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Preventing and Treating Deep Vein Thrombosis

Posted Jul 09 2012 6:52am
 
This article discusses the diagnosisThe process of determining which condition a patient may have. and treatment of Deep Vein Thrombosis, a common circulatory condition. This will be of help to anyone with symptoms such as swelling or pain in the leg who would like further information on how to prevent, or treat, DVTAn abbreviation for deep vein thrombosis: the obstruction of one of the deep veins, often in the calf, by a blood clot..

Deep Vein Thrombosis (DVT) is when a bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. clotBlood that has coagulated, that is, has moved from a liquid to a solid state. known as thrombusA blood clot. develops in the deep veins, primarily of the legs and pelvisThe bony basin formed by the hip bones and the lower vertebrae of the spine; also refers to the lower part of the abdomen.. It is a condition that requires urgent medical attention to prevent further complications such as a life-threatening pulmonary embolismObstruction of the pulmonary artery by a blood clot. (PEpulmonary embolism) or permanent long-lasting damage to the leg veins, known as post-thrombotic syndrome.

Diagram of a thrombus in the leg (Deep Vein Thrombosis)

Common symptoms include localised pain or tenderness within a calf or thigh muscleTissue made up of cells that can contract to bring about movement., usually associated with ankle and calf swelling.

Blood clots in deep veins can grow in size, break loose, and then travel through the bloodstream to the lungs resulting in life-threatening pulmonary embolism (PE). Symptoms relating to PE include breathlessness, chest pain, palpitationsThe feeling when you become aware of your heartbeat - when frightened, for example., increased heart rate and coughing.

The most commonly used tests to diagnose DVT are an ultrasound scanThe process of using high-frequency sound waves to produce internal images of the body. of the veins in the affected limb, known as a venousRelating to the veins. duplex scan, and a sensitive blood test (D-dimerA small protein fragment present in the blood after a blood clot.). Specialist scans such as MRIAn abbreviation for magnetic resonance imaging, a technique for imaging the body that uses electromagnetic waves and a strong magnetic field. or CTThe abbreviation for computed tomography, a scan that generates a series of cross-sectional x-ray images Venograms could be used for more detailed images of the clot, especially in the pelvicRelating to the pelvis. area; these are also used to plan endovascular treatment. Extremely rarely, special x-ray Venograms are performed for diagnostic purposes.

A contrast dye needs to be administered intravenously in order to perform CT or x-ray Venograms and there is a small chance of an allergyVarious conditions caused by exaggerated reactions of the immune system (hypersensitivity reactions) to a variety of substances. to the contrast used. If you are known to have an allergy to contrast, you will not be able to have this type of scan. Similarly, if you are known to have impaired kidneyOne of two bean-shaped organs that are located on either side of the body, below the ribcage. The main role of the kidneys is to filter out waste products from the blood. function, the amount of contrast used may have to be altered to avoid causing further damage.

The most common treatment for DVT is primarily with drugs that thin out the blood. These drugs are known as anticoagulants.

This treatment usually entails injections of heparinA substance produced by the body, or given as medication, that reduces the likelihood of the blood to clot, coagulate. which act immediately, whilst oral warfarin is started and the level stabilised. Warfarin works by combatting the vitaminEssential substances that cannot be produced by the body and so must be acquired from the diet. K in the body which is used for blood clotting. It is usually started by giving a loading doseA higher dose of drugs given at the start of treatment to get the right level of the drug in the body; a lower dose is then given for the longer term to maintain this level. for three days and then using blood tests to stabilise the right dose over the next few days to weeks. Contrary to popular belief, blood thinners (anticoagulants) do not actively dissolve the clot, but instead prevent new clots from forming. Over time, the body itself will dissolve the clot.

Diagram of a clot in the lung (pulmonary embolism)

Treatment with Warfarin aims to treat the symptoms of the DVT i.e. pain and swelling, as well as prevent small parts of the clot breaking off and travelling to the lungs thereby causing a life-threatening PE. As the medication works against the normal clotting function of the body, patients are advised that they may bruise more easily than normal.

Rarely if the clot is too big, it may have to be dissolved with other drugs injected directly through a catheterA tube used either to drain fluid from the body or to introduce fluid into the body. in to the clot (catheter-directed thrombolysisBreaking up a blood clot by administering medications called thrombolytics.) or even removed in a minimally invasive way, which is called endovascular mechanical thrombectomy. This involves placing a thin catheter through the vein, into the clot itself. Water jets from the catheter break up the clot before the small pieces are sucked into the catheter and removed from the body.

If necessary, any narrowing in the vein that might lead to future clot formation can be identified and treated with a balloon or stentA tube placed inside a tubular structure in the body, to keep it patent, that is, open. placement. This is again performed using a thin catheter placed into the vein. A stent, which is a metal cage, is placed over the catheter and expanded using a balloon to widen narrowed areas.

In a small group of high risk patients, a minimally invasive operation is needed to place a filter in the large vein above the blocked leg vein. The aim is to stop any blood clots from travelling up to the lungs. This may be considered if anticoagulation cannot be given (for various reasons), or if it fails to prevent clots breaking off and travelling up into the larger veins and to the lungs.

Treatment with oral Warfarin is usually for 3–6 months. On occasions, treatment can extend to 9–12 months or even longer. When the treatment is first started, you will have a blood test to check your INRInternational Normalised Ratio - a test of the blood's clotting ability, used to monitor treatment with anticoagulants such as warfarin. level every day. Once your level is in the ideal range and the dose of Warfarin has stabilised you will have the INR check twice a week for a few weeks. Following this, a blood test will be performed every six weeks until the end of treatment. Follow-up is organised based on local set-up arrangements.

It can take some time before leg swelling completely resolves. Compression stockings can be supplied to help this process and you should keep the leg elevated when at rest.

Low impact, non-contact exercise is safe. Swimming and walking are good forms of exercise.

Yes. There is generally no contraindicationA condition which may make a medical treatment or procedure inadvisable. to travelling. The same advice for long haul flights will apply - you should do foot exercises whilst sitting and walk in the aisle when safe to do so. Use of compression stockings can also be helpful. If you need to travel soon after you have been diagnosed with a DVT, arrangements will need to be made for INR monitoring to ensure you take the correct dose of Warfarin.

If the correct dose of Warfarin is given and the INR is in the target range, it is very rare for this to happen.

The most important side effect of Warfarin is bleeding. Warfarin works by slowing down the clotting time of blood, therefore there is an increased chance of bleeding with minor injuries. Other side effects include rash, headaches, hair loss and abnormal liverA large abdominal organ that has many important roles including the production of bile and clotting factors, detoxification, and the metabolism of proteins, carbohydrates and fats. function.

A new blood thinning medication, similar to Warfarin, has recently been approved. However, the medication, (known as Pradaxa®) is currently only licensed for the prevention of blood clots in patients with irregular heart beats and NOT for the treatment of DVT/PE.

Generally not. DVT’s affect the deep veins whereas a heart attack or stroke involves the arteries. In patients who have a hole in the heart allowing the venous and arterial systems to mix, there can be an increased risk of this happening.

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