New Technique Dissolves Blood Clots in Leg, Relieves Symptoms
Daniel J. DeNoon
WebMD Health News
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Reviewed By Louise Chang, MD
Jan 29, 2008 -- National Institutes of Health researchers appear to have found a safe way to dissolve the painful blood clots that swell the legs of people with deep vein thrombosis or DVT.
If you suffer DVT -- a blood clot deep in your leg -- doctors usually can keep it from killing you. But this treatment is incomplete: Doctors cannot make the painful condition go away.
This may soon change, thanks to a major study by Richard Chang, MD, chief of the interventional radiology section of the NIH Clinical Center, and colleagues. Chang's team has been able to make all DVT symptoms go away for 18 of 20 patients who underwent their experimental treatment.
"Eventually this will be a practical, complete treatment. We will be able not only to treat DVT, but to restore venous function in the leg. It will be as though you did not have DVT," Chang tells WebMD.
Does it work? WebMD asked Rebecca McDonald, one of the 20 patients in the Chang study. McDonald was 35 when she suffered a huge DVT after giving birth to her third child.
"My clot ran from my calf to my stomach. It became obvious to my husband and me that I was going to lose my leg," McDonald says. "After the second day of treatment, the swelling started to dissipate. A week later I was walking, and a week after that I was running again."
It's been five years since her treatment. McDonald remains symptom free.
DVT = Emergency
Deep vein thrombosis is a very serious condition, as pieces of the clot can break off and block blood flow to the lung. These pulmonary embolisms can be fatal. Fortunately, emergency treatment with blood thinners -- anticoagulants such as Coumadin -- greatly reduces the chance that this will happen.
But anticoagulants don't go to the heart of the problem. They do not remove the blood clots that plug small veins in the leg. The body may eventually dissolve these clots by itself, but not in time to prevent permanent damage to the delicate structure of the vein.
Interventional radiologists sometimes use infusions of clot-busting drugs such as tPA to dissolve DVT clots. Patients who receive these continuous infusions of clot-dissolving drugs are at high risk of dangerous bleeding in the brain and in other organs.
To avoid this problem, Chang and colleagues apply tiny doses of tPA directly to the clot. None of the study's 20 patients suffered bleeding.
"The beauty of tPA is it is cleared in five minutes by the liver, so any excess is quickly removed. The tPA we put into the clot stays on the clot and continues to work. So we reduce the duration of time the circulation is exposed to these enzymes," Chang says.
DVT Symptoms Gone
According to the Society for Interventional Radiology, 60% to 70% of DVT patients suffer post-thrombotic syndrome. These people have abnormal pooling of blood in the leg, chronic leg pain, fatigue, swelling, and sometimes even severe skin ulcers.
And about half of DVT patients suffer a second DVT, says Jorge J. Guerra Jr., MD, professor of vascular/interventional radiology and associate vice president for clinical affairs at the University of Miami Miller School of Medicine.
Guerra is impressed that in the Chang study, which followed patients for an average 3.4 years -- and up to 8.5 years -- none of the patients had a second DVT and none of the patients suffered further vein deterioration.
"By getting the veins back to normal, he is preventing a second DVT, which is more disturbing than a first one," Guerra tells WebMD. "This is a laudable study."
Dissolving DVT Clots: Lots of Doctor/Patient Time, Patience
To treat DVT patients, Chang and colleagues started off with standard anticoagulant treatment. Despite this treatment, they found that 40% of patients already had a pulmonary embolism; fortunately, these were not fatal.
Next, patients had to be treated within two weeks of suffering their DVT, while the clots were still fresh. Once a DVT clot hardens, Chang says, the treatment will not work.
During treatment, NIH interventional radiologists painstakingly threaded catheters into the tiny veins blocked by blood clots. This process took as long as four and a half hours, Chang says.
But that's not all. The doctors then "laced" the clot with tPA by repeatedly injecting small amounts of the drug through the catheter as they slowly moved it along the clot. There could easily be 100 small injections at 30-second intervals, Chang said.
The procedure is then repeated up to four times as needed, although the most time-consuming part -- threading the catheters into the veins -- does not have to be repeated. Most patients needed two or three treatments.
"We will have to bring the time down. We have to make it simpler. But then, eventually, we will see a practical treatment," Chang says.
"This is tedious as hell. And most of us don't have just one set of veins in the calf, but duplicate veins -- so it's a double procedure," Guerra says. "But if it can save those people with post-thrombotic syndrome, you might be doing a large service, particularly in young women, who get a double whammy: a swollen leg covered with spider veins."
If the procedure is tough on the doctor, it's no easier on the patient.
"I am not sure what they did with the others, but they did not put me out on the first day," McDonald says. "I'd just had a baby three weeks before, and I have back problems, so that was the hardest part. There were three catheters, two in my groin and one in my neck, and my back was in spasms the whole time. I cried for the whole eight hours of the procedure. The next day they put me out. That was better."
Was it worth it?
"It was not very fun, but I would do it again in a heartbeat because it saved my leg," McDonald says.
The new treatment has huge advantages over another new treatment. Interventional radiologists already are using a mechanical suction device to vacuum away blood clots loosened by infusion of clot-dissolving drugs.
"The advantage of the mechanical device is it is quick," Chang says. "If the clot is fresh and soft, you can establish a channel in half an hour. But the problem is that DVT often involves the small veins of the calf, and these devices are not easy to move into calf veins. Whereas you can get enzymes into the calf with a catheter."
"Improving the Chang technique is the future, because sucking the clot out doesn't do it," Guerra says. "He has an 80% of patients with complete resolution of blood flow and resolution of symptoms. He said no patient had recurrent DVT -- that is a significant statistic, because the occurrence of new DVT three to five years later is not small."
Chang stresses that the technique is not ready for prime time. It still must be proved in clinical trials that the technique is safe and effective for the kinds of DVT patients doctors regularly see. But Guerra says the Chang results already pose a dilemma to interventional radiologists who may already be pressed for time.
"This procedure is very labor intensive and needs a very expert professional," he says. "But if a person has significant calf and thigh thrombosis, and is willing to undergo two days of tedious catheterization, we should be able to offer it. Interventional radiologists will be hard pressed not to give patients the chance and step up to the plate and take the time to do the job. I would hate to turn an appropriate patient down."
Chang and colleagues report their findings in the February issue of the journal Radiology.
SOURCES: Chang, R. Radiology, February 2008; vol 246: pp 619-629. Society of Interventional Radiology web site. Richard Chang, MD, chief of interventional radiology, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Md. Jorge J. Guerra Jr., MD, professor of radiology and vascular/interventional radiology and associate vice president for clinical affairs, University of Miami Miller School of Medicine; chief medical officer, University of Miami Medical Group. Rebecca McDonald, patient, NIH pilot study.
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