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Biomedical subjects

G Champsaur

Publications and source records attributed to G Champsaur.

At least 19 recordsLinked to original sources
PubMed1998

Long-term clinical and hemodynamic evaluation of porcine valved conduits implanted from the right ventricle to the pulmonary artery.

OBJECTIVE: This retrospective study was initiated to evaluate the long-term results of valved prosthetic conduits implanted in the right ventricular outflow tract in patients with complex ventricular-pulmonary discontinuity. METHODS: A cohort of 103 patients out of 127 (24 early deaths, 19%) operated on between 1973 and 1996 with porcine valved conduits was available for evaluation, with a follow-up ranging from 1 to 21.6 years (mean follow-up 8.4 +/- 6 years). A total of 74 hemodynamic studies were performed after the operation, 50 patients having undergone at least 1 cardiac catheterization during the follow-up period. RESULTS: There were 16 late deaths, and the actuarial survivals, including early mortality, were 72.9% +/- 4% at 5 years, 63.1% +/- 5% at 10 years, and 58.2% +/- 5% at 15 years, at which time 20 patients were still available for review and exposed to the risk of dying. The mean peak systolic gradient across the right ventricular outflow tract was plotted as a function of time, showing a gradual increase and a significant step-up after the eighth year, from 43 +/- 36 to 69 +/- 19 mm Hg (P < .005). Reoperation was required for progressive conduit obstruction between 1.1 and 17.7 years after implantation (mean 7.4 +/- 4.8 years) in 25 patients (24%, 70% CL 15%-33%), with generally very few symptoms, or for residual ventricular septal defect in 3 patients. Freedom from reoperation was 79.5% +/- 5% at 10 years and 65.8% +/- 7% at 15 years. CONCLUSIONS: Porcine conduits may represent a valuable alternative to biologic substitutes with similar long-term results. Given the few symptoms, progressive conduit stenosis after the eighth postoperative year imposes a yearly noninvasive patient evaluation during the follow-up.

Actuarial Analysis↗
PubMed1998

Effects of various flow types on maternal hemodynamics during fetal bypass: is there nitric oxide release during pulsatile perfusion?

OBJECTIVE: This study investigates the role of various flow conditions on maternal hemodynamics during fetal cardiopulmonary bypass. METHODS: Normothermic fetal bypass was conducted under pulsatile, or steady flow, for a 60-minute period. Fetal lamb preparations were randomly assigned to 1 of the 3 groups: steady flow (n=7), pulsatile flow (n=7), or pulsatile blocked flow bypass (n=7), where fetuses were perfused with Nomega-nitro-L-arginine after the first 30 minutes of pulsatile flow to assess the potential role of endothelial autacoids. RESULTS: Maternal oximetry and pressures remained unchanged throughout the procedure. Under fetal pulsatile flow, maternal cardiac output increased after 20 minutes of bypass and remained significantly higher than under steady flow at minute 30 (8.8+/-0.7 L x min(-1) vs 5.9+/-0.5 L x min(-1), P=.02). Maternal cardiac output in the pulsatile group also remained higher than in both steady and pulsatile blocked flow groups, reaching respectively 8.7+/-0.9 L x min(-1) vs 5.8+/-0.4 L x min(-1) (P=.02) and 5.9+/-0.3 L min(-1) (P=.01) at minute 60. Maternal systemic vascular resistances were significantly lower under pulsatile than under steady flow after 30 minutes and until the end of bypass (respectively, 9.1+/-0.6 IU vs 12.7+/-1.1 IU, P=.02 and 8.9+/-0.5 IU vs 12.9+/-1.2 IU, P=.01). Infusion of Nomega-nitro-L-arginine was followed by an increase in systemic vascular resistances from 9.3+/-0.7 IU, similar to that of the pulsatile group, to 13.5+/-1 IU at 60 minutes, similar to that of the steady flow group. CONCLUSIONS: Maternal hemodynamic changes observed under fetal pulsatile flow are counteracted after infusion of Nomega-nitro-L-arginine, suggesting nitric oxide release from the fetoplacental unit under pulsatile fetal flow conditions.

Animals↗
PubMed1998

Experimental right ventricle to pulmonary artery discontinuity: outcome of polyurethane valved conduits.

OBJECTIVE: The ideal substitute for the treatment of ventricle-pulmonary artery discontinuity remains a topic of controversy, because of calcifications and degeneration of biologic substitutes leading to subsequent reoperations. Because polyurethane valves used in ventricular assist devices show a satisfactory biocompatibility, the aim of this study was to evaluate a valved conduit composed of a Dacron graft incorporating a trileaflet 25 mm polyurethane valve. METHODS: The conduit was implanted between the right ventricle and the main pulmonary artery in adult sheep, with ligation of the proximal pulmonary artery. The animals received no medications. Serial hemodynamic data were collected at the time of implantation and at postoperative intervals of 6 and 12 months. RESULTS: The peak pressure gradient across the valve increased significantly between implantation (0.17 +/- 5.6 mm Hg) and 6 months after operation (7.3 +/- 3 mm Hg, p = 0.0007) and remained stable thereafter (6.7 +/- 3 mm Hg at 12 months), whereas the cardiac output remained unchanged (4.6 +/- 0.6 L/min at implantation, 4 +/- 0.6 L/min at 6 months, and 3.9 +/- 1.1 L/min at 12 months). At the completion of the study, valve samples were processed and vapor coated with carbon for microscopic examination. There was one instance of nonadherent thrombus formation inside a cusp but no structural failures. The other valves were free of calcium deposits and no significant amounts of phosphorus could be detected by scanning electron microscopy and energy dispersive spectrometry. CONCLUSIONS: These data demonstrate the good hemodynamic performance, low thrombogenicity, and acceptable durability of the polyurethane valves implanted in the right side of the heart in a chronic sheep model.

Animals↗
PubMed1998

Mechanical versus biological isolated aortic valvular replacement after the age of 70: equivalent long-term results.

OBJECTIVE: In order to evaluate the long-term outcome of valvular substitutes in the elderly, we retrospectively analyzed two comparative groups of patients consecutively operated on by the same team for an isolated valvular aortic replacement using either a mechanical or a pericardial prosthesis. METHODS: From 1982 to 1996, 206 patients over 70 years (mean 76.5+/-4.4) underwent an isolated aortic valvular replacement using either a St. Jude Medical (Group I, n = 93) or a Mitroflow (Group II, n= 113) prosthesis depending on the surgeon's preference at the time of surgery. Both groups matched for the following pre-operative variables: sex ratio, type of aortic valve disease, NYHA status, cardiac rhythm, mean pulmonary arterial pressure, left ventricular end-diastolic pressure, LV-AO gradient, cardiac index and ejection fraction. RESULTS: Given an early mortality rate of 6.4% in Group I and 4.4% in Group II (NS), follow-up (mean 4.4+/-3.7 years in Group I and 5.3+/-3.1 years in Group II) was 100% complete. Actuarial survival was 69.9+/-6 and 70.2+/-4.6% at 5 years for Group I and Group II, respectively, and 49.6+/-7.7 vs. 51.4+/-6.3% at 10 years (NS). Freedom from valve-related death was 86.5+/-4.8% in Group I vs. 82.7+/-4% in Group II at 5 years (NS) and 66.7+/-8.7 vs. 66.3+/-7% at 10 years (NS). There were no anticoagulant-related deaths or severe accidents in Group 1. A secondary valvular replacement was necessary in 4 patients in Group II vs. none in Group I. CONCLUSION: The study shows a similar late survival in both groups, with a strikingly low incidence of anticoagulant-related deaths in this population. Given a higher rate of reoperation after biological valve replacement, the use of mechanical valve in this aging population seems to be a valid option.

Aged↗
PubMed1998

The hemodynamic effects of hypoxemia in anesthetized pigs: a comparison between right heart catheter and echocardiography.

UNLABELLED: During hypoxemia, hypoxic pulmonary vasoconstriction and tachycardia are often observed in association with increases in pulmonary artery pressure and cardiac output. Nevertheless, the hemodynamic consequences of hypoxemia have never been evaluated by echocardiography and simultaneously compared with invasive hemodynamic variables. Fourteen open-chest, anesthetized piglets (weight 29-36 kg) were submitted to progressive hypoxemia and reoxygenation. Usual invasive hemodynamic variables were obtained from peripheral and central heart catheters. Direct epicardial echocardiography was used to measure right and left ventricular areas on a short-axis view at mid-papillary level. The mean pulmonary artery pressure (MPAP) increased with pulmonary vascular resistance in a dose-related manner as the fraction of inspired oxygen (FIO2) declined from 0.5 to 0.12. The MPAP correlated with right ventricular end-diastolic area (RVEDA) only at FIO2 0.08. There was a 49% reduction in left ventricular end systolic wall stress (LVESWS) between FIO2 0.5 and 0.08. Left ventricular ejection fraction area (LVEFA) increased by 33% above baseline and correlated with the decrease in LVESWS. No correlation was observed between left ventricular end-diastolic area and pulmonary artery occlusion pressure or left atrial pressure and between cardiac output and LVEFA. Systemic vascular resistance underestimates the magnitude of changes in LVESWS but overestimates the afterload compared with LVESWS. This study demonstrates that, for the lowest FIO2 (0.08), changes in MPAP correlated with changes in RVEDA but not in pulmonary vascular resistance. Moreover, LVESWS decreases significantly in a dose-related manner under progressive hypoxemia and normalizes immediately after reoxygenation. This study also shows that, under hypoxemic conditions, echocardiography enhances understanding of hemodynamic changes compared with right heart catheterization alone. IMPLICATIONS: Acute hypoxemia in pigs is responsible for pulmonary vasoconstriction-induced pulmonary hypertension (which is restricted by the right ventricular failure), as well as a PaO2-dependent decrease in left ventricular afterload. These changes are better displayed by echocardiography than by right heart catheter.

Anesthesia↗
PubMed1997

Effects of hypothermia on cochlear micromechanical properties in humans.

The aim of the present experiment was to investigate the influence of hypothermia on transient evoked otoacoustic emissions (TEOAEs) in humans. Hypothermic alterations were brought about directly by cooling the cardiovascular system of young children during open heart bypass surgery. This condition caused TEOAE levels to decrease with a significant positive correlation between total and frequency band TEOAE amplitudes during cooling. TEOAEs were totally abolished at tympanic temperatures around 30 degrees C, without it being possible to find differences in TEOAE alteration among the frequency components. During rewarming, the changes reversed and TEOAEs returned to their initial prehypothermia status, although sometimes only partially. Despite large possible metabolic changes caused by this hypothermic condition at various levels, it is concluded that the motile properties of outer hair cells (OHCs), that are related to TEOAEs, are temperature-sensitive. The total suppression found in deep hypothermia (above 30 degrees C) could conceivably be attributable to a process involving a temperature-dependent energy source.

Auditory Threshold↗
PubMed1997

Flow-induced release of endothelium-derived relaxing factor during pulsatile bypass: experimental study in the fetal lamb.

OBJECTIVE: This study was initiated to test the hypothesis that fetal hemodynamic changes observed under pulsatile flow bypass might be related to the release of endothelium-derived relaxing factor through oscillating shear stress. METHODS: Normothermic bypass was instituted in utero in 21 preterm fetal lambs for a 1-hour period through the right atrium and main pulmonary artery. Ultrasonic flowmeters were positioned around the descending aorta and the umbilical artery. The circuit consisted of an oxygenator and a pump set to either continuous flow (n = 7) or pulsatile flow (n = 7) and adjusted to maintain a fetal main arterial pressure of 50 mm Hg. In seven other animals, endothelium-derived relaxing factor was blocked by a continuous infusion of N omega-nitro-L-arginine after 30 minutes of pulsatile flow. RESULTS: During the first 30 minutes of bypass, pump flows were significantly lower in the continuous-flow group than in the pulsatile-flow or blocked-flow groups (respectively, 612 +/- 144, 907 +/- 153 and 987 +/- 228 ml/min), with similar changes in aortic and umbilical flows. Systemic vascular resistances were significantly lower in the pulsatile-flow and blocked-flow groups than in the continuous-flow group (550 +/- 106 vs 821 +/- 212 dynes/sec/cm-5). However, after blockade of endothelium-derived relaxing factor, resistances increased gradually in the blocked-flow group to reach the level of that of the continuous-flow group at the end of bypass (943 +/- 77 vs 556 +/- 143 dynes/sec/cm-5 in the pulsatile-flow group). CONCLUSIONS: Blockade of endothelium-derived relaxing factor after 30 minutes of pulsatile flow returns fetal hemodynamics to continuous flow conditions. The specific inhibitor of endothelium-derived relaxing factor used in this experiment suggests that nitric oxide may be released by fetal endothelium during pulsatile bypass.

Animals↗
PubMed1997

Mechanical valve in aortic position is a valid option in children and adolescents.

OBJECTIVE: The choice of a valve substitute remains a challenge in young patients, with numerous reports of early degeneration and calcification of biological valves in this age group. Therefore an assessment of the long-term results after mechanical aortic valve replacement in children was initiated. METHODS: A retrospective study was conducted in 54 consecutive patients aged 1.1 to 17 years (mean 12.8 +/- 4 years) operated on between 1975 and 1993. Aetiology was congenital in 34 patients, rheumatic in 13, infectious in 5, and dystrophic in 2. Concomitant surgery included mitral valve replacement (10), aortic annulus enlargement (9), correction of truncus arteriosus (7), Bentall operation (2), coarctation repair (2), tricuspid valvuloplasty (2), correction of double outlet right ventricle (1), and replacement of a right ventricle to pulmonary artery conduit (1). A Bjork-Shiley valve was implanted in 14 patients, and a St Jude Medical valve in 40. All patients were given Warfarin with a monthly INR control. Follow-up was completed through questionnaires mailed to referring physicians and direct clinical examination. RESULTS: Overall early mortality was 13% (7 cases), and 6% (2 cases) in the 32 patients operated on after 1984. Follow-up was complete in 45 survivors (2 lost to follow-up), with a total follow-up of 261 patient-years. There were 6 late deaths, 4 being cardiac and due to persistent LV dysfunction, and 2 valve-related, due respectively to major gastro-intestinal bleeding and massive thromboembolism. Linearized rates of valve thrombosis and anticoagulant-related hemorrhage were both 0.3% per patient-year. Actuarial survival rate was respectively 84.5% at 5 years and 70.2% at 10 years. Reoperation was necessary in 3 patients for recurrent LV outflow tract obstruction. One patient with severe LV dysfunction is awaiting a heart transplant. CONCLUSION: We conclude that the longterm outcome after mechanical aortic valve replacement in children and adolescents is satisfactory and comparable to currently available reports on biological substitutes. The mandatory anticoagulant therapy is well tolerated in this age group.

Adolescent↗
PubMed1997

Malignant neoplasms following cardiac transplantation.

OBJECTIVE: Malignancies have long been recognized as a complication of long lasting immunosuppressive therapy. We reviewed our experience to investigate the incidence and the spectrum of non cutaneous de novo malignant neoplasms. METHODS: Between March 1987 and March 1996, 296 patients underwent 303 cardiac transplantation in our service. The population at risk consists of all patients surviving more than 1 month after transplantation, leading to a total of 267 patients. A triple-immunosuppressive therapy was employed. Moderate doses of antilymphocyte globulin was used as an induction immunotherapy. RESULTS: Neoplasms developed in 18 (6.7%) of the 267 patients at risk. Seventeen patients were male. Mean age was 56 +/- 7 years. Fourteen patients (78%) reported a significant smoking history. Mean interval between transplantation and clinical diagnosis was 36 months. Lung neoplasms (especially adenocarcinoma) were the most commonly encountered tumors (11 of 268 patients, 4.1%). Three Non-Hodgkins' Lymphoma (NHL) were identified (1.1%). No Kaposi's sarcoma were diagnosed. Mean survival after a diagnostic of tumor was 11.7 months. CONCLUSIONS: The incidence of NHL is low in our transplant recipients. Conversely, we observed a high incidence of lung neoplasms (especially adenocarcinoma) which can be correlated with a heavy cigarette use in the study population.

Adenocarcinoma↗
PubMed1997

Glucose versus lactated Ringer's solution during pediatric cardiac surgery.

OBJECTIVE: Whether intraoperative fluid infusion should contain glucose during pediatric cardiac surgery remains controversial. This study was performed to compare the effects of glucose and glucose-free solutions on blood glucose and blood insulin levels during total repair of congenital heart diseases. DESIGN: Prospective randomized and blinded study. SETTING: Cardiovascular university center. PARTICIPANTS: Forty nondiabetic children, weight ranging from 4 to 10 kg, scheduled for cardiac surgical procedures requiring cardiopulmonary bypass (CPB) without total circulatory arrest. INTERVENTIONS: Group R (n = 20) was administered lactated Ringer's solution intraoperatively, and group G (n = 20) received 5% glucose. Fluids were infused at a rate of 3 mL/kg/h in the two groups from the induction of anesthesia to the end of the surgical procedure. Blood glucose and insulin were sampled before infusion (Tzero), before CPB (T1), 10 minutes after initiation of CPB (T2), 10 minutes after initiation of rewarming (T2), and at the end of the procedures (T4). Postoperatively, blood glucose was measured at the first, 12th, and 24th hours. MEASUREMENTS AND RESULTS: During the prabypass period, three children in group R had severe hypoglycemia (blood glucose < 40 mg/dL). After initiation of CPB, blood glucose increased in both groups, with a small difference at the end of the procedure. No infants in the two groups had blood glucose higher than 239 mg/dL. CONCLUSIONS: Glucose withdrawal during pediatric cardiac surgery induces threatening hypoglycemia during the prabypass period, and moderate intraoperative glucose administration (2.5 mg/kg/min) is not responsible for major hyperglycemia.

Anesthesia Recovery Period↗
PubMed1997

[Medium-term results of non-invasive follow-up after cardiac transplantation in childhood and in adolescence].

Between December 1984 and September 1996, 43 cardiac transplantations were carried out in 40 patients aged 2 days to 21 years (one third under 10 years of age) for cardiomyopathy (21 cases), congenital heart disease (19 cases) or retransplantation (3 cases). The average waiting time for transplantation was 80 days: this delay increased by a factor of five in 2 years (from 1 month, before 1994, to 5 months at present). Twelve patients dies, including 6 before the 8th day. The 28 survivors were prescribed triple immunosuppressive therapy: the average follow-up was 4.4 years (range 3 months to 11 years). Monitoring rejection was carried out by non-invasive methods based on clinical, electrocardiographic and Doppler echocardiographic observations. Any suspicion of acute rejection led to endomyocardial biopsy for confirmation and therapeutic guidance. There was a total of 47 episodes of acute rejection (0.3 per patient), mainly in the first 3 months: acute rejection was less common in the younger children. Graft function was normal in 71% of cases. Five children have a pacemaker implanted during the first month. Despite continuous steroid therapy, 82% of patients had normal staturo-ponderal growth. The myocardial mass of the graft increased in parallel with the body surface area. Nephrotoxicity of ciclosparine was responsible for significant renal failure in 19% of patient and seemed more common in the young children. Psychological disturbances were commonest in adolescence and could result in poor treatment compliance (4 cases, with 1 death and 2 retransplantations). Despite satisfactory medium-term results, nephrotoxicity of ciclosporine, long-term graft function and psychological difficulties of adolescents remain unresolved so that transplantation is reserved for terminal cardiac disease resistant to all other forms of treatment.

Adolescent↗
PubMed1997

[Left ventricular assistance by postoperative mechanical devices in neonates].

Circulatory assistance in children and neonates has not been extensively reported. It poses specific problems related mainly to miniaturisation of systems. The authors report three cases of left ventricular assistance with the Biomedicus centrifugal pump followed by functional recovery in neonates operated for d-transposition of the great arteries. The assistance was installed by cannulation of the left atrial appendage and the ascending aorta, the canules being connected to the Biomedicus pump. The duration of assistance was 53, 116 and 120 hours respectively. The beginning of left ventricular recovery was observed after 24, 48 and 70 hours of assistance and the patients were weaned of assistance under stable haemodynamic conditions. One of the major problems during the period of assistance is decoagulation, 2 out of 3 patients requiring removal of thrombi during the first 12 hours of assistance. On the other hand, no cases of systemic embolism or thrombosis in the pump itself were observed. Decoagulation was maintained by continuous intravenous heparin with an initial dosage of 5 U/kg/h adapted to the activated cephalin time and anti Xa levels measured every 6 hours. No infectious complication was observed and the sternal wound healed satisfactorily despite systematic delayed closure of the thorax. The quality of results requires cooperation of a surgical infrastructure used to techniques of circulatory assistance, a well equipped neonatal intensive care unit and a permanently accessible laboratory for monitoring coagulation status.

Cardiac Surgical Procedures↗
PubMed1997

[Coarctation of the aorta and its surgical treatment].

Coarctation or isthmic stenosis of the aorta is defined as an abnormal obstruction situated at the junction of the aortic arch and the descending aorta near the site of ligamentus arteriosus. It is a common malformation representing 5 to 7.5% of all congenital heart diseases. Coarctation of the aorta is 2 to 3 times commoner in boys than in girls. Two clinical forms may be distinguished: asymptomatic isolated coarctation of childhood, the surgical treatment of which was first performed by Crafoord in 1944, and coarctation of the neonate and infant associated in over 2/3 of cases with other cardiovascular malformations, especially tubular hypoplasia of the aortic arch. The surgical correction of isolated coarctation is best performed between 6 months and 1 year of age in other to limit the incidence of residual hypertension. A modified Crafoord technique decreases the risk of restenosis and enables treatment of associated hypoplasia of the aortic arch in the same surgical procedure.

Adult↗
PubMed1996

Long-term results of heart transplantation deteriorate more rapidly in patients over 60 years of age.

It is generally agreed that the upper age limit for heart transplantation is 60 years. However, an increasing number of elderly candidates are accepted for heart transplantation. We retrospectively analyzed our experience with a total of 204 consecutive transplantations, performed in 195 adult patients (9 retransplantations) between March 1987 and September 1993. There were 48 patients older than 60 years (mean 62.9 +/- 3), group I (gr I) and 156 patients between 20 and 59 years old (mean 47.5 +/- 8), group II (gr II). The two groups were matched for sex-ratio (female 10.4 vs 14.2%), indications (cardiomyopathy, ischemic, others), and hemodynamic parameters (pulmonary artery pressure, capillary wedge pressure, cardiac index). A ventricular assist device was used in 14 patients as bridge to transplantation in gr II vs 0 to gr I. There were seven early deaths in gr I (14.6%) vs 14 in gr II (8.97%, NS). A total of 183 survivors (41 vs 142) have been followed up for 1 month-6.3 years (mean follow-up 20.4 +/- 19.3 months in gr I, 35.4 +/- 23 in gr II). No patient was lost to follow-up. There were 11 late deaths in gr I vs 16 in gr II. The most common cause was malignancy (n = 4) in gr I and sudden death (n = 9) in gr II, with a significant difference. The actuarial survival was 68.8% in gr I vs 88.5% in gr II at 1 year 43.5% in gr I vs 76.4% in gr II at 5 years. In conclusion, transplanted patients over 60 years of age have a significantly poorer late survival than younger patients, despite similar good early results. Moreover, the causes of late deaths were different in the two groups. So, heart transplantation in patients over 60 years of age should be carefully considered.

Adult↗
PubMed1996

Primary melanoma of the heart: case report of an association with coronary stenosis.

A 63-year-old man presented with unstable angina. The coronary angiogram revealed a proximal left anterior descending artery (LAD) stenosis and an irregularity on the anterior wall of the left ventricle. Intraoperatively, a malignant melanoma, independent of the coronary stenosis, was identified and resected, and an internal mammary graft was inserted. No primary tumor was found. The patient is alive 18 months after operation, with a normal magnetic resonance imaging (MRI), which seems to be the technique of choice for following-up heart melanomas.

Coronary Disease↗