Deep vein thrombosis is a blood clot that forms in a vein. It most often affects the lower limbs and settles in a deep vein (deep phlebitis) or superficial (superficial phlebitis or para phlebitis). Despite the absence of particular DVT Symptoms, it must be treated because it can sometimes lead to severe complications, particularly pulmonary embolism, responsible for yearly deaths.
The challenges of research today are identifying ways to better predict the risk of DVT Deep Vein Thrombosis and recurrence and improving treatments.
Understanding deep vein thrombosis
There are two types of thrombosis depending on the location of the clot:
- Superficial venous thrombosis, also called para-phlebitis or superficial phlebitis. It affects the small caliber veins in the subcutaneous tissue (saphenous veins).
- Deep Vein Thrombosis or Phlebitis. It originates in more prominent veins, inserted near the arteries in the heart of the muscular system of the leg.
Deep vein thrombosis does not have the same severity, Indeed, the clot from deep phlebitis can accidentally migrate to the pulmonary artery and obstruct it. It then causes a pulmonary embolism whose pulmonary and cardiac consequences are life-threatening.
Paraphlebitis, on the other hand, only rarely causes a pulmonary embolism: the saphenous veins indeed function as a secondary network to the deep venous network. However, superficial venous thrombosis leads to local dermatological complications (ocher dermatitis, varicose ulcer) and functional impairment. It can also be complicated by deep vein thrombosis.
How does the DVT form?
The inner lining of the veins (intima or endothelium) plays a vital role in maintaining the fluidity and circulation of blood. These walls have valves that allow blood to reach the heart, preventing it from flowing back to the periphery. At the same time, the blood contains platelets and proteins (clotting factors), which balance each other to ensure blood flow under physiological conditions or to form a thrombus in the event of bleeding.
A clot forms without bleeding because the intima is damaged or blood circulation is slowed down. In these two situations, the hemostasis system is set in motion as if it were to stop bleeding: the platelets accumulate on the wall and form a “platelet nail”. They release messengers that will stimulate a cascade of reactions: several coagulation factors (factors XII, XI, IX, X, II) are successively activated, promoting the local accumulation of fibrin which will trap red blood cells and consolidate the unwanted thrombus.
Between risk factors and predisposing DVT Symptoms under normal conditions, the mechanism of blood circulation and the balance of the components of the coagulation system protect the body against the risk of thrombosis. Walking is essential for this proper functioning because it triggers a mechanism to return blood to the heart with each step.
However, this protection is no longer guaranteed when the venous wall is altered or when the coagulation system is unbalanced. Deep vein thrombosis thus results from two major risk factors:
It is characterised by an insufficiently efficient venous network, which has trouble returning blood to the deep web. It is a common condition, the vast majority among the female population.
- The sensation of heavy legs
- The presence of telangiectasia (blue or purplish veins under the skin’s surface) or even varicose veins (dilation of a vein under the skin that has become swollen and tortuous).
- Blood hypercoagulability
- It promotes clot formation by an imbalance of the blood coagulation system. It may be due to a genetic predisposition (constitutional thrombophilia), for example, a congenital deficiency in certain coagulation factors: protein S, protein C, and antithrombin.
- Hypercoagulability can also appear in specific contexts: pregnancy, obesity, smoking, and advancing age promote the formation of a thrombus.
- Certain medications, such as hormonal contraception or corticosteroids, also increase this risk.
Finally, any immobility of the lower limbs promotes coagulation:
- Prolonged bed rest
- Wearing a cast
- Traveling for several hours by plane, train, or car
In practice, deep vein thrombosis is a complication of venous insufficiency. Deep phlebitis is mainly the result of hypercoagulability.
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Ellen Diamond, a psychology graduate from the University of Hertfordshire, has a keen interest in the fields of mental health, wellness, and lifestyle.