Ha Hojin, Hwang Dongha, Choi Woo-Rak, Baek Jehyun, Lee Sang Joon
Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea.
Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea; Center for Biofluid and Biomimic Research, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea.
PLoS One. 2014 Oct 31;9(10):e111047. doi: 10.1371/journal.pone.0111047. eCollection 2014.
Although a helical configuration of a prosthetic vascular graft appears to be clinically beneficial in suppressing thrombosis and intimal hyperplasia, an optimization of a helical design has yet to be achieved because of the lack of a detailed understanding on hemodynamic features in helical grafts and their fluid dynamic influences. In the present study, the swirling flow in a helical graft was hypothesized to have beneficial influences on a disturbed flow structure such as stenotic flow. The characteristics of swirling flows generated by helical tubes with various helical pitches and curvatures were investigated to prove the hypothesis. The fluid dynamic influences of these helical tubes on stenotic flow were quantitatively analysed by using a particle image velocimetry technique. Results showed that the swirling intensity and helicity of the swirling flow have a linear relation with a modified Germano number (Gn*) of the helical pipe. In addition, the swirling flow generated a beneficial flow structure at the stenosis by reducing the size of the recirculation flow under steady and pulsatile flow conditions. Therefore, the beneficial effects of a helical graft on the flow field can be estimated by using the magnitude of Gn*. Finally, an optimized helical design with a maximum Gn* was suggested for the future design of a vascular graft.
尽管人工血管移植物的螺旋结构在临床上似乎有利于抑制血栓形成和内膜增生，但由于对螺旋移植物中的血流动力学特征及其流体动力学影响缺乏详细了解，螺旋设计的优化尚未实现。在本研究中，假设螺旋移植物中的旋流对诸如狭窄流等紊乱的流动结构具有有益影响。研究了具有不同螺旋节距和曲率的螺旋管产生的旋流特性，以验证该假设。利用粒子图像测速技术对这些螺旋管对狭窄流的流体动力学影响进行了定量分析。结果表明，旋流的旋流强度和螺旋度与螺旋管的修正热尔曼数（Gn*）呈线性关系。此外，在稳定和脉动流条件下，旋流通过减小回流区的大小，在狭窄处产生了有益的流动结构。因此，螺旋移植物对流场的有益影响可以通过Gn的大小来估计。最后，为未来血管移植物的设计提出了具有最大Gn的优化螺旋设计。
