Westerdale John C, Adrian Ronald, Squires Kyle, Chaliki Hari, Belohlavek Marek
School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona, USA.
Division of Cardiovascular Disease, Mayo Clinic, Scottsdale, Arizona, USA.
Open Cardiovasc Med J. 2015 Jun 26;9:62-8. doi: 10.2174/1874192401509010062. eCollection 2015.
We studied left ventricular flow patterns for a range of rotational orientations of a bileaflet mechanical heart valve (MHV) implanted in the mitral position of an elastic model of a beating left ventricle (LV). The valve was rotated through 3 angular positions (0, 45, and 90 degrees) about the LV long axis. Ultrasound scans of the elastic LV were obtained in four apical 2-dimensional (2D) imaging projections, each with 45 degrees of separation. Particle imaging velocimetry was performed during the diastolic period to quantify the in-plane velocity field obtained by computer tracking of diluted microbubbles in the acquired ultrasound projections. The resulting velocity field, vorticity, and shear stresses were statistically significantly altered by angular positioning of the mechanical valve, although the results did not show any specific trend with the valve angular position and were highly dependent on the orientation of the imaging plane with respect to the valve. We conclude that bileaflet MHV orientation influences hemodynamics of LV filling. However, determination of 'optimal' valve orientation cannot be made without measurement techniques that account for the highly 3-dimensional (3D) intraventricular flow.
我们研究了植入在跳动的左心室（LV）弹性模型二尖瓣位置的双叶机械心脏瓣膜（MHV）在一系列旋转方向下的左心室血流模式。瓣膜绕左心室长轴旋转3个角度位置（0、45和90度）。在四个心尖二维（2D）成像投影中获取弹性左心室的超声扫描图像，每个投影间隔45度。在舒张期进行粒子图像测速，以量化通过计算机跟踪采集的超声投影中稀释微泡获得的平面内速度场。尽管结果未显示出与瓣膜角度位置有任何特定趋势，且高度依赖于成像平面相对于瓣膜的方向，但机械瓣膜的角度定位在统计学上显著改变了所得的速度场、涡度和剪应力。我们得出结论，双叶MHV的方向会影响左心室充盈的血流动力学。然而，在没有考虑高度三维（3D）心室内血流的测量技术的情况下，无法确定“最佳”瓣膜方向。
