New Techniques Safely Remove Deep Vein Clots

They're also quicker, saving health-care costs, studies find

FRIDAY, April 1, 2005 (HealthDay News) -- New techniques that aid in dissolving and removing blood clots in the legs could improve treatment for this painful and often dangerous condition, researchers report.

Deep vein thrombosis (DVT) affects approximately 250,000 people annually, and about half of them go on to suffer from chronic leg pain and swelling, called post-thrombotic syndrome, said Dr. Suresh Vedantham, assistant professor of radiology and surgery at Washington University, in St. Louis.

The condition has received considerable media attention in the past few years after striking passengers on long-distance flights. Many airlines now advocate that passengers do simple exercises during flights to maintain healthy circulation in the legs.

The most common DVT treatment -- a blood-thinner medication that prevents new clots but does not remove the existing clot -- could be improved upon, Vedantham said. "It's been sort of recognized that removing the clot is a better treatment than blood thinner, but the previous treatments to do this are not user-friendly," he said.

The traditional clot-removing treatment, called catheter-directed thrombolysis, involves an infusion of anti-clotting medication that takes as long as two days to break down the clot. The procedure also requires careful monitoring, with a follow-up in a hospital's intensive care unit. Less than 5 percent of individuals with deep vein clots undergo the procedure, Vedantham said.

"The holy grail for us has been, 'Can you remove the clot in one step,' and these [new] techniques may turn out to be what we've been seeking for a long time," he said.

Vedantham presented research on three of these new technologies on Friday at the Society of Interventional Radiology's annual scientific meeting in New Orleans.

The first, called the Power Pulse Spray, delivers clot-dissolving medicine at a high force which helps break up DVT by spreading the drug over a surface area of the clot. Thirty minutes later -- when the clot begins to partially dissolve -- the spray is used to create a vacuum so the clot can be sucked into a catheter and removed.

In studies of the device, 80 percent of 14 patients who tried the technique were treated in a single session, and in 10 cases (71 percent), the clot was completely removed. Three of the patients had a substantial removal of their clots while one achieved only a partial removal.

A second method, called The Trellis(r)-8 Infusion System, first isolates the clot by surrounding it with inflated balloons to minimize bleeding. Doctors then insert a thin vibrating wire filament into the blockage, effectively chewing up the clot. The clot fragments are then pulled into a catheter and removed from the body.

A study compared the Trellis technique to the traditional catheter-directed thrombolysis. The researchers report that patients who underwent the vibrating wire treatment experienced a lower risk of bleeding and required lower doses of clot-dissolving medication. The procedure also took less time, saving hospital costs.

Vedantham also reported on a third technique, the HELIX Clot Buster, a device that works by chewing up the clot. Unlike the other two devices, HELIX is not yet approved by the FDA for use in DVT, although it is FDA-approved for clots related to dialysis, the researchers said.

In an eight-year study involving 36 patients -- 11 of whom had the traditional method of clot removal, and 25 of whom were treated with the HELIX -- researchers found no difference in the overall 86 percent success rate of the two therapies in removing the clots.

In the HELIX group, however, treatment time was significantly shorter and the dose of anti-clotting medicine required was half that of traditional interventions. There was also a trend toward fewer bleeding events, the researchers found.

"This techniques will be a major sea change in the way DVT will be treated," Vedantham said.

But Dr. Samuel Z. Goldhaber, director of the Venous Thromboembolism Research Group at Brigham and Women's Hospital, in Boston, stressed that these techniques, no matter how promising, are still invasive procedures only used for patients at "the most severe end of the spectrum."

"Rigorous clinical trials are needed to determine how broadly applicable these techniques should be," he said.

More information

For an explanation of deep vein thrombosis, visit the National Heart, Lung, and Blood Institute.

SOURCES: Suresh Vedantham, M.D., assistant professor of radiology and surgery, Washington University Medical School, St. Louis; Samuel Z. Goldhaber, M.D., director of the Venous Thromboembolism Research Group at Brigham and Women's Hospital, associate professor, Harvard Medical School, Boston; April 1, 2005, presentation, Society of Interventional Radiology's 30th Annual Scientific Meeting, New Orleans
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