantation, we submitted seven mongrel dogs to heterotopic heart transplantation without immunosuppression for a period of 7 days. At harvesting, all transplanted hearts displayed a grade IV histologic rejection. Compared with native heart, the endothelium-dependent relaxation of the coronary arteries from the graft displayed an increased sensitivity to serotonin, a decreased sensitivity to thrombin, and no change in the response to acetylcholine and adenosine diphosphate; endothelium-independent relaxation to sodium nitroprusside was not affected. Therefore, in the canine heterotopic heart transplant model, acute rejection has no effect on endothelium-independent relaxation of coronary arteries but affects endothelium-dependent relaxation in a receptor-specific manner.

Acetylcholine↗
PubMed1996

Major cardiovascular risk factors in Lyon hypertensive rats. A correlation analysis in a segregating population.

OBJECTIVE: To investigate the association of blood pressure with the other major cardiovascular risk factors in a large population of back-cross to Lyon hypertensive (LH) rats. METHODS: Mean arterial pressure was recorded in male freely moving Lyon normotensive (LN), LH, F1 and backcross to LH rats aged 30 weeks. Plasma cholesterol, triglycerides, insulin, creatinine, urea, fibrinogen and haematocrit levels, and the insulin: glucose ratio were measured in 31-week-old rats and 24h albuminuria in 6-week-old rats. RESULTS: Adult LH rats exhibited a significant increase in plasma lipids, insulin, fibrinogen, creatinine, urea and haematocrit levels compared with LN rats. In young LH rats, at an age at which blood pressure is slightly increased, albuminuria was increased to a greater extent than expected from their blood pressure levels. In the adult back-cross to LH rats, only the plasma cholesterol level was associated with blood pressure. Moreover, the plasma cholesterol level was related to fibrinogen and haematocrit levels. Finally, in the same rats, albuminuria developed early in life was positively related to hypercholinesterolaemia measured later in life. CONCLUSION: Plasma cholesterol, fibrinogen, haematocrit levels and early albuminuria could act synergistically in the enhancement or the development, or both, of vascular and kidney damage in the LH rat. Most interestingly, the association between plasma cholesterol level and blood pressure indicates that, as in essential hypertension, hypercholesterolaemia is a major phenotype associated with hypertension in the LH rat.

Albuminuria↗