Nguyen Yen Ngoc, Ismail Munirah, Kabinejadian Foad, Ong Chi Wei, Tay Edgar Lik Wui, Leo Hwa Liang
Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
Cardiovasc Eng Technol. 2017 Dec;8(4):401-418. doi: 10.1007/s13239-017-0328-8. Epub 2017 Aug 29.
The increased understanding of right heart diseases has led to more aggressive interventions to manage functional tricuspid regurgitation (FTR). In some cases of FTR, prosthetic valve replacement is typically considered when concomitant organic components or significant geometrical distortions are involved in the pathology of the tricuspid valve. However, little is known of the performance of current devices in the right heart circulation. In this study, a novel in vitro mock circulatory system that incorporated a realistic tricuspid valve apparatus in a patient-specific silicon right ventricle (RV) was designed and fabricated. The system was calibrated to emulate severe FTR, enabling the investigation of RV hemodynamics in pre- and post-implantation of tri-leaflet tissue implant and bi-leaflet mechanical implant. 2D particle imaging velocimetry was performed to visualize flow and quantify relevant hemodynamic parameters. While our results showed all prosthetic implants improved cardiac output, these implants also subjected the RV to increased turbulence level. Our study also revealed that the implants did not create the optimal behavior of fluid transfer in the RV as we expected. Among the implants tested, tissue implant created the most dominant vortices, which persisted throughout diastole; its observed strong negative vortex could lead to increase energy expenditure due to undesired fluid direction. In contrast, both native valve and mechanical implant had both weaker vortex formation as well as more significant vortex dissipation. Interestingly, the vortex dissipation of native valve was associated with streamlined flow pattern that tended towards the pulmonary outlet, while the mechanical implant generated more regions of flow stagnation within the RV. These findings heighten the imperative to improve designs of current heart valves to be used in the right circulation.
对右心疾病认识的加深促使人们采取更积极的干预措施来治疗功能性三尖瓣反流（FTR）。在某些FTR病例中，当三尖瓣病变涉及伴随的器质性成分或明显的几何变形时，通常会考虑进行人工瓣膜置换。然而，目前对于现有装置在右心循环中的性能了解甚少。在本研究中，设计并制造了一种新型体外模拟循环系统，该系统在患者特异性硅质右心室（RV）中纳入了逼真的三尖瓣装置。该系统经过校准以模拟严重的FTR，从而能够研究三叶瓣组织植入物和双叶瓣机械植入物植入前后右心室的血流动力学。采用二维粒子图像测速技术来可视化血流并量化相关的血流动力学参数。虽然我们的结果表明所有人工植入物都改善了心输出量，但这些植入物也使右心室的湍流水平增加。我们的研究还表明，植入物并未如我们预期的那样在右心室中产生最佳的液体传输行为。在所测试的植入物中，组织植入物产生的涡流最为显著，且在整个舒张期持续存在；观察到的强烈负向涡流可能会由于不期望的流体方向而导致能量消耗增加。相比之下，天然瓣膜和机械植入物产生的涡流形成较弱，且涡流消散更为显著。有趣的是，天然瓣膜的涡流消散与趋向于肺出口的流线型血流模式相关，而机械植入物在右心室内产生了更多的血流停滞区域。这些发现凸显了改进当前用于右心循环的心脏瓣膜设计的紧迫性。
