The hydrodynamic effect on clot growth at foreign surfaces was investigated quantitatively in vitro. Shear rates from 2 to 1,000 s-1 were applied to a blood sample contained in a cone and plate viscometer. Four different artificial materials were used for cone and plate combination, namely, stainless steel, polytetrafluoroethylene, polycarbonate, and polymethylmethacrylate. Evaluation of clot growth was derived from the clotting ratio (the volumetric fraction of clot in the whole blood), which was experimentally determined from the rate of increase of frictional torque between the rotating cone and the stationary plate. The results show that the clotting ratio decreases markedly as the shear rate increases to 400 s-1, regardless of material used. This study demonstrates that at a shear rate of greater than 400 s-1, clot growth at foreign surfaces is considerably inhibited.
[1]
E. Grabowski,et al.
Platelet aggregation in flowing blood in vitro. II. Dependence of aggregate growth rate on ADP concentration and share rate.
,
1978,
Microvascular research.
[2]
D. A. Mcdonald,et al.
Observations on laminar flow in veins
,
1954,
The Journal of physiology.
[3]
T. Yonaha,et al.
The effect of releasing heparin from the heparinized hydrophilic polymer (HRSD) on the process of thrombus formation.
,
1978,
Transactions - American Society for Artificial Internal Organs.
[4]
R. Whitmore,et al.
Rheology of the circulation
,
1968
.