(1) Blood flow to the heart muscle may even stop if a thrombus , or clot, forms in a coronary vessel, which may cause a heart attack.(2) Thrombin forms clots and thrombi by removal of fibrinopeptides A and B from fibrinogen to form fibrin.(3) The lung showed focal bronchopneumonia, multiple thrombi , and focal hemorrhagic infarcts.(4) Mechanical valves are made with a combination of metals and sophisticated materials to ensure durability and a smooth surface to avoid blood clots, thrombi , forming.(5) Blood clots, or thrombi , trigger most heart attacks and strokes.