Pressure Comparisons at the Clot-Catheter Interface of Tenzing-Assisted Aspiration Thrombectomy Using a Comprehensive Benchtop 3D-Printed Circle of Willis Model

BACKGROUND AND OBJECTIVES: Aspiration thrombectomy is a widely adopted acute ischemic stroke treatment with low complication rates. Traditional aspiration catheter delivery relies on microcatheters and microwires. Their removal before active aspiration has been observed to incidentally promote clot engagement; however, the mechanical basis and clinical relevance of this interaction remain poorly understood. Recently developed internal delivery catheters (DCs), such as Tenzing (Route 92 Medical), closely match the aspiration catheter lumen and appear to accentuate this effect, enabling quantification of the underlying mechanism. METHODS: A physiologic benchtop cerebrovascular model was used to measure vacuum pressures during DC withdrawal and assess their effect on clot interaction. Test configurations included 3 aspiration catheter sizes (0.054″, 0.070″, 0.088″) tested with and without a Tenzing DC using synthetic thrombi. Vacuum pressure data were synchronized with fluoroscopic imaging and correlated with clot engagement and ingestion outcomes. Institutional Review Board approval and patient consent were not required for this in vitro study. RESULTS: Tenzing DC withdrawal produced a brief but substantial negative pressure spike (0.45-1.81 seconds), reaching 52% to 97% of maximum syringe vacuum (-560 mm Hg). This transient vacuum coincided with clot motion before active aspiration. Overall rates of successful clot capture were similar with and without DC use; however, DC-assisted trials showed a higher incidence of corked and fully ingested clots (P < .05), whereas aspiration catheter-only trials more frequently resulted in full clot aspiration. CONCLUSION: Withdrawal of a closely size-matched DC generates a previously unquantified transient vacuum that initiates preaspiration clot engagement. This study identifies synthetic aperture aspiration as a mechanism creating a localized low-pressure field that may promote early clot mobilization and wall detachment before active suction. While DC withdrawal likely contributes to clot engagement, the primary value of a DC remains safe navigation and device delivery.