Abstract 3750: Embolus Adhesion to Activated Endothelium After Embolization: A Parameter To Predict Outcomes Of Mechanical Thrombectomy In Acute Ischemic Stroke

Abstract

Background: In the MERCI trial and a prior animal study (Catch device), it was reported that when the thrombus retrieval maneuver was performed, the deployed device failed to mobilize the thrombus. Increased pulling force was applied and resulted in device rupture. These experiences lead us to hypothesize that the occlusive mass interacts with the activated endothelium, and the stability of the embolus on the vessel wall is related to the outcomes of mechanical thrombectomy. The aim of this study is to establish a methodology to quantitatively characterize the embolus-vessel wall adhesion. Methods: A rabbit CCA stenosis model was developed for creation of embolic occlusion with allogeneic clot. To evaluate the morphology of the embolus analogue (EA)-endothelium interface, two occluded vessel segments were explanted at 5-hour for Martius Scarlet Blue (MSB) staining and double immunofluorescence labeling for glycoprotein (GP) IIb/IIIa and fibrin. A modified test rig with a carbon steel wire (0.6 mm in diameter) fixture was used to detach the EA from the vessel wall (n=4). The wire moved down at the test speed of 0.1mm/s. The mean force was recorded and the energy to dislodge the EA from the vessel wall was calculated by numerical integration of the force versus distance curve below. Data were presented as mean±standard error. Results: MSB results showed that, the EA conformed to the shape of the underlying tunica intima and the undulated internal elastic lamina tended to flatten out after the occlusion. Immunofluorescent staining showed that GP IIb/IIIa (red) co-localized with fibrin(green), mainly observed at the EA-endothelium interface (yellow) ( Fig 1 A). In the detachment tests, a test distance of 6.07±1.18 mm was achieved after imposing 422.9±113.1 gram-force*cm of energy ( Fig 1 B). The mean force was 73.08±8.5 gram-force. Conclusions: Presence of GP IIb/IIIa and fibrin immunoreactivity indicates the interactions between border of the EA and the luminal surface, and this finding is supported by the quantitative adhesion force acquired during the detachment test. This project is ongoing to investigate thrombus-vessel wall interactions caused by acute thrombosis. The fibrin crosslink number and the platelet volume will be characterized by using confocal laser scanning microscope, and correlated with the adhesion results.