Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, South Korea.
Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
PLoS One. 2018 Jun 28;13(6):e0199792. doi: 10.1371/journal.pone.0199792. eCollection 2018.
Although hemodynamic influence of the subprosthetic tissue, termed as pannus, may contribute to prosthetic aortic valve dysfunction, the relationship between pannus extent and hemodynamics in the prosthetic valve has rarely been reported. We investigated the fluid dynamics of pannus formation using in vitro experiments with particle image velocimetry. Subvalvular pannus formation caused substantial changes in prosthetic valve transvalvular peak velocity, transvalvular pressure gradient (TPG) and opening angle. Maximum flow velocity and corresponding TPG were mostly affected by pannus width. When the pannus width was 25% of the valve diameter, pannus formation elevated TPG to >2.5 times higher than that without pannus formation. Opening dysfunction was observed only for a pannus involvement angle of 360°. Although circumferential pannus with an involvement angle of 360° decreased the opening angle of the valve from approximately 82° to 58°, eccentric pannus with an involvement angle of 180° did not induce valve opening dysfunction. The pannus involvement angle largely influenced the velocity flow field at the aortic sinus and corresponding hemodynamic indices, including wall shear stress, principal shear stress and viscous energy loss distributions. Substantial discrepancy between the velocity-based TPG estimation and direct pressure measurements was observed for prosthetic valve flow with pannus formation.
虽然被称为瓣下组织的血流动力学影响可能导致人工主动脉瓣功能障碍，但瓣下组织的程度与人工瓣膜内的血流动力学之间的关系很少有报道。我们使用粒子图像测速法进行了体外实验，研究了瓣下组织形成的流体动力学。瓣下组织形成导致人工瓣膜跨瓣峰值速度、跨瓣压差（TPG）和开口角度发生显著变化。最大流速和相应的 TPG 主要受瓣下组织宽度的影响。当瓣下组织宽度达到瓣口直径的 25%时，瓣下组织形成使 TPG 升高到比无瓣下组织形成时高 2.5 倍以上。仅当瓣下组织累及角度为 360°时才观察到开口功能障碍。虽然 360°累及角度的周向瓣下组织使瓣口开度从大约 82°减小到 58°，但 180°累及角度的偏心瓣下组织不会导致瓣口开口功能障碍。瓣下组织累及角度对主动脉窦内的速度流场和相应的血流动力学指标，包括壁面切应力、主切应力和粘性能量损失分布有很大影响。在有瓣下组织形成的人工瓣膜血流中，基于速度的 TPG 估计与直接压力测量之间存在显著差异。
