Division of Pediatric Cardiology, Department of Pediatrics, Stanford University, Stanford, Calif; Cardiovascular Institute, Stanford University, Stanford, Calif.
Division of Pediatric Cardiac Surgery, Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif.
J Thorac Cardiovasc Surg. 2024 Sep;168(3):923-932.e4. doi: 10.1016/j.jtcvs.2023.12.027. Epub 2024 Jan 10.
Severe congenital aortic valve pathology in the growing patient remains a challenging clinical scenario. Bicuspidization of the diseased aortic valve has proven to be a promising repair technique with acceptable durability. However, most understanding of the procedure is empirical and retrospective. This work seeks to design the optimal gross morphology associated with surgical bicuspidization with simulations based on the hypothesis that modifications to the free edge length cause or relieve stenosis.
Model bicuspid valves were constructed with varying free edge lengths and gross morphology. Fluid-structure interaction simulations were conducted in a single patient-specific model geometry. The models were evaluated for primary targets of stenosis and regurgitation. Secondary targets were assessed and included qualitative hemodynamics, geometric height, effective height, orifice area, and billow.
Stenosis decreased with increasing free edge length and was pronounced with free edge length less than or equal to 1.3 times the annular diameter d. With free edge length 1.5d or greater, no stenosis occurred. All models were free of regurgitation. Substantial billow occurred with free edge length 1.7d or greater.
Free edge length 1.5d or greater was required to avoid aortic stenosis in simulations. Cases with free edge length 1.7d or greater showed excessive billow and other changes in gross morphology. Cases with free edge length 1.5d to 1.6d have a total free edge length approximately equal to the annular circumference and appeared optimal. These effects should be studied in vitro and in animal studies.
在生长中的患者中，严重的先天性主动脉瓣病变仍然是一个具有挑战性的临床情况。病变主动脉瓣的二瓣化已被证明是一种有前途的修复技术，具有可接受的耐久性。然而，对该手术的大多数理解都是经验性和回顾性的。这项工作旨在设计与手术二瓣化相关的最佳大体形态，基于这样的假设，即游离缘长度的改变会导致或缓解狭窄。
用不同的游离缘长度和大体形态构建模型二瓣化主动脉瓣。在单个患者特定的模型几何形状中进行流固耦合模拟。对模型进行狭窄和反流的主要目标评估。次要目标包括定性血流动力学、几何高度、有效高度、瓣口面积和膨出。
随着游离缘长度的增加，狭窄程度降低，当游离缘长度小于或等于瓣环直径 d 的 1.3 倍时，狭窄程度明显。当游离缘长度为 1.5d 或更大时，不会发生狭窄。所有模型均无反流。当游离缘长度为 1.7d 或更大时，会出现大量膨出。
在模拟中，需要游离缘长度 1.5d 或更大，以避免主动脉瓣狭窄。游离缘长度为 1.7d 或更大的病例显示出过度膨出和大体形态的其他变化。游离缘长度为 1.5d 至 1.6d 的病例具有大约等于瓣环周长的总游离缘长度，似乎是最佳的。这些效果应该在体外和动物研究中进行研究。
