Multi-modality image-based computational analysis of haemodynamics in aortic dissection.
Multi-modality image-based computational analysis of haemodynamics in aortic dissection.
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DOI：
10.1007/s10237-015-0729-2
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发表时间：
2016-08
影响因子：
3.5
通讯作者：
Figueroa CA
中科院分区：
文献类型：
--
作者：
Dillon-Murphy D;Noorani A;Nordsletten D;Figueroa CA
主动脉夹层是一种疾病，主动脉壁损伤导致形成一个真腔和一个假腔，假腔由内膜瓣分开，内膜瓣可能包含多个腔腔之间的连通撕裂。它具有高相关的发病率和死亡率，但目前，稳定型B型夹层的手术干预时机仍然是一个有争议的领域。详细的血流动力学知识可以通过更好地了解夹层内和周围的压力、壁剪切应力和速度，从而更好地了解夹层患者的长期预后。在本文中，我们旨在利用医学成像和计算流体动力学建模来进一步了解主动脉夹层的复杂血流动力学。为此，我们创建了一个急性Stanford B型夹层患者的主动脉计算机模型，其中改变了与夹层相关的形态学参数，例如去除隔膜，以及腔腔之间连接撕裂的数量变化。利用升主动脉二维PC-MRI获得的患者特异性血流数据来设定流入边界条件。代表远端血管系统的耦合零维（Windkessel）模型用于定义出口边界条件，并调整以匹配在降主动脉获得的2D PC-MRI血流数据。将剥离主动脉的血流动力学与同等“健康主动脉”的血流动力学进行比较，“健康主动脉”实际上是通过去除内膜皮瓣（隔膜）而形成的。局部区域流速、压力、壁面剪切应力增加，血流分布发生变化，特别是在狭窄的真腔和主要入口撕裂周围。计算的流型与使用4D PC-MRI获得的流型比较有利。一个集总参数心脏模型随后被用来表明，在这种情况下，随着解剖的开始，左心室中风的工作量估计增加了14%。最后，我们还研究了继发性连接撕裂（即不包括主要入口和出口撕裂）的影响，揭示了当模型中不包括继发性撕裂时显著的血流动力学变化，特别是在真正的管腔中，观察到流量增加和峰值压力下降18%。
Aortic dissection is a disease whereby an injury in the wall of the aorta leads to the creation of a true lumen and a false lumen separated by an intimal flap which may contain multiple communicating tears between the lumina. It has a high associated morbidity and mortality, but at present, the timing of surgical intervention for stable type B dissections remains an area of debate. Detailed knowledge of haemodynamics may yield greater insight into the long-term outcomes for dissection patients by providing a greater understanding of pressures, wall shear stress and velocities in and around the dissection. In this paper, we aim to gather further insight into the complex haemodynamics in aortic dissection using medical imaging and computational fluid dynamics modelling. Towards this end, several computer models of the aorta of a patient presenting with an acute Stanford type B dissection were created whereby morphometric parameters related to the dissection septum were altered, such as removal of the septum, and the variation of the number of connecting tears between the lumina. Patient-specific flow data acquired using 2D PC-MRI in the ascending aorta were used to set the inflow boundary condition. Coupled zero-dimensional (Windkessel) models representing the distal vasculature were used to define the outlet boundary conditions and tuned to match 2D PC-MRI flow data acquired in the descending aorta. Haemodynamics in the dissected aorta were compared to those in an equivalent ‘healthy aorta’, created by virtually removing the intimal flap (septum). Local regions of increased velocity, pressure, wall shear stress and alterations in flow distribution were noted, particularly in the narrow true lumen and around the primary entry tear. The computed flow patterns compared favourably with those obtained using 4D PC-MRI. A lumped-parameter heart model was subsequently used to show that in this case there was an estimated 14 % increase in left ventricular stroke work with the onset of dissection. Finally, the effect of secondary connecting tears (i.e. those excluding the primary entry and exit tears) was also studied, revealing significant haemodynamic changes when no secondary tears are included in the model, particularly in the true lumen where increases in flow over and drops in peak pressure of 18 % were observed.