Arterial thrombosis is a blood clot in an artery, which can be very serious because it can stop blood reaching important organs. Arteries are blood vessels that carry blood from the heart to the rest of the body and the heart muscle. A blood clot does not usually have any symptoms
until it blocks the flow of blood to part of the body. This can cause several serious problems, including: These conditions are all medical emergencies. Get medical help straight away by calling 999 if you or someone in your care is experiencing these symptoms. Arterial thrombosis usually affects people whose arteries are clogged with fatty deposits. This is known as atherosclerosis. These deposits cause the arteries to harden and narrow over time and increase the risk of blood clots. The following can increase your risk of developing atherosclerosis: Sometimes arterial thrombosis can be due to a condition that makes your blood more likely to clot, such as atrial fibrillation or antiphospholipid syndrome. It's not
possible to prevent blood clots entirely, but you can reduce your risk by lowering your risk of atherosclerosis. The main things you can do are: If you're at a high risk of
getting a blood clot, your doctor may also recommend taking medicines such as: If you develop arterial thrombosis, it may need to be treated with medicine or surgery. Treatments include: As well as arterial thrombosis, there are several other types of blood clot, including: Page last reviewed: 09
January 2020 Deep vein thrombosis is the formation of blood clots (thrombi) in the deep veins, usually in the legs.
Deep vein thrombosis occurs most often in the legs or pelvis but may also occasionally develop in the arms. Three main factors can contribute to deep vein thrombosis:
During prolonged bed rest and other occasions when the legs are not moving normally (such as after a leg injury or a stroke), blood flow slows because the person is lying down and the calf muscles
are not contracting and squeezing the blood toward the heart. For example, deep vein thrombosis may develop in people who have had a
heart attack
Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina) Acute coronary syndromes result from a sudden blockage in a coronary artery. This blockage causes unstable angina or a heart attack (myocardial infarction), depending on the location and amount...
read more Although deep vein thrombosis is uncomfortable, the main concern is with the complications, including
Blood clots in the legs or pelvis are more likely to become emboli than blood clots in the arms, perhaps because the squeezing action of the calf muscles can dislodge a blood clot in a deep vein. The consequences of pulmonary embolism depend on the size and number of emboli:
Massive emboli are not common, but no one can predict which case of deep vein thrombosis, if untreated, will lead to a massive embolus. Multiple emboli may occur. Multiple emboli typically go to different parts of the lungs. Rarely, a very large blood clot in a leg causes so much swelling that it blocks the blood flow through the leg. The leg becomes pale or blue and extremely painful. Gangrene can develop if the blood flow is not restored. About half of the people with deep vein thrombosis have no symptoms at all. In these people, chest pain or shortness of breath caused by pulmonary embolism may be the first indication that a blood clot is present. In other people, if a deep leg vein is involved, the calf swells and may be painful, tender to the touch, and warm. The ankle, foot, or thigh may also swell, depending on which veins are involved. Similarly, if an arm vein is involved, the arm may swell.
Sometimes doctors do a blood test to measure a substance called D-dimer that is released from blood clots. If the level of D-dimer in the blood is not increased, the person probably does not have a deep vein thrombosis. If the person has symptoms of pulmonary embolism, computed tomography (CT) angiography Chest Imaging or rarely, nuclear lung scanning Chest Imaging using a radioactive marker, is done to detect pulmonary embolism, and Doppler ultrasonography is done to check the legs for clots. These procedures are done except when a person collapses due to very low blood pressure or very low oxygen levels. Collapse suggests massive pulmonary embolism and requires immediate treatment. Although the risk of deep vein thrombosis cannot be entirely eliminated, it can be reduced in several ways:
Preventive measures are selected depending on the person's risk factors and individual characteristics. People at low risk of deep vein thrombosis, such as those who must be temporarily inactive for long periods, as during an airplane flight, and those who are undergoing minor surgery but have no other risk factors for deep vein thrombosis, can take simple measures. Such people should elevate their legs, flex and extend their ankles about 10 times every 30 minutes, and walk and stretch every 2 hours while awake during long flights. People at higher risk of deep vein thrombosis require additional preventive treatment. Such people include
Continuously wearing high-compression elastic stockings (support hose) makes the veins narrow slightly and the blood flow more rapidly. As a result, clotting may be less likely. However, elastic stockings are not sufficient protection against developing deep vein thrombosis. Also, they may give a false sense of security and discourage more effective methods of prevention. If not worn correctly, they may bunch up and aggravate the problem by blocking blood flow in the legs.
Treatment usually consists of
Anticoagulant drugs are blood thinners. They decrease the blood’s ability to clot, so they can prevent new clots from forming and can stop existing clots from getting bigger. They do not break up or dissolve clots that have already formed. All people with deep venous thrombosis are given anticoagulant drugs. Doctors usually use low-molecular-weight heparin (such as enoxaparin, dalteparin, or tinzaparin) or fondaparinux given by injection under the skin (subcutaneously), accompanied by warfarin taken by mouth. The injectable drug works immediately, but warfarin takes several days to be fully effective. Once the warfarin has taken effect, people stop taking the injectable drug. For some people (those with cancer or those with recurrent clotting problems despite treatment with anticoagulants by mouth), doctors only use the injectable drug and do not start warfarin. How long people continue drug treatment (with warfarin or an injectable drug) varies according to the degree of risk. People whose deep vein thrombosis resulted from a specific, temporary cause (such as surgery or a drug they have stopped taking) usually continue drug treatment for 3 to 6 months. When a specific cause is not found, people usually take warfarin for at least 6 months. Warfarin should be continued indefinitely if the cause is not temporary (for example, a blood clotting disorder) or if people have had two or more episodes of deep vein thrombosis. Use of warfarin increases the risk of bleeding, both internally and externally. To minimize the risk, people taking warfarin must have periodic blood tests to see how much their blood is anticoagulated. Doctors then use the blood test result to adjust the dose of warfarin. The blood tests are usually done once or twice a week for 1 or 2 months, and then every 4 to 6 weeks thereafter. Direct oral anticoagulants (DOAC) are an alternative to warfarin. Rivaroxaban, apixaban, edoxaban, and dabigatran are DOACs. These drugs have a faster anticoagulant effect than warfarin and are as effective as warfarin for the treatment of blood clots. The effect of DOACs on people's blood is more predictable than the effect of warfarin. Therefore, unlike people taking warfarin, people taking DOACs do not need to have frequent blood tests to adjust the dose. Also, DOACs tend to cause fewer episodes of serious bleeding than warfarin. However, bleeding caused by DOACs can be harder to stop because antidotes for these drugs are not as widely available as antidotes for warfarin. Excessive bleeding, which may be life-threatening, is the most common complication of anticoagulant drugs. Risk factors for excessive bleeding include being age 65 or older or having For people who are taking warfarin, doctors can give vitamin K, transfusions of plasma (which contains clotting factors), or prothrombin complex concentrate to reverse the effects of the warfarin and stop the bleeding. For people who are taking heparin, doctors can give protamine to partially reverse the effects. For people taking some of the DOACs, doctors can give andexanet alfa or prothrombin complex concentrate to reverse the effects of the DOACs and stop the bleeding. Inferior Vena Cava Filters: One Way to Prevent Pulmonary EmbolismIn people who have deep vein thrombosis, a blood clot may break loose from an affected vein in the leg and travel through the bloodstream. A clot that breaks loose is called an embolus. The embolus travels toward the heart and passes through the right atrium and ventricle and into one of the pulmonary arteries, which carry blood to the lungs. The clot may lodge in an artery in a lung and block blood flow, resulting in pulmonary embolism. Pulmonary embolism may be life threatening, depending on how large the embolus is and the size of the blocked artery. To prevent pulmonary embolism, doctors usually use drugs that limit blood clotting. However, for some people, doctors may recommend that a filter (formerly called an umbrella) be temporarily or permanently placed in the inferior vena cava. The inferior vena cava is a large vein that returns blood to the heart from the lower part of the body. The filter typically is recommended when drugs that limit clotting (anticoagulants, or blood thinners) cannot be used, for example, when a person is also having bleeding. The filter can trap emboli before they reach the heart but allow blood to flow through freely. Emboli that are trapped sometimes dissolve on their own. However, filters do not completely eliminate the risk of emboli. Sometimes other veins from the legs enlarge, allowing blood and emboli to bypass the filter. Also, filters can break loose or become blocked by a clot. Filters are much less effective at preventing pulmonary embolism than treatment with anticoagulants. Doctors only occasionally use intravenous drugs, such as alteplase, to dissolve venous blood clots. These drugs (also called thrombolytic, fibrinolytic, or clot-busting drugs) may be given to a person with extensive blood clots if the blood clot has been present for less than 48 hours and the person does not have risk factors for excessive bleeding. After 48 hours, scar tissue begins to develop in the blood clot, making it less likely to dissolve. Clot-dissolving drugs have a higher risk of bleeding complications. Doctors sometimes use clot-dissolving drugs in combination with mechanical removal methods in people who have large clots in their upper leg. In such cases, doctors may put a small, flexible tube (catheter) into the blocked vein, remove as much clot as possible with an instrument, and administer the clot-dissolving drug through the catheter. Once blood flow in the veins has improved, the ulcer heals by itself. After it has healed, wearing an elastic stocking daily can prevent a recurrence. The stocking must be replaced as soon as it becomes too loose. If possible, the person should purchase seven stockings or pairs of stockings (if both legs are involved)—one for each day of the week so that stockings remain effective considerably longer. Rarely, ulcers that do not heal require skin grafting. After grafting, an elastic stocking must be worn to prevent ulcers from returning. The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource. What is the blood clot at a called?A blood clot is also called a thrombus. The clot may stay in one spot (called thrombosis) or move through the body (called embolism or thromboembolism). The clots that move are especially dangerous. Blood clots can form in arteries (arterial clots) or veins (venous clots).
What is caused by the blockage of blood vessel by a blood clot?If a blood clot blocks the arteries leading to part of the heart muscle, it will cause a heart attack. If it blocks an artery in the brain, it will cause a stroke.
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