Scanning Electron Microscopy Identification of Microscopic Onyx Fragments in Blood Aspirated from a Distal Access Catheter after Arteriovenous Malformation Embolization: A Case Report
Abstract
Objective: Endovascular embolization with Onyx (Medtronic, Minneapolis, MN, USA), a non-adhesive liquid embolic agent, is widely used to treat cerebral arteriovenous malformations (AVMs); however, ischemic complications remain a concern. Although aspiration of blood from a distal access catheter (DAC) after microcatheter retrieval is commonly performed in clinical practice, its mechanistic rationale has not been clarified. We report a case in which scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to evaluate whether microscopic Onyx fragments could be detected in aspirated blood.
Case presentation: A patient with a Spetzler-Martin grade III occipital AVM underwent transarterial embolization using Onyx. Retrieved microcatheters and blood aspirated from the DAC were analyzed using SEM/EDS. Tantalum-containing microscopic aggregates consistent with Onyx were identified on the microcatheter surface and in the aspirated blood. The detected fragments measured approximately 50-90 µm. In addition, a simplified experimental model demonstrated reproducible adhesion of Onyx to microcatheters and frequent detection of Onyx material within the DAC lumen.
Conclusion: This case demonstrates that microscopic Onyx fragments can be detected in blood aspirated from a DAC using SEM/EDS. While the clinical significance of these findings remains uncertain, our findings suggest that microscopic Onyx-derived material may persist within the catheter system…
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