What is Deep Vein Thrombosis/ Pulmonary Embolism
Blood clotting provides us with essential protection against severe loss of blood from an injury to a vein or artery. However, blood is only supposed to clot when it is outside a blood vessel, and clotting within an artery or vein can be dangerous. A deep vein thrombosis (DVT) occurs when a blood clot forms in a vein. The DVT usually forms in a deep leg vein. Deep leg veins are the larger veins that run through the muscles of the calf and thigh.
Fortunately, DVT is a rare condition. It is less common in people under the age of 40 and more common in people over the age of 70. A DVT usually develops in the calf, but it sometimes also occurs in the thigh. Occasionally, other deep veins in the body are affected.
What is Pulmonary Embolism ?
A fraction of the clot from DVT can be detached and travel up to the blood vessels in Lungs causing decrease in the blood flow. This detached clot (called embolus) can seriously affect the normal functioning of lung which is essential for life. This is called pulmonary embolism.
What are the symptoms ?
The symptoms of a DVT in the leg include:
• tenderness, and
• redness, particularly at the back of your leg, below the knee.
A DVT usually (but not always) affects one leg. The pain may be made worse by bending your foot upward towards the knee. In some cases, there may be no signs or symptoms of DVT at all in the leg.
Symptoms of a pulmonary embolism include breathlessness, chest pain and, in severe cases, collapse. Both DVT and pulmonary embolism are serious conditions and require urgent investigation and treatment.
Why do people get DVT ?
DVT sometimes occurs in normal veins for no apparent reason. However, the risk of developing DVT is increased in certain circumstances.
If you are immobile, the blood flow in your veins slows down and increases the chances of a blood clot occurring. Illnesses and injury that cause immobility, such as a stroke, increase the risk of DVT. Also, long journeys by plane, train, and car may also increase the risk slightly.
If the inside lining of your vein becomes damaged, your chances of getting DVT are increased. Conditions such as vasculitis (inflammation of the vein wall) and some forms of medication, such as chemotherapy, can damage veins and increase the risk of DVT. Also, DVT can damage the lining of your vein, increasing your chances of having another DVT in the future.
Medical and genetic conditions
Your risk of DVT is increased if you have a condition that causes your blood to clot more easily than normal. There are a number of medical conditions which can cause this to happen. For e.g. patients with cancer or heart failure, have an increased risk of getting DVT. Pregnancy and obesity also increase your chances of getting DVT, with approximately 1 in 1,000 pregnant women developing the condition.We can test for some of the genetic conditions.
Contraceptive pill and hormone replacement therapy (HRT)
The combined contraceptive pill, and hormone replacement therapy (HRT) both contain the female hormone, oestrogen. Oestrogen causes the blood to clot slightly more easily, so if you are taking either the pill, or HRT, your risk of getting DVT is slightly increased. There is no increased risk from the progestogen-only pill.
How is DVT/PE diagnosed ?
As there are many different causes of a swollen, painful calf, it can be difficult to diagnose deep vein thrombosis (DVT) from the symptoms alone. Various tests used to diagnose them are:
A specialised blood test, known as the D-dimer test, is sometimes used to detect pieces of a blood clot that have been broken down and are loose in your blood stream.
An ultrasound scan can be used to detect a clot in the vein of your leg. A special type of ultrasound, known as Doppler ultrasound, is also sometimes used to find out how fast the blood is flowing through a blood vessel.
CT scan of chest
Special CT scan of the chest can help in diagnosing PE.
How is it treated ?
Treating deep vein thrombosis (DVT) will prevent the clot getting larger, breaking off, and travelling up the vein to the lungs (pulmonary embolism).
Anticoagulation (thinning of the blood)
Anticoagulant drugs are used to prevent the DVT from getting larger. The blood is not actually thinned, but chemicals within it are altered preventing clots from forming so easily.
Warfarin is an anticoagulant that is often used. If anticoagulation treatment is started soon after a DVT develops, the chances of serious embolism occurring are significantly reduced. The dosage of warfarin that is given has to be precise to ensure that the blood will not clot too easily, but it should also not cause excessive bleeding either.
While taking warfarin, you will need to have regular blood tests so that the dosage can be checked and, if necessary, adjusted. For pregnant women, heparin injections may be used instead of warfarin tablets. The length of time that you will need to take anticoagulation medication will depend on your risk of getting DVT in the future.
Compression stockings help to prevent damage to the tissue of the calf that may be caused by the increase in blood pressure that occurs due to the blood being diverted to the outer veins. They may also prevent, or reduce, calf pain, swelling, and the risk of ulcers developing.
Stockings should be worn every day for at least two years because symptoms of post-thrombotic syndrome may develop several months, or even years, after having DVT. If you have had DVT and compression stockings are recommended, make sure that you have them fitted professionally. You should put your compression stockings on in the morning, wear them all day, and take them off before going to bed. However, you can take them off in the evening while you rest with your leg raised.
Raising your leg
As well as wearing compression stockings, you might be advised to raise your leg while you are resting. It helps to relieve the pressure in the veins of the calf, and stops blood and fluid from pooling in the calf itself. Putting a cushion underneath your leg while you are in a reclining position should help raise your leg above the level of your hip. Slightly raising the end of your bed will ensure that your foot and calf are slightly higher than your hip when you are asleep.
What are the Complications of DVT ?
There are two main complications of deep vein thrombosis (DVT) : pulmonary embolism, and post-thrombotic syndrome.
A. Pulmonary embolism
As previously mentioned PE is a serious complication of DVT.
If the pulmonary embolism is small, it might not cause any symptoms. If it is medium sized, it can cause breathing difficulties and chest pain. A large pulmonary embolus can be fatal. About 10% of people with an untreated DVT develop a pulmonary embolism that is severe enough to cause symptoms or death.
B. Post-thrombotic syndrome
Long-term symptoms in your calf can develop if you have DVT and do not receive treatment. This is known as post-thrombotic syndrome, and affects up to 60% of people with untreated DVT.
If you have DVT, the blood clot in the vein of your calf can divert the flow of blood to other veins, causing an increase in pressure that can affect the tissues of the calf. The symptoms can include calf pain, discomfort, swelling, and a rash. In severe cases, an ulcer may develop on of the calf.
There is an increased risk of post-thrombotic syndrome occurring if DVT develops in your thigh vein. It is also more likely to occur if you are overweight, or you have had more than one DVT in the same leg.
Monitoring of anticoagulation ?
We have set up a special clinic to monitor all patients on warfarin in a systematic way. You will be given a special book to record your blood test and the tests will be performed at one lab which is experienced in getting accurate results.Warfarin has to be monitored very closely as increased levels may lead to bleeding. You will be given more information about the special clinic
There are 2 types of heparin
a. Unfractionated Heparin: This is the "old" heparin which has to be given once/twice a day beneath the skin. It is very cheap, but has more side-effects.
b. Low molecular weight Heparin: It is a small molecule of heparin so side-effects are greatly reduced. It is expensive and can be used as once a day injection beneath your skin