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T Carrel

Publications and source records attributed to T Carrel.

At least 19 recordsLinked to original sources
PubMed2005

PPS-PEG surface coating to reduce thrombogenicity of small diameter ePTFE vascular grafts.

AIMS: Patency failure of small vascular synthetic grafts is still a major problem for coronary and peripheral revascularization. Thus, three new surface coatings of small synthetic grafts were tested in an acute pig model to evaluate their thrombogenicity (extracorporeal arterio-venous shunt) and in a chronic rat model to evaluate the tissue reaction they induced (subcutaneous implantation). METHODS: In five domestic pigs (25-30 kg) an extracorporeal femoro-femoral arterio-venous shunt model was used. The study protocol included first a non-heparinized perfusion sequence followed by graft perfusion after 10,000 UI iv heparin. Grafts were perfused for 3 and 9 minutes. The following coatings were tested on ePTFE grafts: poly-propylene sulphide (PPS)--poly-ethylene glycol (PEG) (wet and dry applications) as well as carbon. Two sets of control were used, one dry and one wet (vehicle only). After perfusion grafts were examined by scanning electron microscopy for semi-quantitative assessment (score 0-3) of cellular and microthrombi deposition. To assess tissue compatibility, pieces of each material were implanted subcutaneously in 16 Wistar rats. At 2, 4, 8, 12 weeks four animals each were sacrificed for semi-quantitative (score 0-3) histologic evaluation of tissue reaction. RESULTS: In the pig model, cellular deposition and microthrombi formation increased over time. In non- heparinized animals, the coatings did not improve the surface characteristics, since they did not prevent microthrombi formation and cellular deposition. In heparinized animals, thrombogenicity was lowest in coated grafts,especially in PPS -PEG dry (p<0.05), and highest in controls. Cell deposition was lowest in PPS-PEG dry, but this difference was not statistically significant vs.controls. In the rat model,no significant differences of the tissue reaction could be shown between materials. CONCLUSION: While all coatings failed to add any benefit for lowering tissue reaction, surface coating with PPS -PEG (dry application) reduced thrombogenicity significantly (in heparinized animals) and thus appears to be promising for improving graft patency of small synthetic vascular prostheses.

Animals↗
PubMed2004

Impaired poststenotic aortic pulsatility after hemodynamically ideal coarctation repair in children.

Using echocardiographic quantification of aortic pulsatility distal to the site of the surgical anastomosis, we evaluated whether the preoperatively impaired poststenotic aortic pulsatility returned to normal after repair of coarctation with a hemodynamically ideal result. Patients who underwent repair of aortic coarctation without residual obstruction were compared to a matched group of normal children. A standardized M-mode echocardiographic evaluation of the aorta at the diaphragmatic level was performed for all patients. Measurements consisted of maximum and minimum aortic diameters, time intervals, and a calculated pulsatility index. Compared to normal children (n = 19), 20 children with operated coarctation and with a hemodynamically ideal result showed a significantly smaller increase in aortic diameter in systole (mean of 29 +/- 7% in patients versus 37 +/- 7% in normals; p < 0.01). In contrast to patients with coarctation in whom the maximum aortic distension is reached much later during the cardiac cycle, hemodynamically normalized, operated patients in our study had no such delay (maximum aortic pulsation at 28% of cardiac cycle time compared to 27% in normals; p = not significant). The pulsatility index of the poststenotic aorta was clearly lower in operated children (mean, 130 +/- 50%/sec) compared to a normal mean value of 202 +/- 33%/sec but was still significantly higher than that in patients with unoperated coarctation, who showed a low mean value of 51 +/- 24%/sec (p < 0.01). After correction of aortic coarctation with a hemodynamically ideal result, the pulsatility of the poststenotic aorta, severely impaired prior to repair, did not return to normal during the observation period in the patients studied.

Aorta, Thoracic↗
PubMed2004

Intermediate outcome and risk factor assessment of bovine vascular heterografts used as AV-fistulas for hemodialysis access.

OBJECTIVES: This observational study was set up to prospectively follow all bovine heterograft (ProCol) fistulas implanted for hemodialysis access between 1998 and 2002. METHODS: ProCol was implanted if autogenous vein was not available or if patients presented with a history of failed, infected or otherwise complicated ePTFE grafts and/or on immunosuppressive therapy. Fistula patency was the primary outcome; secondary outcomes were clinical events and the rate of access revisions. RESULTS: Sixty-two ProCol grafts were implanted in 56 patients. The mean primary (PP) and secondary patency (SP) was 334 (SEM 57) and 528 (SEM 59) days, respectively. Coronary heart disease was associated with a significantly better SP (OR 0.2, 95% CI 0.1-0.9) whilst diabetes mellitus was associated with a significantly worse SP (OR 0.2, 95% CI 0.1-0.9). Reinterventions were performed at a mean rate of 1.23 (SEM 0.17) per fistula. The relative risk of access revision was significantly higher in patients with diabetes mellitus (OR 9.2, 95% CI 2.3-37.2). CONCLUSIONS: ProCol grafts, used for AV-fistulas, demonstrate acceptable patency rates in high-risk haemodialysis patients. Diabetes mellitus jeopardizes the patency of these fistulas and is associated with a high revision rate.

Animals↗
PubMed2004

Solid organ transplantation across the ABO histo-blood group barrier: a case report.

The ABO blood group system until recently constituted an insuperable barrier for solid organ transplantation, but cases of heart transplantation in infants and kidney transplantation in adults have been reported, wherein ABO-incompatible grafts have been successful. In 1990, the molecular genetic basis of three major alleles at the ABO locus was elucidated; A and B glycosyltransferases are specified by a variety of functional alleles at this locus. The antibody response to ABH antigens, namely, naturally occurring anti-A/B IgM and IgG isotype agglutinins, are controlled preoperatively by recipient conditioning using plasma exchange, immunoadsorption, and immunosuppressive regimens. We report an O-type patient who accidentally received a B-type cardiac allograft in 1997 who survived for 5 years, dying for an unrelated reason. Over a period of 45 months semiquantitatively we monitored the expression of ABO-type antigens in graft heart vessels using monoclonal antibodies on sections of formalin-fixed, paraffin-embedded biopsies. We observed a progressive change in the antigenic profile of graft endothelial cells from B- to O-type, which was first detected at 1 year posttransplant and most prominent 3 years later, the end of the observation period. No temporal relationship was observed between the transition from B to O expression, the anti-B antibody levels or the immunosuppressive regimen.

ABO Blood-Group System↗
PubMed2003

Endovascular stent-grafting for diseases of the descending thoracic aorta.

PRINCIPLES: Endoluminal stent-grafts are emerging as a less invasive alternative to conventional open surgery in the management of descending thoracic aortic dissections and aneurysms. We describe our experience with endovascular stent-grafting in the treatment of thoracic aorta pathology. METHODS: 17 Patients were treated with 23 endovascular stents. The underlying pathology was an atherosclerotic aneurysm verum (n = 5), a type B dissection with contained rupture (n = 3), an intramural haematoma with contained rupture (n = 1) and a false aneurysm of unknown origin (n = 1). One patient had Marfan's syndrome and six patients had a traumatic rupture of the descending aorta. RESULTS: Overall 23 stent-grafts were implanted. In one patient, conversion to an open graft replacement of the descending aorta was necessary. One patient died. In four patients (23.5%) a left carotid-subclavia bypass or transposition was performed to achieve a sufficient neck for the proximal stent-graft landing zone. The postoperative control-CT scans revealed a total of six endoleaks (EL) (four type I, one type II and one type IV). Two patients needed a graft extension in a second operation (4 days and 18 month after the first operation), two EL (one type I and one type II) disappeared after 9 and 18 months, respectively and two EL are still under observation. One patient developed a paresis after conversion to open graft replacement. CONCLUSIONS: A variety of diseases of the descending aorta can be treated by endoluminal stent-grafting, which seems to be a valid alternative to open repair in well selected cases. Mortality and morbidity in our small series were low. Continuous follow-up is mandatory.

Adult↗
PubMed2002

The relationship between surgeon and basic scientist.

Basic science research has always been the cornerstone of a solid academic career, even for surgeons. In the past, many cardiothoracic and cardiovascular surgeons have used the large animal laboratory to design surgical operations, refine extracorporeal circulation, improve myocardial protection or simply validate clinical concepts. Today, funding for large animal research has almost disappeared. The basic science areas of 'cellular, molecular, genomics or gene therapy' must be involved to be considered for national or even local funding. This endeavor requires a new generation of surgical scientists and perhaps even more importantly, a new environment for the performance of such research. Academic surgery does not exist without active and long-standing commitment to research. Clinical research focusing on patient outcome remains an important task of the academic surgeon but this paper will focus on the relationship between surgeons and basic scientists and shall concentrate primarily on translational research and its challenge now and in the future. The collaboration between basic scientist and clinician is more essential than ever, because the society still optimally rewards science that has potential clinical applicability [1]. Even within surgical departments, active support and very close contact with PhDs can be essential for the clinical faculty members to be productive, using cellular and molecular techniques. In cardiovascular medicine and biology, there is a great potential to prevent or treat diseases with these techniques. The potential to modify ischemia-reperfusion, inflammation, angiogenesis, restenosis, organ tolerance or cardiomyocyte transplantation to remodel ventricles will be accomplished by a better understanding of cardiovascular biology. Surgeons must plan for a speciality that may look quite different in the next future.

Animals↗
PubMed2002

New concepts in organ preservation.

Organ preservation between donor and recipient is an important link in a chain that ultimately should lead to long term survival of the recipient thanks to a well-preserved, functionally intact organ. The period of organ ischaemia outside the body is subject to a number of biochemical stress factors which become known in more detail as knowledge on biochemical and immunological mechanisms improves. Efficacy of preservation fluids hence reduction of ischaemia injury may become enhanced by such additives as ion channel blockers, enzyme inhibitors, haeme oxygenase modulators, endothelin-l-inhibitors, quenchers of free radicals and anti-apoptotic agents. Many of these compounds, albeit of great theoretical interest, have not (yet?) made their way into clinical practice. This contribution is a survey of some promising agents, concentration and physicochemical interactions of which are analysed in some detail.

Acetylcysteine↗
PubMed2002

Infective endocarditis: determinants of long term outcome.

OBJECTIVE: To evaluate predictors of long term prognosis in infective endocarditis. DESIGN: Retrospective cohort study. SETTING: Tertiary care centre. PATIENTS: 212 consecutive patients with infective endocarditis between 1980 and 1995 MAIN OUTCOME MEASURES: Overall and cardiac mortality; event-free survival; and the following events: recurrence, need for late valve surgery, bleeding and embolic complications, cerebral dysfunction, congestive heart failure. RESULTS: During a mean follow up period of 89 months (range 1-244 months), 56% of patients died. In 180 hospital survivors, overall and cardiac mortality amounted to 45% and 24%, respectively. By multivariate analysis, early surgical treatment, infection by streptococci, age < 55 years, absence of congestive heart failure, and > 6 symptoms or signs of endocarditis during active infection were predictive of improved overall long term survival. Independent determinants of event-free survival were infection by streptococci and age < 55 years. Event-free survival was 17% at the end of follow up both in medically-surgically treated patients and in medically treated patients. CONCLUSIONS: Long term survival following infective endocarditis is 50% after 10 years and is predicted by early surgical treatment, age < 55 years, lack of congestive heart failure, and the initial presence of more symptoms of endocarditis.

Adolescent↗
PubMed2001

Successful management of a B-type cardiac allograft into an O-type man with 3(1/2)-year clinical follow-up.

BACKGROUND: In May 1997, a 19-year-old male patient of histo-blood group type O suffering from congenital end-stage heart failure accidentally received a cardiac allograft of type B and is still alive in fair condition. METHODS: In addition to conventional immunosuppressive therapy, plasma exchange (PEX), extracorporeal immunoabsorption (EIA), intravenous immunoglobulins (IVIG), and C1 inhibitor were used. RESULTS: Such treatment successfully reduced both IgM and IgG anti-B levels and complement hyperactivity and allowed to reach the state of accommodation without obvious signs of rejection. The patient has been surviving for 42 months; retransplantation with an O-type heart remained unnecessary. CONCLUSION: Humoral rejection has been avoided in this patient, with PEX, EIA, IVIG, and C1 inhibitor substantially contributing to this success. With future availability of such combined therapies, preferably before transplantation, vascular rejection events caused by preformed antibodies and complement (ABO mismatch or anti-HLA) could be prevented or treated.

ABO Blood-Group System↗
PubMed2001

[Minimally invasive therapy in varicose veins].

In patients with varicose vein a duplex ultrasound is absolutely necessary prior to surgery in order to check the deep and the superficial vein systems. A standard classification is recommended to describe the type of venous insufficiency. Teleangiectasis and small varicose veins can be treated by sclerotherapy, but laser-therapy gets more and more popular. The inverting (partial)stripping of the greater and/or lesser saphenous vein avoiding nerve damage has gained popularity as did the miniphlebectomy. Newer methods using heat by radiofrequency order cryosurgery should generate less complications and have to show similar long term results than the classical procedures. Subfascial endoscopic perforator vein surgery (SEPS) is effective. Local or extended fascioctomy followed by skin transplantation in patients with recurrent ulcerations is considered as an option of therapy.

Endoscopy↗
PubMed2001

Prevention of neointimal proliferation by immunosuppression in synthetic vascular grafts.

OBJECTIVE: Immunosuppressive agents have been proposed to reduce neointimal hyperplasia in synthetic vascular grafts. Thus, the purpose of the present study was to evaluate the safety and efficacy of rapamycins (systemic vs. local vs. oral administration) and mycophenolate mofetil (MMF) to reduce intimal hyperplasia in infrarenal synthetic vascular grafts of the rat. METHODS: Fifty-four Wistar rats (250 g) completed the study after a synthetic vascular graft (ePTFE, Gore-tex, 2 mm diameter, 10 mm length) was implanted end-to-end in the infrarenal aorta. The animals were divided into three groups: group 1 consisted of 12 control animals, group 2 consisted of 37 rats receiving rapamycins, either per os (RAD, 1.5 or 3 mg/kg), intraperitoneally (RPM, 1.5 or 3 mg/kg) or locally (RPM soaking of the graft); and in group 3 (n=5), MMF (40 mg/kg) was administered orally. The animals were followed weekly with weight controls and signs of toxicity for 30 (n=37) and 60 (n=17) days, respectively. All animals were sacrificed and underwent histological examination at completion of the study. RESULTS: All animals survived in groups 1 and 3, but five died in group 2. The weight gain was normal in all groups, except for the subgroup 2a receiving high dose rapamycins orally. All rats in group 3 suffered from diarrhea, whereas animals receiving high dose rapamycins showed toxic signs (hair loss, wound healing problems). Histological examination showed a significant increase in intimal hyperplasia in group 1 (0.03+/-0.01 and 0.14+/-0.05 microm after 30 and 60 days, respectively; P<0.01). Rapamycins in either application or dosage had no significant effect on intimal hyperplasia. CONCLUSIONS: Local or systemic administration of rapamycins has no effect on intimal hyperplasia in synthetic vascular grafts. In contrast, toxic signs with weight loss were observed in animals treated with high dose rapamycins, but not in those treated with MMF. Thus, in the rat model, immunosuppression with rapamycins or MMF cannot be recommended for the prevention of intimal hyperplasia in the synthetic vascular graft model.

Anastomosis, Surgical↗
PubMed2001

Budd--Chiari syndrome and heparin-induced thrombocytopenia.

We report on a patient suffering from Budd--Chiari disease who developed heparin-induced thrombocytopenia preoperatively. Dorsocranial liver resection and hepatoatrial anastomosis were performed with the extracorporeal circulation and perioperative anticoagulation was achieved with r-hirudin. Surprisingly, thrombus formation was observed in the venous reservoir although ACT was 590 s and aPTT 55 s. An additional bolus of hirudin and rinsing the reservoir allowed unproblematic discontinuation of the cardiopulmonary bypass.

Adult↗
PubMed2001

Embolization of a ruptured intercostal artery aneurysm in type I neurofibromatosis.

We present the case of a female with history of a ruptured lumbar aneurysm years ago. She was known to have neurofibromatosis type I with the typical clinical signs. The patient was transferred to us with a hematothorax and an aortic lesion was suspected on the outside CT scan. Reevaluation of the investigation raised suspicion of a ruptured intercostal artery aneurysm, which was consequently demonstrated on angiography. The aneurysm was embolized and the patient recovered uneventful. We will discuss the optimal therapy for vessel lesions in neurofibromatosis type I.

Adult↗
PubMed2001

Dilation of the ascending aorta in childhood: 4 cases without obvious predisposing disease.

Dilation of the ascending aorta is rare in childhood. When seen, it is usually associated with some form of connective tissue disease or predisposing cardiac malformations, especially an aortic valve with two leaflets. We describe four children in whom significant dilation of the ascending aorta was encountered as an incidental finding. No patient had any sign of an associated connective tissue disease, nor did we detect any predisposing cardiac anomalies. One patient had undergone surgical ligation of the arterial duct in infancy, whilst another had undergone repair of aortic coarctation, also in infancy. A third child has had repair of an atrioventricular septal defect with exclusively atrial shunting, whereas the fourth patient had a structurally normal heart. The aortic valve had three leaflets, and was functionally normal in all. The dilation of the ascending aorta was progressive in all patients, and finally surgical treatment was recommended, relying on the guidelines established for the management of patients affected with the Marfan syndrome.

Aorta↗