The heart valve prosthesis must have excellent hydrodynamic performance which is usually tested in vitro, not in vivo. This paper comprehensively introduced the principles and methods of hydrodynamic performance in vitro testing, helping clinicians to understand valve performance parameters, evaluate valve applicability, and reduce clinical risk of the valve prosthesis. In vitro testing not only serves as the "gold standard" for valve prosthesis assessment, but also provides detailed data for design and optimization of the prosthesis. ISO 5840 defines the items and methods for valve in vitro testing, which consists of three parts: (1) pulsatile flow testing, which reproduces the pulsating flow of the valve prosthesis after implantation in the human body; (2) steady flow testing, which assesses valve forward flow resistance; (3) durability testing, which evaluates the durability of the valve prosthesis and determines the expected failure mode. In addition, the paper presented the differences between atrioventricular and aortic valve testing, the method of mitral valve testing, the differences between transcatheter and surgical valve testing, and the method of valve flow visualization.
GB/T 21415－2025 is identical to ISO 17511: 2020 and replaces GB/T 21415－2008. It extends metrological traceability requirements from calibrators and control materials to values assigned to human samples, and introduces enhanced elements such as maximum allowable expanded measurement uncertainty, validation of metrological traceability, commutability assessment, and international harmonization protocols. This article systematically reviews the scope, general requirements, and the six calibration hierarchy structures of the standard. It focuses on key implementation aspects including the definition of the measurand, selection of reference systems, uncertainty budget allocation, and commutability. In addition, it clarifies the responsibilities and requirements for in vitro diagnostic medical device manufacturers, reference material producers, reference measurement laboratories, and medical laboratories, aiming to help relevant institutions establish applicable and verifiable value-transfer chains and to promote accuracy, comparability and mutual recognition of test results.