Impact of Left Common Carotid Cannula Design on Flow Distribution and Cerebral Perfusion Pressure During Bilateral Selective Antegrade Cerebral Perfusion: An Experimental and Computational Study

BackgroundIn aortic arch surgery, bilateral selective antegrade cerebral perfusion (bSACP) maintains cerebral blood flow during circulatory arrest. bSACP is often delivered using a single pump with a Y-connector, dividing the flow. Current practice has veered towards perfusion of the left common carotid artery by cannula and the right subclavian artery or axillary artery by a vascular graft. Under this configuration, inflow distribution may be sensitive to left-sided cannula resistance, particularly in patients with limited collateral circulation, potentially reducing left-hemispheric pressure and flow despite bSACP. We investigated how cannula design influences perfusion pressure and arterial inflow distribution during bSACP. MethodsFour perfusion cannulas with different flow resistances were characterized using bench measurements (40-200 ml/min) and computational fluid dynamics (CFD). The CFD cannula models were then integrated into patient-specific CFD models of the cerebral circulation from three patients with varying collateral circulation/capacity. Both flow- and pressure-controlled pump strategies were simulated. ResultsBench measurements showed substantial variation in flow resistance between the cannulas, which was accurately reproduced by CFD. For the patient-specific analysis, cannula choice affected perfusion through roughly doubled pressure laterality and halved left-side inflow between the most extreme cannulas. Still, perfusion pressure was kept within recommended levels in two subjects but was low in one. Left-side arterial inflow varied between 70-150 ml/min. ConclusionsWe isolated the effects of cannula design on cerebral pressure and blood inflow distribution during bSACP, highlighting potential pitfalls in patients with limited collateral circulation.