Mechanisms of hemolysis with mitral prosthetic regurgitation - Study using transesophageal echocardiography and fluid dynamic simulation
Mechanisms of hemolysis with mitral prosthetic regurgitation - Study using transesophageal echocardiography and fluid dynamic simulation
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DOI：
10.1016/0735-1097(95)00403-3
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发表时间：
1996-02-01
影响因子：
24
通讯作者：
Griffin, BP
中科院分区：
文献类型：
--
作者：
Garcia, MJ;Vandervoort, P;Griffin, BP
目标.本研究的目的是确定人工二尖瓣返流中发生溶血的流体动力学机制，并在数值模拟模型中重现这些机制，以估计峰值剪切应力。尽管体外研究已经证明，剪切应力> 3，000达因/cm（2）与显著的红细胞破坏有关，但尚不清楚这些数值是否会在体内出现异常的假体顺应性流动。我们研究了27例因严重二尖瓣假体返流而接受再次手术的患者，其中16例有溶血，11例无溶血。我们用经食管超声心动图对返流束的起源和几何形状进行了分类。通过使用定义的物理和形态特征，几个流体动力学模式进行了数值模拟，以确定剪切速率。16例溶血患者中有8例（50%）有瓣周漏，另外8例有中心起源的射流，而11例无溶血患者中分别有2例（18%）和9例（82%）（p = 0.12，把握度0.38）。有溶血的患者有碎片（n = 2）、碰撞（n = 11）或快速加速（n = 3）的模式，而没有溶血的患者有自由射流（n = 7）或缓慢减速（n = 4）（p < 0.001，幂0.99）。数值模拟结果显示，这5种模型的峰值剪切速率分别为6，000、4，500、4，500、925和950 dynes/cm（2）。在这些二尖瓣假体溶血患者中观察到的不同的寄生跳蚤模式与快速加速和减速或高峰剪切率或两者相关。在产生临床溶血方面，由假体排斥性病变产生的跳蚤干扰的性质和由此产生的剪切应力增加比流动干扰的起源部位更重要。
Objectives. The aims of this study were to define the hydrodynamic mechanisms involved in the occurrence of hemolysis in prosthetic mitral valve regurgitation and to reproduce them in a numeric simulation model in order to estimate peak shear stress.Background. Although in vitro studies have demonstrated that shear stresses >3,000 dynes/cm(2) are associated with significant erythrocyte destruction, it is not known whether these values can occur in vivo in conditions of abnormal prosthetic regurgitant flow.Methods. We studied 27 patients undergoing reoperation for significant mitral prosthetic regurgitation, 16 with and 11 without hemolysis. We classified the origin and geometry of the regurgitant jets by using transesophageal echocardiography. By using the physical and morphologic characteristics defined, several hydrodynamic patterns were simulated numerically to determine shear rates.Results. Eight (50%) of the 16 patients with hemolysis had paravalvular leaks and the other 8 had a jet with central origin, in contrast to 2 (18%) and 9 (82%), respectively, of the 11 patients without hemolysis (p = 0.12, power 0.38). Patients with hemolysis had patterns of how fragmentation (n = 2), collision (n = 11) or rapid acceleration (n = 3), whereas those without hemolysis had either free jets (n = 7) or slow deceleration (n = 4) (p < 0.001, power 0.99). Numeric simulation demonstrated peak shear rates of 6,000, 4,500, 4,500, 925 and 950 dynes/cm(2) in these five models, respectively.Conclusions. The distinct patterns of regurgitant flea seen in these patients with mitral prosthetic hemolysis were associated with rapid acceleration and deceleration or high peak shear rates, or both. The nature of the flea disturbance produced by the prosthetic regurgitant lesion and the resultant increase in shear stress are more important than the site of origin of the flow disturbance in producing clinical hemolysis.