Virchow triad

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The Virchow triad describes the causal factors in the development of a thrombosis or a phlebothrombosis (deep vein thrombosis). It is named after the German pathologist Rudolf Virchow (1821–1902). According to this, there are essentially three factors that affect the development of thrombosis:

  • Endothelial alterations (changes or damage to the vascular wall): Virchow found that blood clots mainly develop where the vascular wall is no longer intact. A normal inner wall of vessels ( endothelium ) is completely smooth. Inflammatory processes or injuries make them rough. This makes the following mechanism possible: Clots continuously form in flowing blood, but they are reversed just as quickly. However, if such a “mini clot” that is in the process of being formed passes a rough spot in the vessel wall, it will stick there. This creates the starting point for the development of a thrombosis. Further "mini-thrombi" are placed on top of this thrombus, so that ultimately the vascular occlusion occurs. The causes of inflammatory processes that roughen the vessel wall are diverse. Examples of inflammation: phlebitis (inflammation of the veins), arteritis (inflammation of the arteries), endocarditis (inflammation of the lining of the heart).
  • Changes in the speed of blood flow: Virchow found that clots always accumulate where the blood does not flow evenly and at the usual speed. In the arterial system, thrombi therefore tend to form at the points of division (large artery divides into two smaller ones or gives off a side arm), because turbulence occurs at the point of division. The flow velocity decreases in enlarged vessel sections (varicose veins, aneurysms). Vortex formation (e.g. aneurysm , bulging in a blood vessel), varices (varicose veins), vitia (heart defects e.g. valves)
  • Changes in the viscosity of the blood: Finally, Virchow found that “thick” blood coagulates more easily than “thin” blood. This property is called viscosity in liquids. Thickened blood is produced e.g. B. by lack of fluids (drink little, dry air), but also by increased sweating (hard work, fever).

Regardless of the Virchow triad, the tendency of the blood to clot plays an important role in the development of thrombi, for example the lack of physiological inhibitors of blood clotting (e.g. antithrombin III)

literature

  • CN Bagot, R. Arya: Virchow and his triad: a question of attribution. In: Br J Haematol . 143 (2), 2008 Oct, pp. 180-190. PMID 18783400 .
  • Rudolf Beneke: Rudolf Virchow: Thrombose and Embolie (1846-1856). Leipzig 1910 (= Classics of Medicine. Volumes 7–8).

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