An investigation of how blood flows through stents after opening clogged arteries has led a team of researchers at the Medical College of Wisconsin Cardiovascular Center in Milwaukee to suggest that stents designed with thinner and fewer linkages may be the basis of a new generation of stents. Their findings are published in the July 2004 issue of the Journal of Applied Physiology.
One of the most common methods for treating heart blockages is balloon angioplasty, inflating tiny catheters with miniature balloons to open clogged arteries. Stents, tiny metal scaffolds, are then placed at the newly opened site in the arteries to permanently prop them open. However, 30 percent of stent patients experience restenosis, where arteries narrow again due to scar tissue and cellular growth that forms around the device.
“Currently, eliminating restenosis is the holy grail of catheter-based procedures such as angioplasty and stenting,” says John LaDisa, Ph.D., of the Medical College, who studied the stent designs. “Current research has not identified all the contributing factors to restenosis,” says Dr. LaDisa. “Now our research has shown that a stent’s design and its alteration of the blood vessel anatomy influences blood flow in ways that can contribute to restenosis. Also, restenosis rates vary according to an individual’s vessel geometry at the site of stent insertion.”
Using 3D computational fluid dynamic modeling, Dr. LaDisa investigated specific factors of stent geometry that contribute to, or minimize, the likelihood of restenosis. “We tested the hypothesis that differences in the geometric design of an implanted stent -- differences in number, width and thickness of the linkages that compose a stent -- affects the forces exerted on cells lining the vessel walls and ultimately influences restenosis rates,” he says.