Surgical reconstruction of semilunar valves in the growing child: Should we mimic the venous valve? A simulation study.

Neither heart valve repair methods nor current prostheses can accommodate patient growth. Normal aortic and pulmonary valves have three leaflets, and the goal of valve repair and replacement is typically to restore normal three-leaflet morphology. However, mammalian venous valves have bileaflet morphology and open and close effectively over a wide range of vessel sizes. We propose that they might serve as a model for pediatric heart valve reconstruction and replacement valve design. We explore this concept using computer simulation. We use a finite element method to simulate the ability of a reconstructed cardiac semilunar valve to close competently in a growing vessel, comparing a three-leaflet design with a two-leaflet design that mimics a venous valve. Three venous valve designs were simulated to begin to explore the parameter space. Simulations show that for an initial vessel diameter of 12 mm, the venous valve design remains competent as the vessel grows to 20 mm (67 %), while the normal semilunar design remains competent only to 13 mm (8 %). Simulations also suggested that systolic function, estimated as effective orifice area, was not detrimentally affected by the venous valve design, with all three venous valve designs exhibiting greater effective orifice area than the semilunar valve design at a given level of vessel growth. Morphologic features of the venous valve design make it well-suited for competent closure over a wide range of vessel sizes, suggesting its use as a model for semilunar valve reconstruction in the growing child.

无论是心脏瓣膜修复方法还是现有的人工瓣膜都无法适应患者的生长。正常的主动脉瓣和肺动脉瓣有三个瓣叶，瓣膜修复和置换的目标通常是恢复正常的三瓣叶形态。然而，哺乳动物的静脉瓣具有双瓣叶形态，并且在很宽的血管尺寸范围内都能有效地开闭。我们提出它们可能可作为小儿心脏瓣膜重建和置换瓣膜设计的模型。我们利用计算机模拟来探索这一概念。 我们使用有限元方法模拟重建的心脏半月瓣在生长的血管中完全关闭的能力，比较模仿静脉瓣的双瓣叶设计和三瓣叶设计。模拟了三种静脉瓣设计以初步探索参数空间。 模拟结果显示，对于初始血管直径为12毫米的情况，当血管增长到20毫米时，静脉瓣设计仍能正常关闭（67%），而正常的半月瓣设计仅在血管增长到13毫米时仍能正常关闭（8%）。模拟还表明，以有效开口面积来评估的收缩功能并没有受到静脉瓣设计的不利影响，在给定的血管生长水平下，所有三种静脉瓣设计都显示出比半月瓣设计更大的有效开口面积。 静脉瓣设计的形态特征使其非常适合在很宽的血管尺寸范围内完全关闭，这表明它可作为生长中的儿童半月瓣重建的模型。