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Biomedical subjects

M Carrier

Publications and source records attributed to M Carrier.

At least 73 records · Page 4Linked to original sources
PubMed1999

Quantitative angiographic assessment of coronary anastomoses performed without cardiopulmonary bypass.

BACKGROUND: The quality of the anastomosis performed during coronary artery bypass grafting without cardiopulmonary bypass is a current concern, and myocardial wall restraining devices have been designed to optimize results. A quantitative angiographic analysis was performed to assess coronary anastomoses performed on beating hearts. METHODS: We studied 34 patients who underwent coronary artery bypass grafting without cardiopulmonary bypass between February 1996 and April 1997. The left internal thoracic artery was anastomosed to the left anterior descending coronary artery in all patients. Coronary angiograms were performed 4 +/- 2 days after the operation. The diameter of the anastomoses was quantified by computer-assisted analysis of grafts and native coronary arteries at the toe and heel of the anastomosis. RESULTS: Five of the patients who underwent coronary artery bypass without a stabilizer (n = 20) had stenoses of the internal thoracic artery grafted to the left anterior descending coronary artery of more than 50% at the level of the anastomosis proper, 3 had stenoses at the heel of the coronary anastomosis, and 5 had stenoses at the toe. One of the patients in whom a stabilizer was used (n = 14) had a stenosis of more than 50% at the anastomosis, and 1 had stenosis at the heel. Eight patients in whom the anastomoses were performed without stabilization (8/20, 40%) had stenoses of more than 50%, whereas there was only 1 stenosis of more than 50% of coronary luminal diameter among the patients in whom the operation was performed with a stabilizer (P =.02). CONCLUSION: The quantitative angiographic evaluation suggests that left internal thoracic artery graft to left anterior descending coronary artery anastomoses have a lesser degree of intraluminal stenosis when performed with the use of a myocardial wall stabilizer.

Aged↗
PubMed1999

A two-center study evaluating the hemodynamic and pharmacodynamic effects of cisatracurium and vecuronium in patients undergoing coronary artery bypass surgery.

OBJECTIVE: To determine the hemodynamic and pharmacodynamic effects of rapid bolus administration of cisatracurium compared with vecuronium. DESIGN: A randomized, prospective, double-blind study. SETTING: Tertiary-care university hospitals. PARTICIPANTS: Seventy-nine adult patients with diagnosed coronary artery disease (CAD). INTERVENTION: Elective coronary artery bypass graft surgery (CABG). MEASUREMENTS AND MAIN RESULTS: Patients were randomly divided into four groups. Patients received a rapid bolus of two or four times the 95% peak depression of twitch (ED95) of either cisatracurium (groups 1 and 2) or vecuronium (groups 3 and 4). Three minutes after a midazolam induction, all patients received a rapid bolus administration of either study drug. Maintenance of anesthesia was with a standardized propofol-sufentanil-oxygen anesthetic. Patients were monitored with radial and pulmonary artery catheters and electromyography. End points of the study were hemodynamic stability at induction, after bolus administration of study drugs, and after intubation; the quality of intubating conditions; drug interventions to correct hemodynamic instability; the onset, duration, and recovery of neuromuscular function; and drug cost. Mean arterial pressure (MAP) and heart rate (HR) decreased in a similar proportion in all four groups after induction while, following study drug administration, MAP and HR did not change significantly. Both cisatracurium groups required more boluses to maintain neuromuscular block, but spontaneous recovery rates were faster. Both agents, but cisatracurium to a lesser degree, showed increased duration with repeated maintenance doses. Both agents afforded good to excellent intubating conditions, but the cost of cisatracurium was significantly less. CONCLUSION: The authors conclude there is no evidence of a hemodynamic difference between the two neuromuscular blocking drugs (NMBDs). There are some clinical and cost advantages in favor of cisatracurium.

Adolescent↗
PubMed1999

Nitric oxide inhalation in the treatment of primary graft failure following heart transplantation.

BACKGROUND: Primary graft failure from right or left ventricular insufficiency remains a serious cause of early death following heart transplantation. Inhaled nitric oxide (NO) is a potent pulmonary vasodilator that could decrease pulmonary pressure and improve right ventricular function. METHODS: Two cases of early graft failure following orthotopic heart transplantation were treated with NO inhalation. The treatment consisted of inhalation of 20 ppm of NO, introduced 4 to 6 hours following transplantation, in 2 patients supported with high doses of inotropic agents and vasopressors in addition to the intra-aortic balloon pump. RESULTS: In the first and second cases, NO inhalation resulted in a decrease in pulmonary artery pressure, in a decrease in pulmonary vascular resistance and in an increase in cardiac index. In the second patient, systemic oxygenation improved markedly 30 minutes after initiation of NO. In the 2 patients, NO inhalation, mechanical ventilation and the intra-aortic balloon pump were weaned 4 days following transplantation. CONCLUSION: Primary graft failure from donor ischemic damage, reperfusion injury or pulmonary hypertension remains a serious complication. The use of an intra-aortic balloon pump, inotropic agents and of inhaled NO appears to offer the best support for recovery of donor heart function. Primary graft failure from right or left ventricular insufficiency remains a serious cause of early mortality following heart transplantation. Ischemic damage of donor heart, reperfusion injury or pulmonary hypertension are the main causes of early graft failure. Although the cause is multifactorial, treatment of primary organ failure remains difficult with dismal results. The objective of the present study was to review the result of 2 patients with donor right heart failure following heart transplantation treated with inhaled nitric oxide (NO).

Administration, Inhalation↗
PubMed1999

A 10-year experience with intravenous thymoglobuline in induction of immunosuppression following heart transplantation.

BACKGROUND: Intravenous thymoglobuline (125 mg a day for 3 days, Institut Mérieux, France) has been used to induce immunosuppression following heart transplantation. Cyclosporine and prednisone, with and without azathioprine or mycophenolate mofetil were used as maintenance immunosuppression. OBJECTIVE: The objective of the study was to determine the clinical effect of antibody induction of immunosuppression following heart transplantation. METHODS: A retrospective analysis of the clinical experience at the Montreal Heart Institute. From 1988 to 1998, 163 patients were administered a 3-day course of intravenous thymoglobuline immediately following heart transplantation (Group 1). From 1983 to 1987 and during an isolated period in 1994, intravenous and oral cyclosporine was used immediately following heart transplantation in 48 patients (Group 2). Routine endomyocardial biopsies were performed in all patients and only moderate and severe rejection was treated. RESULTS: One, 5- and 10-year actuarial survival rate averaged 85%+/-3, 77%+/-4 and 67%+/-5 in Group 1 compared with 88%+/-5, 81%+/-6 and 76%+/-6 in Group 2 (p = 0.5). At 1 year, the freedom rate from an episode of acute rejection averaged 43%+/-4 in Group 1 and 30%+/-7 in Group 2 (p = 0.03) and the freedom rate from an episode of infection averaged 44%+/-4 in Group 1 and 31%+/-7 in Group 2 (p = 0.2). At 1, 5 and 10 years, the freedom rate from graft coronary artery disease averaged 93%+/-2, 68%+/-5 and 50%+/-7 in Group 1 compared with 93%+/-4, 58%+/-8 and 30%+/-8 in Group 2 (p = 0.1) and the freedom rate from cancer averaged 98%+/-1, 91%+/-3 and 67%+/-8 in Group 1 compared with 100%, 95%+/-3 and 77%+/-8 in Group 2 (p = 0.2). There was no side-effect related to the systemic injection of thymoglobuline. CONCLUSION: In a cyclosporine based protocol of immunosuppression, induction with an initial 3-day course of intravenous thymoglobuline is associated with a lower rate of acute rejection. Moreover, the risk of infection and of developing cancer is not increased whereas there was a trend towards a lower incidence of coronary atherosclerosis 5 and 10 years after transplantation.

Adult↗
PubMed1999

CardioWest total artificial heart: a retrospective controlled study.

The CardioWest total artificial heart (TAH) is a pneumatic device that is used as a bridge to heart transplantation and the only TAH available that totally replaces the failing ventricles. It has been utilized in selected centers in the U.S.A. with approval from the Food and Drug Administration. Strict criteria have been developed to select candidates to be bridged with the TAH. The patient must be a heart transplant candidate of age >18 and <59 years with a body surface area (BSA) > or = 1.7 m2, cardiac index (CI) <2.0 L/min/m2, and 2 inotropic agents or 1 plus an intraaortic balloon pump (IABP). A total of 24 heat transplant candidates (Group A) met the entry criteria and underwent placement of the TAH between January 1993 and July 1996. Group A consisted of 23 males; 16 patients had an IABP. The control group (Group B) consisted of 18 heart transplant candidates who met the TAH entry criteria but never received a TAH. Group B consisted of 15 males; 14 patients had an IABP. Preimplantation pulmonary vascular resistance (PVR) (Wood units), serum creatinine (mg/dl), and total bilirubin (mg/dl) were determined in both groups. The mean values for Groups A and B were, respectively, age: 47 and 47 years, BSA: 2.01 and 1.93 m2, CI: 1.5 and 1.8 L/min/m2, PVR: 2.88 and 2.47 Wood units, creatinine: 1.5 and 1.6 mg/dl, and bilirubin: 1.8 and 1.4 mg/dl. In Group A, 1 patient died on the TAH, 1 patient died after transplant, and 22 patients reached transplant and were discharged home for a survival rate of 91.7%. In Group B, 10 patients died while waiting for a heart transplant. Of the 8 patients transplanted, 7 survived and were discharged home for a survival rate of 38.9% (p = 0.0003). In summary the CardioWest TAH provided an excellent and successful method of bridging patients to heart transplantation with a reasonable risk.

Female↗
PubMed1999

Transmembrane ICa contributes to rate-dependent changes of action potentials in human ventricular myocytes.

The mechanism of action potential abbreviation caused by increasing rate in human ventricular myocytes is unknown. The present study was designed to determine the potential role of Ca2+ current (ICa) in the rate-dependent changes in action potential duration (APD) in human ventricular cells. Myocytes isolated from the right ventricle of explanted human hearts were studied at 36 degreesC with whole cell voltage and current-clamp techniques. APD at 90% repolarization decreased by 36 +/- 4% when frequency increased from 0.5 to 2 Hz. Equimolar substitution of Mg2+ for Ca2+ significantly decreased rate-dependent changes in APD (to 6 +/- 3%, P < 0.01). Peak ICa was decreased by 34 +/- 3% from 0.5 to 2 Hz (P < 0.01), and ICa had recovery time constants of 65 +/- 12 and 683 +/- 39 ms at -80 mV. Action potential clamp demonstrated a decreasing contribution of ICa during the action potential as rate increased. The rate-dependent slow component of the delayed rectifier K+ current (IKs) was not observed in four cells with an increase in frequency from 0.5 to 3.3 Hz, perhaps because the IKs is so small that the increase at a high rate could not be seen. These results suggest that reduction of Ca2+ influx during the action potential accounts for most of the rate-dependent abbreviation of human ventricular APD.

Action Potentials↗
PubMed1999

Beating heart coronary artery bypass grafting: technical aspects and results in 200 patients.

OBJECTIVE: To describe the initial experience of the first 200 patients who underwent coronary artery bypass grafting (CABG) on beating hearts at the Montreal Heart Institute, Montreal. DESIGN: A prospective cohort of 200 patients was analyzed to study immediate and short term (two-year follow-up) results. SETTING: Patients underwent CABG at the Montreal Heart Institute from February 1996 to June 1998. The first 30 patients underwent CABG without the use of a myocardial wall stabilizer (group 1), and a myocardial wall stabilizer was used in the following 170 patients (group 2). PATIENTS: Group 1 patients averaged 60+/-10 years of age compared with 66+/-10 years in group 2 (P=0.002). Twelve patients (40%) in group 1 had unstable angina compared with 107 patients (63%) in group 2 (P=0.03). INTERVENTIONS: Group 1 patients underwent 1.7+/-0.7 CABG per patient compared with 2.4+/-0.8 grafts per patient in group 2 (P=0.001). Sixty-seven patients (39%) in group 2 had an obtuse marginal coronary artery grafted, and 145 patients (73%) of both groups had a complete myocardial revascularization. RESULTS: Ten patients (5%) in both groups were converted to cardiopulmonary bypass during surgery. Seven patients (3.5%) died postoperatively: five from myocardial infarction, one from aortic dissection and rupture, and one from arrhythmia. Seventeen patients (8.5%) suffered a perioperative myocardial infarction. In groups 1 and 2, respectively, actuarial survival was 100% and 95+/-2%, and freedom rate from reoperation, percutaneous balloon dilation and recurrent myocardial infarction averaged 93+/-4% and 97+/-2% 18 months following CABG. CONCLUSION: CABG on beating hearts appears to be an alternative approach to the use of cardiopulmonary bypass in selected patients.

Aged↗
PubMed1999

Videoassisted thrombectomy of mechanical prosthetic heart valves.

BACKGROUND AND AIM OF THE STUDY: Thrombosis of a bileaflet mechanical heart valve is a life-threatening clinical event. Surgical thrombectomy of bileaflet mechanical prostheses remains an appropriate treatment in selected patients. METHODS: Between 1996 and 1998, five patients (three men, two women; average age 56 +/- 1 years; range: 56 to 66 years) with thrombosis of left-sided bileaflet mechanical valves were treated with videoassisted thrombectomy of the prosthesis. Four patients had thrombosis of a bileaflet mitral mechanical valve, and one patient had thrombosis of an aortic valve prosthesis. Preoperatively, patients were in either NYHA functional class IV (n = 4) or class I (n = 1). Surgery was performed through a right anterior thoracotomy or a median sternotomy. A rigid 30 degrees thoracoscope was inserted into the left atrium or aorta to visualize the thrombosed valve. The thrombus was extracted and the prosthesis under-surface examined and cleaned. Leaflet mobility, assessed with transesophageal echocardiography, was normal following surgical thrombectomy. RESULTS: Mean cardiopulmonary bypass time was 102 +/- 30 min; mean aortic cross-clamping time was 47 +/- 25 min. There was no hospital mortality; mean hospital stay was 9 +/- 1 days (range: 6 to 11 days). Anticoagulation with intravenous heparin was resumed 24 h after surgery. Three patients were discharged on coumarin treatment alone; two patients received aspirin plus coumarin. Mean postoperative follow up was 7 +/- 8 months (range: 1 to 21 months). One patient died 21 months after thrombectomy of a mitral prosthesis, with an unconfirmed diagnosis of recurrent mitral valve dysfunction. At 1-15 months after surgery, four patients are in NYHA class I, without evidence of prosthesis dysfunction. CONCLUSION: Videoassisted thrombectomy of a bileaflet mechanical heart valve is a treatment option in patients with acute thrombosis of the prosthesis.

Anticoagulants↗
PubMed1999

Conversion of cyclosporine A to tacrolimus following heart transplantation.

BACKGROUND: Cyclosporine A (CyA) is ususally the immunosuppressive drug of choice in organ transplantation; however, some side effects have limited its use. Tacrolimus is a novel immunosuppressive drug that is more potent than CyA, and has been used as a rescue agent following heart transplantation when the use of CyA is undesirable or inefficient. PATIENTS AND METHODS: Since 1996, 14 heart transplant recipients under CyA were switched to tacrolimus therapy, for refractory rejection or intolerance, to conventional immunosuppression. RESULTS: After a mean of 35+/-7 months of treatment, tacrolimus was substituted for CyA therapy. The reason for substitution was refractory rejection in six patients, gingival hypertrophy in five patients, hypertrichosis in one patient, severe arterial hypertension in one patient and hepatotoxicity in one patient. Five patients underwent a successful rescue therapy and one patient died of refractory rejection despite the use of tacrolimus. All patients with CyA side effects recovered with tacrolimus. After conversion from CyA to tacrolimus, the number of episodes of acute rejection decreased from a mean of 0.42+/-0.17 to 0.14+/-0.09 episodes/patient/month under CyA and tacrolimus therapy (P=0.11), respectively. The mean dose of prednisone was 0.18+/-0.06 mg/kg/day before compared with 0.06+/-0.01 mg/kg/day after conversion from CyA to tacrolimus (P=0.09). Creatinine serum levels averaged 124+/-7 mmol/L under CyA treatment compared with 113+/-7 mmol/L with tacrolimus therapy (P=0.002). CONCLUSION: In patients with refractory rejections or intolerance to CyA after heart transplantation, conversion to tacrolimus-based immunosuppression is safe and effective.

Adult↗
PubMed1999

[Results of surgery after failed mitral percutaneous dilatation].

OBJECTIVES: Percutaneous balloon mitral valve commissurotomy (BMC) is an alternative to surgical commissurotomy. Complications following BMC includes mitral regurgitation, iatrogenic atrial septal defect, residual mitral stenosis, and pericardial hemorrhage. This study analyzes the outcomes of surgery following failed BMC for mitral stenosis. METHODS: In a series of 298 patients treated with BMC, 53 patients (17.7%) had a complication that necessitated a surgical treatment. Twenty-eight patients needed an immediate surgery before the discharge (group I) and 25 patients were operated on an elective basis (group II). RESULTS: In group I, 27 patients have been operated and one died before the operation. In 21 patients an acute mitral regurgitation occurred, 3 patients had a residual mitral stenosis, and 3 had a left atrial perforation. The operation consisted of 26 mitral valve replacements, 20 concomitant reparations of iatrogenic atrial septal defect, and one open mitral valve commissurotomy. Operative mortality was 3.7% (1 out of 27). In group II, 25 patients have been operated at a mean 18 +/- 14 months after BMC. In the 25 patients the operation was indicated for significant mitral regurgitation (2 + and more). The operation consisted of 25 mitral valve replacements, 9 concomitant reparations of iatrogenic atrial septal defect, 3 patients had also coronary artery bypasses. The operative mortality was 8% (2 out of 25). The echocardiographic score was similar for both groups, it was 8.4 +/- 2.0 in group I and 8.0 +/- 1.5 in group II (P = NS). Despite these complications following failed BMC, surgery appears a safe procedure with an acceptable mortality.

Aged↗
PubMed1999

The Canadian Study of Cardiac Transplantation. Atherosclerosis. Investigators of the CASCADE Study.

OBJECTIVES: To describe risk factors associated with the development of transplantation coronary artery disease (TCAD). DESIGN: A retrospective study of the Canadian experience. PATIENTS: Seven hundred and nineteen patients with follow-up of at least 12 months following transplantation and a minimum of one coronary angiogram were analyzed. RESULTS: Two hundred and fourteen patients (30%) developed angiographic evidence of TCAD during an average follow-up of 50+/-25 months. Actuarial freedom rate from TCAD averaged 60%, and survival averaged 85% five years following transplantation. Abnormal coronary angiograms increased from 11% to 40% between the first and the fifth year following transplantation. The Cox multivariate final model showed that recipients of donor hearts of 50 years and older (RR 4.35, 95% CI 2.32 to 8.15), patients with two or more episodes of acute rejection (RR 1.56, 95% CI 1.11 to 2.21) and patients with a diagnosis of ischemic cardiomyopathy before transplantation (RR 1.38, 95% CI 1.03 to 1.84) were at higher risk of TCAD. The same risk factors also had a significant effect on survival, although patients who were administered a hepatic hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor during follow-up had a higher survival rate (95% versus 85%, P=0.01) five years following heart transplantation. CONCLUSIONS: Recipients of hearts from older donors, patients with an ischemic heart disease before transplantation and those with several episodes of acute rejection are at increased risk for TCAD. Patients who are administered an HMG-CoA reductase inhibitor during follow-up have a higher survival rate five years following transplantation.

Adult↗
PubMed1999

Effect of Celsior and University of Wisconsin solutions on myocardial metabolism and function after warm ischemia.

BACKGROUND: Optimal preservation of donor hearts remains a significant concern during transplantation. Organ shortage led to an increase in the use of damaged hearts. METHODS: To study the effect of preservation solutions on recovery of myocardial metabolism and function after warm ischemia, 10 dogs underwent 30 minutes of warm global ischemia under cardiopulmonary bypass. The animals were then administered 1 liter of Celsior (5 dogs), an extracellular crystalloid solution or 1 liter of University of Wisconsin solution (5 dogs), cooled at 4 degrees C, followed by 60 minutes of cold preservation and 30 minutes of warm blood reperfusion. Interstitial myocardial pH and pO2 changes were measured. The left ventricle dP/dt was measured before and after the ischemic episode, as where creatine kinase, troponine T and lactate serum levels. RESULTS: Tissue pH averaged 6.9+/-0.1, 6.2+/-0.1, 6.7+/-0.1 and 6.8+/-0.1 before and after warm ischemia, following the 60 minutes of cold preservation and the reperfusion period in animals treated with the Celsior solution, compared to 6.8+/-0.1, 6.4+/-0.1, 7+/-0.1 and 6.8+/-0.2 respectively in dogs treated with the University of Wisconsin solution (p<0.05). Oxygen tension in the myocardium averaged 36+/-8 mmHg before warm ischemia and 59+/-31 mmHg after in animals that received Celsior compared to 30+/-10 mmHg and 49+/-7 mmHg in dogs treated with University of Wisconsin (p>0.05). Global myocardial function decreased significantly following reperfusion compared to baseline in both groups of animals. The serum levels of creatine kinase, troponine T and lactate increased significantly during the experiment although there was no significant difference between the 2 groups. CONCLUSION: Both preservation solutions (Celsior and University of Wisconsin) resulted in suboptimal recovery of myocardial function and metabolism when administered after a period of warm ischemia. Strategies to improve recovery of damaged donor hearts remain to be appropriately defined.

Acid-Base Equilibrium↗
PubMed1998

Can L-arginine improve myocardial protection during cardioplegic arrest? Results of a phase I pilot study.

BACKGROUND: L-arginine appears to improve myocardial protection during cardioplegic arrest in animal models. METHODS: To study the clinical effect and safety of L-arginine in humans, a phase I pilot study was performed with 50 patients who underwent coronary artery bypass grafting. We randomly assigned half to a treatment group, which received 1 g of L-arginine administered during the first 30 minutes of cardioplegic arrest induced by either warm or cold blood cardioplegia, and half to a control group, which did not receive L-arginine supplementation. RESULTS: Age, sex, and preoperative clinical status were similar in both groups. Seventeen patients of each group were administered intermittent warm antegrade blood cardioplegia, whereas the solution needed to be cooled to obtain complete standstill of the remaining eight hearts in each group. An internal thoracic artery graft to the left anterior descending coronary artery was performed in all patients. There was no death and no myocardial infarction in the treatment group, but there were one death and two infarctions in the control group. The amount of serial release of troponin I during the first 72 hours after the operation was similar between the L-arginine group and the control group (p > 0.05). Peak serum troponin levels averaged 4.9 +/- 1.0 microg/L in the arginine group and 3.9 +/- 1.0 microg/L in the control group (p > 0.05). A multivariate analysis of variance showed no effect of L-arginine (p > 0.05) but a significant effect of the temperature of the cardioplegic solution on the release of troponin I (p < 0.05). Serum troponin I levels averaged 2.2 +/- 0.4 microg/L, 4.5 +/- 0.4 microg/L, and 6.9 +/- 0.4 microg/L in the patients with cold cardioplegia and 1.4 +/- 0.3 microg/L, 2.4 +/- 0.3 microg/L, and 3.3 +/- 0.3 microg/L in the patients with warm cardioplegia 1, 2, and 6 hours, respectively, postoperatively. CONCLUSIONS: The administration of 1 g of L-arginine during the first 30 minutes of blood cardioplegic arrest did not result in a decrease in the postoperative release of cardiac enzyme; however, cold cardioplegic arrest significantly increased the release of cardiac troponin I postoperatively. There was no significant side effect related to the addition of L-arginine to the cardioplegic solution.

Arginine↗
PubMed1998

15-year experience with the Carpentier-Edwards pericardial bioprosthesis.

BACKGROUND: The aim of the study was to evaluate the late results of the Carpentier-Edwards pericardial bioprosthesis, which we have been implanting since 1981. METHODS: The 812 patients who underwent heart valve replacement with a Carpentier-Edwards pericardial bioprosthesis between 1981 and 1996 were reviewed. Their clinical, operative, and follow-up data were prospectively recorded in a computerized database. All but 29 patients were available for follow-up (96% completeness), which averaged 58 months and totaled 3,000 patient-years. RESULTS: There were 598 aortic valve replacements (74%), 149 mitral valve replacements (18%), and 65 double valve replacements (8%). The mean age at the time of surgery was 65 years (range, 18 to 88 years), with 24% of the patients under the age of 60 years. Preoperatively, 558 patients (69%) were in New York Heart Association functional class III or IV. Associated surgical procedures included coronary artery bypass grafting in 219 patients (27%) and tricuspid or mitral valve repair in 40 (5%). Previous cardiac operations had been performed in 149 patients, including 134 valve-related procedures. There were 49 early deaths overall (6%): 29 after aortic valve replacement (4.8%), 11 after mitral valve replacement (7.4%), and 9 with double valve replacement (13.8%). There were 120 late deaths for a 10-year actuarial survival rates of 69%+/-3%, 58%+/-7%, and 38%+/-10% for aortic, mitral, and double valve replacement, respectively. The 14-year survival rate for aortic valve replacement patients is 68%+/-3%. The 10-year and 14-year actuarial freedom rates from events after aortic valve replacement are 92% +/-2% and 88%+/-4% for thromboembolism, 96%+/-1% and 92%+/-4 for endocarditis, 91%+/-2 and 72%+/-6% for reoperation, and 93%+/-2% and 80%+/-5% for structural dysfunction of the valve. The 10-year actuarial freedom rates from events after mitral and double valve replacement are 93%+/-3% and 89%+/-4% for thromboembolism, 95%+/-3% and 88%+/-5% for endocarditis, 76%+/-7% and 70%+/-14% for reoperation, and 81%+/-7% and 72%+/-15% for structural dysfunction. No primary tissue failure of the prosthesis in any position was observed in the 357 patients aged 70 years or more at the time of valve implantation. CONCLUSIONS: The Carpentier-Edwards pericardial valve offers excellent clinical results and durability, particularly in the aortic position and for patients older than 70 years of age.

Actuarial Analysis↗
PubMed1998

In elective coronary artery bypass grafting, preoperative troponin T level predicts the risk of myocardial infarction.

OBJECTIVE: Several combinations of risk factors for death or cardiac events after coronary artery bypass grafting have been described. We studied the prognostic value of the preoperative serum levels of cardiac troponin T. METHODS: We studied 468 patients who underwent elective coronary artery bypass grafting. Preoperative and postoperative levels of cardiac troponin T and creatine kinase MB, electrocardiograms, clinical data, and events were recorded prospectively. No acute ischemic changes were present on the electrocardiogram before the operations, and preoperative creatine kinase MB serum levels were within normal limits in all patients. RESULTS: Ninety-seven (97/468, 21%) patients had serum levels of troponin T greater than 0.02 microg/L within 24 hours before coronary artery bypass grafting. Hospital mortality was similar in this group and in the patients with preoperative levels less than 0.02 microg/L (1% in each group). Nine patients (9/97, 9%) with elevated levels of troponin T before the operation had a perioperative myocardial infarction compared with 12 patients (12/371, 3%) among the group with lower troponin T levels (p = 0.015, RR = 2.9). Congestive heart failure occurred in 10 (10/97, 10%) and 8 (8/371,2%) patients, respectively (p = 0.0009, RR = 4.8). Intensive care unit (p = 0.002) and postoperative hospital length of stay (p = 0.09) were all longer in patients with the elevated preoperative troponin T level. In a logistic regression analysis, troponin T level before the operation was the variable most strongly correlated with postoperative myocardial infarction (p = 0.003). CONCLUSION: Preoperative troponin T stratification before coronary artery bypass grafting identifies a subgroup of patients with increased risk of postoperative cardiac complications.

Biomarkers↗
PubMed1998

Transmural heterogeneity of action potentials and Ito1 in myocytes isolated from the human right ventricle.

Limited information is available about transmural heterogeneity in cardiac electrophysiology in man. The present study was designed to evaluate heterogeneity of cardiac action potential (AP), transient outward K+ current (Ito1) and inwardly rectifying K+ current (IK1) in human right ventricle. AP and membrane currents were recorded using whole cell current- and voltage-clamp techniques in myocytes isolated from subepicardial, midmyocardial, and subendocardial layers of the right ventricle of explanted failing human hearts. AP morphology differed among the regional cell types. AP duration (APD) at 0.5-2 Hz was longer in midmyocardial cells (M cells) than in subepicardial and subendocardial cells. At room temperature, observed Ito1, on step to +60 mV, was significantly greater in subepicardial (6.9 +/- 0.8 pA/pF) and M cells (6.0 +/- 1.1 pA/pF) than in subendocardial cells (2.2 +/- 0.7 pA/pF, P < 0.01). Slower recovery of Ito1 was observed in subendocardial cells. The half-inactivation voltage of Ito1 was more negative in subendocardial cells than in M and subepicardial cells. At 36 degrees C, the density of Ito1 increased, the time-dependent inactivation and reactivation accelerated, and the frequency-dependent reduction attenuated in all regional cell types. No significant difference was observed in IK1 density among the regional cell types. The results indicate that M cells in humans, as in canines, show the greatest APD and that a gradient of Ito1 density is present in the transmural ventricular wall. Therefore, the human right ventricle shows significant transmural heterogeneity in AP morphology and Ito1 properties.

Action Potentials↗