deep vein thrombosis

Deep vein thrombosis 

Definition

Deep vein thrombosis (DVT) is a blood clot in a major vein that usually develops in the legs and/or pelvis.

Description

Deep vein thrombosis is a common but difficult to detect illness that can be fatal if not treated effectively. The disorder is estimated to affect 80 people per 100,000 population annually, but some experts feel this is an underestimate of the disorder because the condition often remains undetected and resolves on its on without complications. About 600,000 people are hospitalized in the United States for DVT each year. If left untreated, DVT can cause pulmonary emboli. This is a potentially fatal complication in which blood clots break off, travel through the circulatory system, and become lodged in and block an artery going to the lungs. Each year about 200,000 people die of pulmonary emboli caused by DVT. Deep vein thrombosis is also called venous thromboembolism, thrombophlebitis or phlebothrombosis.
Deep vein thrombosis is a major complication in patients who have had orthopedic surgery or pelvic, abdominal, or thoracic surgery. Patients with cancer and other chronic illnesses (including congestive heart failure), as well as those who have experienced a recent heart attack (myocardial infarction), are also at high risk for developing DVT. Deep vein thrombosis can be chronic, with recurrent episodes.

Causes and symptoms

Deep vein thrombosis is caused by blood clots in blood vessels that form in veins where blood flow is sluggish or has been disturbed, in pockets in the deep veins of the calf, or in veins that have been traumatized. Symptoms include swelling and tenderness, pain in the calf or thigh, and possibly warmth. Fewer than half of all people with the condition experience symptoms, and symptoms tend to be nonspecific (e.g., leg pain may be caused by many other conditions). Some individuals and families have underlying clotting tendencies that can be tested for.

Diagnosis

Deep vein thrombosis can be detected through venography and radionuclide venography, Doppler ultrasonography, and impedance plethysmography. Venography is the most accurate test, but it is not used much because it is often painful, expensive, exposes the patient to radiation, and can cause allergic reactions and complications. Venography identifies the location, extent, and degree of attachment of the blood clots and enables the condition of the deep leg veins to be assessed. A contrast solution is injected into a foot vein through a catheter. The physician observes the movement of the solution through the vein with a fluoroscope while a series of x rays are taken. Venography takes 30-45 minutes and can be done in a physician's office, a laboratory, or a hospital. Radionuclide venography, in which a radioactive isotope is injected, is occasionally used, especially if a patient has had an allergic reaction to contrast solutions.
Doppler ultrasonography usually is the preferred procedure for detecting deep vein thrombosis. This technique uses sound waves to measure blood flow through leg veins and arteries. A blood pressure cuff is wrapped around the patient's ankle and a transducer with gel on it is placed over pulse points of the foot and lower leg. High-frequency sound waves bounce off the soft tissue, and the echoes are converted into images on a monitor. This procedure is very accurate in detecting clots above the knee that can become pulmonary embolisms. Usually performed in a physician's office or hospital outpatient diagnostic center, Doppler ultrasound takes about 30-45 minutes.
Impedance plethysmography is a noninvasive way to record changes in blood volume and vessel resistance. A blood pressure cuff is wrapped around the leg above the knee, four electrodes are placed near the knee and the ankle, and the cuff is inflated to compress the veins and reduce blood flow. The efficiency with which the veins return to normal is then measured. Performed in a physician's office, impedance plethysmography takes about 15 minutes.

Treatment

Deep vein thrombosis can be treated with drug therapy, bed rest, and gradient elastic stockings. Medications include anticoagulants that "thin" blood to prevent further growth of blood clots, as well as clot-dissolving drugs. Heparin is a common injectable anticoagulant and is usually followed by warfarin (Coumadin) tablets for at least three months. Bed rest with the patient's legs elevated is necessary until the condition improves. Gradient elastic stockings should then be worn, and standing for long periods avoided. In some cases, a filter is surgically placed in the major vein (the inferior vena cava) to trap emboli or clots before they get to the heart and lungs. In another surgical procedure, a catheter is inserted into the vein. When the clot is reached, a balloon at the end of the catheter is inflated, and then withdrawn along with the clot. However, this procedure risks dislodging the clot.

Alternative treatment

Deep vein thrombosis can be life threatening and must be treated with conventional medical therapies. However, some alternative therapies may be used in conjunction with conventional treatments to dissolve the clot. These therapies may help support the body and prevent recurrence. A conventional physician as well as a trained alternative health care practitioner should be consulted due to the severity of this condition.

Prognosis

Complications from DVT can be life threatening or chronically debilitating. Pulmonary emboli develop in about 10% of people with DVT and account for about 10% of all hospital deaths. DVT also can cause inflammation of the blood vessels resulting in loss of contractility and chronically decreased function. On the other hand, about three-quarters of people with DVT remain free of symptoms, and in many cases, the condition resolves with minimal treatment.

Prevention

Deep vein thrombosis can be prevented through prophylactic anticoagulant drugs and venous stasis prevention with gradient elastic stockings and intermittent pneumatic compression of the legs. Individuals should avoid standing or sitting for long periods without moving; walking or exercising the legs on long airplane and car trips helps keep blood from pooling in the legs and helps to prevent DVT. High-risk individuals often need to remain on oral anticoagulants (e.g., Coumadin) indefinitely.

Key Terms

Catheter

A long, thin, flexible tube that can be inserted into a vein and moved through the cardiovascular system.

Pulmonary embolism

An obstruction of a blood vessel in the lungs, usually caused by a blood clot that blocks a coronary artery. Pulmonary embolism can be very serious and, in some cases, fatal.

Thrombosis

The development of a blood clot inside a blood vessel.

For Your Information

Resources

Websites

• "Deep Vein Thrombosis, Thrombophlebitis, and Phlebitis." VascularWeb. 2009 [cited February 18, 2009]. http://www.vascularweb.org/patients/Links_To_Patient_Information/Links_to_Conditions/Deep_Vein_Thrombosis.html.


• Wedro, Benjamin C. "Deep Vein Thrombosis." MedicineNet.com. April 30, 2008 [cited February 18, 2009]. http://www.medicinenet.com/deep_vein_thrombosis/article.htm.


• "Deep Vein Thrombosis." MedlinePlus. February 17, 2009 [cited February 18, 2009]. http://www.nlm.nih.gov/medlineplus/deepveinthrombosis.html.

Organizations

• American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231. (800) 242-8721. http://www.americanheart.org .


• National Heart Lung and Blood Institute Health Information Center. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 592 8573. http://www.nhlbi.nih.gov.


• Society for Vascular Surgery. 633 N. St. Clair, 24th Floor, Chicago, IL 60611; Telephone: 312-334-2300or 800-258-7188. Fax: 312-334-2320; Email: vascular@vascularsociety.org. http://www.vascularweb.org.

Deep vein thrombosis

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deep vein thrombosis (DVT),

a disorder involving a thrombus in one of the deep veins of the body, most commonly the iliac or femoral vein. Symptoms include tenderness, pain, swelling, warmth, and discoloration of the skin. A deep vein thrombus is potentially life threatening. Treatment, including bed rest and use of thrombolytic and anticoagulant drugs, is directed to preventing movement of the thrombus toward the lungs. See also pulmonary embolism.

observations It may be asymptomatic or manifest as tenderness, pain, warmth, and swelling in the affected extremity with deep reddish or blue color. There is a positive Homans' sign in about 10% of cases, which affects a lower extremity. Serial compression ultrasonography is the initial test used for diagnosis. Magnetic resonance direct thrombus imaging may be used for thrombi undetectable on ultrasound. Contrast venography remains the gold standard for detection of lower extremity DVT. Chronic venous insufficiency and pulmonary embolus are the most common complications of thrombosis.

interventions Initial treatment is heparin or enoxaparin followed by warfarin for maintenance treatment for 3 to 6 months. Continued monitoring of prothrombin time and partial thromboplastin time is done during anticoagulant therapy. Ligation, clipping, plication, and thrombectomy are surgical alternatives when thrombus fails to respond to anticoagulant therapy. An extravascular vena cava interruption with possible placement of intracaval filter is used for cases involving probable emboli. Analgesics are given for pain; however, aspirin is contraindicated because it interferes with platelet function. Enoxaparin may be used with patients at high risk for DVT to prevent thrombus formation.

nursing considerations Acute care nursing goals focus on prevention of pulmonary emboli, pain relief, prevention of skin breakdown, and prevention of complications related to anticoagulant therapy. Bed rest is instituted for the first several days after beginning anticoagulant with elevation of affected extremity above the level of the heart and use of warm, moist packs. When ambulation is resumed, compression stockings are used to support vein walls and reduce pain and swelling. Individuals are closely observed for signs of bleeding (e.g., gums, nasal mucosa, stool, and urine). Safety precautions are instituted to prevent bruising while on anticoagulants and to prevent skin ulceration of affected extremity. Individuals are monitored for manifestations of pulmonary emboli, including sudden dyspnea, tachypnea, and pleuritic chest pain. Education is important and includes effects and side effects of anticoagulant therapy; need for ongoing blood tests to monitor clotting and regulate anticoagulant dosage; avoidance of activities that may precipitate bleeding; avoidance of anticoagulant over-the-counter medications that may interfere with clotting (e.g., aspirin/aspirin products, NSAIDs, and herbal products). Education is needed about signs of pulmonary embolus and the need for immediate medical attention should they occur. Instruction is provided to prevent pooled blood in the lower extremities, including regular use of compression garments and avoidance of prolonged standing, sitting, or walking. Teaching also includes prevention of future thrombosis episodes, such as avoidance or correction of modifiable risk factors (e.g., tobacco use or alcohol abuse, use of oral contraceptives or hormone replacement therapy, and prolonged periods of inactivity), regular exercise program, proper posture, and balanced diet with weight loss if indicated.

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deep vein thrombosis

Internal medicine A condition characterized by blood clots in veins, most often of the lower extremity, often giving rise to embolism and tissue necrosis; DVT occurs in¹⁄₂ of total hips without prophylactic anticoagulation, 2-3% of which evolve to fatal PE; acute DVT occurs in 1:1000 of the general population; 92% are idiopathic, ±8% are due to isolated deficiencies of protein C, protein S, antithrombin III, plasminogen Risk factors ↑ Age, immobilization, prior DVT, anesthesia, surgery, pregnancy, CA, hypercoagulability–↓ AT III, ↓ protein C, ↓ protein S, activated protein C resistance, antiphospholipid syndrome, polycythemia vera, erythrocytosis, tissue trauma–which activates coagulation, and ↑ coagulation factor XI Clinical Vague–SOB ±leg swelling, pain, edema, discoloration Diagnosis Phlebography, impedence plethysmography, compression ultrasonography–real time B mode, Doppler flow velocity, MR venography, radionuclide venography, thermography, d-dimer assay Management Anticoagulation–eg, heparin or warfarin or thrombolytic therapy–eg, alteplase or streptokinase; inferior vena caval filters; thrombectomy. See Total hip replacement.

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Patient discussion about deep vein thrombosis.

Q. How can I prevent blood clots? I am 45 years old and am supposed to go on a business trip overseas. The flight itself is 12 hours long and then I have to continue traveling by bus. Could this cause me to have blood clots? If so, how can I prevent it?

A. Sitting or laying in one position for a long period of time can increase the risk of developing DVT- deep vein thrombosis. Here are some methods to prevent it:
Exercise your calf and foot muscles regularly:
Every half hour or so, bend and straighten your legs, feet and toes when you are seated.
Press the balls of your feet down hard against the floor or foot-rest every so often. This helps to increase the blood flow in your legs
Take a walk up and down the aisle every hour or so, when the aircraft crew say it is safe to do so.
If you are allowed, get off the plane and walk about if the plane stops for refueling.
Consider buying a leg exerciser for the journey.
Drink plenty of water (to avoid dehydration).
Do not drink too much alcohol. (Alcohol can cause dehydration and immobility.)
Do not take sleeping tablets, which cause immobility.
Consider wearing compression stockings.
Some people at high risk may also be advised to take anticoagulant medication by their Dr.

Q. Are long flights dangerous? I'm flying next week to my vacation, and the flight is going to be rather long (almost 16 hours non-stop). Several years ago, my 75 years-old aunt had blood clot in her lung after a flight of similar length. I also heard that during flight the blood in the legs clots and that it can cause after that problems with the lungs and breathing. Does this mean it's dangerous for me to fly? Should I change my ticket to shorter connection flights?

A. Long flights, especially when seating in crowded cabins without moving the legs for long periods can cause the blood in you legs to clot and after that to move to your lungs and damage them. You may try to move your legs during the flights (like getting up and walking a little etc.) This video has some suggestions:
http://youtube.com/watch?v=_mte4WsVZUk

Q. Does anyone have any experience or suggestions regarding aerobic exercise post DVT and/or PE?

A. drink a lot of water and be aware. if you take your meds i think there shouldn't be a problem, but i strongly recommend asking your physician about it. he knows you and the problem and can give you a much much better answer.