Platelet Aggregation in the Variable-frequency Thromboviscometer

Abstract

THE importance of platelet aggregation in the initiation of thrombosis is now established, as is the variation in the quantity of these platelet masses with the conditions of flow at the site of deposition^1,2. The morphology of an arterial thrombus consists of large amorphous masses (composed of platelet aggregates) surrounded by leucocytes and embedded in a fibrin network. A venous thrombus contains fewer platelet masses, whereas the glass tube clot has no visible masses on light microscopy and is made up entirely of a network of fibrin with adherent red cells. A quantitative relationship between the degree of aggregation of platelets and the velocity gradient in vitro, using a rotational cone-in-cone viscometer, have recently been demonstrated^3,4 and it was suggested that this apparatus⁵ might provide a more physiological method of investigating coagulation in relation to thrombosis, as at high rates of shear the coagulation produced was identical with an arterial thrombus.