Bioengineering Division, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil.
Artif Organs. 2011 May;35(5):490-6. doi: 10.1111/j.1525-1594.2011.01261.x.
Freeze-drying of biological tissues allows for dry storage and gamma ray sterilization, which may improve their use as a medical prosthesis. The objective of this study was to evaluate the rehydration characteristics and hydrodynamic performance of prosthetic valves before and after lyophilization. Two size 23 bovine pericardium aortic valve prostheses from different manufacturers were evaluated in a Shelhigh (Union, NJ, USA) pulse duplicator (80 ppm, 5 L/min) before and after lyophilization. Flow and transvalvular pressure gradient were registered in vitro and in vivo, and images of opening and closing of the prosthesis were obtained in the pulse duplicator in a digital camera. Rehydration was evaluated by comparison of dry valve weight with valve weight after 15 min, and 1, 24, 48, and 72 h in saline solution, inside the pulse duplicator. In vivo performance was assessed by surgical implantation in Santa Inês young male sheep in the pulmonary position after 30 min rehydration with 0.9% saline. Transvalvular pressure gradient and flow measurements were obtained immediately after implantation and 3 months after surgery when valves were explanted. Captured images showed a change in the profile opening and closing of valve prosthesis after lyophilization. The gradient measured (in vitro) in two valves was 17.08 ± 0.57 and 18.76 ± 0.70 mm Hg before lyophilization, and 34.24 ± 0.59 and 30.40 ± 0.97 mm Hg after lyophilization. Rehydration of both lyophilized valves was approximately 82%. Drying changed the profile of the opening and closing of valve prostheses, and increased on average by 83% the gradient in vitro tests. The result of the in vivo tests suggests maintaining pressure levels of the animal with the lyophilized prostheses within acceptable levels.
生物组织的冷冻干燥允许进行干燥储存和伽马射线灭菌，这可能会改善它们作为医用假体的使用。本研究的目的是评估假体瓣膜在冻干前后的复水特性和水动力性能。在冻干前后，使用来自不同制造商的两个大小为 23 的牛心包主动脉瓣假体在 Shelhigh（新泽西州尤因，美国）脉冲复制器（80ppm，5L/min）中进行了评估。在体外和体内记录了流量和跨瓣压差，并在脉冲复制器中的数码相机中获得了假体打开和关闭的图像。通过比较干燥阀的重量与在盐溶液中 15 分钟、1、24、48 和 72 小时后的阀的重量来评估复水情况，这些都是在脉冲复制器内进行的。通过在 30 分钟 0.9%生理盐水复水后在肺动脉位置对 Santa Inês 年轻雄性绵羊进行外科植入来评估体内性能。在植入后立即以及术后 3 个月瓣膜取出时，进行跨瓣压差和流量测量。捕获的图像显示冻干后假体瓣膜的开口和关闭轮廓发生了变化。在两个瓣膜中测量的梯度（体外）分别为冻干前 17.08±0.57 和 18.76±0.70mmHg，冻干后 34.24±0.59 和 30.40±0.97mmHg。两个冻干瓣膜的复水率约为 82%。干燥改变了假体瓣膜的开口和关闭轮廓，使体外试验中的梯度平均增加了 83%。体内试验的结果表明，使用冻干假体可使动物的压力水平保持在可接受的范围内。
