To understand what happens after a deep vein thrombosis it is necessary to understand how blood flows in the veins of the legs.
The Normal leg and valves
In a normal leg, blood flows from the foot, back to the heart, through tubes called veins. When you stand up, the blood is prevented from falling back to the ankle by a series of one way valves in the deep veins and superficial veins.
The Calf muscle pump
In the calf muscle in each leg, there are many veins. As the muscle contracts, when you walk, run, or move the foot, the muscle squeezes the veins and pumps the blood in the vein back towards the heart. This is called the calf muscle pump. It is a bit like a heart for the veins.
What happens when a clot forms in the deep vein?
This is called a deep vein thrombosis or DVT. Reduced flow in the vein, damage to the wall of the vein or a thickening of the blood can cause blood to clot in the vein. When this happens, no blood can flow through the vein. This means the leg can become hot and swollen as the venous blood has to can only get back to the heart through small channels.
How a thrombus blocks a vein and damages a valve.
An analogy would be a dam being built across a river bed. The fields that drain into the river would become flooded or water-logged ( the swelling of the leg). The fields can only drain through other streams away from the river.
In time, and this varies, the small channels gradually enlarge to carry more of the blood. This is why some people who have had a DVT can develop prominent veins. Some people think these might be varicose veins. If the valves in these veins are working normally, then removing them can make the leg worse. This is why anyone who is going to have varicose vein surgery after a DVT should have a Duplex scan.
As the small channels enlarge, the leg swelling can reduce.
At the same time, several things can happen to the veins that were affected by the DVT. The human body is good at clearing thrombus by a process called thrombolysis.
If all the thrombus is cleared then the deep veins may be undamaged. In many people who have had a DVT, the thrombus leaves scars within the vein. This scarring can damage the valves and narrow the diameter of the veins.
What problems does scarring of the veins cause?
Aching legs and swollen legs.
If the valves in the deep veins are damaged then blood runs in the wrong direction, towards the ankle. This puts extra pressure on the ankle’s blood vessels which means the leg can swell. Many people with this problem of incompetent deep veins ( valves that do not work) have pain in their leg when they stand up. The pain can get worse as the day continues. They only get relief when the lie down again.
Some people have a feeling of a rush of blood into the calf when the deep veins are incompetent.
Failure of the calf pump.
The scarring of the veins can narrow their diameter. This means the calf muscle can only pump small amounts of blood out of the leg. This makes it difficult to drain the blood from the leg.
When the incompetent valves and failed calf pump are combined, the leg can become increasingly swollen and painful. This condition is the Post-Thrombotic or Post-Phlebitic Syndrome.
What can happen if I develop the Post-Thrombotic Syndrome?
Apart from the aching and swelling of the leg, there can be changes in the colour of the skin of the leg. Ultimately, the skin of the leg can become so damaged that an ulcer develops.
The leg can change in appearance to look a little like and upside down champagne bottle.
Can anything be done to help?
The most important thing to do is to prevent the deep vein thrombosis in the first place. For more information on DVT prevention, click here.
When a DVT has occurred, it may be possible to remove the thrombus by dissolving it or removing it surgically. Most doctors will, however, suggest that the DVT is treated by anticoagulation ( thinning of the blood) with an injection called heparin or a tablet called warfarin.
If you have the post-thombotic syndrome, you will have been advised to wear some form of compression stocking. These can help the swelling and pain.
Some patients cannot or do not want to wear stockings. For these patients it may be possible to correct the deep vein problems with an operation.
Mr Braithwaite has been trained in deep venous surgery. He has written about his training in the United States.
Can I have Deep vein surgery?
Mr Braithwaite has a research programme designed to test the best ways to treat the post-thrombotic syndrome. He uses a new method to rebuild a valve in the deep veins. Not everyone is suitable for deep vein surgery. If you want to discuss the possibility of deep vein surgery, please contact Mr Braithwaite.