Abstract WP153: Effects Of Clot Maturation And Intravascular Ultrasound Characteristics On Effectiveness Of Aspiration Thrombectomy

Abstract

Background and Purpose: We examined the relationship between clot maturation and associated echogenicity obtained by intravascular ultrasound (IVUS) on time required to aspirate clots by aspiration thrombectomy device (Penumbra system) in vitro settings. Methods: Clots were formed by 3ml citrate-anticoagulated human venous blood was initiated by recalcification with CaCl2 86 μl/3ml and 5U/ml of thrombin. The clots were matured in saline at room temperature at different time period (2h, 6h, 24h, 48h, 72h) and 10mm of clots in length were transferred into silicone vessels 3mm in diameter with saline. Subsequently, Penumbra perfusion catheter was used proximal to the clot after acquiring the ultrasound image by IVUS. The time to remove clots was defined by the time interval between initiating aspiration and the time when all the clots were aspirated. Analysis of echogenicity on images acquired by IVUS was performed with the image analysis software using the histogram function. The gray scale median (GSM) measurement scale was referenced to GSM values of saline and silicone vessel. Results: A total 50 clots were studied. The time to remove clots increased with increasing clot maturation with longest time recorded at 48 hours (2h: 1.83±0.62, 6h: 2.13±0.54, 24h: 3.43±2.19, 48h: 4.27±2.19, 72h: 1.95±0.28 sec, ANOVA p=0.001). In IVUS study, a total of 50 clots were studied. GSM values increased significantly with increasing clot maturation (2h: 34.5±4.8, 6h: 37.4±6.0, 24h: 35.3±5.2, 48h: 40.6±5.3, 72h: 27.8±8.8, ANOVA p=0.0007). The highest GSM value was observed in 48 hours (p=0.0144,) and the lowest in 72 hours (p=0.0476, t- test, compared to GSM after 2h). Time to remove clot significantly correlated with higher GSM values (echogenicity) as determined by IVUS (Linear Regression, R2=0.13, p=0.0091). Conclusion: The effectiveness of aspiration thrombectomy depends upon the stage of clot maturation. The echogenicity of the clots determined by IVUS can identify the stage of maturation and subsequent response to apiration thrombectomy.