Ismail Munirah, Kabinejadian Foad, Nguyen Yen Ngoc, Tay Lik Wui Edgar, Kim Sangho, Leo Hwa Liang
School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
Department of Biomedical Engineering, Tulane University, United States of America.
Med Eng Phys. 2017 Dec;50:1-11. doi: 10.1016/j.medengphy.2017.08.003. Epub 2017 Nov 6.
There has not been much progress in the development of transcatheter tricuspid valves to treat tricuspid regurgitation because of the difficulty in anchoring a stented valve onto the complex tricuspid annulus. Hence, the concept of heterotopic implantation of the transcatheter tricuspid valve onto the cavo-atrial junction was proposed. However, to date there has been no detailed in vitro investigation of the hemodynamic performance of this new device. The study utilises both 2-D and 3-D particle image velocimetry (PIV) to interrogate the flow patterns in the vicinity of the extra-cardiac tricuspid valves in an in vitro physiological flow loop, specifically at four measurement locations in the cavo-atrial anatomy. Comparison of the 2-D and 3-D PIV results revealed that accuracy of 2-D PIV would be acceptable at time point and at measurement locations where the velocity was mostly planar with minimal or low out-of-plane flow such as at the outlet of the superior vena cava valve at the point of valve closure. The results also showed that the RSS in the vicinity of the valves were relatively low (∼150 dynes/cm) with the exception of that in the leakage jet at the upstream of the valve. The leakage in the leaflets could be a result of the use of aortic valve leaflets which was more suited for the higher pressured environment of the left side of the heart. The stent design could also be customised for implantation in the vena cava. In summary, these issues could be eradicated with improvements to the leaflet and stent design which would enhance the haemodynamics of the post-implantation flow performance.
由于将带支架瓣膜固定在复杂的三尖瓣环上存在困难，经导管三尖瓣治疗三尖瓣反流的发展进展不大。因此，有人提出将经导管三尖瓣异位植入腔房交界处的概念。然而，迄今为止，尚未对这种新装置的血流动力学性能进行详细的体外研究。该研究利用二维和三维粒子图像测速技术（PIV），在体外生理流动回路中研究心外三尖瓣附近的流动模式，特别是在腔房解剖结构的四个测量位置。二维和三维PIV结果的比较表明，在速度大多为平面且平面外流最小或较低的时间点和测量位置，如在上腔静脉瓣膜关闭点的出口处，二维PIV的准确性是可以接受的。结果还表明，除瓣膜上游泄漏射流处外，瓣膜附近的壁面切应力相对较低（约150达因/厘米）。瓣叶的泄漏可能是由于使用了更适合心脏左侧高压环境的主动脉瓣叶。支架设计也可以定制，以便植入腔静脉。总之，通过改进瓣叶和支架设计可以消除这些问题，这将提高植入后血流性能的血流动力学。
