Post-thrombotic syndrome: What it is, why it arises and how it manifests

Post-thrombotic syndrome arises as a complication of venous thrombosis. The condition can significantly affect the quality of life of the affected person.

The course itself and the treatment can be complicated.
Therefore, it is best to prevent this condition.

It is reported that 20-50% of people have post-thrombotic syndrome after one to two years after overcoming phlebothrombosis.

Thrombophlebitis = deep vein thrombosis.

In short...

Deep vein thrombosis is the process of blood clots forming in the deep vein system. This condition is risky in terms of embolization.

Thrombosis= the formation of a blood clot inside a blood vessel. 
Embolism = the lodging of a released blood clot inside a blood vessel. 

Question: What are deep veins?

Vessels, as part of the cardiovascular and lymphatic systems, play an important role in the distribution of blood and lymph throughout the human body.

We all learn early in life that there are two types of blood vessels, namely:

• arteries
• veins

Arteries carry oxygenated blood and are, therefore, rich in oxygen.

Veins are filled with is deoxygenated blood and carry carbon dioxide.

However, this statement is not entirely accurate because...

Arteries are blood vessels that carry blood AWAY FROM the heart.

Veins are blood vessels that carry blood TOWARDS the heart.

Example:

Pulmonary artery = artery = deoxygenated blood.
It branches off the right ventricle and directs blood to the lungs.
In the lungs, the blood is saturated with oxygen.

4 pulmonary veins = veins = oxygenated blood.
They carry oxygenated blood from the lungs to the left atrium of the heart.
From there, it heads to the left ventricle.
The blood is ejected into the aorta.

Besides being classified according to blood gas saturation, blood vessels also differ in other properties.

For example, the composition of the vascular wall. In general, the arteries contain a layer of muscle in their vascular wall.

Similarly, the blood pressure is different in arteries and veins.
Therefore, when the artery is injured, blood will squirt out, and conversely,
if the vessel is punctured - the blood will leak.

However,...

The opposite example is damage to the lower limb varicose veins. Blood will squirt out if in the direction of flow.

The veins of the lower limbs contain valves or flaps. Like heart valves, their job is to direct blood flow.

Venous flaps prevent the backflow of blood in the lower limbs against the force of gravity.

Gravity pushes the blood in a downward direction.
The flaps prevent backflow.

There is also the veno-muscular pump that plays an important role when blood flows in the lower limbs. It helps to return blood from the lower part of the body.

There are deep and superficial veins.

Deep veins are larger vessels located along the arteries, which is important for blood flow in the veins. The muscles of the arteries contract and relax. Thus, they help to return the blood from the feet to the body.

Superficial veins are smaller and richly branched. They collect blood from the periphery, i.e. the end parts of the body. It then flows into the deep vein system.

Damage to the veins and their valves/flaps can lead to a serious condition, e.g. a pulmonary embolism.

The second complication of deep vein thrombosis is...

Post-thrombotic syndrome.

Want to know more about post-thrombotic syndrome?
How is it defined? 
What are its manifestations? 
How does it run its course?
How can it be prevented and treated? 
Just keep reading...

What is post-thrombotic syndrome?

Post-thrombotic syndrome refers to a set of problems that arise as a complication of deep vein thrombosis.

The following are involved in the onset of the disease:

1. narrowing or stenosis of the veins in thrombosis
2. damaged venous valve
3. increase in blood pressure in the veins

These three components lead to a disbalanced hemodynamics, i.e. blood flow in the veins of the lower limbs, which results in other health problems.

It is a chronic disease that arises as a late complication of thrombophlebitis. It is also referred to as postphlebitic syndrome.

The syndrome involves disease changes in terms of:

• persistent vein flow restriction
  • a.k.a. obstruction
• collateral formation, i.e. the formation of vascular glands
• venous valve damage
  • followed by insufficiency, i.e. insufficient blood flow
• accumulation of blood below the level of damage
• associated with venous hypertension
• swelling
• skin changes, such as various pigmentations to the formation of ulcers

This disease can subsequently turn into chronic venous insufficiency accompanied by a number of other problems and complications.

Find out more:
Chronic venous insufficiency
Chronic venous disease

The cause of post-thrombotic syndrome is inflammatory damage with an onset of venous valve dysfunction.

As mentioned, it involves three main components, namely:

1. venous stenosis (narrowing) caused by the presence of a blood clot or the remnants of an inflammatory process
2. venous valve damage resulting from the inflammatory process
3. this leads to blood stagnation (stasis) in the lower limbs
   • in turn, blood accumulation is a risk for thrombus formation

Later on, increased blood pressure in the veins is associated with hemodynamic disorders.

Swelling and skin changes occur, which is due to a number of pathological changes. Examples are damage to small superficial veins and the presence of subcutaneous bleeding.

This process involves a complete inflammatory reaction (not an infection), which manifests itself from pain to skin changes.

In short:

The vein valves are damaged, this leads to their insufficiency = dysfunction = the valves do not close/open properly. This results in regurgitation = backward flow of blood in the direction of gravity. Blood stasis and regurgitation, also known as reflux, lead to the accumulation of blood in the lower limbs.

Damage to the valves, which are involved in proper blood flow
+
onset of blood clot formation
+
onset of inflammation
+
restriction of blood flow (supports thrombosis)
+ 
increase in blood pressure in the vein
+
damage to small veins 
+ 
which leads to typical symptoms...

Risk factors for deep vein thrombosis are described in a special section on the disease itself.

Examples: immobilisation over 72 hours,
long journey,
sedentary lifestyle and inactivity,
dehydration,
hormonal changes and the use of hormonal contraception, 
smoking
genetic predisposition etc.

Risk factors for post-thrombotic syndrome:

1. age above 65 
2. proximal deep vein thrombosis
   • popliteal vein thrombosis (DVT) behind the knee and higher up the body
3. recurrent secondary deep vein thrombosis of the same limb
4. persistent symptoms of deep vein thrombosis more than a month after diagnosis
5. obesity and being overweight
6. poor treatment or lack of DVT treatment during the first three months of treatment
   • insufficient anticoagulant treatment

Table: breakdown of risk factors by severity

+ the percentage is given in the ratio between:
a person with a risk factor present
and
in a person without the presence of a risk factor. 

Also, the following fact needs to be taken into account:

recurrent thrombophlebitis of the same limb increases the risk of post-thrombotic syndrome.

The same rule applies the other way around.

A person with post-thrombotic syndrome has an increased risk of developing deep vein thrombosis, which carries the risk of thrombosis and embolisation.

Symptoms of post-thrombotic syndrome result from a disorder of hemodynamics, which is reflected in the disruption of microcirculation.

The problem is caused by poor blood flow from the lower limbs + impaired blood circulation in the smallest peripheral vessels of the subcutaneous tissue (i.e. under the skin).

Damaged blood vessels rupture, causing subcutaneous bleeding.

The permeability of small capillaries increases. This results in the transfer of blood proteins and other components to the subcutaneous tissue.

The result is objective pathological skin deformations.

Typical manifestations of post-thrombotic syndrome include:

• lower limb pain
  • in the area of damage and thrombosis
• unpleasant sensations at the affected site 
  • itching
  • burning
  • pins and needles
• cramps in the affected area
• heavy feeling in legs
• problems are worsened by
  • sitting for long periods
  • standing for long periods without changing the position
    • symptoms are relieved when lying down
• swelling of limbs - oedema
• varices in the legs - kŕčové žily
  • superficial vein dilation - secondary varicose veins
• skin changes
  • red skin
  • trophic changes
  • hyperpigmentation - due to storing blood components in the subcutaneous tissue
  • minor subcutaneous bleeding is manifested in reddish to purplish dots
  • tumour - venous ulcer, also known as crus (i.e. lower leg) ulcer

Initially, the problems can manifest themselves non-specifically as fatigue, a pulling sensation, heavy legs, or tension in the limb.

Muscle cramps and pain are initially dependent on the position of the limb.

It is aggravated by sitting or standing for a long time without changing position. On the contrary, raising the limb to a higher position will alleviate the effect.

Also, it is seasonal. The condition worsens mainly in the summer.

Also, hormonal levels affect the woman's menstrual cycle.

Swelling of the limb is evaluated objectively. It is unilateral, i.e. on one side of the leg.

Note:
Swelling of both legs may be present in people with concomitant heart disease or kidney disease.
However, thrombosis causes one leg to swell.

Skin changes range from redness to an increase in skin pigmentation, i.e. hyperpigmentation. Over the years, inflammation of the skin, eczema and other trophic changes progress to the venous ulcer on the lower leg.

Venous ulcer, a.k.a. ulcus cruris, crus ulcer

A venous ulcer is a defect of skin extending to varying depths, down to the subcutaneous tissue.

It is a chronic wound that fails to heal spontaneously.

In most cases, it occurs as a result of vascular damage, and thus after phlebothrombosis. Another cause is chronic venous insufficiency.

In post-thrombotic syndrome, it is typical that the skin defect, ie its damage, is accompanied by the following manifestations:

• deep defect
• extensive skin damage
• round shape
• irregular edges
• with exudation - inflammatory effusion and weeping wound
• infected bottom layer
• associated with lower limb swelling

Leg ulcers occur in up to 60% of cases within 2 years in poorly treated or untreated people.

Clinical examination and medical history are especially important for the diagnosis. Pre-existing deep vein thrombosis in the medical history is an important finding. This can arise for a variety of reasons.

Limb immobilisation after injury or general mobility impairment for various diseases are helpful.

Genetic disorders of haemocoagulation should be examined, with increased attention during hormonal changes, but also when using hormonal contraception and smoking at the same time.

Besides medical history, a subjective description of problems given by the affected person is important.

The doctor then assesses the condition of the leg, skin and the presence of swelling and other objective changes.

The symptoms of deep vein thrombosis and post-thrombotic syndrome (PTS) are similar. After diagnosing HRT and searching for PTS, there should be an interval of approximately 3 to 6 months with the associated persistence of typical symptoms.

Family history, i.e. occurrence in the family, supports the diagnosis.

Duplex sonography is one of the most important methods. The overall condition of the lower limb vessels and blood flow as reflux is assessed.

Other methods include measuring venous pressure, which is an invasive procedure during cannulation. X-Ray of the vein with contrast medium (phlebography) or CT and MRI phlebography are useful, too.

Post-thrombotic syndrome occurs as a chronic complication of deep vein thrombosis (DVT). It can affect up to 50% of people after DVT in the first two years.

DVT increases the risk at higher levels in the knee and higher. Calf thrombosis is less risky. Learn more about the manifestations of thrombosis in an article on DVT.

The symptoms tend to be non-specific in the first moments due to increasing fatigue, feeling of heavy legs and tension in the lower limbs.

The symptoms are unilateral and worsen when sitting for a long time or standing in one position. Removing the pressure from the leg and lying alleaviate the pain.

Later, the patient experiences leg pain and unpleasant cramps.

A sign of blood accumulation in the limb is swelling, which is visible due to a increased leg circumference.

Over the years, it is also manifested by skin changes. Initially, there is reddening of the skin, spots of hyperpigmentation, and dilation of blood vessels.

The most serious skin complication of post-thrombotic syndrome is a lower leg ulcer. The skin defect is difficult to treat and takes a long time to heal.

Therefore, prevention of deep vein thrombosis and post-thrombotic syndrome is extremely important.