Overcoming the black box of aspiration thrombectomy in acute ischemic stroke: An early clinical experience of using contrast injections to understand clot-catheter interactions.

BackgroundFactors responsible for failure of aspiration thrombectomy in patients with acute ischemic stroke are poorly understood. In order to examine catheter-clot interactions, we modified our current aspiration thrombectomy technique by performing contrast injections near the tip of the aspiration catheter prior to the initiation of aspiration thrombectomy.MethodsSmall volume injections of contrast were performed using a microcatheter positioned inside the aspiration catheter immediately proximal to the occlusion site. Continuous fluoroscopy during the entire duration of each aspiration pass was recorded. We report our initial results with this new technique and examine potential associations of patterns of contrast behavior with procedural success of each thrombectomy pass.ResultsSeventeen patients were included in final analysis, consisting of 24 total aspiration thrombectomy passes. Microcatheter injections showed no safety concerns. Three angiographic patterns of contrast behavior near the aspiration catheter tip were observed: "occlusive" with no forward contrast flow, "side branch opacification" and "anterograde opacification" with anterograde flow. Movement of the contrast column during aspiration thrombectomy depended on the degree of aspiration catheter redundancy. Manual reduction of excessive catheter turns and higher position of long guide sheath at the petrous or cavernous segments seemed to improve contrast clearance and aspiration force.ConclusionsThis initial experience indicates that multiple complex factors may affect success rates of aspiration thrombectomy. The technique of microcatheter injection near the occlusion site may prove helpful in optimizing the existing aspiration thrombectomy techniques.