This article first appeared in the St. Louis Beacon: October 8, 2008 - It kills more people annually than breast cancer, vehicular accidents, and AIDS combined. The killer is a pulmonary embolism. It's a blood clot in the lung that usually begins with a clot in an interior leg vein (known as deep vein thrombosis) that breaks off and enters the body's circulatory system. A pulmonary embolism often results in a death quick and unanticipated; it is a silent killer.
"Blood clots are very common, very dangerous, and usually preventable," said Dr. Suresh Vedantham, an interventional radiologist and associate professor at Washington University School of Medicine. Vedantham is vice-chair of the Venous Disease Coalition, a group of 34 non-profit health professional organizations that speak with one voice in educating the public about deep vein thrombosis (DVT) and other venous disorders.
Frequent fliers know to walk about the plane on long flights to prevent "economy class syndrome, "another name for DVT. But what people may not know is that most DVTs develop after surgery and trauma such as broken limbs. So prevention also needs to take place at hospitals.
According to Vedantham, only about 50% of surgery patients nationwide get such DVT preventive measures as injectable blood-thinning drugs and machine-operated inflatable stockings that periodically compress the leg to increase venous blood flow. His patients are in the BJC hospitals, which have developed DVT prevention protocols in the last few years. But many hospitals do not yet have these protocols in place. Beginning in 2009, the Joint Commission on the Accreditation of Healthcare Organizations has made DVT prevention a patient safety requirement for hospitals.
Vendantham has been appointed to lead a $10 million, multicenter clinical trial, the ATTRACT Trial, to investigate the long-term efficacy of a new minimally-invasive, aggressive targeted treatment for DVT. The trial is funded by the National Institutes of Health, and involves 28 hospitals nationwide.
Know the Symptoms
The symptoms of Deep Vein Thrombosis should not be ignored. They include:
- Sudden pain in a limb
- Swelling
- Persistent redness or heat in a limb
At particular risk are people who have had trauma, have been immobile due either to illness or circumstance like very long airplane flights, have had recent surgery, have cancer, or who are being treated with hormones. If they develop the symptoms, they should seek immediate medical attention.
DVT can lead to pulmonary embolism which often results in death. Those symptoms include new onset chest pain, shortness of breath, fast heartbeat or coughing up blood.
Prompt treatment can prevent pulmonary embolism
When a deep vein thrombosis is diagnosed in time, the patient is given two blood thinners, heparin and coumadin. These anticoagulants keep the clot from enlarging, and entering the circulatory system. But since the clots remain in place, about half the time patients develop post-thrombotic syndrome: long-term leg pain, swelling, difficulty walking, and even venous ulcers or open sores on the leg that are difficult to treat.
Vedantham is investigating a treatment intended to reduce post-thrombotic syndrome in patients with confirmed diagnoses of DVT.
Study aims to find if post-DVT treatment can be improved
The new treatments in Vedantham's ATTRACT Trial aim for a complete cure. About 700 patients with newly diagnosed DVT will be divided into two groups. The first group will be treated conventionally with blood thinners. The second group will receive blood thinners, and will also undergo radiology procedures to dissolve the clot.
Two similar interventional procedures will be tested, according to the preference of the investigator. Both procedures will use intravenous catheters, analogous to those employed in cardiac catheterization procedures. Guided by ultrasound and x-ray imaging, the physician will thread a tiny apparatus through the veins until it reaches the clot.
Once the catheter reaches the clot, it will deliver the clot-busting drug TPA directly into the clot. TPA (tissue plasminogen activator) is the drug administered to patients with strokes and heart attacks. It activates the enzyme in plasma that chews up the fibrous protein in a clot. While the TPA is released, the apparatus will mechanically disrupt the clot to enable the clot-dissolving enzymes to act faster.
The radiologist will use one of two devices. One inflates tiny balloons on each side of the clot, before injecting the TPA. Because the drug is confined to the area between the balloons, a very small dose can have a locally heavy concentration. A wire in the catheter then rotates within the clot to loosen it. When the clot has dissolved, any remaining material is sucked into the catheter.
The other device uses a system of saline jets to forcefully "pulse" the TPA into the clot and vacuum it into the catheter.
The patients will be followed for two years after the DVT. In addition to physical evaluation, the physicians will use questionnaires to assess quality of life. The investigators will then try to reach a conclusion about whether deep venous clots should be routinely removed rather than simply using blood thinners to prevent further clots. "We are looking at changing the basic DVT treatment paradigm that has been in place for nearly 50 years," Vedantham said..
What you can do to help yourself.
Each year, nearly 1 million patients in the U.S. are diagnosed with DVT or pulmonary embolism. About 300,000 of the cases are new ones. A national awareness campaign launched this fall by the U.S. Surgeon General is aimed a greatly reducing these numbers.
Vedantham suggests three measures everyone should take:
- If you have the symptoms of DVT mentioned above, immediately seek medical care to prevent pulmonary embolism. If you have symptoms of pulmonary embolism, you should probably go the emergency room immediately.
- If you go into the hospital for surgery or trauma treatment or a medical illness, ask your physicians what measures they are taking to prevent blood clots.
- If your whole leg is swollen, ask your doctor if new clot-busting treatments are appropriate for you. If your doctor is not familiar with these techniques, ask for a consultation with an interventional radiologist.
Jo Seltzer is a freelance writer with more than thirty years on the research faculty at the Washington University School of Medicine and seven years teaching tech writing at WU’s engineering school.