Thrombus deflector stent for stroke prevention: A simulation study

Atrial fibrillation (AF) is a dysfunction of heart rhythm and represents an increased predisposition to ischemic stroke in AF patients. It has been shown that the AF-induced hemodynamic conditions may contribute to the increased embolic propensity through the carotid arteries. We simulated a stroke-prevention device with a unique strut structure to deflect the trajectory of a blood clot to the carotid artery. We identified the important determinants of functionality in a device design using computational fluid dynamics simulations. Quantitative assessment of deflection efficacy over various clot dimensions was carried out for the device with different strut configurations under AF flow conditions. The simulations demonstrate that the trajectory of a clot destined to the left common carotid artery (LCCA) can be deflected by a strut-structured device at the LCCA inlet with virtually no change in flow resistance. The deflection efficacy of the device is dependent on the clot properties and strut designs of the device. A configuration of 0.75 mm thick and 0.75 mm distant struts with 50% of surface convexity were found to provide maximum deflection efficacy (e.g., 36% greater deflection efficacy than a flat filter) among the strut structures considered. The results suggest that a deflector stent implanted in the aortic branch may be an effective stroke-prevention device. The present simulations motivate pre-clinical animal studies as well as further studies on patient-specific design of the device that maximize the deflection efficacy while minimizing device safety issues.