Transcatheter pulmonary valve replacement in sheep: medium-term evaluation of a novel polymeric prosthetic heart valve

Abstract

Objective To evaluate medium-term valvular functionality after transcatheter pulmonary valve replacement in sheep using a novel polymeric prosthetic pulmonary valve(PPHV). Methods In this study, we designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflet was made of 0.1mm expanded polytetrafluoroethylene(ePTFE). We chose bovine pericardium valve as control. Pulmonary valve stents were implanted in situ by right ventricular apical approach in 12 healthy sheep(10 for polymeric valve and 2 for bovine pericardium valve) weighing an average of(22.1±2.3)kg. Echocardiography, angiography, 64-row computed tomography(CT), and autopsy were used to assess valvular function 12 weeks after implantation. Results Two PPHVs failed to be implanted in situ of pulmonary valve position. Implantation was successful in the other 10 sheep.One sheep died of pneumonia, and the other 9 sheep survived at the end of follow-up. Echocardiography 12 weeks after implantation showed all the PPHVs exhibited good functionality and no significant insufficiency. The peak-peak transvalvular pressure gradient of the PPHVs was(28.2±8.0)mmHg(16-38 mmHg) (1 mmHg=0.133 kPa), while that of two bovine pericardium valves were 16 and 21 mmHg. Angiography and CT 12 weeks after implantation demonstrated orthotopic position and normal operation of the valves, and no deformation of the valved stents. Pathological examination of the explanted PPHVs 12 weeks after implantation showed no degradation or damage of the ePTFE leaflets and most of the leaflets were thin and pliable, without significant thrombus or calcification, while visible pannus overgrowth was found at the bottom of the valve leaflets, in the commissural areas and on the sealing cuff. Conclusion The medium-term effects of the novel ePTFE pulmonary valve after transcatheter pulmonary valve implantation in sheep is good. The novel PPHV exhibits good anti-adhesion, anti-degradation, anti-thrombus, anti-calcification performance and good biomechanical property. The hemodynamic parameter of PPHV is comparable to bovine pericardium valve. Optimizing the valve design might eliminate the problem about pannus overgrowth. Key words: Polymer material; Prosthetic heart valve; Transcatheter pulmonary valve replacement; Polytetrafluoroethylene; Animal experiment; Medium-term follow-up