Influence of clot composition on elasticity and friction in thrombectomy devices

Introduction Mechanical thrombectomy is the standard of care for stroke intervention. However, despite advancements in mechanical thrombectomy technology, a significant portion of patients do not achieve complete recanalization. A comparison of recanalization rates with histological analysis of patient derived clots demonstrate a direct relationship of red blood cell (RBC) content, with higher RBC containing clots achieving recanalization versus clots with a higher plasma content. Therefore, in this study, we examined how changes in RBC and fibrin contents affect the elasticity and frictional forces of experimental clot analogues. Methods Citrated bovine blood was used to prepare eleven unique clot formulas which vary in the RBC: Plasma ratio. Coagulation was initiated using CaCl 2 alone or in combination with thrombin and fibrinogen. Friction forces were determined and the coefficient of friction was calculated to measure the friction. Elasticity was measured by obtaining the tensile strain of each clot type. Results Our results showed that in frictional experiments, fibrin‐rich clots tend to have higher frictional forces when compared to the clots made of high RBC content. Compared to WB clots, our analysis showed that all the remaining clot types are more elastic, except 95% RBC clots, and are statistically significant (p<0.05). In general, plasma clots made using thrombin and fibrinogen showed higher frictional forces than those made using CaCl 2 . Tensile strain experiments showed that clots rich in RBC have lower tensile strain than fibrin‐rich clots. There is a statistically significant difference between the WB group and all other clot groups, except clots comprising 20% RBC and 80% plasma (p< 0.00001). A moderate positive correlation between coefficient of friction and tensile strain, which was statistically significant (r = 0.37, p = 0.025). The 95% confidence interval for the correlation coefficient ranged from 0.05 to 0.62, suggesting that higher frictional coefficients are associated with increased tensile strain. To further investigate this association, a simple linear regression analysis was performed, The regression model was statistically significant ( F (1, 34) = 5.47, p = 0.025), explaining approximately 13.9% of the variance in tensile strain, with the coefficient of friction accounting for this variance ( R 2 = 0.139; adjusted R 2 = 0.113). Conclusion Changes in the clot RBC and fibrin content alters the mechanical properties of the clots These results may help in understanding the clots and designing better devices to improve the recanalization rates during mechanical thrombectomy.