Vein thrombosis (phlebothrombosis) - symptoms and treatment
Vein thrombosis is the formation of blood clots (thrombi) inside the lumen of a vein. Most commonly, venous thrombosis develops in the vessels of the lower extremities, but it can also occur in any other part of the body, such as the veins of the upper extremities, the neck, and the chest.
Thromboses can occur in the superficial vein system and in the deep vein system. In the vast majority of cases, thromboses are localized in the superficial veins. Deep vein thrombosis (DVT) of the lower extremities develops in 5-10% of cases.
The incidence of acute venous thrombosis reaches 160 cases per 100,000 people. There is a high risk of a dangerous complication - pulmonary embolism (TELA). Nonfatal TELA occurs in 20 cases per 100,000 population and fatal TELA in 50 cases.
There are three main causes of venous thrombosis (the so-called "Virchow Triad"):
Hypercoagulation - increased activity of the blood coagulation system (hereditary predisposition, genetic defects, autoimmune diseases).
Violation of the vascular wall. Normally, the inner surface of a blood vessel (endothelium) is smooth. Pathological changes make the endothelium rough. Platelets, moving freely with the blood flow, cling to the rough surface of the affected endothelium, and a clot forms in this place.
Blood flow disorder (stasis - blood stasis). Blood flow is one of the main mechanisms preventing clot formation, because the rate of blood flow does not allow platelets to accumulate in a certain place. Consequently, a decrease in the rate of blood flow promotes the formation of blood clots.
Provocative factors for the development of venous thrombosis:
- Abnormal vein structure.
- Varicose veins.
- Excessive body weight. Obesity of various stages leads to venous stasis in the lower extremities, provoking thrombosis.
- Prolonged bed rest.
- Oncologic diseases.
- Injuries and surgical interventions.
- Taking drugs that increase blood clotting.
- Smoking. During smoking more than 300 different carcinogenic and toxic substances are emitted, which get into the systemic bloodstream through the alveoli of the lungs and cause damage to the vascular wall.
If a person has varicose veins of the lower extremities, a small trigger mechanism ("trigger") - blood clotting, infections of various nature, stress factors and physical activity, trauma, surgery - is enough for a thrombus to form in the venous system. In varicose veins of the lower extremities, the diameter of the veins expands due to valve insufficiency, which leads to a slower flow of blood. Because the venous wall becomes tortuous, the blood flow changes from laminar (smooth) to turbulent (swirling). The change in the velocity of blood flow is one of the causes of blood clots.
In addition, the risk of venous thrombosis doubles with travel and flights of more than four hours. It should not be forgotten that the risk is not reduced immediately after the end of the trip, the propensity for possible thrombosis persists for four weeks . In general, a sedentary lifestyle, lack of physical activity contribute to the occurrence of thromboses in the veins of the lower limbs.
All of the above factors upset the balance of the hemostasis system, which on the one hand keeps the blood in a liquid state, and on the other hand forms thrombi in places of blood vessel damage to stop bleeding, and then dissolves the thrombi that have fulfilled their function. Thrombosis is the result of a disturbance in this system.
Complications of vein thrombosis
Particularly dangerous are clots that are not fully attached and loosely located in the lumen of the vessel. They are called flotation clots. Flotating clots are the most likely to "break off" and migrate with the flow of blood to the heart.
A serious complication of venous thrombosis is a pulmonary embolism, a blockage of large or small branches of the pulmonary artery, which carries venous blood to the lungs. As a consequence, blood flow in the lungs is hampered, the patient develops sharp shortness of breath, heart pain, dizziness, up to unconsciousness.
According to V.S. Savelyev, 240,000 cases of deep vein thrombosis and 100,000 cases of TELA were registered in Russia in 1999. The incidence of complications increases with age: in children the incidence of venous thromboembolism is 5:100,000, and at the age of 80 and over - 400:100,000. Without adequate treatment, many patients die within hours of the onset of pulmonary embolism.
According to the World Health Organization, a number of factors contribute to the risk of various venous thromboembolic complications, including deep vein thrombosis and pulmonary embolism. The main ones are obesity, use of oral contraceptives (increases the risk by 25 times), hereditary blood diseases with a tendency to increased clotting (coagulopathies), sedentary lifestyle, and being too tall (over 190 cm) or too short (under 160 cm).
Another complication is postthrombotic syndrome. This is a serious pathology with a chronic course, which can occur in patients who have undergone deep vein thrombosis; it is manifested by severe edema, trophic skin disorders and secondary varicose veins.