Gülan Utku, Calen Christelle, Duru Firat, Holzner Markus
Institute of Environmental Engineering, ETH Zurich, Zurich, Switzerland; Department of Cardiology, University Hospital Zurich, Zurich, Switzerland.
Department of Cardiology, University Hospital Zurich, Zurich, Switzerland.
J Biomech. 2018 Jul 25;76:152-159. doi: 10.1016/j.jbiomech.2018.05.033. Epub 2018 Jun 8.
An aortic aneurysm is defined as a balloon-shaped bulging of all three histologic components of the aortic vessel walls (intima, media and adventitia). This dilation results from vessel weakening owing to remodeling, i.e. due to cystic degeneration of the Tunica media (Marfan), progression of atherosclerosis or presence of a bicuspid aortic valve. The growth rate of the aortic diameter varies from patient to patient and may progress until the aneurysm ultimately ruptures. The role of hemodynamics, i.e. blood flow patterns, and shear stresses that are supposed to intensify during aneurysm growth are not yet fully understood, but thought to play a key role in the enlargement process. The aim of this study is to characterize the aortic blood flow in a silicone model of a pathological aorta with ascending aneurysm, to analyze the differences in the blood flow pattern compared to a healthy aortic model, and to single out possible blood flow characteristics measurable using phase contrast magnetic resonance imaging (MRI) that could serve as indicators for aneurysm severity. MRI simulations were performed under physiological, pulsatile flow conditions using data obtained from optical three dimensional particle tracking measurements. In comparison to the healthy geometry, elevated turbulence intensity and pressure loss are measured in the diseased aorta, which we propose as a complimentary indicator for assessing the aneurysmal severity. Our results shed a light on the interplay between the blood flow dynamics and their contribution to the pathophysiology and possible role for future risk assessment of ascending aortic aneurysms.
主动脉瘤被定义为主动脉血管壁的所有三个组织学成分（内膜、中膜和外膜）呈气球状膨出。这种扩张是由于血管重塑导致的血管壁薄弱，即由于中膜囊性变（马凡综合征）、动脉粥样硬化进展或二叶式主动脉瓣的存在。主动脉直径的生长速度因人而异，可能会持续进展直至动脉瘤最终破裂。血流动力学的作用，即血流模式以及在动脉瘤生长过程中应该会增强的剪切应力，目前尚未完全了解，但被认为在扩张过程中起关键作用。本研究的目的是在一个患有升主动脉瘤的病理性主动脉硅树脂模型中表征主动脉血流，分析与健康主动脉模型相比血流模式的差异，并找出使用相位对比磁共振成像（MRI）可测量的可能的血流特征，这些特征可作为动脉瘤严重程度的指标。使用从光学三维粒子跟踪测量获得的数据，在生理搏动血流条件下进行了MRI模拟。与健康几何形状相比，在患病主动脉中测量到湍流强度和压力损失升高，我们将其作为评估动脉瘤严重程度的补充指标。我们的结果揭示了血流动力学之间的相互作用及其对升主动脉瘤病理生理学的贡献以及在未来风险评估中的可能作用。
