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University of Iowa News Release


March 22, 2007

UI Engineer Receives Grant To Study Medical Implant Design

Improving the quality of life for individuals who receive certain types of implants in connection with cardiovascular surgery is the goal of a University of Iowa College of Engineering researcher who has received a two-year, $221,250 grant from the National Institutes of Health.

Madhavan L. Raghavan, associate professor of biomedical engineering and project principal investigator, says that more than 3,000 patients in the United States annually receive an implant called an "endovascular graft" (EVG). The implant is typically used to repair aortic aneurysms, an incident occurring when a blood vessel in the abdomen becomes abnormally large or balloons outward.

Researchers plan to study the role that certain EVG design aspects play in its post-implant performance and whether these design elements may be improved, according to Raghavan. Dr. Jafar Golzarian, clinical professor of radiology in the UI Roy J. and Lucille A. Carver College of Medicine is the clinical collaborator on the project. He is an expert in EVG implantation and is providing the engineers with clinical insights and advice. Jarin Kratzberg, a biomedical engineering doctoral student and Bill Barnhart, who recently retired as a radiology technician from UI Hospitals and Clinics, are working with Raghavan on the project.

"Improvements in implant design will significantly minimize post-operative complications and/or additional procedures for patients in the United States and world-wide," Raghavan says.

In particular, the project will examine EVG barbs, needle-like structures designed to penetrate the aortic wall, hold the implant in place and prevent it from failing.

Although there have been many studies comparing commercial EVGs, few have assessed specific EVG design variables in a controlled environment with the aim of optimizing them. This is important because a significant number of EVGs tend to migrate during the first few years following implantation. Also, there are a wide variety of commercial EVG designs on the market and their relative merits are unclear, making it difficult for physicians to choose devices for specific patients.

Raghavan says his EVG design studies evaluating graft size and barb length will be performed in an in vitro system that simulates the hemodynamics of human endovascular repair. The overall objective is to identify the optimal combination of graft oversizing and barb length that maximizes graft attachment strength following the implant. He says it is logical for engineers to be involved in such studies, since the question of implant safety is similar, for example, to bridge safety. Both involve materials and variables that change over time due to the forces acting on them.

"The findings from this study may aid physicians in making prudent, educated decisions on graft oversizing. It may also aid device manufacturers in designing EVG barbs that minimize migration risk," he says.

STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Suite 301, Iowa City, Iowa 52242-2500.

MEDIA CONTACT: Gary Galluzzo, 319-384-0009,