Reclogging after angioplasty Don't know if this already got posted. Deals with the reclogging of arteries after angioplasty issue--Monday March 16, 8:30 am Eastern Time
Company Press Release
SOURCE: Columbia-Presbyterian Medical Center
Radiation May Prevent Heart Vessels from Re-Clogging
After Angioplasty
NEW YORK, March 16 /PRNewswire/ -- A new treatment that prevents arteries from re-clogging
after angioplasty is being evaluated in clinical trials at Columbia-Presbyterian Medical Center. In the
treatment, radiation is applied to the interior of the arteries immediately after balloon angioplasty.
Columbia-Presbyterian is currently the only institution testing this procedure.
''Each year, about a half-million people undergo interventional procedures to open clogged heart
arteries. In 30 to 40 percent of these patients, the vessels close back up, or restenose, necessitating
either another procedure of the same sort or bypass surgery,'' explains study leader Judah
Weinberger, MD, who is associate professor of Clinical Medicine and Pharmacology at
Columbia-Presbyterian. The use of stents (metal scaffolds inserted in the artery) has helped, but
restenosis remains a significant problem.
Several years ago, Dr. Weinberger and his colleagues hypothesized that radiation therapy might
forestall restenosis. In their view, vessels restenose because of injuries suffered during the angioplasty
procedure itself. During angioplasty, a balloon-tipped catheter is inserted into the vessel and inflated,
compressing plaque against the vessel's interior wall. Although this opens the artery, it also damages
a portion of the vessel in the process. ''If you injure these cells, they react by proliferating and
forming scar-like lesions, which eventually clog the artery,'' says Dr. Weinberger.
In animal experiments, the researchers demonstrated that this process can be inhibited by applying
radiation, via a specially designed catheter, directly to the angioplasty site.
In the treatment, known as intracoronary irradiation, a balloon-tipped catheter is placed at the
angioplasty site and filled with a radioisotope that emits beta radiation. The catheter is left in place for
five to 10 minutes. Once irradiated, the cells stop growing, and the vessel wall heals without the
formation of occlusive lesions. (The latest results from animal testing were presented in November
1997 at the annual meeting of the American Heart Association in Orlando, Fla.)
The treatment has also shown promise in humans. In a pilot study conducted elsewhere, only 15
percent of patients restenosed, far below the expected rate.
''This is the first therapy that holds significant hope for achieving long-term suppression of
restenosis,'' says Dr. Weinberger. Up to 90 percent of patients who undergo interventional
procedures could be eligible for intracoronary irradiation.
The current study at Columbia-Presbyterian, involving 60 patients with angina, is primarily intended
to test the safety of intracoronary irradiation, although the researchers will also take a number of
objective and subjective measures of the patients' condition. In addition, each patient will undergo a
follow-up angiogram at six months to measure the extent of restenosis.
Beta radiation, the kind being used at Columbia-Presbyterian, is thought to be much safer than
gamma radiation, another type of radiation used in this procedure. ''Gamma radiation is riskier
because it penetrates farther into the surrounding normal tissue than beta radiation,'' explains Peter
Schiff, MD, PhD, chairman of Radiation Oncology. ''Beta radiation penetrates only about half a
centimeter or less, so we are better able to confine the dose of radiation to the affected segment of
the target vessel.
''A risk associated with the procedure would be that the balloon breaks and radioactive material
gets into the blood stream,'' adds Dr. Schiff. ''The risks of balloon rupture are about one in 1,000 or
less. In that eventuality, the patient would only be subjected to a dose of radiation comparable to
what they would get with a bone or kidney scan.''
Aneurysms are another remote possibility. ''But in the doses that we are studying, there has never
been a reported aneurysm,'' says Dr. Weinberger. |
