In the United States alone, approximately 600,000 new cases of deep vein thrombosis (DVT) are diagnosed each year. Of these, one in every 100 will die, generally due to a pulmonary embolism (PE). If these conditions can be diagnosed early and appropriate therapy started, such as catheter-directed thrombolysis, the mortality rate of PE could be reduced from approximately 30% to less than 10%.
DVT
occurs when a blood clot forms in a vein deep within the body, particularly the deep veins that lie near the center of the legs. Generally, contractions of the muscles in the arms and legs help force blood back through these deep veins to the heart. In fact, nearly 85% of the circulating blood flow is returned to the heart through the deep veins of the legs.
DVT is generally the result of the combination of two factors:
- Sluggish blood flow
- Clotting factors
Sluggish blood flow can be the result of sitting still for long periods of time (this is why DVT is sometimes referred to as “economy class syndrome”) or long periods of bed rest, such as after surgery, serious illness, or injury.
Clotting factors are substances that circulate naturally in the blood to regulate clot formation. However, certain insults to the body, such as surgery, injury, or giving birth, may increase the level of clotting factors circulating in the blood. This, in combination with the reduced mobility that results from these insults, may set the stage for DVT.
Typically, these clots come on suddenly and without warning. They can cause swelling and pain in the leg. The greatest problem, however, is that so long as the clot is present, the patient is at risk for a
PE
.
A PE is a potentially fatal complication of DVT. A PE is a blockage of an artery that occurs when a clot formed in another part of the body breaks loose and travels through the bloodstream until it becomes stuck in a blood vessel in the lungs.
The clot, called an embolus, is usually a blood clot (although it can also be an air bubble, or a piece of fat, bone marrow, or tumor tissue), and generally originates in the deep veins of the legs or hips. Once the clot becomes stuck in the artery in the lungs, it prevents blood flow to that portion of the lung, causing it to become malnourished and eventually die. This can cause the lung to quit working properly and, if not treated, may lead to death.
The most recent highly publicized death due to PE was that of David Bloom, a 39-year-old veteran journalist for NBC who was traveling with the US 3rd Infantry Division about 25 miles south of Baghdad when he fell ill. Despite being airlifted to a nearby medical unit, he did not survive.
Catheter-directed thrombolysis is performed in a hospital radiology suite by an interventional radiologist. The physician inserts a catheter into a vein in your leg (generally the popliteal vein) and carefully threads it through your veins until it reaches the site of the blood clot. The catheter, which has a small camera on the end of it, allows the doctor to watch the entire procedure on an x-ray video monitor.
Once the tip of the catheter reaches the clot, a thrombolytic (clot-dissolving) drug is infused into the clot through the catheter. In most cases, the blood clot will completely dissolve within a few days. This process will be monitored using special x-rays called
venograms
and ultrasound scans. These images will also allow the doctor to determine if your vein wall is narrowed or damaged, making it prone to more clots in the future. If this type of damage has occurred, your doctor will likely perform a balloon
angioplasty
or place a small mesh
stent
into the vein to keep it from clotting again.
Unfortunately, the traditional treatments for DVT, such as anticoagulants (drugs which prevent the blood from clotting), venous compression stockings, and leg elevation are often insufficient for treating patients with significant pain and swelling from DVT.
Additionally, a significant proportion of patients develop post-thrombotic syndrome (permanent abnormalities in the affected leg and their valves), an under-recognized, but relatively common after-effect of having DVT and being treated with anticoagulation therapy alone. This syndrome commonly develops within two months of developing DVT and results in abnormal pooling of the blood in the leg, chronic leg pain, fatigue, swelling, and in extreme cases, severe skin ulcers.
Fortunately, there is increasing evidence that clot removal using interventional catheter-directed thrombolysis may improve the quality of life and prevent the debilitating after-effects of post-thrombotic syndrome. Indeed, as many as 85% of the patients with DVT who are treated with catheter-directed thrombolysis experience diminished pain and the restoration of normal blood flow in the affected leg.
If you have symptoms of PE, you should go to an emergency room to seek help. If you have symptoms of DVT, such as leg pain and swelling, you should consult with your doctor for further evaluation.
