Cardiologists at Rush study use of low-dose radiation to prevent restenosis in leg arteries

November 30, 2001

Blood vessels and arteries in the legs can become blocked just like those in the heart, but a new study being conducted at Rush-Presbyterian-St. Luke's Medical Center in Chicago seeks to offer patients with peripheral arterial disease (PAD) hope. Approximately 40 percent of people over age 70 experience symptoms of PAD, including numbness in the feet, pain, cramping or burning sensations in the legs and decreased mobility. A recent study in the Journal of the American Medical Association found that many doctors miss symptoms of PAD and fail to diagnose these symptoms as indicating significant risks for coronary artery disease.

Currently, patients with PAD receive angioplasty and a stent, which is a small metal spring that props open the blood vessel. But, between 50 and 80 percent of patients who receive this treatment suffer restenosis, or re-narrowing of the leg artery that was treated.

To prevent restenosis, Rush interventional cardiologists are testing a catheterization technique using low-dose radiation in much the same way they have used radiation as a method to prevent restenosis from occurring in arteries in the heart.

In this new study, patients will receive treatment using a device called the RDX Peripheral Radiation Delivery System made by Radiance Medical Systems. Previous studies have shown that using radiation inside the catheter is effective, but incorporating the radiation into the balloon, which compresses the blockage onto the sides of the artery, seems to be more effective at lowering restenosis rates.

"The system is unique because the radiation is integrated into the membrane of a balloon catheter," said Dr. Jeffrey Snell, co-director of the Cardiac Catheterization Laboratories and principle investigator of the study. The trial is called "Radiation After PTA is Done or RAPID." Snell explained that when inflated, the balloon is brought into complete contact with the leg vessel wall, providing more uniform, complete coverage and distribution of the radiation. Since penetration depths of beta isotopes are limited to four or five millimeters in tissue or fluid, this device is more ideally suited for treating larger arteries in the leg.

"This re-narrowing happens because cells in the artery wall divide and proliferate as a healing response to the injury caused by the angioplasty balloon or stent placement. Low-dose local radiation therapy actually inhibits the cells' ability to respond in this way, thereby substantially reducing the re-narrowing response," Snell said.

"This is significant because the arteries in the leg are larger than the chest so the radiation needs to penetrate completely to have any effect," he said.

The catheter used in the RAPID trial is administered through the femoral artery, just like an angioplasty for heart disease. With PAD patients, the cardiologist directs the catheter down the leg to the blocked area where the balloon at the tip is expanded to open up the blockage. After receiving treatment, patients return for check ups at 30 days, six months and 12 months.

According to Dr. Gary Schaer, director of the Rush Cardiac Catheterization Laboratories, preliminary trials using the RDX Peripheral Radiation Delivery System have shown the restenosis rates can be reduced significantly. "A study published last year showed that restenosis rate was 28 percent in those patients receiving radiation for PAD but 53 percent in those receiving standard treatment opening up the blockage but no radiation," he said. People who are interested in enrolling in the study should call 312/942-4655 between the hours of 9 - 5 Monday through Friday.

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Additional Contact:
John Pontarelli

Rush University Medical Center

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