A team of engineers and surgeons led by Dr. Clement Kleinstreuer, professor of mechanical and aerospace engineering at North Carolina State University, is using computer simulation to pioneer new, experimental methods of designing synthetic arteries, veins and bypass grafts.
The goal of the research is to design biocompatible synthetic blood vessels that promote smooth, even blood flow.
If successful, the research -- which is now in the virtual prototyping stage -- would be a boon for patients whose blood vessels are damaged or partially occluded, such as patients at risk of stroke due to arterial plaque buildup, or dialysis patients who must endure repeated trauma to their veins as they receive weekly blood-cleansing treatments.
Kleinstreurer is an expert on the use of computer simulation to model fluid-particle dynamics. His research team includes 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.
Their research is sponsored by the National Institutes of Health, the National Science Foundation and industry.
For dialysis patients, Kleinstreuer’s virtual prototyping technology could result in better arteriovenous access grafts. These grafts provide a portal through which the patient’s blood is removed, purified in an artificial kidney and then returned to the body. The conventional teflon-based, tubular graft now 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.
A synthetic arteriovenous access graft, based on a design by Kleinstreuer’s team and manufactured by a company that specializes in vascular products, shows promise of resolving this problem. It’s performed well in clinical trials and laboratory tests. "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."
Kleinstreuer’s team’s research involves virtual prototyping, or designing and testing in virtual reality, rather than in the real world. Using computer tools helps researchers accurately determine 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, in a laboratory environment. This may be possible in the near future, Kleinstreuer says.
For now, however, his 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," he said. In addition to a better dialysis graft, other possible 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.
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