University of Florida Physicians At Shands Cardiovascular Center Study Use Of Low-Dose Radiation In Angioplasty
GAINESVILLE—University of Florida physicians at Shands Cardiovascular Center at UF are the first in the state to test whether low-dose radiation administered within a coronary artery at the time of angioplasty can help keep the vessel open.
Less costly and less invasive than heart bypass surgery, balloon angioplasty is often the treatment of choice for reopening arteries clogged with fatty build-up, a condition known as atherosclerosis. But in up to 40 percent of patients, the procedure itself can mildly injure the vessel wall, spurring the body to mount an exaggerated healing response that leads to excess scar formation — and renarrowing of the artery.
“That renarrowing, known as restenosis, usually leads to recurrent symptoms, and if that occurs then you’re likely to need repeat angioplasty. A number of patients eventually need surgery if angioplasty is not effective,” said Dr. Richard Kerensky, an associate professor of medicine at UF’s College of Medicine and director of the cardiac catheterization laboratory at the Shands at UF medical center.
“There is evidence from dermatology and plastic surgery that low-dose radiation can shrink scars on the skin,” he added. “The theory behind this treatment for restenosis prevention is that if we give low-dose radiation at the time of injury, which in this case is at the time of angioplasty or stenting, you might prevent the overexuberant scar. There are lots of animal studies to support this theory, but we need to determine if this strategy is effective in patients.”
During balloon angioplasty, physicians thread a catheter into the narrowed portion of an artery and inflate a small balloon, compressing plaque against the artery’s wall and enlarging the channel where blood flows. Sometimes they use a stent, a tiny mesh tube crafted from metal that acts as a scaffolding inside the artery, to help prop it open.
More than 400,000 angioplasties are performed in the United States each year, according to the American Heart Association.
UF researchers are participating in two national, multicenter studies to see whether radiation inhibits scar formation in two groups of patients: those undergoing traditional angioplasty and those who have had stents implanted. Other sites include the University of Maryland, Wake Forest University Baptist Medical Center and Duke University. The UF team includes Dr. Robert Zlotecki, an assistant professor of medicine in the department of radiation oncology, and registered nurses Kurt Malphurs and Gwen Thomas, among others.
Patients undergoing angioplasty who elect to participate are randomly assigned to undergo either traditional angioplasty or angioplasty plus radiation therapy. Neither they nor their physicians will know which treatment they received until after the study is completed. About 1,200 participants will be tracked nationwide.
Physicians administer the radiation through a device that contains radioactive pellets. The unit, called the Beta-Cath System and manufactured by Norcross, Ga.-based Novoste Corp., is attached to a catheter similar to the one used during the actual angioplasty and placed in the treated artery. The pellets radiate the vessel from inside the catheter for two to five minutes and never come in direct contact with tissue.
A second study of 900 patients will involve radiation therapy to treat patients who have had stents placed in their coronary arteries and then developed restenosis inside the stent, said interventional cardiologist Dr. Karen Smith, an assistant professor of medicine at UF’s College of Medicine.
“That problem is probably a little different than treating the original coronary artery disease, but either way we are trying to determine whether radiation keeps those vessels and those stents open longer,” Smith said.
After eight months, participants in both studies will undergo cardiac catheterization so physicians can determine whether the treated vessel has remained open.
“We need both angiographic and clinical follow-up of these patients in order to determine if low-dose intracoronary radiation is effective in preventing restenosis,” Kerensky said.