Deep vein thrombosis: You're so vein

Most people are familiar with diseases of the arteries since they account for heart attacks (coronary arteries), most strokes (the carotid arteries and smaller arteries in the brain), and many amputations (the leg arteries). And here’s more: Arterial disorders are also the culprits in many cases of kidney failure, dementia, intestinal bleeding, and even erectile dysfunction.

But the circulatory system has another set of blood vessels — the veins. Arteries carry oxygen-rich blood from the heart to all the body’s tissues. Then veins swing into action, collecting the blood from the tissues and returning it to the heart and lungs so it can be circulated again and again. Arteries get all the press, but veins deserve some respect, too. More than that, they deserve the care that can help prevent venous disorders. Many venous disorders are mild, but some are serious. And one, deep vein thrombosis (DVT) — the formation of a blood clot (thrombus) inside a blood vessel — can be life-threatening.

Clot Formation

DVT develops in the larger deep veins that are the final conduits funneling blood back to the heart. It mostly occurs in the largest veins of the legs and pelvis (see illustration), although DVT may occasionally develop in the arms. Many factors can make you more prone to DVT, including:

• Certain cancers, especially pancreatic, brain, lymph node and lung cancers, or chemotherapy.

• Advanced age or medical circumstances that require you to be in prolonged bed rest.

• A past incident of DVT or pulmonary embolism.

• Use of hormone replacement therapy or birth control pills.

• Pregnancy and especially recent childbirth.

• A family history of blood clots, which may indicate an inherited blood-clotting disorder.

• Lifestyle factors such as obesity.

In addition, any one of several situations may be a triggering event leading to DVT. Even after the triggering event is over, risk of DVT may be heightened for up to three months. Triggering events include:

• Hospitalization for a sudden medical problem. Trauma to the leg area or pelvis or a fracture of a leg or pelvic bone puts you at especially high risk.

• Major surgery. This especially includes hip or knee replacement or surgery in the pelvic area.

• Long periods of sitting. Airplane flights that are around six or more hours are among the main culprits, but long car or train rides can be, too.

Hard To Detect

Many DVTs can develop and grow quite large before causing any symptoms. Still, almost all cause signs and symptoms eventually. These may include:

• Swelling in the ankle area of the affected leg. Typically, only one leg is affected.

• Leg pain that often starts in the calf and can feel like a cramp.

• Redness or warmth over the affected area and fever.

If your doctor suspects DVT, ultrasound imaging is typically the first test used because it’s safe, widely available, and quite accurate. Additional testing, such as advanced imaging scans or additional blood testing, may be done to aid in the diagnosis, identify the root cause of the problem or help establish effective therapy.

Pulmonary Embolism

From the deep veins of the legs and pelvis, it’s a straight shot to the heart, and only a short distance farther to the lungs. If a fragment — or, more commonly, several fragments — of a deep vein thrombosis breaks loose, it can be carried to the lungs, blocking blood flow. This is called pulmonary embolism, and it can be fatal.

Signs and symptoms of pulmonary embolism vary. Sometimes, no symptoms are evident. However, seek medical care if you experience:

• Unexplained shortness of breath, which can come on gradually or suddenly.

• Sharp chest pain when you inhale or cough.

• Feeling light-headed or dizzy or even fainting.

• Coughing up blood.

Stabilization

If you’re found to have DVT, the immediate focus of treatment is preventing the clot from getting bigger and reducing the risk of pulmonary embolism. The mainstays of therapy are drugs to prevent blood clotting (anticoagulants). These won’t dissolve the blood clot, but they help prevent blood clots from breaking off your DVT and prevent further blood clot growth.

Initial anticoagulant therapy involves injections of a fast-acting drug such as heparin. The oral anticoagulant warfarin (Coumadin) may be started along with heparin. Warfarin takes a few days before it’s fully effective. As the warfarin takes effect, you will be instructed to stop heparin. Most people with DVT can expect to take an anticoagulant drug for a minimum of three months. That’s often how long it takes for the body to dissolve the blood clot. However, depending on the causes of your DVT and your risk of developing another, you may need to continue anticoagulants for as long as your risk remains increased. With anticoagulant use, there’s increased risk of bleeding, so it’s important to work closely with your doctor to monitor your risk.

If you can’t take anticoagulants, a clot-trapping filter may be placed in the large vein in your abdomen that leads from your legs to your heart. The filters may be able to block a clot from reaching your lungs. However, they’re not risk-free and may actually increase the risk of developing clots in the legs. In addition, evidence showing they can save lives is lacking. In rare cases, clot-dissolving drugs (thrombolytics) may be used to dissolve DVT. For most, the risk of potentially deadly bleeding outweighs the clot-dissolving benefit.

Collateral Damage

A deep vein blood clot is likely to cause vein damage or result in residual vein blockage. This may impair blood flow. Blood that should be getting pumped up to your heart can instead pool in your legs when you’re upright. The result is leg swelling due to fluid accumulation (edema). Without treatment, additional skin problems and large, difficult-to-heal sores may occur.

When swelling occurs as a result of DVT, it’s called a post-thrombotic syndrome. About 30 to 50 percent of those who have DVT will develop post-thrombotic syndrome. The chances of developing it are highest within the first one to two years. But anyone who has had DVT is at risk of developing post-thrombotic syndrome at some point later in life. Well-fitted compression stockings that are put on the affected leg the moment you get out of bed and worn all day are the main treatment of post-thrombotic syndrome. How they’re worn varies. Some doctors recommend that everyone with DVT wear them for one to two years. Others feel they’re only needed if significant swelling is present. Once post-thrombotic syndrome develops, you’ll probably need to wear a compression stocking on the affected leg.

Stopping Clots

For most healthy adults, DVT is rare and not worth worrying about. If you’re at elevated risk of DVT or are working up to prevent a second episode, help keep your legs clot-free by:

• Taking precautions when traveling. Stay hydrated, avoid alcohol, and take hourly breaks from sitting to walk around. The extra legroom of an aisle or business-class seat may help. For those at especially high risk, a below-the-knee compression stocking or an injection of heparin prior to travel may be needed.

• Making lifestyle changes. Losing weight if you’re obese may help reduce your risk of DVT.

• Following instructions from your doctor. There are well-established guidelines for preventing DVT in many medical situations, particularly with surgery. Anticoagulants feature prominently in almost every DVT prevention plan. It’s important to take anticoagulants for the length of time recommended by your doctor or surgeon — which may be several weeks or longer — and to carefully follow any additional instructions.

Indeed, you should show your veins the respect they deserve! — Source: “On the alert for deep-vein blood clots,” Howard Health Publications (May 2009); heart_letter@hms.harvard.edu