Wendt M O, Pohl M, Pratsch S, Lerche D
Institut für medizinische Physik und Biophysik Medizinische Fakultät Charite, Humboldt-Universität zu Berlin, Germany.
Int J Artif Organs. 1992 Nov;15(11):681-5.
Hemolytic and subhemolytic blood damage by mechanical heart valve prostheses have been observed in both clinical and in vitro investigations. A direct comparison between these studies is not possible. Nevertheless the transfer of some in vitro results to the behaviour of the valve in situ may be performed considering the similarity principle. This requires the use of dimensionless similarity numbers such as the plasma's hemoglobin concentration (PHb) or others, instead of dimensioned parameters. To evaluate the in vitro hemolysis of valve prosthesis a test chamber filled with human banked blood was used. An artificial ventricle ensuring an oscillatory flow through the valve was also used. The rise of PHb was evaluated in terms of a similarity number, called the lysis number. This number describes the probability of destroying a single red blood cell participating once in the hemolytic process under consideration. The lysis number, a Björk-Shiley valve (TAD 29), was found to be in the order of 2 x 10(-4). From this, the survival time of erythrocytes in patients with an artificial heart valve was estimated. It was found to be in the order of 20 d of T50 Cr in agreement with clinical results.
在临床和体外研究中均观察到机械心脏瓣膜假体造成的溶血和亚溶血血液损伤。这些研究之间无法进行直接比较。然而，考虑到相似性原理，可以将一些体外研究结果应用于瓣膜在体内的行为。这需要使用无量纲相似性数值，如血浆血红蛋白浓度（PHb）或其他数值，而非有量纲的参数。为评估瓣膜假体的体外溶血情况，使用了一个充满人库存血的测试腔室。还使用了一个人造心室以确保血液通过瓣膜产生振荡流动。PHb的升高根据一个称为溶血数值的相似性数值进行评估。该数值描述了在考虑的溶血过程中单个参与其中的红细胞被破坏的概率。发现一种Björk-Shiley瓣膜（TAD 29）的溶血数值约为2×10⁻⁴。据此，估算了人工心脏瓣膜患者红细胞的存活时间。结果发现其T50 Cr约为20天，与临床结果相符。
