Hereditary defects in one or more of the clotting factors can cause the formation of potentially dangerous blood clots (thrombosis). Approximately 5-8% of the U.S. population has one of these clotting disorders collectively called thrombophilia, a propensity for blood clotting in which a genetic defect can be identified that often results in thrombosis. Deep vein thrombosis is a blood clot in a vein deep within the body. Veins are blood vessels. The muscles in the arms and legs contract and help force the blood through the veins back to the heart. A system of valves within the veins helps prevent the blood from flowing backwards. More than 60,000 Americans die each year from venous thromboembolism; in addition, nearly half of patients with deep vein clots experience long-term health consequences that adversely affect their quality of life.
Deposits of red blood cells and clotting elements in the blood can accumulate in a vein and lead to blood clot formation. Clots usually occur in the legs but can occur in other locations. As the clot grows, it blocks blood flow in the affected vein.
Causes
Several factors contribute to clot formation, including:
-
Slow blood flow, often due to lying or sitting still for an extended period of time
-
Pooling of blood in a vein, often due to:
-
-
-
-
Injury to a blood vessel
-
Clotting problems (can occur due to aging or disease)
-
Catheters placed in a vein
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.
-
Not moving your body
-
Hospitalization
-
Surgery, especially involving bones or joints
-
Medical conditions such as:
-
-
-
-
-
-
-
Obesity
-
History of deep vein thrombosis
-
Taking birth control pills or estrogen therapy
-
Pregnancy
Symptoms
Symptoms occur when:
-
The clot interferes with blood flow in the vein
-
Local inflammation occurs
-
A clot breaks free and travels to the lungs
Some patients may not experience any symptoms until the clot moves to the lungs, a condition called pulmonary embolism.
Symptoms of deep vein thrombosis may include:
-
Pain
-
Swelling of a limb
-
Tenderness along the vein
-
Warmth
-
Redness, paleness, or blueness of the skin of the affected limb
Diagnosis
The doctor will ask about your symptoms and medical history, and perform a physical exam.
Tests may include:
Duplex Venous Ultrasound – a test that uses sound waves to detect changes in blood flow
Venography – x-rays taken after dye is injected into a small vein to show areas of normal and abnormal blood flow
Impedance Plethysmography – measures changes in blood volume in the veins as a blood pressure cuff wrapped around the thigh is inflated and deflated
Treatment
Treatment aims to:
-
Prevent pulmonary embolism
-
Stop the clot from growing
-
Dissolve the clot (sometimes)
Treatments include:
Supportive Care
This may include:
A recent study among 103 patients recently admitted to the hospital with deep venous thrombosis suggested that strict bed rest may not be necessary. In fact, early ambulation (walking) may be beneficial as long as adequate treatment with heparin (see below) and compression stockings are provided. *
Medications
Anticoagulant drugs to prevent additional clot formation include:
-
Heparin injection – fast-acting drug that prevents more clot formation (given for several days)
-
Warfarin (taken by mouth) – slowly prevents more clot formation (usually given for several months)
-
Fibrinolytic enzymes – helps to dissolve a major clot. These include:
-
-
-
Surgery
In certain situations, doctors may place a filter in the inferior vena cava, a major vein returning blood from the lower body to the heart. The filter may trap any clots that break loose and travel toward the lungs.
Prevention
General prevention measures include:
If you are admitted to the hospital, talk to your doctor about how to prevent blood clots, such as:
-
Getting out of bed and walking as soon as possible during your recovery
-
If you are restricted to bed:
-
-
-
Wearing compression stockings, which promotes venous blood flow
-
Taking anticoagulant medication if advised by your doctor
-
Using a pneumatic compression device (a device that uses air to compress your legs and help improve venous blood flow)
RESOURCES:
American Heart Association
http://www.americanheart.org
American Venous Forum
http://www.venous-info.com/index.html
References:
AHA Medical/Scientific Statement: Management of Deep Vein Thrombosis and Pulmonary Embolism; 1996.
Cecil Textbook of Medicine. 21st ed. W.B. Saunders Company; 2000.
Conn's Current Therapy 2001. 53rd ed. W.B. Saunders Company; 2001.
Emergency Medicine: Concepts and Clinical Practice. 4th ed. Mosby-Year Book, Inc; 1998.
Harrison's Principles of Internal Medicine. 14th ed. The McGraw-Hill Companies; 2000.
Church V. Staying on guard for DVT and PE. Nursing. Feb 2000.
Dowling NF. Austin H. Dilley A. Whitsett C. Evatt BL. Hooper WC. The epidemiology of venous thromboembolism in Caucasians and African-Americans: the GATE Study. Journal of Thrombosis & Haemostasis. 1(1):80-7, 2003.
Hooper WC, Evatt BL. The role of activated protein C resistance in the pathogenesis of venous thrombosis. Am J Med Sci 1998;216:120-128.
*Updated section on Supportive Care on 10/27/06 according to the following study, as cited by DynaMed's Systematic Literature Surveillance: Junger M, Diehm C, Storiko H, Hach-Wunderle V, Heidrich H, Karasch T, et al. Mobilization versus immobilization in the treatment of acute proximal deep venous thrombosis: a prospective, randomized, open, multicentre trial. Curr Med Res Opin. 2006 Mar;22(3):593-602.
