新型高分子材料介入肺动脉瓣膜的动物实验研究——中期随访结果

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

目的 评价自主研制的新型高分子材料介入肺动脉瓣膜动物体内原位置换后的中期实验效果.方法 选用超微孔膨体聚四氟乙烯（ePTFE）材料制作成三叶球囊扩张型介入瓣膜,选用牛心包介入瓣膜作对照.雄性羊12只,体质量（22.1±2.3）kg,10只置入高分子材料瓣膜（PPHV）,2只置入对照瓣.右侧开胸经导管经右心室心尖途径原位置换肺动脉瓣.术后随访12周,通过超声心动图、胸部CT、心血管造影、尸检等对介入瓣膜进行中期评价.结果 两枚PPHV未成功原位移植,其余10只羊手术获得成功.术后1只置入PPHV的羊因肺部感染死亡,其余9只存活到随访终点.超声心动图提示,术后12周时PPHV均无明显反流,瓣膜峰值跨瓣压差16～38 mmHg（1 mmHg=0.133 kPa）,平均（28.2±8.0）mmHg;牛心包瓣峰值跨瓣压差分别为16 mmHg和21 mmHg.术后12周胸部CT、心血管造影提示所有人工心脏瓣膜均正常工作,支架无移位或变形.尸检结果提示：术后12周时ePTFE瓣叶无降解或损伤,大部分保持光滑,无血栓、钙化,但密封套囊、瓣叶流出面根部、瓣窦底部、3个瓣叶交界处有血管翳增生.结论 超微孔ePTFE介入肺动脉瓣膜动物体内原位置换后中期效果良好,PPHV有良好的抗组织粘附性能,有良好的抗降解、抗血栓、抗钙化和生物力学性能,血流动力学参数与牛心包对照瓣相当.局部血管翳增生可能通过优化瓣膜设计来改善.

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 anaverageof（22.1±2.3）kg. Echocardiography,angiography,64-rowcomputedtomography（CT）,andautopsywereusedto assess valvular function 12 weeks after implantation. Results Two PPHVs failed to be implanted in situ of pulmonary valve po-sition. 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 sig-nificant 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 over-growth was found at the bottom of the valve leaflets, in the commissural areas and on the sealing cuff. Conclusion The medi-um-term effects of the novel ePTFE pulmonary valve after transcatheter pulmonary valve implantation in sheep is good. The no-vel 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.