Hydoro-dynamic analysis for effect of cannula shapes on the diseased aorta during extracorporeal circulation.-Basic and clinical study-

目的：本研究旨在阐明动脉插管内喷流对老年病变主动脉的流体动力学影响。这项研究的最终目标是开发更复杂的插管形状来减弱主动脉壁上的剪应力。材料和方法：本研究由两个基础研究和一个临床研究组成。第一个基础研究是使用正常和病变的主动脉的模拟玻璃模型进行的。用粒子图像速度法测量了正常和病变(弓状动脉瘤)主动脉模型的切应力和切变速度，并分析了血流流线。根据模型实验得到的数据，建立了数学模型，并对扭曲、简化的主动脉模型内的流动进行了计算模拟分析。在临床研究中，分别采用主动脉外膜和经食道双功及彩色标测技术对体外循环期间的血流速度和向量进行了分析。结果：1.遮盖玻璃模型分析了…更多的姐姐。在正常和病变的主动脉模型中，分析了不同类型的主动脉管内的流态特征：弯曲端孔管、弥散型管、选择性3D管和软流型管。不同的插管形成不同的大涡和螺旋流。在端孔插管内观察到高速流动，导致主动脉弓产生高应变。离散管的血流使主动脉弓外弯处的应力减小。在软流插管中，流速和应变进一步降低。在SELECT 3D插管中，沿主动脉弓内曲观察到高应变。2.在简化的数学模型中，采用端孔插管作为动脉灌流插管。血流矢量和流线分析结果与玻璃模型相似。3.临床研究结果与玻璃模型分析结果基本一致。结论：动脉粥样硬化患者不应使用端孔插管。根据这一结果，应特别注意插管和插管部位的选择。较少

Objectives :This study was conducted to elucidate the fluid dynamic effect of jet flow from the arterial cannulae on the aged, diseased aorta. The final goal for this study is to develop more sophisticated cannula shape to attenuate shear stress on the aortic wall.Materials and methods :This study was composed of two basic and one clinical investigation. The first basic investigation is performed using mocked glass model of the normal and diseased aorta. Particle image velocity method was used to measure shear stress and shear velocity and to analyze stream line in the normal and diseased (arch aneurysm) aortic model. Based on data obtained from the model experiment, mathematic model was constructed and computed simulation of the flow in the twisted, simplified aortic model was analyzed. In clinical study, flow velocity and vector analysis during cardiopulmonary bypass were performed using epi-aortic and trans-esophageal duplex and color mapping scan.Results :1.Mocked glass model analy … More sis. The characteristics of flow pattern in different types of aortic cannulae were analyzed in normal and diseased aortic models: curved end-hole cannula, dispersion cannula, SELECT 3D cannula and Soft-Flow cannula. Different patterns of large vortices and helical flow were made by each cannula. The high velocity flow was observed in end-hole cannula, causing high strain on the aortic arch. The flow from dispersion cannula brought about decreased strain on the outer curvature of the aortic arch. In Soft-Flow cannula, further decreased flow velocity and strain were observed. In Select 3D cannula, high strain was observed along the inner curvature of the aortic arch.2.In simplified mathematic model, end-hole cannula was used as arterial perfusion cannula. Flow vector and stream line analysis showed similar pattern with glass model.3.Clinical investigation revealed essentially the same result obtained in glass model analysis.Conclusions :The end-hole cannula should not be used in atherosclerotic aorta. Particular attention should be paid both for selection of cannulae and cannulation site based on this result. Less