Modified stentless porcine valve enhances accelerated cuspal calcification in the juvenile sheep model

Abstract

Objective: Stent mounting of any bioprosthesis, induces a loss of mobility and reduces the effective valve orifice. By contrast, for stentless procedures, the higher surgical technicality remains a major obstacle for many surgeons. In an attempt to facilitate the insertion of the stentless porcine aortic valve (Toronto SPV), we tried to alter the design by lowering the invasive profile at the depth of the sinuses on both coronary sites. This could theoretically facilitate the implant of the modified stentless valve with an easygoing single layer suture at the challenging subcoronary level and make it more attractive for every surgeon.Methods: Modifications of the standard model were done by lowering the profile at the depth of the sinuses on both coronary sites, whether by plication or excision of the protruding porcine aortic wall at the nadir of each coronary sinus. Nine juvenile sheep underwent implantation of stentless porcine aortic valves in pulmonary position: 3 standard Toronto SPV, 3 plicated Toronto SPV and 3 excised Toronto SPV. In each series, valves were explanted after 3 months. Valves were analyzed.Results: The cusps of standard Toronto SPV were perfectly functioning and pliable, without visible calcification after three months. The calcium content of the cusps was less than those in the plicated and excised Toronto SPV (2.4±0.7 μg/mg versus 10.8±5.9 and 6.7±3.4 μg/mg). In the plicated and excised valves, calcification of the cusp was more pronounced in the commissural region (3.9±1.9, 29.0±16.7, 13.8±9.5 μg/mg in the standard, plicated and excised Toronto SPV, respectively). On the other hand, the aortic wall from the plicated Toronto SPV had more calcium than that from the other groups (53.6±6.3, 41.2±7.1, 45.2±7.4 μg/mg in the plicated, standard and excised Toronto SPV, respectively).Conclusions: The modification of stentless porcine valve enhanced accelerated cuspal calcification in the commissural region. It accentuated that the correct implantation technique for stentless procedures is extremely important in order to prevent early degeneration.