Deep vein thrombosis pathophysiology
Editors-in-Chief: C. Michael Gibson, M.S., M.D. Associate Editor-In-Chief: Ujjwal Rastogi, MBBS [1]
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Overview
Venous thrombosis is a conglomerate of three mechanisms, described as the Virchow's triad:
1).Alterations in blood flow (stasis): Venous stasis is a major risk factor for development of thrombosis and occurs in certain pathological conditions (as in heart failure) wherein it causes an increase in platelet to endothelium contact and decrease the dilution of clotting factors. This increases the risk of clot formation and form microthrombi, which further grow and propagate.
2).Injury to the vascular endothelium or Endothelial dysfunction: Intrinsic or secondary to external trauma (Eg. catheterization) can cause intimal damage and stimulate clot formation. For details, please see Coagulation.
3).Alterations in the constitution of blood or hypercoagulability: Increased propensity to develop thrombosis due to an abnormality in the coagulation system.
These three conditions are collectively known as Virchow's triad and lead to intravascular coagulation, forming a mass of red blood cells, leukocytes, and fibrin.
More DVT's occur in the left leg than in the right, because the right common iliac artery compresses the left common iliac vein.(see May-Thurner syndrome)
Thrombi usually develop first in the calf veins, "growing" in the direction of blood flow. DVTs are distinguished as being above or below the popliteal vein. Very extensive DVTs can extend into the iliac veins or the inferior vena cava. The risk of pulmonary embolism is higher in the presence of more extensive clots.
Deep venous thrombosis (DVT) mainly affects the large veins in the lower leg and thigh. The clot can block blood flow and cause swelling and pain. When a clot breaks off and moves through the bloodstream, this is called an embolism. An embolism can get stuck in the brain, lungs, heart, or other area, leading to severe damage.
Blood clots may form when something slows or changes the flow of blood in the veins.
<youtube v=X_POCRsy7i4/> This video explains the process of thrombosis.