What is Warfarin?
Warfarin is an oral anticoagulant. (brand names - Coumadin and Marevan) Warfarin pills are taken every day to slow normal blood clotting
What is treated with Warfarin?
- Deep vein thrombosis - Painful swollen legs
- Pulmonary embolus - Clots on the lung
- Heart attacks - Clots in the coronary vessels
- Heart valves - To prevent clotting on the heart valve
- Atrial fibrillation - Irregular heart beat, Enlarged atrium
What are blood clots?
Blood clotting is a natural process to stop bleeding after an injury. Blood does not normally clot in the circulation, but can in some medical conditions. The medical term for a blood clot in the circulation is a thrombus or thrombosis.
Types of clots
Clots can form in arteries or veins. Blood clots that block arteries cause heart attacks and strokes. Clots in veins cause deep vein thrombosis and pulmonary embolus.
Clots in veins
A clot in a vein is called a venous thrombosis. These clots may be in superficial veins or deep veins.
Superficial vein thrombosis
- These form in veins just under the skin.
- They can cause a local area of tenderness.
- Often the skin becomes red and hot over the clot.
- The condition is sometimes called superficial phlebitis
Deep Vein Thrombosis
- These clots form in veins deep inside the leg. The veins involved cannot be seen.
- These most commonly form in the leg veins but can occur in other parts of the body such as the arms or intestines.
How do I know if I have a deep vein thrombosis?
Your doctor may suspect that you have a deep vein thrombosis if you have some of the following symptoms.
- Pain - this can be anywhere in the leg but is commonly felt in the calf.
- Swelling - often most obvious around the ankle, but can involve the whole leg.
- Redness - a slight dusky discolouration of the leg is common.
- Warmth - the leg feels warm to touch.
These are the most common symptoms of a deep vein thrombosis but they are not all present in all cases.
What causes the symptoms?
Blood is carried to the leg through an artery and should drain out of the leg through the deep veins. If there is a clot in the veins the blood cannot drain out normally. The pressure in the leg rises and causes pain, swelling and inflammation.
Why did I develop a blood clot?
In many cases we don’t know why blood clots form but a number of things are known to increase your risk of having a clot. It is often a combination of these factors that causes a clot.
Risk factors
- Recent surgery – especially hip, knee, pelvic or abdominal surgery.
- Recent injury – fractures needing a plaster
- The oral contraceptive
- Hormone replacement therapy
- Pregnancy
- Slowing of the blood in the veins caused by lack of mobility due to illness, injury or a long air flight
- Having cancer
- Having a family history of deep vein thrombosis
Some people have a lifelong inherited clotting tendency.
Inherited blood disorders
The clotting process is very complicated and involves many different proteins in the blood. Some people are born with abnormalities of one or more of these proteins which increases their tendency to develop clots in later life. These abnormalities are quite rare, but the likelihood of finding one is higher in patients with:-
- a blood clot before the age of 40 years
- a family history of DVT.
- a DVT or PE with no obvious cause
- repeated blood clots
Blood tests will be taken to look for these inherited disorders if your doctor feels that testing is appropriate.
The finding of an inherited disorder may alter your treatment.
Are members of my family at risk of a blood clot?
If you have an identified inherited disorder you should discuss the implications of this with your doctor. Your children will have a 50% chance of having the same problem. It may be appropriate for your children or other members of your family to be tested. Affected family members may need counseling about oral contraceptive use and treatment at the time of surgery.
Will I get more clots?
There is a risk of having another blood clot when your warfarin treatment is stopped. This depends to some extent on why the clot occurred in the first place. If your blood clot was related to an operation, wearing a plaster cast or a long air flight, you are very unlikely to have another clot. However if your clot occurred for no obvious reason or you have a strong family history of clots your risk of another clot may be as high as one in twenty in the first year after stopping warfarin.
Can the risk of another clot be reduced?
Many clots form in high-risk situations such as surgery, trauma or immobility. The risk can be reduced if precautions are taken to prevent thrombosis. To ensure that you get the right treatment, you should remind your doctor that you have previously had a blood clot.
Are there any long term complications from a DVT?
Post thrombotic syndrome
Post thrombotic syndrome is a problem that can develop some time after you have had a deep vein thrombosis. It is caused by damage to the small valves in the leg veins. These valves are there to stop blood flowing in the wrong direction. When you have a DVT the valves can be damaged and stop working properly. This leads to poor blood flow which can cause pain and swelling during prolonged standing or exercise.
How do I know if I have post thrombotic syndrome?
Post-thrombotic syndrome can be difficult to diagnose as it can be mistaken for a new DVT. The symptoms are due to the poor blood flow and high pressure in the veins. In some people the symptoms are mild and cause heaviness and cramps after prolonged standing or exercise, but in others they can be more severe with persistent swelling, skin discolouration and even leg ulcers. If you have any of the following symptoms in your legs it may mean you have post thrombotic syndrome.
- Heaviness, aching feeling or cramps
- Skin changes
- Redness or a blue discolouration
- Dry flaky skin
- Hardening of the skin
- Skin ulcers
- Dilated blood vessels
Is post-thrombotic syndrome common?
Unfortunately 1 in 3 people with a DVT will develop some features of post thrombotic syndrome within 5 years. People who have a thrombosis more than once are more likely to get post-thrombotic syndrome.
How can I prevent post-thrombotic syndrome?
There are several things you can do to reduce your risk of post thrombotic syndrome.
- Probably the most helpful thing you can do is to wear special graduated compression stockings. These extend from the foot to just below the knee and must be properly fitted. Ideally they should be worn every day for 2 years after a clot but can be removed when you go to bed.
- When resting, elevate your legs above the level of your heart to help drain blood from your legs.
- Exercise regularly to keep your calf muscles strong. Walking, cycling and swimming all help calf muscle tone.
- Control your weight to reduce the pressure in the leg veins.
- Take care of your skin. The skin around the ankle can become dry and flaky and is easily damaged. Regularly use a moisturiser and see your doctor if you damage the skin around your ankle as ulcers can develop very quickly.
Can I have a heart attack or a stroke from a DVT?
No. If part of a blood clot in your leg breaks off it will cause a pulmonary embolus; the clot will travel through your leg veins and the main vein in your abdomen then through your heart to your lungs. The clot will not affect the blood supply to the heart to cause a heart attack and the clot cannot get to your brain to cause a stroke.
Am I at risk of a heart attack or stroke in the future?
Heart attacks and strokes are due to disease in the arteries. Your problem is a clot in a vein. There is no clear link between DVT or PE and future heart disease or stroke.
Can I have my treatment for DVT at home?
Yes, most treatment for DVT is given at home. Many patients give their own heparin injections, but if you are not able to do this, a district nurse will visit you to give your treatment.
Should I exercise with a blood clot?
You do not need to rest in bed with a blood clot. Gentle exercise is good as it helps to improve the blood flow in the legs, however vigorous exercise should be avoided for a few weeks after a DVT. Several short walks a day are more beneficial than an occasional long walk. Some people find that their legs swell more with exercise, if this is the case rest your legs up on a stool after exercise.
Can I get blood tests overseas?
Yes, warfarin or very similar drugs are used in most countries. The INR is the standard test for warfarin control internationally.
How long will I be on treatment?
Your specialist will decide how long the warfarin needs to be continued. If the warfarin is stopped too soon you may be at risk of getting another blood clot. For a deep vein thrombosis in the veins above your knee or for a pulmonary embolus you will normally need treatment for at least 6 months, but some patients may benefit from longer treatment.
For a small blood clot in the veins below the knee you may only need treatment for 3 months or even less.
Your doctor may recommend that you continue on warfarin lifelong if you have had several blood clots.
How is a PE confirmed?
A pulmonary embolus is confirmed using a special scan of your lungs, either a CT pulmonary angiogram or a ventilation perfusion lung scan.
When your lungs are scanned (CT Pulmonary angiogram) a dye is injected into your blood stream which shows the blood flowing through your lungs on x-ray. A pulmonary embolus will show up as a blockage in the blood flow.
Another test – a ventilation-perfusion lung scan is also used to diagnose a pulmonary embolus and may be used if you are unable to have a CTPA or the diagnosis is uncertain from other tests. The ventilation perfusion scan can show where the blood flow in the lungs is blocked by a blood clot.
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