Magnitude and Direction of Pulsatile Displacement Forces Acting on Thoracic Aortic Endografts
Magnitude and Direction of Pulsatile Displacement Forces Acting on Thoracic Aortic Endografts
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DOI：
10.1583/09-2738.1
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发表时间：
2009-06-01
影响因子：
2.6
通讯作者：
Zarins, Christopher K.
中科院分区：
文献类型：
--
作者：
Figueroa, C. Alberto;Taylor, Charles A.;Zarins, Christopher K.
目的：使用3D计算技术评估作用于胸覆膜支架的3维（3D）脉动位移力（DF）方法：使用一种新的计算方法来量化基于心脏门控计算机断层扫描（CT）扫描的患者特定解剖模型中的脉动3D流场和压力场以及主动脉壁动力学，以构建近端和中段降胸主动脉的模拟。在这些患者特定模型中植入不同长度和直径的覆膜支架。计算DF矢量的大小和方向，并以牛顿（N）表示。结果：DF的大小随覆膜支架直径和长度的增加而增加。降主动脉中段的36 mm覆膜支架的平均DF为21.7 N，峰值收缩期DF为27.8 N，舒张末期DF为16.7 N。相反，近端降主动脉中的30 mm覆膜支架的平均DF为14.9 N，峰值收缩期和舒张末期DF分别为18.9和11.5。DF作用于覆膜支架的方向根据主动脉成角和迂曲度而变化;通常，矢量垂直于覆膜支架的大弯，而不是通常认为的沿着主动脉的下游纵向中心线轴线。对于近端下行覆膜支架，DF向量主要指向头部方向，对于中段下行覆膜支架模拟，DF向量主要指向侧面方向。此外，它表明，升高的压力起着重要的作用，在DF的幅度和方向;平均血压的增加导致在DF近似线性成比例的增加。结论：DF的方向取决于曲率和覆膜支架的位置，但在所有情况下，它是在头部，而不是尾部方向轴向成像。这与位移力沿血流的向下方向作用的直观概念相反。因此，我们假设胸腔覆膜支架的移位可能不同于腹部覆膜支架，因为它可能涉及覆膜支架的向上移动而不是向下移动。计算方法可以增强对胸主动脉覆膜支架体内承受的载荷大小和方向的理解，从而改善其设计和性能。J Endovasc Ther. 2009;16：350-358
Purpose: To assess 3-dimensional (3D) pulsatile displacement forces (DF) acting on thoracic endografts using 3D computational techniques.Methods: A novel computational method to quantitate the pulsatile 3D flow and pressure fields and aortic wall dynamics in patient-specific anatomical models based on cardiac-gated computed tomography (CT) scans was used to construct simulations of the proximal and mid-descending thoracic aorta. Endografts of varying lengths and diameters were implanted in these patient-specific models. The magnitude and direction of the DF vector were calculated and expressed in Newtons (N). This DF included the effects of both the pressure and shearing stresses of blood.Results: The magnitude of DF increased with endografts of increasing diameter and length. A 36-mm endograft in the mid-descending aorta had a mean DF of 21.7 N with a peak systolic DF of 27.8 N and an end-diastolic DF of 16.7 N. Conversely, a 30-mm endograft in the proximal descending aorta had a mean DF of 14.9 N, with peak systolic and end-diastolic DFs of 18.9 and 11.5, respectively. The orientation of the DF acting on the endograft varied depending on aortic angulation and tortuosity; in general, the vector was perpendicular to the greater curvature of the endograft rather than along the downstream longitudinal centerline axis of the aorta as is commonly believed. The DF vector pointed primarily in the cranial direction for the proximal descending endograft and in the sideways direction for the mid-descending endograft simulation. Furthermore, it was shown that elevated pressure plays an important role in the magnitude and direction of DF; an increase in mean blood pressure resulted in an approximately linearly proportional increase in DF.Conclusion: The orientation of the DF varies depending on curvature and location of the endograft, but in all instances, it is in the cranial rather than caudal direction on axial imaging. This is counter to the intuitive notion that displacement forces act in the downward direction of blood flow. Therefore, we postulate that migration of thoracic endografts may be different from abdominal endografts since it may involve upward rather than downward movement of the graft. Computational methods can enhance the understanding of the magnitude and orientation of the loads experienced in vivo by thoracic aortic endografts and therefore improve their design and performance. J Endovasc Ther. 2009;16:350-358