What is Deep Vein Thrombosis (DVT)?
Deep vein thrombosis, commonly referred to as "DVT", occurs when a blood clot, or thrombus, develops in the large veins of the legs or pelvic area. Some DVT’s may cause no pain, whereas others can be quite painful. With prompt diagnosis and treatment, the majority of DVT’s are not life threatening. However, a blood clot that forms in the invisible "deep veins" can be an immediate threat to your life, as compared to a clot that forms in the visible "superficial" veins, the ones beneath your skin. A clot that forms in the large, deep veins is more likely to break free and travel through the vein. It is then called an embolus. When an embolus travels from the legs or pelvic areas and lodges in a lung artery, the condition is known as a "pulmonary embolism," or PE, a potentially fatal condition if not immediately diagnosed and treated.
What are the causes of DVT?
Generally, a DVT is caused by a combination of two or three underlying conditions:
- slow or sluggish blood flow through a deep vein
- a tendency for a person’s blood to clot quickly
- irritation or inflammation of the inner lining of the vein.
There are a variety of settings in which this clotting process can occur. First, individuals on bed rest (such as during or after a surgical procedure or medical illness, such as heart attack or stroke), or confined and unable to walk (such as during prolonged air or car travel) are common settings. It can occur in certain families in whom there is a history of parents or siblings who have suffered from prior blood clots. It can also occur in individuals whom active cancer or its treatment may predispose the blood to clotting.
Having a recent major surgical procedure, especially a hip and knee orthopedic surgeries or those requiring prolonged bed rest, predispose the blood to clotting. Irritation or inflammation occurs when a leg vein is injured by a major accident or medical procedure.
Also, there are specific medical conditions that may increase your risk of developing a DVT via these three mechanisms, such as congestive heart failure, severe obesity, chronic respiratory failure, a history of smoking, varicose veins, pregnancy and estrogen treatment. If you are concerned that you may be at risk due to any of these conditions, please consult with your physician.
What is Thrombophilia?
Thrombophilias can be defined as a group of inherited or acquired disorders that increase a person's risk of developing thrombosis (abnormal "blood clotting") in the veins or arteries.
The human body is equipped with a sophisticated and well-balanced blood coagulation (or clotting) system, in which platelets (the "clotting" blood cells) and multiple coagulation proteins mingle in order to avoid both excessive bleeding and excessive clotting. Thrombus (blood clot) formation is a good thing after injuries to blood vessels, regardless of whether the injury results from an accidental cut, major trauma, a broken bone, or surgery. If blood clotting did not occur, you would experience unstoppable (and even life threatening) bleeding. This normal blood clot formation should be localized to the area where blood vessel injury occurred and should be stopped as soon as the leak of blood from the vessels is contained and/or the vessel injury is healed or repaired. In the presence of thrombophilias, the well-balanced coagulation system has a predisposition toward thrombosis, which is also referred to as "hypercoagulability" or "hypercoagulable state."
Thrombophilias can be inherited (hereditary), acquired (not inherited), or both. Inherited thrombophilias are abnormalities of the genes that are responsible for making the coagulation proteins (known as genetic mutations). Acquired thrombophilias are due to increased levels of certain clotting substances in the blood or special proteins called antibodies which may also lead to clotting. The most common inherited thrombophilias include Factor V Leiden (a symptom-free condition that increases the risk of deep vein thrombosis), and the Prothrombin gene mutations, as well as the uncommon but well-known deficiencies of Protein C, Protein S, or Antithrombin. Individuals who are born with an inherited thrombophilia are also referred to as "carriers" of that particular genetic mutation. The most common acquired thrombophilias are commonly encountered during surgery, injury, or medical conditions including congestive heart failure and certain respiratory conditions, and these are called Antiphospholipid antibodies (APLA). These represent a family of several different individual antibodies which may, as a group or independently, lead both to clotting events and also recurrent miscarriages. Some thrombophilias can both have a genetic predisposition and be acquired. Research studies have estimated that nearly 10% of the world population has an underlying thrombophilia, the most common being the Factor V Leiden and the Prothrombin gene mutations.
Both inherited and acquired thrombophilias appear to "tilt" the well-balanced coagulation system towards clotting (thrombosis). Such an imbalance in the coagulation system results in a greater risk of clotting events, such as deep venous thrombosis (DVT) or pulmonary embolism (PE). However, the simple fact that a person has a thrombophilia and a greater chance of developing abnormal clotting than a person without thrombophilia does not mean that the former individual will ever have a clotting event. Fortunately, not all people with thrombophilia will have a blood clot in their lifetime, whereas unfortunately many patients who do experience thrombotic events (such as DVT) may not have any detectable thrombophilia at all.
Learn more at Vascular Disease Foundation website.