February 15, 2001

Computer-Aided Designs of Blood Vessels and Bypass Grafts: Goals of NC State Engineer

The term "computer simulation" conjures up images of virtual reality, movie sequences and video games; however, another use for this technology is of tangible benefit to humankind. Dr. Clement Kleinstreuer, professor of mechanical and aerospace engineering at NC State and an expert in modeling fluid-particle dynamics via computer simulations, has developed criteria and a new method for designing better arteries, veins and bypass grafts for patients whose own blood vessels are damaged or partially occluded. The goal of this research is to design synthetic or biocompatible blood vessels that promote smooth, even blood flow.

For example, dialysis patients must endure repeated trauma to their veins as they receive weekly treatments. Arteriovenous access grafts (AVGs), as the name implies, provide a portal through which the blood is removed, purified in an artificial kidney and then returned to the body. The traditional teflon-based, tubular graft used to administer dialysis is subject to frequent failure at the graft-to-vein junction, meaning a patient may run out of healthy vein entry ports.

Kleinstreuer’s research group tested a recently developed AVG manufactured by a company that specializes in vascular products. "Basically, we analyzed the product, which was based on one of our previous designs, and showed fundamentally why it performed better in clinical trials," said Kleinstreuer. "We then went one step further and developed a graft-hood design more complicated in terms of the geometry but with the positive effect that it generates an even nicer, smoother blood flow." Technical details of the AVG geometries may be found in the May/June 2000 issue of the Journal of Medical Engineering and Technology.

The research analysis involves virtual prototyping, or designing and testing in virtual reality rather than in the real world. Using computer tools helps researchers determine accurately the three-dimensional geometry of the design.

Unfortunately, the geometry of these artificial blood vessels is highly complex, making manufacturing difficult. To produce them, manufacturers would have to grow them outside the body, ie, in a laboratory environment. This may be possible in the near future, when blood vessels containing any type of geometric features could be grown.

For now, Kleinstreuer’s team continues to develop new ideas for blood flow analysis and optimal blood vessel geometries using virtual prototyping. "We are investigating these questions with the computer, trying to duplicate the real-world physico-biological processes," according to Kleinstreuer. In addition to a better dialysis graft, concurrent applications include a streamlined carotid artery that would greatly reduce the buildup of arterial plaque. This design could help prevent stroke in patients due to thrombosis in the carotid, which is the main artery to the brain and face.

In collaboration with Dr. Joseph P. Archie Jr., a vascular surgeon at Wake Medical Center and adjunct professor in NC State’s Department of Mechanical and Aerospace Engineering, and Dr. George A. Truskey, associate professor of biomedical engineering at Duke University, this research is sponsored by the National Institutes of Health, the National Science Foundation and industry.

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Technical Contact: Dr. Clement Kleinstreuer, 919-515-5261, ck@eos.ncsu.edu
Media Contact: Linda E. Rudd, 919-515-3848, linda_rudd@ncsu.edu

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