C. Latremouille

Aortic cusp extension valvuloplasty for rheumatic aortic valve disease: midterm results

BACKGROUNDnThe surgical management of rheumatic aortic insufficiency in the young remains problematic owing to the drawbacks of prosthetic valve replacement at this age. In young foreign patients, for whom long-term anticoagulation therapy is unavailable, we have used a glutaraldehyde preserved autologous pericardium cusp extension technique to repair rheumatic aortic valve insufficiencies resulting from cusp retractions.nnnMETHODSnFrom September 1992 to December 2000, 89 consecutive patients with a mean age of 16 +/- 5 years underwent triple pericardial aortic cusp extension valvuloplasty. Eighty patients had pure aortic insufficiency, 9 had mixed aortic disease. Twenty-nine patients (33%) had isolated aortic valve disease and 60 patients (69%) had combined aortic and mitral valve disease with significant tricuspid valve disease in 21 (24%). Aortic repair consisted of free edge aortic cusp extension using three rectangular strips of glutaraldehyde stabilized autologous pericardium. Twenty-nine patients (33%) underwent an isolated aortic repair, 39 patients (44%) underwent combined aortic and mitral procedures (34 mitral repairs, 3 mitral homografts, and 2 prosthesis replacements), and 21 patients (23%) underwent a triple valve repair.nnnRESULTSnThe hospital mortality was 2.2%. Primary failure of the aortic repair requiring immediate reoperation occurred in 2 patients. During follow-up (mean of 62 +/- 22 months) 1 patient died and 7 underwent redo valvular surgery. At 5 years the actuarial survival rate was 96.4%, and 92.1% of the patients were free from redo valvular surgery. At 7 years 90% of the patients were free from valve-related complications. Among the 76 patients free from redo valvular surgery at follow-up, 6 had deterioration of the repair resulting in grade II aortic and mitral insufficiencies.nnnCONCLUSIONSnOur midterm results of glutaraldehyde stabilized autologous pericardial aortic cusp extension are encouraging and suggest that this technique should be considered as a viable alternative palliative procedure in a young rheumatic population, allowing for growth of the annulus and delaying to a less critical period the need for the lifelong anticoagulation therapy required for a prosthetic mechanical valve.

Does glutaraldehyde induce calcification of bioprosthetic tissues

BACKGROUNDnGlutaraldehyde has been said to be responsible in part for the calcification of glutaraldehyde-treated tissues after implantation in animals or humans. We investigated whether the origin of the tissue, autologous or heterologous, could have a more prominent role in the process of calcification.nnnMETHODSnThree-month-old sheep received sheep pericardial samples (n = 133) and human pericardial samples (n = 123) implanted subcutaneously. Samples were treated with 0.6% glutaraldehyde for 5, 10, or 20 minutes or 7 days and then rinsed thoroughly before implantation. Samples were then retrieved after 3 months. Calcium content was assessed by spectrophometry.nnnRESULTSnThe results show a low calcium content in the autologous group (mean 1.14+/-2.07) and a high calcium content in the heterologous group (mean 38.97+/-26). These results were the same regardless of the duration of the treatment.nnnCONCLUSIONSnGlutaraldehyde treatment (0.6%) does not play a significant role in the calcification of glutaraldehyde-treated tissue regardless of the origin, autologous or heterologous, of the tissue. Glutaraldehyde-treated autologous tissues are associated with an incidence of calcification lower than heterologous tissues.

Association of electrostimulation with cell transplantation in ischemic heart disease

BACKGROUNDnUntil now, cell therapy has constituted a passive therapeutic approach; the only effects seem to be related to the reduction of the myocardial fibrosis and the limitation of the adverse ventricular remodeling. Cardiac resynchronization therapy is indicated in patients with heart failure to correct conduction disorders associated with chronic systolic and diastolic dysfunction. The association of electrostimulation with cellular cardiomyoplasty could be a way to transform passive cell therapy into dynamic cellular support. Electrostimulation of ventricles following skeletal myoblast implantation should induce the contraction of the transplanted cells and a higher expression of slow myosin, which is better adapted for chronic ventricular assistance. The purpose of this study is to evaluate myogenic cell transplantation in an ischemic heart model associated with cardiac resynchronization therapy.nnnMETHODSnTwenty two sheep were included. All animals underwent myocardial infarction by ligation of 2 coronary artery branches (distal left anterior descending artery and D2). After 4 weeks, autologous cultured myoblasts were injected in the infarcted areas with or without pacemaker implantation. Atrial synchronized biventricular pacing was performed using epicardial electrodes. Echocardiography was performed at 4 weeks (baseline) and 12 weeks after infarction.nnnRESULTSnEchocardiography showed a significant improvement in ejection fraction and limitation of left ventricular dilatation in cell therapy with cardiac resynchronization therapy as compared with the other groups. Viable cells were identified in the infarcted areas. Differentiation of myoblasts into myotubes and enhanced expression of slow myosin heavy chain was observed in the electrostimulated group. Transplantation of cells with cardiac resynchronization therapy caused an increase in diastolic wall thickening in the infarcted zone relative to cells-only group and cardiac resynchronization therapy-only group.nnnCONCLUSIONSnBiventricular pacing seems to induce synchronous contraction of transplanted myoblasts and the host myocardium, thus improving ventricular function. Electrostimulation was related with enhanced expression of slow myosin and the organization of myoblasts in myotubes, which are better adapted at performing cardiac work. Patients with heart failure presenting myocardial infarct scars and indication for cardiac resynchronization therapy might benefit from simultaneous cardiac pacing and cell therapy.

Triple valve repair for young rheumatic patients.

BACKGROUNDnFacing young foreign polyvalvular rheumatic patients, for which long-term anticoagulation is not available, we have chosen to attempt triple valve repair procedures in order to avoid prosthetic implantation in this particular population suffering from triple valve disease.nnnMETHODSnTwenty-one young rheumatic patients (mean age:11+/-4 years) underwent triple valve repair procedures including cusp extension on the aortic valve aortic between September, 1992 and December, 2000. Valvular pathology characteristics according to Carpentiers classification included mitral insufficiency type III post+II ant (n=10), type III post (n=4), type II ant (n=2), mitral stenosis (n=5), type III aortic insufficiency (n=21), type I (n=13) and type III (n=8) tricuspid insufficiency.nnnRESULTSnFirstly, the mitral valve disease were corrected using Carpentiers techniques of repair: prosthetic ring annuloplasty (n=16), commissurotomy (n=12), chord transposition (n=11) or shortening (n=4), papillary muscle sliding plasty (n=4) and pericardial patch leaflet enlargement (n=6). Secondly, aortic lesions were corrected using glutaraldehyde stabilized autologous pericardium triple cusps extension technique (n=21). Lastly, tricuspid repairs were always performed on beating hearts using commissurotomy (n=8), prosthetic ring (n=12) or other techniques (n=9) of annuloplasty. The operative mortality was 4.7% (one patient died). Echocardiograms before discharge showed grade I mitral insufficiency in seven patients and grade I aortic insufficiency in five patients. There was no late death during a mean follow-up of 51+/-31 months. Two patients underwent valvular redo surgery because of aortic and mitral plasty deterioration due to rheumatic disease progress. After 5 years, 90% of the patients were free from redo valvular surgery.nnnCONCLUSIONSnIn rheumatic patients, autologous pericardial patch extension of the aortic valve permitted widespread use of reconstructive surgery even in patients suffering from triple valve disease. Triple valve repair, in this particular challenging setting of patients, has provided satisfactory initial and mid-term results and could be considered as an interesting palliative surgical approach.

Treatment of atrial fibrillation by surgical epicardial ablation: bipolar radiofrequency versus cryoablation.

UNLABELLEDnAtrial fibrillation is the most frequent form of cardiac arrhythmia. Its surgical management has improved in recent years with major advances in our knowledge of the underlying pathogenic mechanisms. This has led to simpler therapeutic strategies such as epicardial ablation. The aim of this comparative experimental study was to evaluate the efficacy of this treatment, achieved with either bipolar radiofrequency or cryoablation.nnnMATERIALS AND METHODSnTwelve sheep were used. After left thoracotomy, epicardial ablation of the junction between the left pulmonary veins and the left atrium was achieved by means of bipolar radiofrequency in group A (n=6) and by cryoablation in group B (n=6). Electrical stimulation thresholds were determined before and after ablation. Four weeks after ablation, sheep were killed for pathologic studies.nnnRESULTSnThe mean stimulation threshold was 3.5+/-0.6 mA before ablation and 15.6+/-5.6 mA after ablation. The difference was significant in both groups, showing that effective conduction blockade was obtained with the two ablation methods. Histologic studies after radiofrequency and cryoablation showed limited coagulation necrosis and cellular rarefaction, respecting the supportive tissue.nnnCONCLUSIONSnBoth methods of surgical ablation by the epicardial route yielded effective electrical isolation of the pulmonary vein junction with the left atrium. This conduction blockade was due to limited coagulation necrosis with myocyte rarefaction, of similar extents in the two procedures. Standardization and refinement of this technique could extend the treatment indications for atrial fibrillation associated with other cardiac disorders that require surgical treatment without opening the left atrium.

Arterial Pulsatility and Circulating von Willebrand Factor in Patients on Mechanical Circulatory Support

BACKGROUNDnThe main risk factor for bleeding in patients with continuous-flow mechanical circulatory support (CF-MCS) is the acquired von Willebrand factor (VWF) defect related to the high shear-stress forces developed by these devices. Although a higher bleeding rate has been reported in CF-MCS recipients who had reduced pulsatility, the relation between pulsatility and the VWF defect has never been studied.nnnOBJECTIVESnThe purpose of this study was to investigate the relation between pulsatility and VWF under CF-MCS.nnnMETHODSnWe assessed the effect of 2 CF-MCS on VWF multimer degradation in a mock circulatory loop (model 1). Using these devices, we investigated in a dose-effect model (model 2) 3 levels of pulsatility in 3 groups of swine. In a cross-over model (model 3), we studied the effects of sequential changes of pulsatility on VWF. We reported the evolution of VWF multimerization in a patient undergoing serial CF-MCS and/or pulsatile-MCS.nnnRESULTSnWe demonstrated the proteolytic degradation of VWF multimers by high shear CF-MCS in a circulatory loop without pulsatility. We observed both in swine models and in a patient that the magnitude of the VWF degradation is modulated by the pulsatility level in the high shear-stress level condition, and that the restoration of pulsatility is a trigger for the endothelial release of VWF.nnnCONCLUSIONSnWe demonstrated that the VWF defect reflects the balance between degradation induced by the shear stress and the endothelial release of new VWF triggered by the pulsatility. This modulation of VWF levels could explain the relationship between pulsatility and bleeding observed in CF-MCS recipients. Preservation of pulsatility may be a new target to improve clinical outcomes of patients.

Intérêt du contrôle des connaissances après dissection

But de l’etude dans certaines facultes de medecine, les dissections sont programmees dans le cursus au debut des etudes medicales. Pour donner toute leur valeur a ces seances, il nous est apparu necessaire qu’elles soient sanctionnees par un examen. C’est cette experience que nous voulons rapporter. Materiel et methodes pendant trois ans (deux ans, Necker, 120 etudiants et un an, Rene Descartes, 350 etudiants), les etudiants ont eu 12 seances de deux heures de dissection. Tout le corps humain a ete disseque. Les seances debutaient par un expose ou un film sur la region a dissequer. Dans la salle, des coupes anatomiques et des radiographies etaient a la disposition des etudiants. L’examen etait theorique (120 questions en amphi) et pratique (48 questions sur sujet) : la moitie des questions portaient sur une structure a reconnaitre et l’autre moitie complementaire de la premiere question. Les resultats ont porte sur l’annee 2005-2006. Resultats l’enseignement a ete accepte et suivi avec assiduite avec un encadrement (un enseignant pour 20 etudiants). Au moment de l’examen, 14 sur 350 etudiants etaient absents. Pour les epreuves pratiques (48 questions) les notes s’echelonnaient entre 20 et 35 (extremes 10-47). Pour les epreuves (120 questions) les notes s’echelonnaient entre 81 et 105. Conclusion la verification des connaissances a stimule l’interet des etudiants pour la dissection. Concluant l’enseignement de l’anatomie, elles ont ete une revision de toute l’anatomie vue au cours des deux dernieres annees et une valorisation de celle-ci.

Évolution 3D de la valvule mitrale au cours de la période embryonnaire

Objectif Etudier les variations morphologiques et morphometriques de la valvule mitrale au cours de la periode embryonnaire. Materiel et Methodes L’etude a ete realisee a partir des coupes histologiques de 12 embryons dont la taille s’echelonnait entre 12 et 56 mm couvrant les stades XV a XXIII du developpement embryonnaire. Resultats Une reconstruction tridimensionnelle des valvules cardiaques a ete realisee sur 5 embryons de 12, 25 31 44 et 69 mm en crânio-caudal. Conclusion L’etude morphologique et morphometrique de la cardiogenese au cours de la croissance embryonnaire a un interet pour l’enseignement de l’anatomie et pour la comprehension des cardiopathies congenitales.