Formation of Occlusive Platelet Aggregates in Whole Blood Caused by Low Concentrations of ADP

Abstract

Minute concentrations of ADP are released when platelets are exposed to shear stress during extracorporeal flow. However, based on current methods, these low concentrations have not been shown to have a significant impact on platelet function. We report here the formation of rigid microaggregates (MA) in response to low concentrations of ADP. A newly developed light scattering whole blood aggregometer (LSWBA) was used to detect an aggregation dose response to ADP (0-2 microM) in heparinized (1.5 U/ml) human blood. Although the LSWBA showed that ADP induced MA were reversible, evidence provided by constant pressure filtration (50 mm Hg) suggested that aggregates existed as rigid particles in the blood for up to 6 minutes. The possible implications of these findings to extracorporeal circulation are discussed.

Rapid separation of bacteria from blood – Chemical aspects

“…Adenosine diphosphate (ADP) is known to cause platelet aggregation in anticoagulated blood [34]. Several experiments were done in which ADP was added to the blood samples at concentrations of 0.5–1.1 g/L before spinning to aggregate the platelets, as large aggregates would sediment out faster than bacteria and individual platelets.…”

“…We tried to remove platelets by reversing their anti-aggregation with ADP. However, addition of ADP at the concentrations employed for platelet aggregometry made no significant difference in platelet concentration in recovered plasma, perhaps because the rate of forming large aggregates is on the time scale of minutes [34], and in these experiments the spinning started in less that a minute following addition of ADP.…”

A numerical study on the effect of side hole number and arrangement in venous cannulae

“…the concentration of ADP generated at 10 Pa is about 0.5 mmol and platelet microaggregate formation is induced by a smaller concentration of ADP (0.25-2.0 mmol). Thus, shear stress should be reduced by as much as is possible (Hall et al, 2000). Moderate reductions in mean WSS occur as the number of side holes increases (Fig.…”

Computational Fluid Dynamics‐Analysis of the Niagara Hemodialysis Catheter in a Right Heart Model

“…The latter are believed to be responsible for mechanical hemolysis (8–10). Yet, local flow velocities and shear rate values must not become too low as this may cause thrombus formation (11) and platelet adhesion and aggregation (12,13).…”