Related Experiment Video
Updated: Aug 19, 2026

A Microfluidic Flow Chamber Model for Platelet Transfusion and Hemostasis Measures Platelet Deposition and Fibrin Formation in Real-time
Published on: February 14, 2017
The release of beta-thromboglobulin and platelet factor 4 during extracorporeal circulation for open heart surgery
Abstract:
Cardiopulmonary bypass is extremely damaging to platelets and it causes a quantitative and qualitative alteration in their functions. We evaluated the release of two platelet-specific proteins, beta-thromboglobulin (beta TG) and platelet factor 4 (PF4), in patients who underwent extracorporeal circulation for open heart surgery. A parallel release (basal value beta TG: 119.6 ng/ml, PF4 30 ng/ml) was present for both proteins in a time dependent fashion until the end of extracorporeal circulation. High average levels were observed in patients in whom the bypass was stopped after about 1 h (beta TG 1606 ng/ml, PF4 745 ng/ml) and similarly in those in whom the bypass was stopped after about 2 h (beta TG 1540 ng/ml, PF 4754 ng/ml). No correlation was found either between the level of PF4 and the additional heparin administered after the initial standard dose (r = 0.29, P greater than 0.10) and between the level of PF4 and the amount of heparin consumed during the bypass (r = 0.05, P greater than 0.5).
Related Concept Videos
Introduction to Hemostasis
The three phases of hemostasis involve many clotting factors present in plasma and several substances released by platelets and injured tissue cells. It is a fast, localized, and...
Formation of the Platelet Plug
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
Coagulation
During the coagulation phase, clotting factors, or procoagulants, play a vital role in initiating and progressing the coagulation cascade. This cascade is a series of reactions...
Extrinsic and Intrinsic Pathways of Hemostasis
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which forms a...
Clot Retraction and Fibrinolysis

