Aortic valve replacement (AVR) does not usually restore physiological flow profiles. Complex flow profiles are associated with aorta dilatation, ventricle remodeling, aneurysms, and development of atherosclerosis. All these affect long-term morbidity and often require reoperations. In this pilot study, we aim to investigate an ability to optimize the real surgical AVR procedure toward flow profile associated with healthy persons. Four cases of surgical AVR (two with biological and two with mechanical valve prosthesis) with available post-treatment cardiac magnetic resonance imaging (MRI), including four-dimensional flow MRI and showing abnormal complex post-treatment hemodynamics, were investigated. All cases feature complex hemodynamic outcomes associated with valve-jet eccentricity and strong secondary flow characterized by helical flow and recirculation regions. A commercial computational fluid dynamics solver was used to simulate peak systolic hemodynamics of the real post-treatment outcome using patient-specific MRI measured boundary conditions. Then, an attempt to optimize hemodynamic outcome by modifying valve size and orientation as well as ascending aorta size reduction was made. Pressure drop, wall shear stress, secondary flow degree, helicity, maximal velocity, and turbulent kinetic energy were evaluated to characterize the AVR hemodynamic outcome. The proposed optimization strategy was successful in three of four cases investigated. Although no single parameter was identified as the sole predictor for a successful flow optimization, downsizing of the ascending aorta in combination with the valve orientation was the most effective optimization approach. Simulations promise to become an effective tool to predict hemodynamic outcome. The translation of these tools requires, however, studies with a larger cohort of patients followed by a prospective clinical validation study.

中文翻译：

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“外科主动脉瓣置换术：我们能否改善血流动力学结果？”

主动脉瓣置换术 (AVR) 通常不会恢复生理血流曲线。复杂的血流曲线与主动脉扩张、心室重塑、动脉瘤和动脉粥样硬化的发展有关。所有这些都会影响长期发病率，并且经常需要再次手术。在这项试点研究中，我们的目标是研究优化真实外科 AVR 程序的能力，使其能够适应与健康人相关的血流分布。研究了四例手术 AVR（两例使用生物瓣膜，两例使用机械瓣膜）具有可用的治疗后心脏磁共振成像 (MRI)，包括四维流动 MRI 并显示异常复杂的治疗后血流动力学。所有病例都具有复杂的血液动力学结果，与瓣膜射流偏心和以螺旋流和再循环区域为特征的强二次流相关。商业计算流体动力学求解器用于使用患者特定的 MRI 测量边界条件模拟真实治疗后结果的峰值收缩血流动力学。然后，尝试通过修改瓣膜尺寸和方向以及减小升主动脉尺寸来优化血流动力学结果。评估压降、壁剪切应力、二次流动程度、螺旋度、最大速度和湍流动能以表征 AVR 血流动力学结果。所提出的优化策略在所调查的四个案例中的三个中取得了成功。尽管没有单个参数被确定为成功流量优化的唯一预测因素，但结合瓣膜方向缩小升主动脉的尺寸是最有效的优化方法。模拟有望成为预测血液动力学结果的有效工具。然而，这些工具的转化需要对更多患者进行研究，然后进行前瞻性临床验证研究。