Preclinical testing for aortic endovascular grafts: results of a Food and Drug Administration workshop.

Background: Since their introduction into clinical trials in the United States, endovascular aortic grafts have shown various types of problems. Although details of design and construction vary between different endovascular grafts and failure modes have had a variety of causes and clinical effects, the inability of preclinical testing to predict these failures remains common to all endovascular grafts. The need to improve preclinical testing in an attempt to reduce clinical device failures resulted in a Food and Drug Administration-sponsored workshop on endovascular graft preclinical testing held in Rockville, Md, from July 31 to August 1, 2001. FORMAT: The workshop was not designed as a consensus conference. Instead, it provided a forum for bringing stakeholders together to define problems and identify areas of agreement and disagreement. The workshop had 34 invited participants who represented device manufacturers, the medical community, the Food and Drug Administration, and testing facilities, and international attendance was more than 120 people.

Outcome: Discussion centered on: 1, defining the physiologic, anatomic, and morphologic characteristics of abdominal aortic aneurysms before and after endovascular graft treatment; 2, identifying the types of failures that have been observed clinically; and 3, determining which characteristics should be considered during preclinical modeling to better predict clinical performance. Attendees agreed to the need to better define and address anatomic characteristics and changes in the aneurysm after endograft treatment to optimize preclinical testing. Much discussion and little agreement occurred on the importance of flow-related forces on graft performance or the need or ability to define and model physiologic compliance during durability testing. The discussion and conclusions are summarized in this paper and are provided in detail at: http://www.fda.gov/cdrh/meetings/073101workshop.html.

Conclusion: The workshop raised awareness of significant performance issues and the challenges of modeling the extremely variable and relatively undefined environment of abdominal aortic aneurysms. Through the interactive format of the workshop, participants identified areas of preclinical testing, device design, and aspects of the simulated environment that need further consideration.