Evolution and future of preclinical testing for endovascular grafts

The preclinical testing of endovascular grafts has evolved significantly since the creation and early testing of these devices; however, there are continued limitations in using preclinical testing to predict clinical performance. Early testing was conducted in the absence of standards and guidance specific to endovascular grafts, and references available for vascular grafts and stents did not adequately account for the complexity of endovascular graft systems. Failure of early-generation devices suggested that the testing being conducted was inadequate and that there was a lack of understanding of the in vivo environment. These concerns led to several efforts to improve preclinical testing. The Food and Drug Administration (FDA) sponsored a workshop to discuss the limitations inherent in testing of endovascular grafts, and an ISO standard for endovascular grafts was developed. Publication of the standard in 2003 succeeded in standardizing testing and reporting across device manufacturers; however, several clinical failure modes, such as migration and stent fractures, continued to be unpredicted by current preclinical testing. This, coupled with knowledge gained from additional clinical experience, led the FDA to hold a second workshop to discuss the benefits and limitations of current testing and propose future testing that may better predict device performance. This workshop was successful in accurately describing past testing, determining what has been learned, identifying issues that have not been adequately addressed, proposing modifications to address these limitations, and discussing how the proposed modifications should be implemented. While significant progress has been made in endovascular graft testing, continued collaboration among industry, academia, regulators, and clinicians will provide continued improvement in the predictability of device performance.