Causes of Thrombosis

Causes of emergence

Thrombosis is a vascular disease in which blood clots (Thrombi) arise in the vessels. Often the deep veins of the legs or pelvis (Phlebothrombosis) affected. But there are also arterial thromboses or thrombosis of the venous sinus of the brain. The focus of this article is on the development and causes of deep vein thrombosis.

There are various causes and risk factors that contribute to the development of a thrombosis. A distinction is made between genetic predispositions and coagulation tendencies from external factors.
The formation of a thrombus and the causal factors, i.e. the pathogenesis, is in the Virchow triad very well described. This model explains the mechanisms underlying thrombus formation. It is often more important for patients to understand which clinical pictures, risk factors and behaviors favor the development of the thrombosis.
An important aspect in the development of thrombosis are hereditary thrombophilias. It refers to congenital disorders of the coagulation systemwhich lead to an increased coagulability of the blood, as a result of which a thrombosis develops with a high probability. People with congenital thrombophilia are up to 80 times more likely to develop a thrombosis than people who do not have this tendency to clot. In addition, if other risk factors are present or if several thrombophilias are present at the same time, the risk is increased to an even greater extent. One of these congenital thrombophilias is APC resistance, of the Protein C of the Protein S and the Antithrombin deficiency as well as the Prothrombin mutation.

Particularly in the case of very frequent thromboses or a very young age of onset, a detailed special thrombophilia diagnosis is recommended. Other causes of thrombosis are old age (over 60) and cancer. Pregnant women and women in the puerperium are also at increased risk. This is related on the one hand to increasing immobilization and on the other hand to hormonal causes. During the birth, more coagulant substances are released. A prolonged immobilization of the extremities, for example during a long bus trip, bed rest or a paralyzed extremity, is also a massive risk factor for the development of a thrombosis. This has to do with the fact that the blood flow is slowed down during immobilization and this promotes clotting. This is how blood clots form.

Another risk factor is estrogen therapy, e.g. as part of a menopausal replacement treatment or when taking oral contraceptives. However, it is important to differentiate here that it is not a monocausal connection but rather a multifactorial event. That is to say that the thrombosis does not arise solely from taking medication, but rather from many mutually potentiating factors.

Obesity and nicotine abuse also promote thrombosis. Another very important risk factor is antiphospholipid syndrome. This disease occurs either without an apparent cause (primary) or in the context of an underlying disease such as cancer, HIV, lupus erythematosus and rheumatism (secondary) and leads to many thromboses in a wide variety of locations. Antibodies are responsible for the formation of the clot. In women, frequent abortions in the anamnesis are typical.

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Virchow triad

The Virchow triad - also called Virchow’s triad - describes the Development processesunderlying the formation of a thrombosis. There are 3 mechanisms that play a crucial role in the formation of thromboses.

1. Damage to the vascular endothelium: Vessels (veins and arteries) are lined with so-called endothelium. The endothelium can be thought of as a thin layer that covers the The vessel is completely covered from the inside. It performs important tasks, including ensuring good blood flow. It is smooth and contains important blood clotting factors. The endothelium is damaged by trauma or inflammation, for example as a result of various diseases such as diabetes or high blood pressure.
2. Decrease in blood flow velocity and change in hemodynamics: You have to imagine that the blood flows very regularly in the vessels. In technical terms, this type of flow is called laminar. Vascular changes can lead to a turbulent flow come, this causes damage to the vessel wall through shear forces. The counterflow causes the blood to flow more slowly. Factors that reduce the flow velocity of the blood are, for example: Immobilization or external pressure on an extremity.
3. Change in blood composition: When the blood composition changes and the blood becomes thicker (more viscous), blood clots (thrombi) can develop more easily. The blood composition is e.g. changed in the case of congenital thrombophilia (tendency to clot) or in the course of various diseases. It results in a increased willingness to clotwhich one as Hypercoagulobility designated.

Thrombosis causes in cancer

About 20% of all venous thromboembolism arise on the basis of cancer. It is not out of hand that one cancer patient is one significantly increased risk of thrombosis compared to the remaining healthy population to have. This is due to different contexts.
First of all, there are cancers that affect the hematopoietic system and thus also those involved in the Cells involved in clotting affect directly. On the other hand, tumors change through their localization also the Conditions of blood flow and thus intervene in the normal, physiological cycle.

Much more important, however, is the keyword "Paraneoplastic Syndrome". This term describes a constellation of symptoms or findings that result from cancer, however not the direct consequence of local tumor growth or metastases is. But how exactly can you imagine this? The tumor not only causes damage by growing somewhere in the body and displacing or impairing the surrounding structures and organs, but it also has a lot harmful metabolism. Metabolic products are created, or even hormones in some cases, which intervene in the physiological (natural) system of the human organism. For example, an increased tendency to clot (thrombophilia) or even an antiphospholipid syndrome can develop on the basis of such metabolic products. Tumors For example, pour coagulant substances like the tissue thromboplastin.

Another important factor that increases the risk of thrombosis in cancer patients is the therapy. Operations lead to a Immobilization of the patientwhich may increase the risk of thrombosis. Furthermore there is Chemotherapy drugs and other drugsthat are used in cancer therapy, which are also associated with an increased risk of thrombosis. The consequences are Thrombosis and Thromboembolismwhich can be fatal at times. Thrombosis or thromboembolism is the most common in cancer patients second leading cause of death represent.
There the risk differs with the different types of cancer partly considerable. Especially high is the risk e.g. with Glioblastoma. Furthermore, the risk is considerably increased by a Immobilization, an advanced disease, a Dehydration and the presence of Metastases influences and increases.

Unfortunately, there is no real prophylaxis. Cancer patients should try to avoid dehydration and long periods of immobilization. It is also recommended Risk factors as the Smoke or high blood pressure strictly set. However, prophylactic administration of anticoagulant drugs is controversial and is always an individual decision. You have to weigh up the risk of thrombosis and the presumably increased risk of hemorrhage caused by the medication.

Risk factors

There are a number of risk factors that promote the development of a thrombosis. The most important risk factors are listed below and briefly explained if necessary:

1. Preparations containing estrogen: Estrogen is contained in oral contraceptives or hormone replacement therapy during menopause, for example. In combination with nicotine abuse, the risk increases.
2. Obesity
3. Age over 60
4. Hereditary (congenital) coagulation tendencies: APC resistance, factor 5 Leiden mutation, protein C, protein S, antithrombin deficiency, factor 8 increase, prothrombin deficiency
5. Antiphospholipid Syndrome: This is a disease in which autoantibodies make the blood more coagulable. It mainly affects women. Repeated thromboses at a young age and frequent abortions are characteristic.
6. Pregnancy and puerperium
7. Smoke
8. Cancers e.g .: glioblastoma, stomach, pancreas, gynecological and urological tumors
9. Frequent thrombosis in the family
10. Intravenous substance abuse: This injures the vessels and increases the likelihood of thrombosis.
11. Immobilization e.g. in long-haul flights or operations

Alcohol as a cause of thrombosis

Alcohol is not considered to be an immediate risk factor for the development of thrombosis. However, it is true that alcohol is a rather dehydrating (draining) effect which can be a cofactor for other risk factors present. In general, however, it is not the case that moderate alcohol consumption leads to an increased tendency to thrombosis.
The opposite is actually the case. At Severe alcohol addicts with cirrhosis of the liver is the Coagulation even severely impaired. Since important coagulation factors are formed in the liver, coagulation is severely impaired in cirrhosis or liver dysfunction. The result are increased bleeding.

Consequences of thrombosis

The consequences of a thrombosis can be very different and depend on the location of the thrombus and the underlying causes. For many patients, however, there is a therapeutic consequence that is at least the Reduction of risk factors (Lack of exercise, smoking, etc.). At a Leg vein thrombosis is mostly a temporary treatment with Compression stockings, as well as anticoagulant drugs, whereas congenital thrombophilia sometimes require lifelong medication.