The effect of distal aspiration catheter position on collateral flow in mechanical thrombectomy - an in vitro study

Introduction: Endovascular mechanical thrombectomy for ischaemic stroke is one of the most effective treatments. Despite the devices and techniques that have been developed, thrombi are not always successfully retrieved. The incidence of futile reperfusion after successful clot retrieval also remains a major concern. We hypothesise that simply placing an aspiration catheter in the system compromises collateral flow which may have an impact on functional outcomes.Methods: An in vitro study was conducted using a physical pulsatile flow model designed in glass to mimic the anterior cerebral circulation with middle cerebral artery M1 segment occlusion. A 5Fr aspiration catheter was positioned at the supra-clinoid internal carotid (SC-ICA), carotid terminus (T-ICA) and M1. For each catheter position, the flow rate through the model's anterior cerebral (ACA) and posterior communicating (PCOM) arteries was measured (no aspiration applied).Results: Our results showed significant mean percentage flow reductions in the ACA and PCOM with the catheter positioned at the SC-ICA (PCOM 59.14% +/- 0.93, ACA 59.52% +/- 0.82, p < 0.001), T-ICA (PCOM 81.54% +/- 0.55, ACA 85.65% +/- 1.54) and M1 (PCOM 75.79% +/- 0.98, ACA 84.20% +/- 0.43) (Mann-Whitney U Test, p < 0.001).Conclusion: These results indicate a significant reduction in collateral flow following the insertion of a wide bore catheter in an in vitro model. In a clinical setting, this could have an impact on patient outcome, particularly in prolonged procedures and those requiring several passes to achieve recanalisation.