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Biomedical subjects

C Chartrand

Publications and source records attributed to C Chartrand.

At least 19 recordsLinked to original sources
PubMed1992

Decreased plasma atriopeptin response to volume-overloading maneuvers and exercise after atriopulmonary anastomosis of Fontan.

Atriopulmonary anastomosis results in a chronic right atrial pressure-volume overload. Water and salt retention is a frequent clinical observation in patients after atriopulmonary anastomosis. The purpose of this study was to examine if this could be related to an inability to increase already elevated circulating atriopeptin (ANP) in response to central volume-overloading conditions. Eighteen patients (mean age 16 +/- 6 years) with an atriopulmonary anastomosis underwent routine cardiac catheterization during which a 5-minute head-down 10 degrees tilt was performed. Peripheral venous and right atrial blood samples were obtained under basal conditions, and after tilting and angiography for determination of ANP concentrations. At a different time, circulating ANP levels were measured during a maximal graded exercise protocol. Increased circulating ANP concentrations were found under basal conditions (114 +/- 10 pg/ml). Tilting and cardioangiography resulted in significant increases in mean atrial pressure (basal: 12 +/- 0.7 mm Hg; tilt: 13.4 +/- 0.63 mm Hg; after angiography: 15.8 +/- 0.8 mm Hg), but not in atrial or peripheral ANP. Compared with the expected threefold increase in plasma ANP induced by maximal exercise in healthy control subjects, only a slight (0.25-fold) increase was found in patients. These observations suggest a reduced stimulus-release response after atriopulmonary anastomosis, which could be related to a loss of atrial stretch receptor sensitivity, achievement of the limit for maximal right atrial secretion, or an alteration in right atrial compliance, or a combination.

Adolescent↗
PubMed1992

Efficacy of isoproterenol on the failing transplanted heart during early acute rejection.

Acute rejection often leads to severe myocardial failure and death. The beneficial hemodynamic effects of isoproterenol in improving immediate postoperative heart failure have prompted its routine use after transplantation. However, because of the physiopathological alterations documented during rejection, an inappropriate response of the graft to isoproterenol administration could be expected. Six dogs received orthotopic transplants and were prepared with implantable devices for serial hemodynamic studies. The studies were performed on the resting unanesthetized subject 3 hours after operation when transient heart failure was present and repeated when myocardial failure secondary to rejection occurred. After basal state measurement, various doses of isoproterenol were infused and the hemodynamic responses during each period were compared. During rejection, the hemodynamic response to 0.05 and 0.10 micrograms.kg-1.min-1 was significantly lower when compared with the response in the postoperative period. To achieve similar postoperative chronotropic and inotropic effects, 0.35 microgram.kg-1.min-1 of isoproterenol was necessary. Isoproterenol is therefore effective in controlling myocardial failure during acute rejection despite a reduced sensitivity of the sinoatrial node and myocardial tissue.

Acute Disease↗
PubMed1992

Electrophysiologic effects of sotalol on the immature mammalian heart.

Sotalol is a beta-blocker with class III antiarrhythmic properties that has recently been used in children for the treatment of supraventricular and ventricular arrhythmias. However, little is known about its electrophysiologic effects on the immature heart. Using intracardiac electrocardiographic recordings and stimulation techniques, 15 canine neonates (8-15 days) and 15 adult mongrel dogs were studied with cumulative doses of sotalol (0.5, 1, 2, and 4 mg/kg plus an additional dose of 8 mg/kg for neonates). Heart rate decreased significantly in the two groups, but more in adult dogs (-43% in adult dogs versus -25% in neonates, p less than 0.05). There was no significant change for QRS duration and His-Purkinje system conduction time interval. QT and atrioventricular nodal conduction time intervals increased in adult dogs and neonates. Sinus node recovery time increased significantly in the two groups, but more in adult dogs. Refractory periods of the atrioventricular (AV) node increased significantly in neonates. Atrial flutter was no longer inducible in 12 of 15 neonates after the 2 mg/kg dose. Atrial effective refractory period increased significantly more in neonates (96%, p less than 0.001) than in adult dogs (58%, p less than 0.001). Ventricular effective refractory periods increased significantly both in neonates (46%) and adult dogs (50%), in a similar way. In conclusion, sotalol has greater electrophysiologic effects on the immature heart at the atrial level when compared to the adult, and similar effects on the refractory period of AV node and ventricle.

Animals↗
PubMed1992

Graft-related endocarditis caused by Neosartorya fischeri var. spinosa.

The first case of endocarditis caused by Neosartorya fischeri var. spinosa is reported. The patient was a child who received a calf pericardium graft after removal of a previously inserted Dacron graft associated with deterioration of adjacent tissue. Copious vegetations removed from the heart were found to be composed of septate hyaline fungal filaments. The fungus was recognized in culture by its bivalved, winged, spiny ascospores, its Aspergillus fischerianus anamorph, and its thermotolerance.

Animals↗
PubMed1992

Surgery for critical aortic stenosis in newborns is still good therapy after 25 years.

Because of the high operative mortality in newborn infants with critical aortic stenosis, new therapeutic modalities have emerged. The authors reviewed their results of surgery for this condition in newborn infants between January 1964 and December 1990. Thirty-seven infants were operated on for critical aortic stenosis, which was diagnosed at a mean patient age of 14.5 days. The surgical procedure was done at a mean patient age of 37 days. Five infants died intraoperatively of ventricular fibrillation at the time of incision. Transventricular valvotomy was attempted in 4 infants, and the remaining 28 infants underwent transaortic valvuloplasty. Overall survival improved markedly in the last 5 years of the study, from 31% to 75%. All patients who had transventricular valvotomy died, as did the only infant with previous percutaneous aortic valvuloplasty. Of the infants who died, 38% weighed less than 3000 g at the time of operation compared with 13% of the survivors (p < 0.05). The duration of cardiopulmonary bypass was also identified as a risk factor (p = 0.001). Of the surviving infants, 93% were followed up at a mean of 66 months. All but one were in New York Heart functional class I or II. The following risk factors were identified for operative mortality: year of surgery, preoperative hemodynamic condition, associated anomalies of the left ventricle, surgical weight less than 3000 g, transventricular valvotomy, year of surgery and prolonged cardiopulmonary bypass. Because of the much improved survival recently, surgery remains a good therapeutic choice for critical aortic stenosis in the newborn infant.

Aortic Valve Stenosis↗
PubMed1991

Pediatric cardiac transplantation despite atrial and venous return anomalies.

Congenital anomalies of the atrium, pulmonary venous return, and systemic venous return are often regarded as anatomical contraindications to orthotopic cardiac transplantation. Among our pediatric transplant patients, 10 children aged 3 to 15 years, weighing 9 to 45 kg, and all previously operated on for a total of 18 interventions had 32 anomalies needing correction at the time of transplantation. Besides the 18 instances of great vessel abnormalities, 14 anomalies of the atrium and of the venous return were encountered either alone or in combination: single atrium or previous septectomy (4), hypoplastic left atrium (2), previous Mustard procedure (1), cor triatriatum (1), anomalous pulmonary venous return (3), and anomalous systemic venous return (3). The preparation of the donor heart was modified in four ways: right atrial paraseptal incision, left atrial flap technique, full-length mobilization of the pulmonary arteries, and aortic arch incision. Correction of the atrial and venous return anomalies was carried out at the time of orthotopic transplantation with the following techniques: atrial septation, atrial enlargement, superior systemic venous return reroofing, inferior systemic venous return reroofing, double venous rerouting (pulmonary and systemic), and septal realignment. One child died of pulmonary hypertension in the early postoperative period. After a follow-up ranging from 1 month to 52 months, all survivors are asymptomatic. Based on echocardiography, heart catheterization, and angiography, there are no stenoses and no shunts, and the atrial dimensions are good. Based on the results achieved with these surgical techniques, we conclude that most atrial lesions, anomalous pulmonary venous returns, and anomalous systemic venous returns are correctable at the time of orthotopic transplantation and do not preclude a successful outcome in children.

Adolescent↗
PubMed1991

Peripheral vasodilator and cardiac properties of the 1,5-benzothiazepine calcium antagonist analog, TA-3090, in dogs.

Diltiazem, a 1,5-benzothiazepine, has demonstrated efficacy in the treatment of numerous cardiovascular diseases. TA-3090, a newly synthetized 1,5-benzothiazepine compound was studied in open-chest anesthetized dogs to characterize its hemodynamic properties, to compare it with diltiazem, and finally to correlate hemodynamic properties and plasma level concentrations. Anesthetized open-chest dogs were instrumented with electronic devices and fluid-filled catheters to monitor cardiac, coronary, and peripheral hemodynamic changes. A cumulative intravenous bolus administration of TA-3090 (n = 16) or diltiazem (n = 15) (15, 50, 200, and 400 micrograms/kg) was carried out, and blood samples were taken before and 5 min following each dose administration. Hemodynamic changes were followed for 30 min after each administration, at which time most hemodynamic parameters were back to baseline levels. The results indicate that both TA-3090 and diltiazem elicit slight peripheral and coronary vasodilator properties at low doses (15 and 50 micrograms/kg). With higher dosage, hemodynamic effects were maximal: coronary blood flow increased by 75%, arterial pressure decreased by 25%, and reflex positive inotropic effects were also observed. Heart rate was significantly reduced (10%). Comparison between TA-3090 and diltiazem indicates that both drugs elicit coronary vasodilator selectivity and TA-3090 has a prolonged duration of action compared with that of diltiazem. A straightforward relationship is demonstrated between vasodilator properties and plasma levels of either TA-3090 or diltiazem. Our data suggest that with plasma levels between 40 and 80 ng/mL, significant hemodynamic changes were observed with TA-3090. Changes of heart rate were not correlated with plasma levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Pediatric heart transplantation 1990].

In this presentation the author updates the progress made in pediatric cardiac transplantation through a review of the results obtained at Ste-Justine Hospital (SJH) and of the recent literature. Of 56 children referred to SJH for cardiac transplantation, 27 met the selection criteria; 10 died before receiving a new heart and 2 are still awaiting transplantation. Fifteen children, aged 3 to 16 years, have received a transplant. Ten of them had 32 birth defects, all of which were repaired at the time of transplantation thanks to improved graft removal methods and innovative surgical techniques. This study demonstrates that birth defects are not a contraindication to cardiac transplantation in children. Triple-drug immunosuppression was used, and the cyclosporine blood levels were maintained in the range of 100 to 200 ng/mL. Survival at 2 years was 78%. Episodes of acute rejection occurred at a rate of 0.5 per patient, 85% of them within the first 3 months after transplantation. Adequate renal function was preserved (creatinine clearance between 89 and 102 mL/min.m-2). The use of low-dose cyclosporine might explain in part the lack of significant nephrotoxicity. Reversible high blood pressure was observed in 5 of 13 patients during the first 6 months postoperatively. Multifactorial analysis identified, as a likely cause, a higher dose of steroids and cyclosporine during this period. Annual coronary angiography did not reveal any lesion, and apart from the acute rejection episodes, cardiac function was normal at rest, and the transplanted children have maintained an excellent level of activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Critical aortic stenosis in newborn infants. Twenty-five years' experience].

Operative mortality for critical aortic stenosis in newborn having been reported as high as 20-80%, the percutaneous aortic valvuloplasty is looked upon as an alternative therapy. We elected to review our surgical experience in the last 25 years before changing our therapeutic approach. Among 37 infants included in the study, 28 were boys and 9 girls. Mean age at diagnosis was 14.5 days (1 to 113 days) and decreased to 4.1 days in the last 5 years. Surgery was done at a mean of 37.2 days; 22 infants were operated on before one month of age and 9 in their first week of life. Five died from ventricular fibrillation at incision. Trans-ventricular valvulotomy was attempted in 4 and remaining 28 had trans aortic valvuloplasty. The overall survival of 40% had improved in last five years to 75%. All patients with trans-ventricular approach died and also did the only child with percutaneous angioplasty. Only 13% patients weighing less than 3 kg survived the operation. Follow-up was of 93.3% with a mean time of 66 months. All but one are in NYHA class 1 or 2. Our study identified the following risk factors: preoperative hemodynamic state, surgical weight, associated anomalies of the left ventricle, transventricular valvulotomy and the year of surgery. In view of improved survival, surgery remains a good therapeutic choice.

Aortic Valve Stenosis↗
PubMed1991

[Development of organ transplantation in Quebec from 1985 to January 1990].

In Québec, the first organ transplantations have been realized in 1958. Several kidney transplant programs started at that time. Cardiac, liver, pancreas and lungs programs followed and reached a full development in the eighties when Cyclosporin became available. Today, there are 4 university transplant programs in Québec (McGill, Montréal, Laval and Sherbrooke) with a total of 7 kidney, 4 liver, 4 heart, 2 pancreas and 2 lungs centers. More than 2,900 transplantations have been realized. Since 1970, organ procurement and distribution is organized by a central agency called Québec-Transplant (previously Métro-transplantation). Organ donation is done on a voluntary basis as every where in North America. More than 90% of the organs comes from cadaveric donors and more than 90% of the relatives accept organ donation. 50% of the donors have deceased from head trauma and 50% from cerebral hemorrhage. In 1989, multi-organ harvesting has been realized in 64% of the donors. Despite efforts and progresses, the number of patients awaiting an organ transplant is steadily growing and outlast the number of available organs. It is hoped that maximal utilisation of the donors and growing exchanges at a national and international level will help to solve this crucial problem.

Heart Transplantation↗
PubMed1990

Acute hypercalcemia and increased work load in canine transplanted heart. Coronary blood flow adjustments.

Coronary vasodilator adjustments following cardiac transplantation might be adversely affected during severe rejection. We studied the coronary blood flow response following intravenous bolus administration of calcium (0.04-0.05 mEq/kg) in canine cardiac transplants. Fifteen dogs were submitted to orthotopic heart transplantation and equipped with electronic implants for monitoring of hemodynamic parameters. Of these animals, 9 were not immunosuppressed, while 6 were treated with ciclosporin, azathioprine, and prednisone. The effects of calcium administration upon cardiac function were evaluated during the postoperative period, at recovery (2-3 days after transplantation) and during severe rejection (7-10 days after transplantation), and also in immunosuppressed animals. Rapid calcium administration elicits brief increases in arterial pressure, cardiac index, stroke work, and coronary blood flow. There were significant differences in these effects, depending on the hemodynamic status of these animals. Coronary blood flow was significantly increased in all experiments, except when severe rejection was evidenced. These results indicate that changes in myocardial metabolic demand (work load) are not adequately matched with coronary blood flow adjustments in the presence of severe rejection.

Acute Disease↗
PubMed1990

Postoperative evaluation after end-to-end subclavian-left coronary artery anastomosis in anomalous left coronary artery.

In most instances of anomalous left coronary artery originating from the pulmonary artery, surgical treatment is recommended. Because establishment of a direct systemic to coronary blood flow is expected to provide the best recovery of left ventricular function, various corrective procedures have been proposed. Subclavian-left coronary artery anastomosis appears to be a logical approach. Four patients operated on at Sainte-Justine Hospital, at an average age of 33 months (27 to 44), with an end-to-end subclavian-left coronary artery anastomosis were evaluated 6 to 46 months postoperatively. The anastomosis was patent in all cases. End-diastolic volume index (74.6 +/- 24.7 versus 122.7 +/- 15.3 ml/m2) and ejection fraction (0.58 +/- 0.07 versus 0.33 +/- 0.06) were improved significantly. Subclavian-left coronary artery anastomosis appears to meet the main criteria for an optimal physiologic correction of anomalous left coronary artery: restoration of a two-coronary artery system, improvement of left ventricular function, and likelihood of long-term patency.

Anastomosis, Surgical↗
PubMed1989

Comparison of cardiovascular adjustments to exercise in adolescents 8 to 15 years of age after correction of tetralogy of fallot, ventricular septal defect or atrial septal defect.

Surgical correction of tetralogy of Fallot (TF) has generally been associated with a reduced maximal exercise tolerance, possibly related to the ventriculotomy inherent to the intracardiac repair procedure. This study documents the exercise hemodynamics of a group of patients operated on for TF who showed similar clinical and functional characteristics, and compares these responses to those of age-matched patients operated on for an isolated ventricular septal defect (VSD) or atrial septal defect (ASD) in an attempt to better understand the role of the ventriculotomy in the exercise limitation. Thirty patients, ages 12 to 19 years, operated on before 5 years of age for complete repair of TF (n = 13), VSD (n = 7) or ASD (n = 10) and 10 age-matched control subjects underwent a progressive maximal cycling test to determine the maximal oxygen uptake (VO2 max), and completed submaximal cycling at intensities of 33 and 66% VO2 max, respectively, to determine the cardiac output (CO2-rebreathing). No significant differences in VO2 max were observed (TF = 37.6 +/- 10; VDS = 34.0 +/- 9.2; ASD = 36.5 +/- 7; controls = 41.3 +/- 6.0 ml/kg/min). The maximal heart rate, however, remained lower in all patient groups in comparison with control subjects (p less than or equal to 0.05) (TF = 178 +/- 14; VSD = 172 +/- 17; ASD = 179 +/- 16; controls = 191 +/- 12 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1989

Human thymic dendritic cell-thymocyte association: ultrastructural cell phenotype analysis.

In rodent thymus, associations between dendritic cells (DC) and thymocytes have been suggested to be implicated in differentiation and/or maturation processes. In this study, we report intimate associations formed between human thymic DC and thymocytes in culture and we analyze their ultrastructural cell phenotype. Observations by phase contrast microscopy showed that DC present long and thin dendrites and bind many thymocytes. Transmission (TEM) and scanning electron microscopy (SEM) revealed that both cellular populations were in close connection and tight membrane contact could be observed. The phenotype of DC and attached thymocytes was characterized with a series of monoclonal antibodies by protein A-gold TEM and SEM immunolabelings. Quantitative evaluation of immunolabeling (number of gold granules/microns of cellular membrane) suggests the presence of two subpopulations of CD1+ thymic DC (strong and weak), whereas this discrepancy is not observed in DR+ and CD4+ DC populations. On the other hand, the majority of thymocytes bound to DC strongly express the CD1, CD4, CD8 and CD2 antigens and weakly the CD3 antigen, indicating that they represent double-positive immature thymocytes. Uniform distribution of DC and thymocytes membrane antigens was confirmed with a backscattered SEM study. This morphological and immunolabeling TEM and SEM analysis demonstrates that human thymic DC may form associations with CD4+CD8+CD3weak thymocytes and raises questions about their physiological relationship.

Antigens, CD1↗
PubMed1989

Positive hemodynamic interaction between amrinone and diltiazem in anesthetized dogs.

The direct negative inotropic actions of calcium channel blockers limit the use of these otherwise effective systemic and coronary vasodilators in patients with heart failure. We studied the effects of amrinone pretreatment on the dose--hemodynamic response curve of diltiazem in order to test the hypothesis that amrinone might potentiate diltiazem's positive effects in anesthetized dogs. The control group (no pretreatment, n = 6) had a typical dose-related response to diltiazem (50, 100, and 150 micrograms/kg): coronary and systemic vasodilation, increased stroke volume, and no change in myocardial work and power. Amrinone pretreatment of the study group (n = 7) altered the hemodynamic response, thus maximal systemic vasodilation and stroke volume increase at a lower diltiazem dose, a 15 to 35% increase in myocardial work and power, and more profound coronary vasodilation. We propose that amrinone, by inhibiting phosphodiesterase, potentiates diltiazem vasodilation and reflexly secreted catecholamines' actions on the heart. This positive interaction may permit effective use of lower doses of diltiazem, thus circumventing its dose-limiting direct negative effects while still profitting from beneficial peripheral, reflex, and coronary actions.

Amrinone↗
PubMed1989

[Arrhythmia disorders after repair of ventricular septal defects. Comparison of atrial and ventricular approaches].

Post-operative disorders of conduction and of ventricular and supraventricular excitability were studied in 50 patients operated upon for ventricular septal defect (VSD). The VSD was approached by right ventriculotomy in 29 patients aged 4.4 +/- 3.1 years at surgery and 15.1 +/- 6.5 years at evaluation. The VSD was closed by the atrial route in 21 patients aged 6.6 +/- 3.9 years at surgery and 12.1 +/- 6.8 years at evaluation. Complete right bundle branch block (CRBB) was significantly more frequent in patients who underwent ventriculotomy (62 p. 100 vs 33 p. 100, p less than 0.05), but 2 late complete atrioventricular blocks were observed in patients in whom the atrial route was used. 34 p. 100 of the patients with ventriculotomy and 26.5 p. 100 of those without ventriculotomy had significant ventricular arrhythmias on Holter recordings (greater than or equal to Lown's grade 2, p = NS). The occurrence of ventricular arrhythmias in the patient population as a whole increased significantly with age at surgery and age at evaluation (p less than 0.05); this increase was also noted in each group (p = 0.06). Pre-operative right ventricular systolic pressure, severity of intraventricular disorders of conduction or duration of extracorporeal circulation and aortic clamping had no influence on the occurrence of ventricular arrhythmias. Disorders of supraventricular excitability were found in 1 patient who had ventriculotomy and in 2 patients whose VSD was corrected by the atrial route. No sinus dysfunction was observed. It is concluded that the ventricular approach of VSD significantly increases the occurrence of post-operative CRBB.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗