Vacuum Method Breaks Up DVT Blood Clots

Lingering deep vein clots can cause serious trouble, doctors warn

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By
HealthDay Reporter

FRIDAY, March 2, 2007 (HealthDay News) -- A new non-surgical treatment for the removal of blood clots appears to be safer, faster and more effective than traditional therapies in reducing the risk for pulmonary embolism and disability among patients with deep vein thrombosis (DVT).

DVT involves a blood clot in a vein, usually in the lower leg or thigh. In some cases, the clot can break off and move up into the lung, triggering a potentially fatal condition called pulmonary embolism. DVTs gained media prominence as so-called "economy class syndrome" after a number of passengers on long-haul flights developed the dangerous condition.

But the new clot-removal method, called the "rapid lysis" technique, could offer fresh hope to patients.

"There's a tremendous benefit to patients as a result of this technique," said study lead author Dr. Mark J. Garcia, an interventional radiologist in the department of radiology at Christiana Care Health System in Wilmington, Del.

His team's findings were scheduled to be presented Friday at the annual scientific meeting of the Society of Interventional Radiology in Seattle.

DVT clots develop in situations where circulation slows down, causing blood to pool. Although it can strike at any age, the risk is highest among men and women over the age of 60. Patients being treated for cancer and those experiencing surgery, injury, or prolonged immobility are also at an elevated risk, as are women in the early stages of pregnancy and patients who have varicose veins or who are overweight.

Standard treatment typically involves injectable or pill-form blood thinners, also known as anticoagulants, which can prevent the formation of new clots and halt the growth of clots already formed.

Such treatment does not, however, help to dissolve an existing clot. While most clots eventually dissolve on their own, large clots provoking severe symptoms may not. In such instances, clots can be dissolved by means of a thrombolytic drug delivered by catheter.

This approach is not without its drawbacks, however. According to the researchers, the clot-busting procedure can take as much as two to four days to work, significantly raising the risk for sudden bleeding. So, doctors usually only use the drug as a last resort.

But without quick and complete clot removal, permanent vein damage can occur over time, resulting in permanent disability. This condition -- known as post-thrombotic syndrome (PST) -- is characterized by chronic leg pain and swelling, along with skin thickening and severe ulceration. In extreme cases, gangrene and amputation can ensue.

In fact, half of the patients treated with blood thinner alone for a leg DVT eventually go on to develop PST, the researchers said.

So, Garcia and his team tested the potential of the new "rapid lysis" technique to safely and quickly dissolve clots.

They focused on 102 men and women, averaging 47 years of age, who were all seeking care for extensive, large-volume DVTs. In most of these cases, the DVT ran the entire length of the leg -- from ankle to pelvis, or even beyond.

Radiologists first used imaging equipment to direct a catheter through the affected leg to the point of the clot. Using a high-powered spray device, a diluted, clot-dissolving drug was then delivered into and throughout the clot, effectively breaking it up.

The remnants of the clot were then sucked up by a saline jet that essentially vacuumed the clot into the catheter, removing it from the bloodstream as the catheter was pulled down and out of the affected leg.

After a year tracking patient progress, Garcia and his colleagues found that the rapid lysis treatment achieved full clot removal and blood flow restoration in over half of patients.

Another 31 percent of the patients had blood flow restored after the removal of a substantial amount of clot -- a little below two-thirds of the total blockage.

Partial and minimal clot removal occurred in 11 percent and four percent of patients, respectively.

Forty-three percent of patients needed just a single treatment session to experience a benefit. Ultrasound exams conducted six months later showed that 78 percent of the affected veins remained clear of DVT. At 12 months, that figure rose to 83 percent.

In terms of PST, surveys up to one year after treatment revealed that just under 70 percent of the patients said they had no leg pain or swelling, and nearly 80 percent said they experienced no heat or burning discomfort in the affected limb.

Garcia and his colleagues conclude that the new technique is useful in treating the largest and most difficult clots safely and quickly, representing a significant advancement in DVT therapy.

"Clearly, the medical standard of care doesn't nearly work well enough," said Garcia. "It's not adequate. If you have a clot, and you can't get rid of it, there's the constant threat of pulmonary embolism and death -- 200,000 deaths every year. And, while we don't really know what percentage of patients go on to post-thrombotic syndrome, if you have a non-dissolved clot, you have a real chance of going on to develop life-changing and life-threatening issues over time."

"So, while I'm not saying everyone who has a clot needs to get this new treatment, patients have to know they can't just sit back," Garcia stressed. "Their clot needs to be closely followed. And, if it's dissolving, wonderful. If not, they should be very aggressive in getting help to dissolve these clots -- within two weeks from symptoms, ideally -- and this technique can really help."

Dr. Samuel Goldhaber, director of the venous thromboembolism research group at Brigham and Women's Hospital in Boston, took a more conservative view.

"This treatment would address only a small niche of patients," said Goldhaber, who is also a professor of medicine at Harvard University School of Medicine. "It could help those who need more than an anticoagulant but who have had recent surgery or have a preexisting bleeding risk of some kind, and so are not eligible for traditional clot-busting therapy."

"This type of catheter -- one that basically sucks up the clot -- is one of several more aggressive options for treating DVT now under development," Goldhaber added. "The example they looked at seems promising, and hopefully this will lead to larger trials that will test these catheters more thoroughly."

More information

For additional information on DVT, visit the U.S. National Institutes of Health.

SOURCES: Mark J. Garcia, M.D., interventional radiologist, department of radiology, Christiana Care Health System, Wilmington, Del.; Samuel Goldhaber, M.D., professor, medicine, Harvard Medical School, and director, venous thromboembolism research group, Brigham and Women's Hospital, Boston; presentation, March 2, 2007, presentation, Society of Interventional Radiology annual meeting, Seattle

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