Impact of left common carotid cannula design on flow distribution and cerebral perfusion pressure during bilateral...

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 by a vascular graft. Flow distribution may therefore depend on left-sided cannula resistance, particularly in patients with limited collateral circulation. We investigated how cannula design influences perfusion pressure and flow distribution during bSACP.MethodsFour clinically available carotid perfusion cannulas were characterized using bench measurements (40-200 mL/min) and computational fluid dynamics (CFD). The resulting resistance models were integrated into patient-specific CFD models of the cerebral circulation in three patients with varying collateral capacity. Both flow- and pressure-targeted perfusion strategies were simulated.ResultsBench testing demonstrated a 3-4-fold difference in flow resistance between the lowest- and highest-resistance cannulas, which was accurately reproduced in CFD simulations. Importantly, resistance did not correlate with nominal French size. In the patient-specific CFD models, increasing left side cannula resistance roughly doubled the pressure laterality (7-9 to 14-23 mmHg) and halved the left side inflow (135-160 to 70-100 mL/min) for the cannulas tested. Effects were most pronounced in patients with limited collateral circulation. Sensitivity analyses confirmed robustness across physiological and geometric perturbations.ConclusionsCannula resistance does not correlate with nominal French size. Cannula design may influence cerebral perfusion pressure and flow distribution during bSACP and may warrant increased attention.