Novel method for emboli analog formation towards improved stroke retrieval devices

Abstract

Background: Unsuccessful recanalization attempts in stroke patients have been associated with fibrin-rich thromboemboli linking retrieval mechanism performance and clot composition. To continue development of stroke retrieval mechanisms, the material properties of cerebral thromboemboli must be replicated; however, current methods for emboli analog formation lack quantitative measurements for both material stiffness and composition of cerebral thromboemboli. This study investigates emboli analog (EA) formation to mimic the material stiffness and composition of cerebral thromboemboli to develop new retrieval mechanisms.

Methods: To induce static and dynamic environments for clot replication, a 9:1 ratio of porcine whole blood and 2.45% calcium chloride remained stationary or rotated at 34, 50 and 80 RPM. Histology and a custom MATLAB code provided composition analysis results. Likewise, quantitative results from biomechanical testing were obtained for direct comparison of the material stiffness of cerebral thromboemboli.

Results: Fibrin/platelet content as well as material stiffness increased due to increasing rotational speed. Approximately 11% of the biomechanical testing results exhibited nonlinearity after an initial yield point, of which 60% were from statically formed EAs. Those formed at 50 RPM were most similar in material stiffness to thromboemboli extracted from carotid endarterectomy (CEA) procedures (p = 0.97).

Conclusions: The dynamically formed EAs may be altered to obtain a range of fibrin/platelet to erythrocyte ratios. The proposed methodology for EA formation offers a platform for continued development of retrieval mechanism prototypes.

Keywords: Emboli analogs; Erythrocytes; Fibrin; Material stiffness; Stroke.