Hanafizadeh Pedram, Mirkhani Nima, Davoudi Mohammad Reza, Masouminia Mahtab, Sadeghy Keyvan
Center of Excellence in Design and Optimization of Energy Systems, School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
Biomedical Engineering, Katholieke Universiteit Leuven, Leuven, Belgium.
Artif Organs. 2016 Oct;40(10):E179-E191. doi: 10.1111/aor.12787.
Coronary arteries, which are branched from the sinuses, have tangible effects on the hemodynamic performance of the bileaflet mechanical heart valve (BMHV), especially in the diastolic phase. To better understand this issue, a computer model of ascending aorta including realistic sinus shapes and coronary arteries has been generated in this study in order to investigate the BMHV performance during diastole. Three-dimensional transient numerical analysis is conducted to simulate the diastolic blood flow through the hinges and in coronary arteries under the assumption of non-Newtonian behavior. Results indicate that as blood flows to the coronary arteries mainly during diastole, leakage flow from the hinge and other gaps will change considering the influence of coronary arteries. In addition, BMHV in the case of aortic replacement will increase blood flow rate into the coronary arteries about 100% as the mechanical valve resistance is higher than a native heart valve. Also, it will change the wall shear stress (WSS) distribution and increase coronary artery disease (CAD) potential. It is found out that although less leakage flow reduces the velocity magnitudes through the gaps, the shear stress acting on blood elements with non-Newtonian assumption will be detrimental in the hinge corner at the ventricular side. High WSS of 1800 Pa is observed at beginning of diastole at this region.
冠状动脉从主动脉窦分支出来，对双叶机械心脏瓣膜（BMHV）的血液动力学性能有显著影响，尤其是在舒张期。为了更好地理解这个问题，本研究建立了一个包含真实主动脉窦形状和冠状动脉的升主动脉计算机模型，以研究舒张期BMHV的性能。在非牛顿行为假设下，进行三维瞬态数值分析，以模拟通过铰链和冠状动脉的舒张期血流。结果表明，由于血液主要在舒张期流向冠状动脉，考虑到冠状动脉的影响，铰链和其他间隙的泄漏流将会改变。此外，在主动脉置换的情况下，由于机械瓣膜阻力高于天然心脏瓣膜，BMHV会使进入冠状动脉的血流速度增加约100%。这也会改变壁面剪应力（WSS）分布，并增加冠状动脉疾病（CAD）的风险。研究发现，虽然较少的泄漏流会降低通过间隙的速度大小，但在非牛顿假设下作用于血液单元的剪应力在心室侧的铰链角处是有害的。在舒张期开始时，该区域观察到高达1800 Pa的高WSS。
