Thrombolytic therapy and TPA.

In an undamaged, healthy blood vessel, blood flows smoothly past the lining of the vessel wall. If a blood vessel wall breaks or there is damage to its lining, however, a complex series of biochemical reactions occur to stop the flow of blood. The blood vessel spasms (vascular spasm), platelets in the bloodstream clump together to form a plug, and proteins form to cause the blood to clot (coagulate). This process is rapid, localized to the area of injury, and carefully controlled. It involves many clotting factors normally present in blood, as well as specialized clotting particles called platelets and some substances that are released by the injured tissues.