RESUMO
Background: Data are limited on long-term outcomes in patients who have undergone a reoperation following failure of a stentless aortic valve. Methods: Between 2006 and 2016, a retrospective analysis was performed on 24 patients who underwent open aortic valve replacement surgery for a failed stentless aortic valve prosthesis at Health Sciences North, Sudbury, Ontario, Canada. The primary outcome was a low mortality rate from cardiac-related deaths after 5 years. Results: All patients underwent insertion of a Medtronic Freestyle bioprosthesis (Minneapolis, MN) implanted using the modified subcoronary technique for their initial operation. The interval from the first operation to the stentless redo surgery ranged from 6 to 13 years. Aortic valve reoperation was performed for structural valve deterioration in 96% (n = 23) of the cases. Reoperations involved a removal of the stented valve leaflets and standard aortic valve replacement within the stentless casing in 20% (n = 5) of the cases, with the remaining cases requiring complete removal of the stentless prosthesis and aortic valve replacement. In those in whom a complete removal of the stentless valve was possible (n = 19), no disruption of the native aortic root occurred, with a 0% rate of conversion to a Bentall procedure. No intraoperative mortality occurred. The 30-day and 10-year operative mortality rates were 4% and 16%, respectively. Conclusions: Redo surgery for failing stentless valves can be done with relatively low risk and with acceptable long-term outcomes without resorting to root-replacement techniques.
Contexte: Il existe peu de données sur les résultats à long terme chez les patients qui ont subi une réintervention chirurgicale après une défaillance d'une valve aortique sans armature (stentless) ayant été implantée. Méthodologie: Nous avons réalisé une analyse rétrospective, de 2006 à 2016, auprès de 24 patients ayant subi une intervention chirurgicale invasive de remplacement de valve aortique en raison de la défaillance d'une prothèse aortique sans armature à l'hôpital Health Sciences North situé à Sudbury (Ontario), au Canada. Le paramètre principal d'évaluation était un faible taux de mortalité d'origine cardiaque après 5 ans. Résultats: Tous les patients avaient initialement subi l'implantation d'une bioprothèse Medtronic Freestyle (Minneapolis, Minnesota) par la technique sous-coronaire modifiée. La période écoulée entre la première intervention chirurgicale et la réintervention au niveau de la valve sans armature allait de 6 à 13 ans. Dans 96 % des cas (n = 23), la réintervention était réalisée en raison d'une détérioration de structure de la valve aortique. La réintervention avait consisté en un retrait des cuspides avec armature et un remplacement de valve aortique standard dans la membrane sans armature dans 20 % des cas (n = 5) et un retrait complet de la prothèse sans armature avec remplacement de la valve aortique avait été nécessaire dans les autres cas. Chez les patients pour qui le retrait complet de la valve sans armature a été possible (n = 19), aucune déchirure de la racine aortique native n'est survenue et le taux de passage à une intervention de Bentall était de 0 %. Aucun décès peropératoire n'est survenu. Les taux de mortalité à 30 jours et à 10 ans s'élevaient à 4 % et à 16 %, respectivement. Conclusions: La réintervention chirurgicale après la défaillance d'une valve aortique sans armature peut être réalisée avec des risques re-lativement faibles et des résultats à long terme acceptables sans avoir recours à des techniques de remplacement de la racine aortique.
RESUMO
OBJECTIVE: It has been reported that unmatched adult bone marrow stromal cells could be tolerated by immune-competent allotransplant or xenotransplant recipients under various conditions. This study examined whether xenogeneic bone marrow stromal cells implanted immediately after myocardial infarction can survive and differentiate, attenuating deterioration in left ventricular function. METHODS: In groups I and II (n = 34), myocardial infarctions were created in immunocompetent adult Lewis rats by proximal left coronary artery ligation. In group I, 3 x 10(6)lacZ-labeled mouse bone marrow stromal cells were immediately injected into the peri-infarct area of the left ventricle, whereas in group II, only culture medium was injected. There were 10 early and 4 late deaths. At 4 weeks after injection, hearts were stained for beta-galactosidase and troponin IC. In groups IIIA and IIIB, lacZ-labeled mouse skin fibroblasts were implanted into rat myocardium (n = 10 each) with and without left coronary artery ligation, respectively, and the rats were killed serially. In group IV, animals underwent sham surgery (n = 5, no deaths). At 4 weeks, surviving rats in groups I, II, and IV (n = 10, n = 10, and n = 5, respectively) underwent blinded transthoracic echocardiography for ventricular function studies. RESULTS: In group I, labeled mouse-derived bone marrow stromal cells were found within rat myocardium that stained positively for troponin IC 4 weeks after implantation. Functionally, mean left ventricular ejection fraction (P = .007), stroke volume (P = .03), and fractional shortening (P = .02) were all significantly higher in group I than in group II. In groups IIIA and IIIB, mouse fibroblasts induced cellular infiltration with rapid loss of donor cells. No labeled cells were found after 4 days. In group IV, there was no change in cardiac function. CONCLUSION: Xenogeneic bone marrow stromal cells implanted into acutely ischemic myocardium induced by coronary artery ligation were immunologically tolerated, survived and differentiated, resulting in a cardiac chimera which improved left ventricular function. This unique immunologic tolerance may suggest the feasibility of using bone marrow stromal cells as universal donor cells.
