Keeping the blood flowing—
stents open clogged arteriesLast year 1.1 million patients worldwide were treated for clogged arteries with a surgical intervention known as balloon angioplasty. A significant percentage of those surgical procedures fail. Thanks to the invention of a special stent by a Health Science Center radiologist, however, many of those patients have a second chance at life.
When blood vessels feeding the heart become clogged with fat (atherosclerosis) they may shut down, causing a heart attack. To treat the blockage, a balloon-tipped catheter is surgically inserted into the artery at the site of the blockage. The balloon is inflated, which opens the artery, and the catheter is then removed. Such balloon angioplasties have a 40 percent failure rate. Even when the procedures are initially successful, some patients experience a recurrence of the blockage within six months.
Julio C. Palmaz, MD, Stewart R. Reuter Distinguished Professor and chief of cardiovascular and interventional radiology at the Health Science Center, invented a tiny tube made from woven, surgical-grade stainless steel to help patients who have had an unsuccessful angioplasty procedure. The Palmaz Balloon-Expandable Stent is mounted on an angioplasty catheter and introduced through a thin-walled sheath into the cardiac and iliac arteries to prevent closure (see illustration).
In 1997 half of the 1.1 million balloon angioplasty patients received a stent, according to the publication Cowen Cardiology Device Update. The stent, which has been in use for about 10 years, can expand as much as a half-inch in diameter after it has been inserted into a large artery. This creates a scaffold which covers 10 percent of the affected artery wall and keeps it open so blood can flow through it. Tissue grows around the stent in less than three weeks, forming a smooth artery wall. Dr. Palmaz calculates his stent will last throughout the patient’s lifetime.
"This device also is useful in patients who undergo bypass surgery in which the grafts become narrowed," Dr. Palmaz explained. "One of the most famous stent recipients was Mother Teresa, and the person who holds the ‘world’s record’ for the most number of stents is the Health Science Center’s director of laboratory animal resources, Dr. Robert H. Wolf."
"One week I was working with Dr. Palmaz putting these stents in dogs, and the next week I was on the receiving end," recalled Dr. Wolf, a veterinarian. "Dr. Palmaz put nine stents in me. A couple of decades ago, people with my condition would simply lose their legs."
"Hopefully, someday we’ll be able to prevent atherosclerosis," Dr. Palmaz added. "This is the direction medicine is going—toward preventing rather than treating disease. If surgery is needed, the trend is to do it without major trauma, but until atherosclerosis can be eliminated, the stent is available. It’s like a Band-Aid® or a tire patch, but at least we have it." And that makes millions of patients very happy.
