Post-Thrombotic Syndrome And Venous Insufficiency

Introduction 

Post-thrombotic syndrome (PTS) is a condition characterised by swelling and pain in the leg, and it is a common complication of deep vein thrombosis (DVT), developing in 20-50% of patients who experience an event.¹ In PTS, a DVT has caused vein damage, leading to venous insufficiency. 

The arterial system contains oxygen-rich blood, which flows away from the heart and is delivered down to the various muscles and tissues in the body. The function of the veins is to return the blood, now low in oxygen, back to the heart. In the legs, the veins have valves, that hold the blood in compartments as it moves through the body, against gravity, towards the heart. DVT can damage the vein vessel walls and subsequently the valves, resulting in an inability to stop the blood returning down the leg. This all results in reduced blood being carried away from the lower leg and foot. Blood is then diverted down smaller veins and into tissue in the calf, which increases venous pressure. 

Common causes of thrombosis 

Deep vein thrombosis (DVT) 

• Long periods of physical inactivity due to a hospital stay, mobility issues, or long-distance travel 
• Blood coagulation disorders such as thrombophilia 
• Cancer and cancer treatment 
• Pregnancy 
• Previous DVT or previous DVT in the family 
• The combined oral contraceptive pill and hormone replacement therapy (HRT) 
• Surgical intervention causing vessel wall injury² 

Superficial vein thrombosis (SVT) 

• Varicose veins, often in the legs 
• Blood coagulation disorders such as thrombophilia 
• Autoimmune conditions, such as Behçet's disease, cause blood vessel inflammation. 
• Insertion of cannulas into the superficial veins 

Pathophysiology 

Mechanisms leading to post-thrombotic syndrome 

As previously mentioned, DVT can damage the venous valves, resulting in ‘incompetent’ valves, that prevets blood from travelling up the veins in the leg, and this is called venous insufficiency. Incompetent valves, combined with a persistent blockage in the deep veins result in increased venous pressure. This pressure can cause the symptoms associated with PTS, such as swelling, aching, and, with time, the development of leg ulcers. Additionally, inflammation can increase the likelihood of developing PTS, as it can slow thrombus clearance, and increase vein wall scarring.³

Clinical presentation 

Symptoms of post-thrombotic syndrome 

• Pain, swelling, or heaviness in the limb 
• Itching or tingling, 
• Varicose veins 
• Skin changes, such as discolouration and hardening of the skin, also known as varicose eczema 
• Skin ulcers and infections 
• Oedema 

As described by Thrombosis UK, symptoms can range between mild, moderate or severe, and can vary between patients. Symptoms tend to worsen after long periods of standing or walking and can be relieved by resting with the limb raised. 

Diagnosis 

Diagnosis can involve a physical examination, where a medical professional will assess the lower limb for signs of PTS such as lower limb swelling, skin discolouration, or ulceration. A medical history would also be taken, including any previous DVT diagnosis.

Imaging studies may then be carried out, such as venous duplex ultrasound. During this examination, a healthcare professional called a vascular scientist, or sonographer will use an ultrasound machine to assess the direction of the blood flow in the leg veins, along with identifying any blockages or narrowing in the vessels. The superficial and deep veins will be assessed, and the scan may involve light squeezing of the calf muscle to test the valve function. The scan usually starts in the groin area, and you will be covered in ultrasound gel, to ensure adequate transmission of the ultrasound waves. Duplex ultrasound is non-invasive and non-ionising.

Another mode of diagnostic imaging for PTS is venography, which is an X-ray examination where contrast is injected, and the blood flow through the veins is assessed. Venography is the most accurate form of imaging but is ionising, invasive, and more expensive than Duplex ultrasound. 

Treatment 

Conservative measures 

One type of conservative measure for PTS involves compression stockings, which work to squeeze the ankle and calf to improve blood flow through the leg. This reduces the pressure on the valves, helping them work correctly and reducing the chance of further damage to the valves. All of these effects mean a reduction in swelling and increased comfort in the leg. Different classes of stockings can be obtained from medical professionals, or the pharmacy depending on the severity of symptoms. Further information on compression stockings can be found on this NHS website.

Also, elevating the leg can help with venous drainage, therefore reducing venous pressure and improving symptoms.

Medications 

In cases of severe PTS, anticoagulants (blood thinners) are often prescribed to prevent further DVT development and recurrence. Anticoagulants work to disperse blood clots, and studies have shown that early clearance of thrombus is associated with better preservation of valves and a reduction in valvular incompetence.⁴ 

Over-the-counter pain medication may also be required to reduce calf discomfort, such as paracetamol and ibuprofen. 

Interventional procedures 

PTS is a result of blood flow travelling the wrong way through the superficial veins, as well as the deep veins. In this case, superficial venous treatment may be helpful to reduce the amount of blood building up in the calf. The superficial veins, such as the great saphenous vein (GSV) and the short saphenous vein (SSV) can be closed off in interventions such as radiofrequency ablation (RFA), foam sclerotherapy, or endovenous laser treatment (EVLT). This can help to reduce the venous pressure in the lower limb and prevent further damage to the valves. These procedures can often be carried out as day cases with a local anaesthetic, located in theatres or vascular laboratories. 

For patients with extensive DVT that are unresponsive to anticoagulants, a thrombectomy can be carried out. This is a surgical procedure where blood clots are retrieved using suction, or other devices, to restore normal blood flow through the vein. This is usually considered a minimally invasive procedure. 

Venous stenting can be carried out for those with recurrent DVT specifically in the iliac veins and the inferior vena cava, which are veins located in the abdomen. Venous stents are tubes composed of different types of braided metal, such as nickel and cobalt.⁵ This is again, a minimally invasive procedure and is often carried out at the same time as thrombectomy. The stent is advanced through the common femoral vein in the groin region or through the popliteal vein behind the knee, to sit within the iliac vein in the abdomen. Patients with venous stents will often be under ultrasound surveillance for the years following the procedure to ensure stents remain open and no narrowing or blockages have formed. 

Venous bypass is a relatively rare procedure and is carried out in the case of chronic blockage of the abdominal veins. This involves using a vein or a plastic graft to divert blood flow around a blocked vein to an open region. These types of bypass can travel from one groin to the other to provide an alternative pathway for venous return. 

Prevention 

To reduce the chance of further DVT, and therefore PTS, lifestyle changes can be made, such as carrying out regular exercise, stopping smoking, and for obese patients, losing weight. 

For high-risk individuals, long-term preventative anticoagulants may be prescribed to prevent the development of future DVT. Frequent follow-ups with medical professionals are important to ensure a therapeutic dose of anticoagulants is being given.⁶

Early detection and management of thrombotic events are essential to reduce the chance of PTS development. 

Prognosis 

The symptoms of PTS can have a drastic effect on quality of life, and the chronic pain caused by venous insufficiency can have disabling consequences. On the other hand, symptoms often improve with treatment and lifestyle changes. If predisposed to DVT, patients may also experience recurrent episodes of thrombosis.⁷

FAQs 

How long does PTS last?

PTS may develop within six months to two years after the initial DVT. PTS is a chronic condition, so symptoms may continue for many months or years. 

Can you cure PTS? 

PTS cannot be cured, but treatments such as compression stockings and anticoagulation, along with painkillers, can help in improving symptoms. Furthermore, lifestyle changes such as regular exercise and stopping smoking. 

Can you fly with PTS? 

During air travel, long prolonged periods of sitting, along with lower air pressure during the flight can increase the risk of developing DVT. If you have had a DVT recently, do not travel for at least four weeks, and consult your medical health professional before travel. 

Summary 

To conclude, PTS is a condition that can have lasting effects, causing chronic pain and long-term circulatory issues. PTS is linked with venous insufficiency, brought on by venous valve damage after DVT. Diagnosis can involve duplex ultrasound and venography, and treatment can involve compression stockings and anticoagulation, or more invasive procedures such as thrombectomy, venous stenting, or bypass grafting. Steps must be taken to reduce the likelihood of developing subsequent DVT, which can further exacerbate PTS. When DVT does arise, early detection is essential, along with comprehensive management to reduce the chance of further damage to the venous system.