ABSTRACT
Platelets play an even more important role in the earliest stages of thrombosis than the blood clotting system which is, from the phylogenetic point of view, a later development. Thrombosis after heparin administration exists even though this claim may sound odd. Thrombosis factors related to blood flow may be divided into rheological and hemodynamic, the latter dependent on the properties of the vascular bed such as size, smoothness of surface, etc. Hemodynamic changes are particularly important for thrombosis in large vessels such as stasis resulting from a decreased venous tonus, decreased pumping activity of the heart on the venous side, or various defects in flow-laminarity in large arteries caused mostly by stenotic atherosclerotic changes. A vascular lesion often plays a primary role in thrombosis in the sense that a major lesion may take along both blood clotting and platelet activation.
