Deep Vein Thrombosis
Dr. Sanjay Agarwal
A deep vein thrombosis is a blood clot or thrombus that develops in deep vein usually in leg; here they pass through the centre of leg, surrounded by muscles, less commonly DVT occurs in deep veins of arm of pelvis. DVT is primarily related to the stasis of blood flow, vascular wall damage, activation of clotting system and hypercoaguable state.
Blood passing through the deepest vein in calf or thighs flows relatively slow then from a solid clot which becomes wedged in the veins.
The deep veins are responsible for returning the blood to heart and lungs and these veins weaken in their functions of propelling blood over a period of time especially when a person is confined to immobilization.
The veins may be partially or completely blocked but the blood clot causing DVT. Presence of hypercoagulable state such as pregnancy, deficiency of antithrombin III, protein C and protein S, myeloproliferative disorders and other hyperviscosity syndrome increase the vulnerability for DVT. Many DVTs disappear without problem, but they can return. Some people may have long – term pain and swelling in the leg known as post – phlebitis syndrome. Wearing tight stockings during and after the DVT may help prevent this problem.
DVT is common in individuals who have a long distance travels especially in the aircraft or car. The commonest risk factors are individuals after the age of forty with prolonged immobilization such as prolonged bed rest due to medical and surgical ailments such as respiratory failure, heart failure, paralysis, after fracture pelvis or femur, after heart attack, after trauma or accident, after extensive abdominal, thoracic or neurosurgery and in cancer patients. Obese individuals with diabetes are more prone to DVT patients with malignancy and smokers and those women who are on oral contraceptive pills are more vulnerable.
The commonest complications of DVT are – fatal pulmonary embolism, post thrombotic syndrome and recurrence of venous thrombosis or pulmonary embolism etc.DVT can be prevented by regular physical activity especially if an individual is immobilized fir longer time. The need of DVT prophylaxis cannot be over emphasized.
Only 10 percent of individuals who require DVT prophylaxis actually get it, remaining 90 percent of individuals are deprived of this DVT prophylaxis because of ignorance, lack of awareness or lack of skill. The need of DVT prophylaxis is usually underestimated. People who already had a DVT can take some precautions to avoid uncomfortable complications.
Taking blood thinning drugs such as aspirin is one way to cut the risk of developing a clot. Taking a low dose of aspirin before a long fight may reduce a risk. There are number of things you can do to reduce your risk, such as stop smoking if you do that, and losing weight if you are overweight.
Regular walking can also help to improve the circulation in your legs and help to prevent another DVT from developing. Foot exercises while sitting down, rotating the ankles and wiggling the toes prevents the blood pooling in the feet and then struggling to climb up through the veins. Wearing the compression stockings may also be advised for those at risk of developing a DVT. Immediately after an operation, people are encouraged to get out of bed as early as possible. Anticoagulant medicines are the standard treatment for DVT. They can change chemicals in your blood to stop clots forming so easily. Anticoagulant includes heparin and warfarin.
It can also stop new blood clots from forming and old ones from getting bigger. They can’t dissolve clots that you already have. Your body will do that itself overtime. Apart from that thrombolytic medicines dissolve blood clots, but they can cause bleeding and so are rarely used to treat DVT.
If you are having surgery then you must know that surgery and some medical treatments can increase your risk of developing DVT. So if you’re going to hospital for an operation, you will usually have an assessment to check your risk of developing DVT before you have your operation. But there are many measures that can be done to keep your risk of developing DVT during surgery as low as possible.
Pulmonary embolism is the most serious complication of DVT. It happens when a piece of the blood clot breaks off and travels through your bloodstream to your lungs, where it blocks one of the blood vessels. This is serious and can be fatal. Post thrombotic syndrome is an another complication of DVT, this happens if the damage caused by a DVT permanently reduces the ability of your veins to efficiently return blood from your lower leg and leads to pooling of fluid.
This can eventually lead to long- term pain and swelling. In severe cases these may lead to ulcers on your leg. Limb ischemia is a rare complication that only happens with a large DVT. The blood can cause the pressure in your vein to become high. This can block the flow of bold through your arteries, so less oxygen is carried to your affected leg. This can be painful and lead to skin ulcers, infection and even gangrene. DVT is rare in young people, usually occurring in people aged over 40. It is however recommended that you should call your doctor if you are at the risk of DVT.
(The author is the chief of surgery and the head of Orthopaedics P.D. Hinduja National Hospital, Mumbai)