Fehske W, Köhler J, Rabahieh R, Braun P, Hostert A, Lüderitz B
Medizinische Universitätsklinik, Innere Medizin--Kardiologie, Bonn.
Z Kardiol. 1991 Jul;80(7):441-8.
In a flow model the effective orifice areas (Ae) of 17 mechanical heart valve prostheses were determined. We measured the Ae-values of several sizes of three types of mechanical prostheses (Medtronic-Hall, St. Jude Medical, and Omnicarbon) under quasi-steady flow conditions using the continuity equation: Ae = flow/maximal transprosthetic velocity. The flow through the model could be determined exactly by directly measuring the decreasing fluid level within the feed tank, while the maximal velocities were calculated from CW-Doppler echocardiographic spectra. It was found that 1) over a range of 200-800 cm3/s Ae was constant for all prostheses and 2) in small aortic prostheses the Ae could be determined with only little scattering of the obtained values, while in large mitral prostheses there was a considerable variation within the results of repeated investigations. For example, in the 21- and 31-Omnicarbon-valves mean values of Ae were calculated as 1.41 and 4.03 cm2, respectively, with standard deviations of 0.05 and 0.49 cm2 as a result of about 70 single calculations in each valve. 3) The absolute values of Ae were smaller than those of comparable in vitro studies based on the Gorlin formula. We conclude that the effective orifice areas of prosthetic heart valves can be easily determined in a flow model by the combination of flow and Doppler echocardiographic measurements. As determinations are based on the same principle, the obtained values should clinically be referred to patients where the corresponding continuity equation for pulsatile flow is used as Ae = stroke volume/time integral of the maximal transvalvular velocity.
在一个血流模型中，测定了17种机械心脏瓣膜假体的有效瓣口面积（Ae）。我们在准稳态血流条件下，使用连续性方程：Ae = 流量/最大跨假体流速，测量了三种类型机械假体（美敦力 - 霍尔、圣犹达医疗和全碳）几种尺寸的Ae值。通过直接测量进料罐内下降的液位可以精确确定模型中的流量，而最大流速则根据连续波多普勒超声心动图频谱计算得出。结果发现：1）在200 - 800 cm³/s的范围内，所有假体的Ae均保持恒定；2）在小型主动脉假体中，Ae的测定值离散度很小，而在大型二尖瓣假体中，重复测量结果存在相当大的差异。例如，在21号和31号全碳瓣膜中，由于每个瓣膜大约进行了70次单次计算，Ae的平均值分别计算为1.41和4.03 cm²，标准差分别为0.05和0.49 cm²。3）Ae的绝对值小于基于戈林公式的类似体外研究的值。我们得出结论，通过结合流量和多普勒超声心动图测量，可在血流模型中轻松测定人工心脏瓣膜的有效瓣口面积。由于测定基于相同原理，临床应用中，所得值应参考使用脉动血流相应连续性方程（Ae = 每搏量/最大跨瓣流速的时间积分）的患者。
