Causes
The formation of blood clots can have various causes. The natural formation of blood clots as a result of injury is the result of a series of reactions of the body to external stimuli. First of all, the blood vessels are narrowed to reduce the blood flow and thus keep blood loss as low as possible.
The damage to the tissue activates the platelets circulating in the blood, the so-called thrombocytes. They attach themselves to the wound and form a clot that stops the bleeding for the time being. This is followed by a series of activations of other coagulation factors, which further stabilise the unstable clot of platelets with various proteins.
After this, the wound is primarily closed, protected from contamination, bacteria and viruses and can heal secondarily. However, blood clots can also form on the bottom of other causes. For example, if the blood in a blood vessel flows very slowly or even becomes congested, more blood platelets can accumulate.
The platelets stick together and form a blood clot – without any injury. Another cause of blood clot formation is pre-damage to the inner walls of the blood vessel. The so-called arteriosclerosis is one of the most common pre-existing conditions.
Ultimately, the injured vascular wall causes the blood platelets to stick together – forming a blood clot. An equally important and frequent source of blood clots is the heart, especially in cases of atrial fibrillation or a heart rhythm disorder with very fast beating atria. Here blood clots can easily form due to the turbulence of the blood in the atrium of the heart.
A genetic and thus congenital mutation of the coagulation factors or a tumour disease can also lead to an increased effect and binding tendency of the coagulation factors and can be the cause of a blood clot. A genetic and therefore congenital mutation of the coagulation factors or a tumour disease can also lead to an increased effect and binding tendency of the coagulation factors and can be the cause of a blood clot. After a major operation, the fracture of a bone or a serious illness, it often happens that the affected extremity is not moved sufficiently for a long time.
Muscles play an important role in transporting our blood back to the heart via our venous blood system. By means of the so-called muscle pump, the muscles support the return transport of the blood up to the heart, even against gravity, by compressing the veins. If the muscles do not provide this support, the blood flows slowly back to the heart and accumulates in the veins.
This accumulation of blood leads to an accumulation of platelets and coagulation factors in a small space. Over time, these can stick together to form a blood clot and a so-called venous thrombosis occurs. These thromboses can become dangerous if parts of the blood clot come loose and are ejected into the bloodstream.
The most common consequence of this is a carry-over of the thrombosis into the pulmonary vessels, a so-called pulmonary embolism. However, it is also possible for the thrombus to enter the vessels supplying the head if the atria of the heart are connected by a small hole, a so-called paradoxical embolism. In arterial vessels, the immobilization after a fall rarely or never leads to a blood clot, since there is a continuous blood flow in this vascular system due to the maintained blood pressure. Blood clots here usually have a different cause.
