Wednesday, March 18, 2009

DVT: What you should know

Deep Vein Thrombosis (DVT) is a condition affecting an estimated 600,000 Americans each year, and as the population ages that number is expected to grow. With March recognized as DVT Awareness Month, the Massachusetts General Hospital Vascular Center is hoping to improve awareness among the population and health care providers about the risk factors, signs and symptoms of DVT.

In September, acting U.S. Surgeon General Steven K. Galson issued a Call to Action to reduce the number of cases of and deaths caused by DVT in the United States. At the Vascular Center, leaders in the field are encouraging a re-evaluation of the standard treatments for DVT that they hope will ease the chronic problems that some serious iliofemoral DVTs cause.

“DVT is a hot topic right now,” says Stephan Wicky, MD, an interventional radiologist at the Vascular Center. “There’s a focus on developing evidence-based practices for screening, preventing, diagnosis and treating DVT, and we hope that some of the work being done here will contribute to that effort.”

What is DVT?

DVT occurs when a blood clot forms in the large veins, usually in the lower leg or thigh, causing a partial or complete blockage of circulation. The result can cause pain, swelling and skin discoloration. In more serious cases, the blood clot breaks loose and travels through the bloodstream to the lungs, blocking circulation to that organ. This condition – known as pulmonary embolism (PE) – is life threatening and requires immediate medical attention.

Nearly 40 percent of patients with a DVT will develop PE, and PE causes approximately 300,000 deaths each year in the United States.

DVT and PE can affect almost anyone. Common risk factors include those with blood-clotting disorders or who have had a recent surgery or trauma. Obesity, smoking, pregnancy, congestive heart failure and some cancers can also increase risk.

“Anticoagulants are the most common treatment used to reduce the progression of DVT. These work by altering the body’s normal blood-clotting process and may help reduce the risk of PE,” says Wicky.

With early intervention, patients with DVT reduce their risk of developing PE to less than 1 percent. However, Dr. Wicky points out this standard of care does not treat the clot itself, leading to possible vascular complications in the future.

Post-Thrombosis Syndrome

After the formation of an iliofemoral DVT, the body must work to clear the clot and re-establish blood flow. This process can damage the vein’s function, says Wicky, causing a condition called Post-Thrombotic Syndrome (PTS).

“Valves in the vein prevent backflow of blood leaving the leg. However, the body’s recanalization process can damage the valves and cause vein pump dysfunction. The resulting reflux is a common problem associated with PTS,” says Wicky.

PTS may develop months or years after a DVT, causing chronic leg swelling, pain, skin discoloration and ulcers that are difficult to treat. The result is 2 million work days lost per year, says Wicky.

A 10-year follow-up study, published in the Annals of Surgery, of 39 patients with iliofemoral DVT treated with anticoagulation alone found that 81 percent of the limbs had reflux, 34 percent had skin changes or ulcers and most patients reported a decrease in their overall quality of life as a result of PTS.

The Vascular Center is waiting for approval to join a National Institutes of Health-funded trial weighing the benefits of interventional clot removal for treating DVT. The ATTRACT trial is the first major national trial of a catheter-based treatment combining the use of a catheter-directed clot dissolving drug (thrombolysis) with a percutaneous mechanical clot removal device (thrombectomy). This process allows an interventional radiologist to break up the clot and remove it from the vein. Wicky has been performing this combination of thrombolysis and thrombectomy since 1995 and at Mass General since 2003.

“PTS is a serious complication of DVT that may be preventable if we are able to dissolve the clots early, before permanent damage to the vein occurs,” says Dr. Wicky. “We hope the findings of the ATTRACT trial will result in the inclusion of interventional clot removal as the standard care for DVT.”

Learn more about DVT treatment at the Vascular Center

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