BackgroundBalloon guide catheters (BGCs) achieve proximal flow control during thrombectomy but antegrade intracranial flow often persists via the Circle of Willis. Closely sizing an aspiration catheter to the target vessel might achieve greater flow control and improve technical performance. Our objective was to measure the impact of aspiration catheter size on distal flow control and flow reversal with and without the use of BGCs. Clot retrieval testing was performed to establish the impact of these parameters on revascularization.MethodsAn in vitro thrombectomy model replicated in vivo conditions. Flow was measured continuously using ultrasonic flow sensors placed 20 cm distal to the catheter tip in the middlel cerebral artery (MCA). Four aspiration catheters of increasing size were evaluated: ACE 60 and 64 (Penumbra), SOFIA Plus (MicroVention), and Millipede 088 (Perfuze). Two clot analog types (red blood cell-rich and fibrin/platelet-rich) were used for clot retrieval testing.ResultsThe larger area of the ‘superbore’ Millipede 088 catheter resulted in a larger reduction in antegrade flow than standard aspiration catheters, even when the latter were combined with a BGC. During aspiration, 6Fr catheters were unable to cause flow reversal in the distal MCA while the Millipede 088 achieved significant distal flow reversal (−146 mL/min) (P<0.0001*) (*denotes significance). The solo use of Millipede 088 resulted in better recanalization outcomes and significantly reduced distal emboli for internal carotid artery (P=0.015*) and MCA (P=0.014*) occlusions compared with all other devices and combinations.ConclusionsMaximizing the catheter-to-vessel size facilitates near flow-arrest on catheter insertion, potentially negating the need for a BGC. A 0.088 inch aspiration catheter enables significant flow reversal in the distal MCA during aspiration.

BACKGROUND Various mechanical thrombectomy devices including stent retrievers (STRs), contact aspiration (CA) catheters, and balloon guide catheters (BGCs) are used in both isolation and combination for the treatment of acute ischemic stroke. A new generation of Super‐Bore 088″ aspiration catheters are being trialed clinically. We evaluated the in vitro revascularization performance of current and novel thrombectomy approaches in treating soft (red blood cell–rich) and stiff (fibrin/platelet‐rich) clots at internal carotid artery (ICA) and middle cerebral artery (MCA) occlusion sites. METHODS National University of Ireland Galway Research Ethics Committee approved the study. Two human blood clot phenotypes were used to form ICA‐terminus (20‐mm) and MCA–M1 segment (10‐mm) occlusions in an in vitro thrombectomy model. Thrombectomy setups tested were CA: Millipede 088, SOFIA Plus+conventional guide catheter, SOFIA Plus+BGC and C ombination; Millipede 088+STR, SOFIA Plus+BGC+STR, SOFIA Plus+conventional guide catheter+STR. Ten replicates of each experiment were performed totaling 120 tests. Revascularization endpoints were first‐pass effect, final modified Thrombolysis in Cerebral Infarction (mTICI) 2c/3, and procedural‐related distal emboli. RESULTS Millipede 088 CA achieved the highest first‐pass effect rate in ICA‐terminus (60%) and MCA–M1 segment (100%) occlusions and lowest number of procedural‐related distal emboli compared with all other device setups, followed by the combined Millipede 088+STR technique. Amongst the conventional techniques, higher first‐pass effect rates were observed with the combined technique using a BGC (40%) than 6F CA (20%) in ICA‐terminus occlusions whereas the reverse was seen in MCA–M1 segment occlusions, with 6F CA performing better than combined approaches (60% versus 50%). BGCs may provide a revascularization benefit in ICA‐terminus occlusions. Rates of first‐pass effect and final mTICI 2c/3 were better for stiff clots compared with soft clots for all treatment approaches at both occlusion sites. CONCLUSION Millipede 088 CA was the most effective technique for all clot types and occlusion locations. Across conventional techniques, CA seems to be more effective in MCA–M1 segment occlusions, while the combined technique performed better in ICA occlusions. Clot composition influences the success of each technique.

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