Department of Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Med Eng Phys. 2011 Apr;33(3):263-80. doi: 10.1016/j.medengphy.2010.10.014. Epub 2010 Nov 13.
Progress in the field of prosthetic cardiovascular devices has significantly contributed to the rapid advancements in cardiac therapy during the last four decades. The concept of mechanical circulatory assistance was established with the first successful clinical use of heart-lung machines for cardiopulmonary bypass. Since then a variety of devices have been developed to replace or assist diseased components of the cardiovascular system. Ventricular assist devices (VADs) are basically mechanical pumps designed to augment or replace the function of one or more chambers of the failing heart. Computational Fluid Dynamics (CFD) is an attractive tool in the development process of VADs, allowing numerous different designs to be characterized for their functional performance virtually, for a wide range of operating conditions, without the physical device being fabricated. However, VADs operate in a flow regime which is traditionally difficult to simulate; the transitional region at the boundary of laminar and turbulent flow. Hence different methods have been used and the best approach is debatable. In addition to these fundamental fluid dynamic issues, blood consists of biological cells. Device-induced biological complications are a serious consequence of VAD use. The complications include blood damage (haemolysis, blood cell activation), thrombosis and emboli. Patients are required to take anticoagulation medication constantly which may cause bleeding. Despite many efforts blood damage models have still not been implemented satisfactorily into numerical analysis of VADs, which severely undermines the full potential of CFD. This paper reviews the current state of the art CFD for analysis of blood pumps, including a practical critical review of the studies to date, which should help device designers choose the most appropriate methods; a summary of blood damage models and the difficulties in implementing them into CFD; and current gaps in knowledge and areas for future work.
在过去的四十年中，人工心血管设备领域的进展极大地促进了心脏治疗的快速发展。机械循环辅助的概念是随着第一台用于心肺转流的成功临床应用的心肺机而建立的。从那时起，已经开发出各种设备来替代或辅助心血管系统的患病部件。心室辅助装置（VAD）基本上是设计用来增强或替代衰竭心脏的一个或多个腔室功能的机械泵。计算流体动力学（CFD）是 VAD 开发过程中的一种有吸引力的工具，允许在不制造物理设备的情况下，对各种不同的设计进行虚拟的功能性能特性化，以满足广泛的操作条件。然而，VAD 运行在一个传统上难以模拟的流动状态下；层流和湍流边界的过渡区域。因此，已经使用了不同的方法，并且最佳方法是有争议的。除了这些基本的流体动力学问题外，血液还包含生物细胞。器械诱导的生物并发症是 VAD 使用的严重后果。并发症包括血液损伤（溶血、血细胞激活）、血栓形成和栓塞。患者需要持续服用抗凝药物，这可能导致出血。尽管付出了很多努力，但血液损伤模型仍然没有令人满意地应用于 VAD 的数值分析中，这严重削弱了 CFD 的全部潜力。本文综述了目前用于分析血泵的 CFD 技术，包括对迄今为止的研究进行了实际的批判性回顾，这应该有助于设备设计师选择最合适的方法；总结了血液损伤模型及其在 CFD 中实施的困难；以及目前知识的差距和未来工作的领域。
