An In Vitro Evaluation of Emboli Trajectories Within a Three-Dimensional Physical Model of the Circle of Willis Under Cerebral Blood Flow Conditions

• Published in: Annals of biomedical engineering 2015-09, Vol.43 (9), p.2265-2278
• Main Authors: Fahy, Paul, Malone, Fiona, McCarthy, Eugene, McCarthy, Peter, Thornton, John, Brennan, Paul, O’Hare, Alan, Looby, Seamus, Sultan, Sherif, Hynes, Niamh, Morris, Liam
• Format: Article
• Language: English
• Subjects: Average velocity; Biochemistry; Biohazards; Biological and Medical Physics; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedicine; Biophysics; Blood; Blood Flow Velocity; Blood pressure; Blood vessels; Cerebrovascular Circulation; Circle of Willis - physiopathology; Classical Mechanics; Crustaceans; Flow rate; Hemodynamics; Human; Humans; In vitro testing; Intracranial Embolism - physiopathology; Models, Cardiovascular; Trajectories
• ISSN: 0090-6964; 1573-9686
• DOI: 10.1007/s10439-015-1250-6

In vitro simulations of the trajectory and lodgement locations of emboli within the circle of Willis (CoW) are crucial in understanding the associated hemodynamic effects in stroke patients. A clot was fabricated from the hemolymph of a crustacean species. Clots were injected into the internal carotid artery via a cerebral flow facility housing a manufactured CoW human model. The trajectory of the clot was tracked and its hemodynamic effects monitored. The clots traveled with an average velocity of 88 mm/s along the ipsilateral side with momentary pauses along high curvature regions before finally lodging within the distal branches of the ipsilateral middle cerebral artery (MCA). These clots either elongated along the branching vessels or compressed against a bifurcation point. A blocked M1-segment of the MCA reduced the efferent blood pressure and flow rates by (15–77%) and (20–100%) respectively with a re-distribution of the flow towards the other efferent vessels. Mimicking blood clots with crustacean hemolymph provides a much lower biohazard risk than using human or mammalian blood clots and a superior alternative to synthetic materials. The geometry of the distal MCA vasculature will determine the end morphology of the lodged clot. Clotting severely reduces the distal flow rates and pressures.