Vetter H, Nerlich A, Welsch U, Liao K, Dagge A, Strenkert C, Reichart B
Department of Cardiac Surgery, University of Munich, Herzklinik Augustinum, Munich, Germany.
J Thorac Cardiovasc Surg. 1996 Mar;111(3):595-604. doi: 10.1016/s0022-5223(96)70311-2.
Mitral valves, including the papillary muscles, were harvested from freshly slaughtered sheep and implanted in 10 recipient growing sheep. A strip of ovine pericardium was used to reinforce the anulus and a patch of expanded polytetrafluoroethylene was used to cover the donor papillary muscle. In four valves the natural chordae tendineae at the anterior cusp were supported by two pairs of 5-0 expanded polytetrafluoroethylene sutures. At the beginning of the experiment two animals died early of valve incompetence. Another animal had to be put to death because of paraplegia after extracorporeal circulation and one died on postoperative day 41 of endocarditis. Six sheep were electively put to death, five after 153 +/- 8 days and one after 43 days. At the time of follow-up, a complete hemodynamic study including echocardiography and stress testing was performed. Heart rate at rest was 91 +/- 14 beats/min, left ventricular systolic pressure 96 +/- 20 mm Hg, left ventricular end-diastolic pressure 11 +/- 5 mm Hg, cardiac output 2.04 +/- 0.40 L/min, and the mean transvalvular pressure gradient was 4.9 +/- 2.8 mm Hg as measured by cardiac catheterization. Echocardiography showed excellent movement of all valve components. However, minor regurgitation was evident in one case. Gross morphologic characteristics showed good healing at the anulus and host papillary muscle; in one case there was a rupture of one small first-order chorda. On radiography no signs of calcification were evident. Light microscopy revealed minor to moderate collagen degeneration in all valve components. However, on electron microscopy the presence of numerous fibroblasts within the long-term implants indicated the biosynthesis of new collagen. In summary, allograft mitral valve replacement seems to be a promising procedure if the chordae tendineae are reinforced by expanding polytetrafluoroethylene sutures.
二尖瓣，包括乳头肌，取自刚宰杀的绵羊，并植入10只受体生长绵羊体内。用一条羊心包条带加固瓣环，用一片膨体聚四氟乙烯补片覆盖供体乳头肌。在四个瓣膜中，前叶的天然腱索由两对5-0膨体聚四氟乙烯缝线支撑。实验开始时，两只动物因瓣膜功能不全早期死亡。另一只动物因体外循环后截瘫而不得不被处死，还有一只在术后第41天死于心内膜炎。六只绵羊被选择性处死，五只在153±8天后，一只在43天后。在随访时，进行了包括超声心动图和负荷试验在内的完整血流动力学研究。静息心率为91±14次/分钟，左心室收缩压为96±20毫米汞柱，左心室舒张末期压力为11±5毫米汞柱，心输出量为2.04±0.40升/分钟，通过心导管检查测得的平均跨瓣压力梯度为4.9±2.8毫米汞柱。超声心动图显示所有瓣膜组件运动良好。然而，有一例有轻微反流。大体形态学特征显示瓣环和宿主乳头肌愈合良好；有一例一根小一级腱索破裂。X线检查未见钙化迹象。光镜检查显示所有瓣膜组件有轻度至中度胶原退变。然而，电镜检查显示长期植入物内有大量成纤维细胞，表明有新胶原的生物合成。总之，如果用膨体聚四氟乙烯缝线加固腱索，同种异体二尖瓣置换术似乎是一种有前景的手术方法。
