Mechanisms of Thrombus Formation

Hemostasis is the process that maintains the integrity of a closed, high-pressure circulatory system after vascular damage. Vessel-wall injury and the extravasation of blood from the circulation rapidly initiate events in the vessel wall and in blood that seal the breach. Circulating platelets are recruited to the site of injury, where they become a major component of the developing thrombus; blood coagulation, initiated by tissue factor, culminates in the generation of thrombin and fibrin. These events occur concomitantly (Figure 1A; also see Video, available with the full text of this article at www.nejm.org), and under normal conditions, regulatory mechanisms contain . . .