Implanting 'stents' with staying power.

Implanting "stents' with staying power

Another approach to treating renarrowed arteries has produced the latest in implantable cardiac-care gadgets. In order to give these newly opened vessels some "backbone,' researchers are placing tubes called stents inside the affected area. All the various stents discussed at the Anaheim meeting are designed to hold open a vessel that threatens to close, but they differ in structure. There are about a dozen models being evaluated worldwide. The only one thus far approved by the Food and Drug Administration for clinical use was developed at the University of Texas Health Science Center in San Antonio.

Made of a tube of collapsed stainless steel mesh, the Texas stent is delivered to a partially blocked artery on a balloon catheter, which opens up the stent as the balloon expands (the balloon catheter is then removed). About a half-inch long and the diameter of spaghetti before expansion, the stent has been used successfully in 13 patients in Texas and West Germany, says Richard A. Schatz, now at the Arizona Heart Institute Foundation in Phoenix. The first was implanted about six months ago, and all treated vessels are still open, he says. This particular stent, however, has not been approved for use in the heart's own arteries, but is used mainly in the arms and legs. Approval for use in the heart awaits more conclusive results in animal experiments. Other stents--being tested at Vaudois University Hospital Center in Lausanne, Switzerland, and at Emory University School of Medicine in Atlanta--are performing well when placed in coronary arteries, say their designers. An added feature of these models, say the Swiss and Atlanta scientists, is their flexibility, which allows them to bend along twisting vessels.