Deep Vein Thrombosis

Veins carry blood from your feet and legs back to the heart. The deep veins carry 90% of the blood back to your heart. If a deep vein in your leg is damaged, your circulation back to the heart may be reduced. When blood moves slowly in the deep vein of the leg, it may become sticky and gather in the vein wall to form a blood clot. This is called a deep vein thrombosis (DVT). The blood clot may increase in size to completely block the leg vein, and a DVT can damage the vein and cause the leg to ache, swell, change color, and develop leg sores, known as venous stasis ulcers.

DVT can cause serious and long-lasting health problems. If a piece of a clot in the leg breaks off, it can travel through the heart and into the lungs and cause serious health problems which may be life-threatening. When the clot breaks loose and travels through the bloodstream to the lungs, it is called a pulmonary embolism (PE). Serious vein problems can be treated with proper medical care.

RISK FACTORS
Major risk factors for DVT are prolonged bed rest greater than three days, surgery, major injury such as paralysis from a spinal cord injury, cancer and cancer treatment, or having a central venous catheter while in a hospital. There are also certain inherited or familial risk factors for DVT. Minor risk factors for DVT include taking a long airplane flight or car trip, being over 40 years of age, smoking, having a heart attack, heart failure, stroke, being overweight, taking hormones (including birth control pills and hormone-replacement therapy), and having varicose veins. These risk factors may become more significant in combination.

TREATMENTS
Treatments for DVT and PE begin right away to prevent the blood clots in the leg from growing larger or breaking loose and traveling to the lungs. Treatment starts with blood-thinner medications such as heparin, low-molecular-weight heparins (enoxaparin, dalteparin, innohep) or fondaparinux (Arixtra). Heparin can be given intravenously (IV) in the hospital or as an injection. Low-molecular-weight heparins and fondaparinux are given only as an injection, which includes self-injection at home. Treatments will depend upon the patient's condition.

Other treatment options include the use of thrombolytic agents such as tissue plasminogen activator (rt-PA) or streptokinase and mechanical thrombectomy. This is particularly true in the case of a persistent DVT that extends into the iliofemoral (hip vein) or iliac (pelvic) veins as well as a clot accompanied by a large amount of leg swelling. With thrombolytic therapy, a small catheter is threaded to the area of the clot and "clot-busting" drugs dissolve the clot. With mechanical thrombectomy, a catheter is used to remove the clot from the legs or pelvis. Pulmonary embolectomy (surgical removal of the emboli) is used for people with a large PE who cannot be treated with thrombolytic therapy.

Warfarin is a pill that is started at the same time as heparin but takes several days to become effective. When warfarin becomes effective (usually about five days of combined therapy), the heparin is stopped. Warfarin may be taken for at least three and up to six months or longer to prevent the existing clot from growing. Warfarin must be monitored by frequent blood tests to see how well the medication is working to thin the blood. Too much medication can cause bleeding of the gums, excessive bruising, or even more serious bleeding requiring transfusion; too little warfarin can increase the risk of developing a new clot. Other medications, such as antibiotics, diet, and daily lifestyle habits can affect how well the warfarin is working to thin the blood.

If a person cannot take blood thinners, a filter may be placed in the patient's vena cava (the big vein returning blood to the heart) to prevent blood clots from reaching the lungs. The filter is inserted through a catheter placed in a vein in the neck or groin.

Other treatments for DVT include rest, leg elevation, heat and frequent walks to reduce the ongoing pain and leg swelling that may occur in a patient with DVT. After their leg swelling goes down, patients are fitted with elastic support stockings. The elastic support stockings are put on first thing in the morning. They may be removed before taking a shower or going to bed. A new pair of support stockings must be purchased when the original stockings are worn out, after about six months. These elastic support stockings are very important as they prevent the swelling that could cause serious tissue damage in the lower leg.

PREVENTING DVT
DVT preventative measures are used before and after procedures that may decrease the risk of DVT. Intermittent compression devices are used to prevent deep vein thrombosis from occurring in the leg. The device inflates and deflates knee-high sleeves on the legs, which result in decreasing the stagnant blood flow in the legs while the convalesing patient is confined to bed rest. Other measures include the use of heparin, low-molecular-weight heparin, or fondaparinux in lower doses in order to help prevent clots from forming. Early ambulation after surgery is very important.

When people find themselves on a long flight or car trip, it is recommended that they walk up and down the aisle every hour, flex and point their toes every 20 minutes when sitting, drink plenty of water, and avoid alcohol and caffeinated beverages. Leg elevation can improve blood flow whenever the leg feels swollen or heavy.

People who have had a DVT may be at increased risk for future blood clots. Recurrence is most common in people who have cancer or an inherited blood-clotting problem. Special tests of the blood may screen for inherited blood clotting abnormalities in the patient and for immediate family members who have had a blood clot. Reocurrence is lowest in people who have had a DVT related to temporary inactivity or surgery. Individuals at risk should discuss their past medical history, concerns, and procedures with their primary health-care provider.

About the Author: Victoria Gilpin, MSN, FNP-BC is a nurse practitioner for the Vascular Surgery Division at the University of Missouri Health Care System in Columbia, MO.