Kheradvar Arash, Milano Michele, Gharib Morteza
Cardiovascular and Biofluid Dynamics Laboratory, California Institute of Technology, Pasadena, California 91125, USA.
ASAIO J. 2007 Jan-Feb;53(1):8-16. doi: 10.1097/01.mat.0000249870.44625.22.
One of the most important fluid phenomena observed in the left ventricle during diastole is the presence of vortex rings that develop with a strong jet entering through the mitral valve. The present study is focused on the rapid filling phase of diastole, during which the left ventricle expands and receives blood through the fully open mitral valve. The atrioventricular system during the rapid filling phase was emulated experimentally with a simplified mechanical model in which the relevant pressure decay and the dimension of mitral annulus approximate the physiologic and pathologic values. Digital particle image velocimetry measurements were correlated with the force measurements on the mitral annulus plane to analyze the relation between flow and the mitral annulus motion. The recoil force on the displaced annulus plane was computed on the basis of plane acceleration and plane velocity and correlated with the inflow jet. Measurements of the recoil force for different values of the mitral annulus diameter showed that the recoil force was generated during fluid propulsion and that it is maximal for an annulus diameter close to the normal adult value in a healthy left ventricle. We also tested annulus diameters smaller and larger than the normal one. The smaller annulus corresponds to the stenotic valves and the larger annulus exists in dilated cardiomyopathy cases. In both conditions, the recoil force was found to be smaller than in the normal case. These observations are consistent with the previously reported results for dilated cardiomyopathy and mitral stenosis clinical conditions.
在舒张期左心室内观察到的最重要的流体现象之一是，随着一股强劲的射流通过二尖瓣进入，会形成涡环。本研究聚焦于舒张期的快速充盈阶段，在此期间左心室扩张并通过完全打开的二尖瓣接收血液。在快速充盈阶段，利用一个简化的力学模型对房室系统进行了实验模拟，其中相关的压力衰减和二尖瓣环的尺寸近似于生理和病理值。数字粒子图像测速测量结果与二尖瓣环平面上的力测量结果相关联，以分析血流与二尖瓣环运动之间的关系。基于平面加速度和平面速度计算了移位的瓣环平面上的反冲力，并将其与流入射流相关联。对不同二尖瓣环直径值的反冲力测量表明，反冲力是在流体推进过程中产生的，并且对于健康左心室中接近正常成人值的瓣环直径，反冲力最大。我们还测试了小于和大于正常直径的瓣环直径。较小的瓣环对应于狭窄瓣膜，而较大的瓣环存在于扩张型心肌病病例中。在这两种情况下，发现反冲力均小于正常情况。这些观察结果与先前报道的扩张型心肌病和二尖瓣狭窄临床情况的结果一致。
