Thrombosis is the formation of a blood clot, known as a thrombus, within a blood vessel. It prevents blood from flowing normally through the circulatory system. Show Thrombosis can be deadly, and can affect any age, race, gender, and ethnicity.  Blood clotting, also known as coagulation, is the body’s first line of defense against bleeding. When we hurt ourselves, our clotting system forms a “plug” or “seal” to protect us from losing too much blood. Our bodies often break down the clot after we’ve healed – but sometimes, clots form inappropriately or fail to dissolve after an injury. A blood clot that forms and stays in a blood vessel is called a thrombus. Other medical terms used to describe blood clots include:
There are two main types of thrombosis:
Risk factors that contribute to thrombosis include:
Can blood clots be dissolved or removed?The safest way to dissolve a clot is to let the body’s own clot-dissolving processes take effect. This can take anywhere from weeks to years, although some blood clots do not go away. In the case of massive or life-threatening clotting, clot dissolving drugs can be administered via catheter directly into the blocked blood vessels to dissolve recently formed clots. Thrombolytic drugs do come with a risk of bleeding. In certain emergency situations, clots can be removed surgically, but this increases the risk of further clotting. What are the risks of blood clots recurring?The chances of a recurrent blood clot is dependent on the circumstances leading up to the first clot. For example, if the blood clot occurred as a result of surgery or trauma, then the chances of re-occurrence is relatively low. On the other hand, for people who developed unprovoked blood clots and have stopped treatment after 6 months, the chance of recurrence is approximately 20% in the first 4 years and roughly 30% after 10 years. What are the risks of taking an anticoagulant?With all anticoagulant medications, there is an increased risk of bleeding. Signs of excessive bleeding can include prolonged nose bleeds, severe bruising, bleeding gums, vomiting or coughing up blood, and, for women, increased bleeding during menstruation. Patients with cancer, over the age of 65, and with renal or liver failure, face a higher risk of bleeding. It is important for patients on anticoagulants to immediately seek medical attention if they experience:
Patients who are concerned about risks associated with taking an anticoagulant should speak with their doctors about their concerns. Newly Diagnosed?Interested in learning more about diagnosis or joining a patient support group? Check out some of our resources! Blood has a seemingly impossible job: It must flow continuously and smoothly throughout your body for an entire lifetime, but quickly shut off to prevent spills when you get a cut or injury. Blood clots are healthy and lifesaving when they stop bleeding. But they can also form when they aren't needed and cause a heart attack, stroke, or other serious medical problems. How Does Blood Clot?The life cycle of a normal blood clot depends on a series of chemical interactions. 1. Platelets form a plug. Tiny bits in your blood called platelets get "turned on" by triggers released when a blood vessel is damaged. They stick to the walls in the area and each other, changing shape to form a plug that fills in the broken part to stop blood from leaking out. When activated, platelets also release chemicals to attract more platelets and other cells, and to set off the next step. 2. The clot grows. Proteins in your blood called clotting factors signal each other to cause a rapid chain reaction. It ends with a dissolved substance in your blood turning into long strands of fibrin. These get tangled up with the platelets in the plug to create a net that traps even more platelets and cells. The clot becomes much tougher and more durable. 3. Reactions stop its growth. Other proteins offset extra clotting factor proteins so the clot doesn't spread farther than it needs to. 4. Your body slowly breaks it down. As the damaged tissue heals, you don't need the clot any more. The tough fibrin strands dissolve, and your blood takes back the platelets and cells of the clot. What Causes Blood Clots?The process begins whenever flowing blood comes into contact with specific substances in your skin or in blood vessel walls. When they touch, it usually means the skin or blood vessel wall is broken. Waxy cholesterol plaques that form in arteries have these things inside, too. If the plaque breaks open, they'll start the clotting process. Most heart attacks and strokes happen when a plaque in your heart or brain suddenly bursts. Blood clots can also form when your blood doesn't flow properly. If it pools in your blood vessels or heart, the platelets are more likely to stick together. Atrial fibrillation and deep vein thrombosis (DVT) are two conditions where slowly moving blood can cause clotting problems. Some drugs stop platelets from signaling each other so they won't stick together. Medicines called blood thinners make it hard for your body to make clotting factors, or they prevent proteins in the clot-forming process from working. Clot-dissolving drugs such as alteplase, streptokinase, and tenecteplase activate the protein that breaks down the fibrin strands. Sometimes doctors prescribe it as a treatment for heart attack or stroke. SOURCES: Merck Manual: "How Blood Clots." World Federation of Hemophilia: "The clotting process." American Stroke Association: "Anti-Clotting Agents Explained." Lipe, B. Circulation, Oct. 4, 2011. Furie, B. New England Journal of Medicine, 2008. Hoffman, R. Hematology: Basic Principles and Practice, 5th edition, Churchill Livingstone Elsevier, 2009. |
