Platelets: Role in Thrombosis
{"Image DocumentName": "Platelets: Role in Thrombosis", "Image ImageDescription": "High Flow Slow Flow. Fibrin. RBCs. Platelets. Fibrin. RBCs. Platelets. Thrombi are composed of fibrin and blood cells. The relative proportion of one type of cell to another and to fibrin is influenced by hemodynamic factors; therefore, the proportions differ in arterial vs venous thrombosis. Arterial thrombi formed under conditions of high flow are composed mainly of platelet aggregates bound together by fibrin strands. The resulting thrombi are sometimes referred to as white thrombi because they have few red blood cells. These thrombi are usually flat, tightly adherent, and relatively small. Arterial thrombi usually occur in association with preexisting vascular disease, the most common of which is atherosclerosis. They produce clinical manifestations by inducing tissue ischemia, primarily through the obstruction of local blood flow. Venous thrombi form in areas of stasis and are composed of red cells with a large amount of interspersed fibrin and relatively fewer platelets. These red thrombi are large, friable casts of the venous channel with branching arms that may extend into tributary veins. Too often such thrombi have only a weak proximal attachment to the venous intima, usually at a valve or a bifurcation, and may detach and embolize to occlude downstream vessels. Venous thrombi usually occur in the lower limbs, particularly in the deep veins of the calf or thigh. They are usually silent, but produce acute symptoms if they cause inflammation of the vessel wall or obstruction to flow, damage the venous valves, or embolize into the pulmonary circulation. References. Hirsh J, et al. Pathogenesis of Thrombosis. In: Hemostasis and Thrombosis: Basic Principles and Clinical Practice, 3rd ed. Coleman RW, Hirsh J, Marder VJ, Salzman EW (eds). Philadelphia: JB Lippincott Company;1994: White Thrombus. Coagulation Thrombus. RBCs, red blood cells.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}