Maximizing the catheter-to-vessel size optimizes distal flow control resulting in improved revascularization in vitro for aspiration thrombectomy

Abstract

Background: Balloon 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.

Methods: An 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.

Results: The 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.

Conclusions: Maximizing 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.

Keywords: balloon; catheter; device; stroke; thrombectomy.

Figure 1

Placement of catheter and resulting flow profiles. (A) Circle of Willis (COW) model from the in vitro thrombectomy setup used to test flow profiles following catheter placement in the left middle cerebral artery (MCA). The ultrasonic flow sensor measures flow in the distal MCA. (B) Distal MCA flow profile of Sofia Plus+balloon guide catheter demonstrating the changes in flow on catheter insertion, during aspiration, and on removal of the catheter. (C) Distal MCA flow profile of Millipede 088 showing presence of flow reversal during aspiration. ICA, internal carotid artery.

Figure 2

Effect of catheter size and use of a balloon guide catheter (BGC) on distal middle cerebral artery (MCA) flow control and on flow reversal during aspiration. (A) The percentage reduction in MCA flow of the aspiration catheters when used with a conventional guide catheter (CGC) (blue) or a BGC (red). (B) Distal MCA flow during aspiration with each catheter with both a CGC (blue) and BGC (red) during aspiration. CGC=blue, BGC=red, antegrade=forward flow, retrograde=flow reversal. *Denotes a significant difference between the CGC and BGC groups.+Denotes a significant difference between Millipede 088 and all other groups.

Figure 3

Results from the in vitro clot retrieval study. (A, B) Complete revascularization success rate after passes 1, 2, and 3 for middle cerebral artery (MCA) (A) and internal carotid artery (ICA) (B) occlusions. (C, D) The average number of distal emboli of each size (>1000, 500, 250, and 50 µm) generated during the clot retrieval attempts for MCA (C) and ICA (D) occlusions. Millipede 088=blue, SOFIA Plus+BGC (balloon guide catheter)=green, SOFIA Plus+CGC (conventional guide catheter)=red.