DeLaria G A, Phifer T, Roy J, Tu R, Thyagarajan K, Quijano R C
Division of Cardiac Surgery, Scripps Clinic and Research Foundation, La Jolla, CA 92037.
J Vasc Surg. 1993 Oct;18(4):577-84; discussion 584-6. doi: 10.1067/mva.1993.49081.
A prosthetic venous valve must be biocompatible and nonthrombogenic and function in the venous circulation. Biocompatibility and thrombogenicity of our prosthesis have been examined in prior animal experiments, and 91% of valve conduits including early prototypes are patent at 3 weeks. However, evaluation of valve function is much more difficult in animals; therefore in this study the function of excised valves was evaluated ex vivo.
Nine bovine jugular vein conduits, each with one bileaflet venous valve, were harvested and placed in a venous flow simulator. Flows and pressures were adjusted to mimic human respiratory and hydrostatic variations. Each valve and conduit was tested for variations in valve diameter and sinus expansion in response to flow. Valve opening and closing times and valve competence were measured in response to pressure changes. After testing, each specimen was glutaraldehyde fixed and assessed a second time.
Valve orifice area increased in response to flow in both fresh and fixed tissues. Maximum valve orifice area was reduced by fixation (27.7%) at full flows (p < 0.05). Valve sinus dimensions increased in response to increased pressure until maximum expansion was achieved (33 mm Hg). This was reduced 15.3% in fixed tissue (p < 0.05). Valve opening times (at < 1 mm Hg gradient) were slightly longer in fixed compared with fresh tissue (0.43 +/- 0.09 vs 0.41 +/- 0.13 second; p < 0.05). Valve closing times were comparable in both states (0.43 +/- 0.08 vs 0.49 +/- 0.07 second). Three fresh and seven fixed specimens that were subjected to 287 mm Hg back pressure exhibited minimal reflux.
Size and availability make the bovine jugular vein valve an ideal venous valve substitute. Glutaraldehyde fixation renders the tissue biocompatible and nonthrombogenic while preserving anatomic integrity and leaflet strength and flexibility. Mounted and stented in a sewing sleeve, this prosthesis could represent the first generally applicable clinical solution to chronic venous insufficiency and venous hypertension.
人工静脉瓣膜必须具有生物相容性且不致血栓形成，并能在静脉循环中发挥作用。我们的假体的生物相容性和血栓形成性已在先前的动物实验中进行了研究，包括早期原型在内的91%的瓣膜导管在3周时保持通畅。然而，在动物中评估瓣膜功能要困难得多；因此，在本研究中，对离体瓣膜的功能进行了体外评估。
收集9条牛颈静脉导管，每条导管带有一个双叶静脉瓣膜，并将其置于静脉血流模拟器中。调整血流和压力以模拟人体呼吸和静水压变化。测试每个瓣膜和导管在血流作用下瓣膜直径和窦扩张的变化。测量瓣膜开闭时间和瓣膜功能对压力变化的反应。测试后，将每个标本用戊二醛固定并再次评估。
新鲜组织和固定组织中的瓣膜孔面积均随血流增加而增大。在全流量时，固定使最大瓣膜孔面积减小（27.7%）（p<0.05）。瓣膜窦尺寸随压力增加而增大，直至达到最大扩张（33 mmHg）。固定组织中这一数值降低了15.3%（p<0.05）。与新鲜组织相比，固定组织中瓣膜开启时间（压力梯度<1 mmHg时）略长（0.43±0.09秒对0.41±0.13秒；p<0.05）。两种状态下瓣膜关闭时间相当（0.43±0.08秒对0.49±0.07秒）。3个新鲜标本和7个固定标本在承受287 mmHg的背压时表现出最小反流。
牛颈静脉瓣膜的尺寸和可用性使其成为理想的静脉瓣膜替代品。戊二醛固定使组织具有生物相容性且不致血栓形成，同时保持解剖完整性以及瓣叶强度和柔韧性。安装并支撑在缝合套筒中，这种假体可能代表了慢性静脉功能不全和静脉高压的首个普遍适用的临床解决方案。
