PB0047 - Dynamic mechanical properties of shear-induced platelet aggregation clots and coagulation clots

Background: Arterial occlusion by thrombosis is the immediate cause of some heart attacks and strokes. Shear-induced platelet aggregation (SIPA) clots and coagulation clots differ in terms of their formation mechanism and composition. These clots may have different dynamic mechanical properties that is necessary to resist cyclic blood pressure in our body.

Aims: Measure the elasticity of SIPA versus coagulation thrombi and predict deformation under blood pressure.

Methods: SIPA clots are made with porcine whole blood under stenotic arterial hemodynamics. Whole blood and platelet-rich plasma (PRP) coagulation thrombi are made by recalcifying citrate porcine whole blood under stagnant conditions. We measured the material mechanical properties of elasticity using a dynamic mechanical testing machine. The measured elasticities were used to model the fluid-structure interaction to calculate deformation under physiological conditions.

Results: The average elastic modulus of SIPA clot was 2.9 ± 1.9 kPa, for whole blood coagulation clot was 1.2 ± 0.9 kPa, and for PRP coagulation clot was 0.8 ± 0.5 kPa (Fig 1). At a physiological frequency of 1 Hz and 0.5 mm displacement, SIPA clot showed 2.8 times higher modulus than a whole blood coagulation clot (p < 0.0001). The fluid-structure model predicted lower stresses and reasonable deformation of SIPA thrombus under arterial pressures compared to the softer coagulation clots with a large deformation (Fig 2).

Conclusion(s): This study shows that the SIPA thrombi, formed quickly under high shear hemodynamics, is about three-fold stiffer compared to coagulation clots. A force balance calculation shows a SIPA clot has the strength to resist arterial pressure, consistent with coronary pathology.