儿童主动脉瓣单叶置换术后瓣叶适应性的数值分析

Objective To explore the biomechanical mechanism of aortic insufficiency (AI) after single aortic valve replacement (SAVR) in children and propose countermeasures. Methods Idealized aortic valve models and postoperative growth models were constructed. The length of the free edge of the replacement leaflet, the height of the leaflet, and an improved concave structure were changed, and the effects of different structural dimensions on the postoperative aortic valve motion synchrony and closure performance were compared. Results The closure of the replacement leaflet lagged behind that of the autologous leaflet, and the autologous leaflet adhered 2 mm below the free edge of the replacement leaflet. Obvious AI occurred 6 years after the operation. Increasing the leaflet height could not improve the postoperative effect and would increase the maximum stress of the leaflet. Increasing the free edge length by 10% could improve the postoperative effect. When the free edge was increased by 15%, the aortic valve would be too long, resulting in poor adhesion of the aortic valve. The concave aortic valve was more conducive to leaflet coaptation than the traditional structure and could effectively reduce the maximum stress by 20%, with the best effect. Conclusions After SAVR in children, the leaflet motion is asynchronous, the coaptation point is shifted, and the AI phenomenon occurs 6 years after the operation. It is recommended to cut into a concave structure with a 10% increase in the free edge length, and increasing the leaflet height is not recommended.

目的探究儿童主动脉瓣单叶置换(single aortic valve replacement, SAVR)术后主动脉瓣关闭不全(aortic insufficiency, AI)的生物力学机制,并提出应对措施。方法构建理想化主动脉瓣模型及术后生长模型。改变置换瓣叶游离缘长度、瓣叶高度以及改进设计的一种凹型结构,比较不同结构尺寸对术后主动脉瓣运动同步性和关闭性能的影响。结果置换瓣叶的闭合滞后于自体瓣叶,自体瓣叶贴合于置换瓣叶游离缘下方2 mm处。术后6年出现明显AI。增加瓣叶高度不能改善术后效果,且会增加瓣叶的最大应力。增加游离缘长度10%能够改善术后效果,当游离缘增加15%,会造成主动脉瓣过长,导致主动脉瓣产生不良的贴合。凹型主动脉瓣较传统结构更有利于瓣叶对合,能够有效降低最大应力20%,效果最佳。结论儿童行SAVR术后,会使瓣叶运动不同步,对合点发生偏移,术后6年出现AI现象。建议裁剪为增加游离缘长度10%的凹型结构,不建议增加瓣叶高度。