超微孔膨体聚四氟乙烯(ePTFE)自膨式介入肺动脉瓣膜动物实验研究

Transcatheter pulmonary valve implantation in sheep:4-week evaluation of a novel self-expanding ultramicroporous expanded polytetrafluoroethylene (ePTFE) valved stent

目的评价自主研制的超微孔膨体聚四氟乙烯(expanded polytetrafluoroethylene,ePTFE)自膨式介入肺动脉瓣膜动物体内原位置换后的早期实验效果。方法选用厚度0.1mm经磷酰胆碱表面接枝的超微孔ePTFE材料制作成三叶自膨式介入心脏瓣膜。雄性绵羊7只,体质量(27.2±1.2)kg,全麻右侧开胸,右室近心尖处缝荷包,将人工瓣膜经导管从右室心尖送入肺动脉瓣行原位置换。术后即时通过心血管造影、右心导管检查,术后4周通过经胸心脏超声、右心导管检查对介入瓣膜功能进行早期评价。结果 7只羊手术均获得成功,术后即时心血管造影提示人工瓣膜位置满意,开闭良好。1只羊因肺部感染合并感染性心内膜炎于术后16d死亡,其余6只羊随访4周状况良好。术后4周经胸心脏超声提示人工瓣膜工作正常,无明显血栓或赘生物,4只羊无明显反流,2只羊微量反流。右心导管检查提示术后即时人工瓣膜峰值跨瓣压差为(6.0±2.2)mmHg(1mmHg=0.133kPa),术后4周为(9.5±2.7)mmHg,且术后4周与术前[(3.5±1.0)mmHg]相比差异有统计学意义(P<0.05)。结论超微孔ePTFE自膨式介入肺动脉瓣经右室心尖入路置入成功率高,人工瓣膜早期功能良好。

Objective To evaluate the early valve function following in situ transcatheter pulmonary valve implantation in sheep using a novel self-expanding ultramicroporous expanded polytetrafluoroethylene （ePTFE） pulmonary valve. Methods We designed a novel polymeric trileaflet transcatheter pulmonary valve with a self-expanding nitinol stent; the valve leaflet was made of 0.1-mm phosphorylcholine coated ultramicroporous ePTFE. Pulmonary valve stents were implanted in situ via the right ventricular apical approach in 7 healthy sheep, with an average weight of （27.2±1.2） kg. Right anterolateral thoracotomy was performed in the sheep under general anesthesia. Then the right ventricular apex was exposed, two purse-string sutures were made and the transcatheter valved stents were implanted in situ by puncturing the right ventricular apex. Angiography and hemodynamic measurements were obtained immediately after implantation to assess the valve function. Color Doppler echocardiography and hemodynamic measurements were used to assess the valve function 4 weeks after implantation. Results Implantation was successful in all the 7 sheep. Angiography immediately after implantation showed that all the prosthetic valves were in the orthotopic position and exhibited normal open and close function, without stenosis or insufficiency. One sheep died 16 days after implantation due to pulmonary infection with infective endocarditis. All the other sheep were in a good condition during a 4-week follow-up. Echocardiography 4 weeks later showed that all the prosthetic valves were at the orthotopic position and had normal function, with no significant thrombus or neoplasm. Echocardiography demonstrated no regurgitation in 4 sheep and trace regurgitation in 2 sheep. Hemodynamic findings showed that the peak-to-peak transvalvular pressure gradient of the polymeric valves was （6.0±2.2） mmHg （1 mmHg=0.133 kPa） immediately after operation and （9.5±2.7） mmHg at 4 weeks after operation, with the latter being significantly higher than that before implantation （[3.5±1.0] mmHg, P〈0.05）. Conclusion The right ventricular apical approach has a high successful rate for transcatheter pulmonary valve implantation, and the early function of the self-expanding ultramicroporous ePTFE pulmonary valved stents is satisfactory in sheep.