1.1 本指南旨在提供一种实验方法来评估和确定植入式心血管医疗器械的结构疲劳寿命。 1.2 本指南还旨在提供确定疲劳寿命统计界限的方法 体内 使用从超生理测试到骨折的全部或部分得出的测量疲劳寿命的使用条件。 1.3 本指南可用于评估或表征设计开发期间的设备耐久性，并用于测试设备产品规范。 1.4 微动、磨损、蠕变疲劳和可吸收材料不在本指南的范围内，尽管本指南的内容可能适用。 1.5 作为指导，本文件提供了方向，但不推荐具体的行动方案。其目的是提高对信息和方法的认识。本指南不是测试方法。 本指南并没有建立在所有情况下都要遵循的标准实践。 1.6 本指南是对其他监管和设备特定指导文件或标准的补充，并不取代此类文件的建议或要求。 1.7 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.8 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 该方法的使用: 5.1.1 本指南提供了使用断裂数据、疲劳寿命模型和统计技术估计预期植入医疗器械结构疲劳耐久性的方法的信息概要 体内 加载模式。高周疲劳评估方法依赖于旨在导致设备断裂的超生理测试。使用FtF方法，测试期间不应避免破裂；相反，它们提供了在各种生理和超生理测试条件下统计评估设备寿命所需的信息。 5.1.2 通过评估骨折位置、骨折后的几何形状和器械的使用条件，本指南可用于帮助评估器械的安全性。 5.1.3 本指南可用于帮助评估不同设备或设备历史之间的疲劳寿命差异。 可使用本指南评估设备几何形状、加工或材料变化对疲劳寿命的影响。 5.1.4 本指南的用户必须记住，台架试验是在用条件的模拟。遵守本指南可能无法保证结果转化为个别临床场景。因此，在评估设备的疲劳性能时，应结合其他可用数据（如动物研究、临床经验和计算模拟）审查疲劳至断裂测试的结果。 5.2 该方法的意义: 5.2.1 虽然FtF方法仅适用于台架试验，但它可以深入了解设备行为，而这些行为在通常侧重于患者结果的临床研究中并不一定明显。在确定了适当的边界条件（如载荷、夹具和材料）后，FtF方法可以在比实际寿命短10到1000倍的时间内提供关于设备预期寿命的广泛信息- 时间临床研究。 5.2.2 FtF在表征设备在各种负载和循环下的行为方面提供了信息。当 体内 负荷模式是可以理解的，但负荷大小和周期要求并不清楚，或者当需要在患者寿命、活动水平和生理状态的广泛范围内表征设备性能时。 5.2.3 在FtF中，使用大于设备预期使用条件的测试负载。因此，可以相对于预期值测量安全系数 体内 加载/变形严重程度和循环次数的使用条件。 5.2.4 在FtF中，观察到的作为负载函数的裂缝性质和位置有助于深入了解设备对施加负载的响应。确定的主要和后续骨折位置和模式可用于评估设备计算模型的可信度，以及评估对临床安全性和疗效的潜在影响，尤其是术后- 骨折 5.2.5 FtF方法可以快速、可靠地评估工艺、材料或几何形状的微小变化对 体外 疲劳寿命。这些关于断裂的评估可以量化，并作为验证设计变更的一部分，证明设备符合产品规范，或作为指导设计改进的一部分。 5.2.6 FtF测试通常可以在比测试成功测试更短的时间内完成，因为FtF测试通常在更少的周期内终止。具体来说，当循环外推适当时，比较较低循环次数下的载荷或断裂频率可以提供有用的等效性度量。

1.1 This guide is intended to provide an experimental methodology to assess and determine the structural fatigue life of implantable cardiovascular medical devices. 1.2 This guide is also intended to provide methodologies to determine statistical bounds on fatigue life at in vivo use conditions using measured fatigue life derived in whole or in part from hyper-physiological testing to fracture. 1.3 This guide may be used to assess or characterize device durability during design development and for testing to device product specifications. 1.4 Fretting, wear, creep-fatigue, and absorbable materials are outside the scope of this guide, though elements of this guide may be applicable. 1.5 As a guide, this document provides direction but does not recommend a specific course of action. It is intended to increase the awareness of information and approaches. This guide is not a test method. This guide does not establish a standard practice to follow in all cases. 1.6 This guide is meant as a complement to other regulatory and device-specific guidance documents or standards and it does not supersede the recommendations or requirements of such documents. 1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health and environmental practices and determine the applicability of regulatory limitations prior to use. 1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Use of this Methodology: 5.1.1 This guide provides a compendium of information on methods to use fracture data, fatigue life models, and statistical techniques to estimate the structural fatigue durability of an implantable medical device under anticipated in vivo loading modes. The methodology for high-cycle fatigue assessment relies on hyper-physiological tests intended to cause device fractures. Using the FtF methodology, fractures should not be avoided during testing; instead they provide the information required to statistically assess device longevity under a wide variety of physiological and hyper-physiological test conditions. 5.1.2 Through evaluation of fracture locations, the geometries after fractures, and the use conditions of the device, this guide may be used to help assess device safety. 5.1.3 This guide may be used to help assess differences in fatigue life between different devices or device histories. The effects on fatigue life due to changes to a device’s geometry, processing, or material may be assessed using this guide. 5.1.4 Users of this guide must keep in mind that bench tests are simulations of in-use conditions. Adherence to this guide may not guarantee that results translate to individual clinical scenarios. Therefore, in assessing a device’s fatigue performance, the results from Fatigue to Fracture testing should be reviewed in combination with other available data, such as animal studies, clinical experience, and computational simulations. 5.2 Significance of this Methodology: 5.2.1 While the FtF methodology applies only to bench tests, it can provide insights into device behavior that would not necessarily be apparent in clinical studies that typically focus on patient outcomes. After appropriate boundary conditions such as loadings, fixturing, and materials have been determined, the FtF methodology can provide extensive information on the expected longevity of a device in a period 10 to 1000 times shorter than a real-time clinical study. 5.2.2 FtF is informative in characterizing device behavior over a wide range of loads and cycles. This is especially valuable when the in vivo loading mode is understood but the load magnitude and cycle requirements are not well known or when characterizing device performance over a wide range of patient lifetimes, activity levels, and physiological states is desired. 5.2.3 In FtF, test loads greater than the devices’ expected use conditions are used. Thus, factors of safety can be measured relative to expected in vivo use conditions in both loading/deformation severity and number of cycles. 5.2.4 In FtF, the nature and location of fractures observed as a function of load can help provide insights into the device response to the applied loading. The identified primary and follow-on fracture locations and modes may be used to assess the credibility of device computational models, as well as to evaluate potential impacts on clinical safety and efficacy, especially post-fracture. 5.2.5 The FtF methodology can quickly and reliably assess the impact of changes in processes, materials, or small changes in geometry on in vitro fatigue life. These assessments with respect to fracture can be quantified and used as part of validating design changes, demonstrating that the device meets product specifications, or as part of guiding design improvements. 5.2.6 FtF testing can often be completed in a shorter period of time than test-to-success testing since the FtF tests are typically terminated at a smaller number of cycles. Specifically, when extrapolation in cycles is appropriate, comparisons of the loads or the frequency of fracture at a lower number of cycles can provide a useful measure of equivalence.