Cold as ice: Opening arteries with cryoplasty

Experimental technique freezes away blockages

Researchers use a device like this one during cryoplasty, an experimental technique that freezes plaque in clogged arteries to remove it.

By Eleni Berger
CNN

(CNN) -- What if there were a way to improve on one of the most common treatments for heart disease? -- a method both easier on the body and requiring fewer repeat procedures?

Researchers say they may have found just that: a new way to clear blocked arteries that's less traumatic to the blood vessels and appears to have a lower incidence of restenosis, the reclogging of an artery that can necessitate repeat surgery.

The technique is called cryoplasty -- in effect, it's angioplasty on ice.

"Our preliminary research with cryoplasty is very promising," says Dr. James Joye, the interventional cardiologist who developed the procedure.

He and his colleagues are presenting the results of that research at the 14th annual International Symposium on Endovascular Therapy, going on this week in Miami Beach, Florida.

Laughing gas is the key

Angioplasty and cryoplasty are performed in essentially the same way: A catheter is threaded into the clogged artery, where a balloon is inflated to compress the blockage and reopen the vessel.

But there's one essential difference. In traditional angioplasty, the balloon is inflated with saline solution; in cryoplasty, the balloon is inflated with nitrous oxide -- commonly known as laughing gas.

The nitrous oxide cools to a temperature of -10 degrees Celsius, freezing the plaque and inducing a process called apoptosis, a type of cell death.

"It's almost like the cells have a switch that's like a self-destruct button," Joye says. In apoptosis, "the body compartmentalizes the cell -- sort of pinches off little pieces at a time -- and removes it."

That process is gentler on the artery wall than angioplasty, preventing much of the inflammation and scarring that contribute to restenosis, says Joye, director of peripheral vascular interventions at El Camino Hospital in Mountain View, California. He's also co-founder of CryoVascular Systems, the company that markets the device used in the procedure.

Promising early results

Cryoplasty also might eliminate the need for stents, the mesh tubes sometimes used to keep an artery propped open, Joye says. While the stents can reduce restenosis, having a foreign body in the artery can also spur more aggressive restenosis, he says.

Of the 15 patients treated in initial trials in Europe and South America, 12 have shown no signs of restenosis nine months after treatment, when renarrowing typically occurs. None has needed a stent to maintain a clear artery.

The patients were all treated in leg arteries, where restenosis rates with standard angioplasty typically approach 50 percent to 60 percent. In coronary arteries, the restenosis rate is about 20 percent to 30 percent.

"If in fact the cryoplasty continues to work as it has, what we're looking at is a very dramatic change in the outcomes of these procedures," says Joye.

With the approval of the Food and Drug Administration (FDA), Joye and his colleagues have begun a first-phase clinical trial to test cryoplasty in the coronary arteries of about 100 patients, 70 of them in the United States. Another FDA-approved trial of the technique on leg arteries is also beginning.

Joye says the cryoplasty technique is safe, with the same risks as standard angioplasty.

But he cautions that his work is in the early stages.

"It's 15 patients," he says. "It's a start. We're obviously very encouraged."