Keep a Clear Path: Deep Vein Thrombosis

Wednesday, February 1, 2012

Illustration by Stephen Sauer.

DVT Risk Factors

Sitting for long periods of time, such as when driving or flying
Inheriting a blood-clotting disorder
Prolonged bed rest, such as during a long hospital stay or paralysis
Injury or surgery
Pregnancy
Cancer
Inflammatory bowel disease
Heart failure
Birth control pills or hormone replacement therapy
A pacemaker or a thin, flexible tube (catheter) in a vein
A history of deep vein thrombosis or pulmonary embolism
A family history of deep vein thrombosis or pulmonary embolism
Being overweight or obese
Smoking
Over age 60
Being tall
Click here for a complete list and more information.

Deep vein thrombosis can be serious.

It's easy to liken the blood vessels of the circulatory system to interconnecting highways and byways, as they transport precious cargo nonstop to various destinations. And since time is certainly of the essence when your circulatory system is concerned, it's crucial to prevent delays brought on by conditions such as deep vein thrombosis, which features speed bumps that can bring traffic to a crawl, or stall it altogether.

Deep vein thrombosis begins with a blood clot in a vein, usually a vein located deep within a leg, that can grow and impede blood flow, initially causing no symptoms in about half of all cases, according to the Society for Vascular Surgery. If a clot breaks free and travels through the bloodstream to the lungs, it creates a condition known as pulmonary embolism, blocking blood flow and possibly stopping your heart, says D. Thomas Akey, MD, a pulmonary specialist at Concord Pulmonary Medicine and Concord Hospital.

Estimating your odds

Deep vein thrombosis (DVT) is estimated to affect one to two people in every 1,000 in the United States, and one in 100 people over the age of 80, according to the Centers for Disease Control and Prevention. It can occur in just about anyone, male or female, old or young - but is clearly more prevalent in older adults. An array of factors can increase your risk of developing DVT. Some are uncontrollable, such as being over the age of 60 and having a family history of clotting abnormalities; others involve lifestyle choices, such as smoking and being obese. Patients with significant varicose veins also carry increased risk, says Patricia C. Furey, MD, FACS, a vascular and endovascular surgeon at Catholic Medical Center in Manchester.

But one of the primary triggers for DVT is immobility, especially hospitalization that occurs in conjunction with other risk factors. "When [patients] are hospitalized, they are under a unique set of circumstances where they're on bed rest, they're getting medications, they're having surgery - we're doing things to them that put them at increased risk of developing blood clots," Furey says.

Long-distance travel, with its confined, prolonged sitting, can also contribute to deep vein thrombosis and pulmonary embolism. "You're at increased risk if you're on a plane for more than four hours or a flight that's greater than about 3,100 miles or 5,000 kilometers," Akey says. "If it's a cross-country trip or certainly a transcontinental trip, there's about a two- to four-fold increase in your risk of developing venous thromboembolism," a disease that includes deep vein thrombosis and pulmonary embolism. But "if the flight is less than three hours, it does not seem to be a big issue," he says.

Regardless of whether you journey to far-flung locales or spend time as a hospital patient, most cases of DVT occur in patients who have a combination of risk factors. For sure, pretty much any kind of lengthy immobility promotes clot development - as does taking birth control pills, which thicken the blood, Akey says. But multiple risk factors, such as being a smoker who takes birth control, raise a larger red flag.

Eliminating the obstacles

To help keep your blood clot-free, of course you should heed the usual health axioms - don't smoke, stay active and maintain a healthy diet. But, in addition, take steps to keep your blood flowing when you know you'll be faced with a long stretch of inactivity. If you're on a long-distance trip get up and move at least once every two hours, or at least point and flex your toes to encourage blood flow, or consider wearing a compression stocking that applies graduated pressure from the ankle up, to help prevent blood pooling, says Furey. And remember, the same rule applies to vacation road trips, bad commutes and intense stints at the computer: Take breaks and walk around.

Be aware of your clotting risk and point out any concerns to caregivers' attention, particularly if you are going to be hospitalized, because although activities like sitting through long-haul travel and spending hours in front of your computer do increase your risk of developing blood clots, being ill and hospitalized raises it even more, Furey says. "We need to be aware as a medical community of which patients represent a high risk for blood clotting," she says, to help prevent clot-related trouble during hospitalization.

Although many patients with DVT do not have symptoms, know the signs in case you experience them; they include calf pain, tenderness, swelling, and redness. If you suspect that you may have a problem, alert your doctor so that you can be evaluated. Diagnosis usually involves non-invasive ultrasound imaging of the vein, Akey says.

If tests confirm that you have deep vein thrombosis, it doesn't necessarily mean that the clot will break away and create a pulmonary embolism, but early detection and treatment can head potential trouble off at the pass. "If you start treatment before clots travel into the lungs, then you pretty much avoid the serious part of things," Akey says.

Treatment varies depending on factors like where and why the clot formed and the patient's health status, but the standard treatment for DVT relies on anti-coagulation medicine, Akey says. "Your own body will break down and dissolve the clots that are there," he says, but medicines commonly known as blood thinners, such as heparin and warfarin (aka Coumadin), can help prevent any further clots from forming.

Some patients need to undergo mechanical thrombolysis, in which a catheter is placed inside the vein and the clot is mechanically removed as well as dissolved via a chemical that is put inside the vein. The procedure can help to preserve the vein valves, which can be damaged when blood clots occur, possibly leading to chronic problems and discomfort in the legs, Furey says. Less commonly, doctors implant a device called an inferior vena cava filter, which is inserted either through the groin or the neck, to prevent blood clots from traveling to the lung, she says.

On the horizon, there are new drugs awaiting FDA approval as blood clot treatment. They offer convenience to patients in terms of dosing and monitoring, Furey says. Unlike the blood thinner Coumadin, for example, which requires patients to have blood drawn frequently, the newer drugs need to be taken only once daily and do not require monitoring. "These are significant pharmacologic advances for patients and probably soon will be approved for anti-coagulation use," she says. NH