Deep Vein Thrombosis
Deep vein thrombosis
Definition
Deep vein thrombosis is a blood clot in a major vein. DVT usually affects the thigh, calf or pelvis however it can also affect the arms, chest or other areas of the body.
Description
Deep vein thrombosis is a common but difficult to detect illness that can be fatal if not treated effectively. While arteries bring oxygen-rich blood from the heart to the rest of the body, veins return oxygen-deficient blood to the heart. There are three types of veins in the body including superficial veins that are close to the skin, deep veins situated within groups of muscles, and perforating veins that connect the superficial and deep veins with one-way valves. Deep veins are extremely vital to the body's function because they lead to the body's largest vein called the vena cava, which is directly connected to the heart. According to the American Heart Association, more than two million Americans develop deep vein thrombosis annually. An estimated 600,000 of these develop pulmonary embolism , a potentially fatal complication where the blood clots break off and form pulmonary emboli, plugs that block the lung arteries. Sixty thousand people die of pulmonary embolism each year. Deep vein thrombosis is also called venous thromboembolism, thrombophlebitis or phlebothrombosis. DVT can be chronic, with recurrent episodes.
While the majority of DVT cases occur in the legs, DVT cases involving the upper portion of the body is becoming more common. Individuals with implanted devices such as catheters, pacemakers , or defibrillators are at increase risk for developing clots.
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 calf's deep veins, or in veins that have been traumatized. Some individuals and families have underlying clotting tendencies that can be tested for.
Deep vein thrombosis may be caused by:
- a broken hip or leg
- hereditary blood clotting abnormalities
- a recent heart attack
- major hip, knee, leg, calf, abdomen, or chest surgery
- cancer and other chronic illnesses including congestive heart failure
- prolonged travel (this condition is often referred to as economy class syndrome because of the decreased mobility of the legs that people experience during air travel in coach class)
Approximately half of patients with DVT do not experience any symptoms. However, the most common symptoms include:
- swelling or tenderness of the calf or thigh (made worse by walking or standing).
- skin that feels warm to the touch
- skin that turns blue or red
Diagnosis
The three most common tests used to diagnose DVT include:
- Ultrasound. Ultrasound is the preferred test for diagnosing deep vein blood clots. This method uses sound waves to generate images of blood flowing through the veins and arteries in the affected leg or other area of the body.
- A D-dimer test. The A D-dimer test gauges a substance in the blood that is released when a blood clot dissolves. If high levels of the substance is detected, this may indicate the presence of a deep vein blood clot.
- Venography. A venography test is used if ultrasound fails to provide a definite diagnosis. Venography involves injecting dye into a vein, and then taking an x ray of the leg. The dye makes the vein visible on the x ray. If the x ray indicates that blood flow in the vein is slow, this may indicate a blood clot.
KEY TERMS
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.
Other tests used to diagnose DVT include computed tomography (CT) scanning and magnetic resonance imaging (MRI). Blood tests are useful in determining whether an individual has an inherited blood clotting disorder that can trigger DVT.
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 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 of time avoided. In some cases, a filter is placed in the major vein (the inferior vena cava) to trap emboli or clots before they get to the heart and lungs.
Therapy
Deep vein thrombosis can be life-threatening and must be treated with conventional medical therapies. However, there are alternative therapies that can be used in conjunction with emergency treatments to dissolve the clot that help support the body and prevent recurrence. A trained alternative health care practitioner should be consulted due to the severity of this condition.
Prognosis
In many cases, deep vein thrombosis can be successfully treated if diagnosed early. However, some populations are more at risk for developing DVT. Postoperative Cancer patients have as a minimum twice the risk of developing postoperative DVT than non-cancer patients that undergo similar procedures. Approximately 60% of patients in the United states who undergo total hip replacement surgery may develop DVT if proper preventative measures are not taken. In the elderly, a 21% one-year mortality rate exists for those who develop DVT.
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. High-risk patients often need to remain on anticoagulants like Coumadin indefinitely.
Resources
PERIODICALS
JAMA and Archives Journals. “Patients Who Develop Blood Clots At Risk Of Recurrence Within Three Years.” Science Daily Online. February 25 2008. March 17 2008. http://www.sciencedaily.com/releases/2008/02/080225213715.htm.
JAMA and Archives Journals. “Studies Assess Blood Clot Prevalence Outside Hospital, Prevention In Hospital.” Science Daily Online. July 31 2007. March 17 2008. http://www.sciencedaily.com/releases/2007/07/070723163555.htm.
Radiological Society of North America. “New Therapy Effectively Treats Deep Vein Thrombosis, Study Suggests.” Science Daily Online. January 30 2008. March 17 2008. http://www.sciencedaily.com/releases/2008/01/080129080704.htm.
ORGANIZATIONS
National Heart, Lung, and Blood Institute. National Institutes of Health, Building 31, Room 5A48 31 Center Drive MSC 2486, Bethesda, MD, 20892, (301) 592 8573, http://www.nhlbi.nih.gov.
Society for Vascular Surgery, 633 N. St. Clair, 24th Floor, Chicago, IL, 60611, (800) 258-7188, http://www.vascularweb.org.
The Coalition to Prevent Deep-Vein Thrombosis, 55 Corporate Dr., Bridgewater, NJ, 08807, (800) 981-2491, http://www.preventdvt.org.
Lisa M. Piazza
Deep Vein Thrombosis
Deep Vein Thrombosis
Definition
Deep vein thrombosis (DVT) is a blood clot in a major vein, usually 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. According to the American Heart Association, more than two million Americans develop deep vein thrombosis annually. An estimated 600,000 of these develop pulmonary embolism, a potentially fatal complication where the blood clots break off and form pulmonary emboli, plugs that block the lung arteries. Sixty thousand people die of pulmonary embolism each year. 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 suffered a recent 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 calf's deep veins, or in veins that have been traumatized. Symptoms include swelling and tenderness of the calf or thigh, and possibly warmth. Only 23-50% of patients experience symptoms, so it's often "silent." 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 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 reactions to contrast solutions.
Doppler ultrasonography is usually 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 sounds bounce off the soft tissue, and the echoes are converted into images on a monitor. It 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 usually takes 30-45 minutes.
Impedance plethysmography records 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. How efficiently the veins return to normal is measured. Performed in a physician's office, it 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 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 of time avoided. In some cases, a filter is placed in the major vein (the inferior vena cava) to trap emboli or clots before they get to the heart and lungs.
Alternative treatment
Deep vein thrombosis can be life-threatening and must be treated with conventional medical therapies. However, there are alternative therapies that can be used in conjunction with emergency treatments to dissolve the clot that help support the body and prevent recurrence. A trained alternative health care practitioner should be consulted due to the severity of this condition.
Prognosis
In many cases, deep vein thrombosis can be successfully treated if diagnosed early.
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. High-risk patients often need to remain on anticoagulants like Coumadin indefinitely.
Resources
PERIODICALS
Davidson, Bruce L., and Eric J. Deppert. "Ultrasound for the Diagnosis of Deep Vein Thrombosis: Where to Now?" British Medical Journal 316 (January 3, 1998): 2.
KEY TERMS
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.