Purpose Recent catheter technology has enabled the use of larger lumens and higher aspiration forces for the aspiration thrombectomy, yet the successful reperfusion rate of the first pass remains at 25.1- 40.9%. To investigate the mechanism of unsuccessful reperfusion, we performed aspiration thrombectomy in the different sizes of target vessels by using a unique swine large vessel occlusion (LVO) model, which allows transmural visualization of real-time vessel responses.
Materials and Methods Under general anesthesia, a common carotid artery (CCA) and a superficial cervical artery (SCA) of Yorkshire swine were surgically exposed, and an LVO was reproduced by injecting a radiopaque clot analog. Each target artery was treated with various sizes of aspiration catheters (0.058, 0.068, and 0.088 inches). The SCA group, with bifurcations, represented small diameter vessels (2-3mm) simulating a human MCA and the CCA group represented large diameter vessels (4-5mm) simulating a human internal carotid artery (ICA). Fluoroscopy and a high-resolution digital microscope camera were used simultaneously to monitor angiographic and transmural vessel behavior during the procedure. Thrombectomy was started as remote aspiration (5-20mm), and contact aspiration was performed if flow restoration was not achieved. Finally. Average vessel diameter, the presence or absence of vessel collapse/reverse flow during the procedures, and pre-and post-angiographic findings were evaluated.
Results A total of 13 aspiration thrombectomies were performed on 4 animals. Transluminal visualization was achieved in all vessels with real-time observation of thrombectomy. With remote aspiration, all vessels in the SCA group (Mean Diameter: 2.34 ± 0.49mm) showed immediate vessel collapse followed by absence-of-flow within the aspiration system, and all failed to recanalize the vessels regardless of their lumen size. Effective clot ingestion occurred only with direct contact aspiration(5 of 6 vessels). All vessels in the CCA group (Mean Diameter: 5.16 ± 0.54 mm) showed constant blood flow in the aspiration system until the catheter ingested the clot and none showed vessel collapse. Six out of 7 vessels (85.7%) with remote aspiration generated a local reverse flow followed by complete reperfusion. One CCA vessel required direct contact aspiration to achieve clot ingestion.
Conclusion Vessel size appears to influence the performance of aspiration thrombectomy. Absence of flow in the aspiration system did not always reflect the clot engagement. It is important to apply contact aspiration especially in small vessels to prevent vessel collapse and to increase efficacy of the treatment.
Disclosures I. Yuki: 4; C; AquaTeX Medical. T. Shimizu: None. Z. Hsu: None. H. Kaur: None. E. Steward: None. S. Suzuki: 2; C; Medtronic. 4; C; AquaTeX Medical.
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