Surgical replacement of the diseased aortic valve consists in the implantation of a prosthetic heart valve (PHV), either biological or mechanical (BHV and MHV, respectively). Risks of complication have been linked to high levels of turbulence and consequent energy dissipation induced by the PHV.

As helicity is an emergent feature in cardiovascular flows, deemed to impact blood flow organization, stability and the turbulent energy cascade, in this study the interplay between the production/decay of phase-averaged and turbulent kinetic energy and helicity in the presence of a BHV or MHV was investigated. Technically, direct numerical simulations of the coupled fluid–structure interaction problem were conducted using the immersed boundary method. A quantitative description of phase-averaged and fluctuating helicity, mean and turbulent kinetic energy was adopted to explore the nature of the kinetic energy vs. helicity relationship.

A clear PHV-type dependence of the helicity production/decay in the downstream hemodynamics emerged, with MHVs hemodynamics presenting larger phase-averaged and fluctuating helicity than BHVs. For both heart valve types strong linear correlations were found between volume-average kinetic energy and helicity when based on phase-averaged or fluctuating quantities (Pearson's correlation coefficient r up to 0.98, p<0.001). The generation of turbulent kinetic energy or fluctuating helicity for both heart valve types was delayed with respect to the inflow waveform or the generation of both mean kinetic energy and phase-averaged helicity (up to 5.4% of the cardiac cycle). The exploration of the link between helical and turbulent hemodynamic flow features expands the current understanding of the PHV hemodynamic features associated with clinical complications, potentially translating into improvements of the design of PHVs.

病变主动脉瓣的手术置换包括植入人工心脏瓣膜 (PHV)，无论是生物瓣膜还是机械瓣膜（分别为 BHV 和 MHV）。并发症的风险与 PHV 引起的高水平湍流和随之而来的能量耗散有关。

由于螺旋度是心血管血流中的一个新兴特征，被认为会影响血流组织、稳定性和湍流能量级联，因此在本研究中，在 BHV 存在下相位平均和湍流动能的产生/衰减与螺旋度之间的相互作用或 MHV 进行了调查。从技术上讲，耦合流固耦合问题的直接数值模拟是使用浸没边界法进行的。采用相位平均和波动螺旋度、平均和湍流动能的定量描述来探索动能与螺旋度关系的性质。

出现了明显的 PHV 型依赖性，即下游血流动力学中的螺旋度产生/衰减，其中 MHV 血流动力学呈现出比 BHV 更大的相位平均和波动螺旋度。对于两种心脏瓣膜类型，当基于相位平均或波动量时，体积平均动能和螺旋度之间存在强线性相关性（皮尔逊相关系数r高达 0.98，p<0.001)。相对于流入波形或平均动能和相位平均螺旋度的产生（高达心动周期的 5.4%），两种心脏瓣膜类型的湍流动能或波动螺旋度的产生都延迟了。对螺旋和湍流血流动力学特征之间联系的探索扩展了当前对与临床并发症相关的 PHV 血流动力学特征的理解，有可能转化为 PHV 设计的改进。