What symptoms can you expect in the long term after DVT, and how do you tackle them? What medication should you take? We asked Mr Philip Coleridge Smith, one of London's leading vascular surgeons:
How does the body recover after DVT?
Once a DVT has developed, the process of removing the blockage begins. It is removed by the body’s own natural processes. This takes many weeks or months, especially in the larger veins, such as the femoral vein. The process by which the flow of blood is restored in blocked veins is referred to as recanalisation.
During this time you will be prescribed anti-coagulant (blood-thinning) medication, such as heparin or warfarin. This can help prevent further episodes of DVT and reduce your risk of pulmonary embolism, where the blood clot breaks off and travels to your lung.
What is post-thrombotic syndrome?
Post-thrombotic syndrome is a group of symptoms you may experience as a result of increased pressure in your legs following DVT.
Unfortunately, recanalisation is not a perfect process. Some veins remain permanently blocked and blood flow is never restored in these veins. Other veins will have increase in size to accommodate the blood that flows around your legs.
Even if a vein does recanalise, the valves in that vein may be permanently damaged. Normally, valves ensure that blood flows exclusively towards the heart – against gravity, in the case of the legs. If the valves are damaged, blood may flow towards the feet as well as the heart. To compensate for this, your calf muscles will have to work harder to manually pump the blood back into the heart. This increased pressure on the veins can lead to leg pain when walking and is referred to a venous claudication.
Increased pressure in the veins can also damage the skin, leading to ulceration (a chronic non-healing wound) at the ankle. All of the tissues which are subjected to increased venous pressure may become swollen due to oedema (increased tissue fluid), so another common problem is swelling of the ankle, foot and calf.
The combination of leg pain, skin changes, ulceration and swelling what we call post-thrombotic syndrome.
How is post-thrombotic syndrome treated?
The main treatment for patients with damage to their deep veins following a DVT is the use of compression stockings. These reduce swelling of the foot and ankle as well as minimising the risk of ulceration at the ankle.
A number of surgical procedures are available to repair damaged valves and to bypass blocked veins. These must be carried out by a vascular surgeon with specialist experience in treating DVT.
It is important to note that surgery is only a feasible treatment option if the damage to the leg veins is limited. Following an extensive DVT, there are simply too many damaged veins to treat. In a patient with extensive deep vein thrombosis it may be necessary for them to wear compression stockings for the rest of their life.
What is the outlook in the long term?
In the longer term (over many years) the valves do not recover and symptoms of post-thrombotic vein damage tend to worsen.
Unfortunately, having damaged veins also increases your chances of further episodes of DVT, so long-term treatment with anticoagulants may be necessary. While these are effective in preventing thrombosis, they do carry a risk of life-threatening haemorrhage. It is important that you have a full conversation with your consultant to weigh up the risks and benefits of anti-coagulant medication.
The good news is that the choice of anti-coagulants has increased significantly in recent years, and there is a huge amount of research into finding even more effective medication.
To book a consultation with Mr Coleridge Smith about post-thrombotic syndrome, click here.