Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Tex.
Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Tex; Department of Radiology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio.
J Thorac Cardiovasc Surg. 2014 Apr;147(4):1326-1333.e1. doi: 10.1016/j.jtcvs.2013.09.069. Epub 2013 Dec 15.
Increased use of continuous-flow left ventricular assist devices for long-term mechanical support necessitates a better understanding of hemodynamic changes in the native heart and the ascending aorta. By using patient-specific computational models, correlations of potentially adverse hemodynamic conditions with the orientation of the left ventricular assist device outflow graft and their relationship with aortic insufficiency and ischemic events were investigated.
Computed hemodynamic parameters, including wall shear stress, pressure in the ascending aorta, and dissipation of turbulent energy, were correlated with the orientation of the left ventricular assist device graft outflow in 5 patients (4 with the HeartMate II device [Thoratec Corp, Pleasanton, Calif] and 1 with the HeartWare Ventricular Assist Device [HeartWare Inc, Framingham, Mass]; 3 patients experienced moderate aortic insufficiency, and 2 patients experienced ischemic events). Hemodynamic conditions for aortic insufficiency and ischemic events were differentiated by linear discriminant analysis.
Positive correlations between left ventricular assist device outflow graft orientation and wall shear stress, pressure, and turbulent energy dissipation in the ascending aorta were found (R(2) > 0.68). Linear discriminant analysis indicated a relationship of the velocity magnitude of retrograde flow toward the aortic root with aortic insufficiency and of the turbulent energy and wall shear stress with ischemic events.
Computational fluid dynamic simulations using clinical image data indicate altered hemodynamic conditions after left ventricular assist device implantation. Consequently, the left ventricular assist device outflow graft should be placed so the jet of blood is aimed toward the lumen of the aortic arch to avoid turbulences that will increase wall shear stress and retrograde pressure of the aortic root. Further investigations are warranted to confirm these findings in a larger patient cohort.
为了长期机械支持，越来越多地使用连续血流左心室辅助装置，这需要更好地了解原生心脏和升主动脉的血液动力学变化。通过使用患者特异性计算模型，研究了左心室辅助装置流出移植物的方向与潜在不良血液动力学条件之间的相关性，以及它们与主动脉瓣关闭不全和缺血事件的关系。
在 5 名患者（4 名使用 HeartMate II 装置[加利福尼亚州普莱森顿的 Thoratec 公司]和 1 名使用 HeartWare 心室辅助装置[马萨诸塞州弗雷明汉的 HeartWare 公司]）中，将计算血流动力学参数（包括壁面切应力、升主动脉压力和湍流能量耗散）与左心室辅助装置移植物流出方向相关联。3 名患者患有中度主动脉瓣关闭不全，2 名患者患有缺血事件。通过线性判别分析对主动脉瓣关闭不全和缺血事件的血液动力学条件进行区分。
发现左心室辅助装置流出移植物方向与升主动脉壁面切应力、压力和湍流能量耗散之间存在正相关关系（R²>0.68）。线性判别分析表明，逆向血流向主动脉根部的速度大小与主动脉瓣关闭不全有关，而湍流能量和壁面切应力与缺血事件有关。
使用临床图像数据的计算流体动力学模拟表明，左心室辅助装置植入后血液动力学条件发生改变。因此，左心室辅助装置流出移植物应放置在血液射流朝向主动脉弓腔的位置，以避免增加壁面切应力和主动脉根部逆行压力的湍流。需要进一步的研究来在更大的患者队列中证实这些发现。
