Pump Versus Syringe: Aspiration Thrombectomy Direct Pressure Comparisons in a Comprehensive Benchtop 3-Dimensional-Printed Circle of Willis Model.

Background and objectives: Experiments have shown that 60-cc syringes generate stronger vacuum forces than mechanical pumps. However, few studies have measured catheter tip suction pressure during thrombus engagement. Therefore, this study aimed to compare aspiration forces and pressure drops, generated by mechanical pumps and 60-cc syringes connected to various catheters when aspirating synthetic clots in a 3-dimensional-printed model.

Methods: The system includes a programmable pulsatile pump, a 3-dimensional-printed tissue-matched circle of Willis model, radiopaque synthetic blood clots positioned in the left internal carotid artery terminus, and pressure recording at 500 ± 10% mL/min and 120/80 ± 10 mm Hg. Each catheter underwent 3 soft and hard clot removal trials using a 60-cc syringe and an aspiration pump. Aspiration source pressure was recorded before, during, and after aspiration. The evaluated variables included engagement pressure change (∆Pengagement), aspiration pressure drops (∆Paspiration), and pressure efficiency (PE), defined as the percentage of peak pressure maintained during aspiration.

Results: Aspirating soft clots with syringes showed low engagement pressure drops (∆Pengagement) (0-14 mm Hg), high PE at 93%-99% of Pp, and minimal aspiration pressure drops (∆Paspiration) (6F catheters: 4-8 mm Hg, 8F catheters: 19 mm Hg). Conversely, using a pump generated moderate ∆Pengagement (6F: 16-51 mm Hg, 8F: 122 mm Hg), lower PE (69%-93% of Pp), and greater ∆Paspiration (6F: 143-151 mm Hg, 8F: 270 mm Hg). For hard clots, syringes exhibited minimal ∆Pengagement and ∆Paspiration (4-13 mm Hg and 3-12 mm Hg, respectively), whereas pumps showed moderate ∆Pengagement (2-34 mm Hg) and large ∆Paspiration (6F: 82-162 mm Hg, 8F: 280 mm Hg).

Conclusion: Syringe aspiration generates higher vacuum pressures and smaller pressure drops than aspiration pumps, likely because of vacuum tubing resistance in aspiration pumps. This effect is particularly evident with hard clots and larger inner diameter catheters.