Objective To construct an anatomical pulsatile flow right atrium in vitro evaluation platform to quantify the effects of dialysis flow rate, catheter arteriovenous port spacing, and tip position on the recirculation rate of step-tip dialysis catheters. Methods Based on CT image-derived 3D printed right atrium model, an in vitro pulsatile circulation loop was established. The recirculation rate was measured using dye tracing-ultraviolet spectrophotometry. Results A decrease in dialysis flow rate, an increase in port spacing, and the catheter tip penetrating deeper into the right atrium all increased the recirculation rate. When the arteriovenous port was fixed at 15 mm and the tip was located at the junction of the atrium and ventricle, the recirculation rates were 31.32%±4.06%, 26.49%±3.89%, and 16.17%±4.14% at dialysis flow rates of 100, 200, and 400 mL/min, respectively. When the flow rate was fixed at 400 mL/min, the recirculation rates were 16.17%±4.14%, 17.96%±5.96%, 21.68%±2.11%, and 29.74%±7.11% with the port spacing 15, 20, 25, and 30 mm, respectively. When the spacing was fixed at 15 mm and the catheter tip was moved from the superior vena cava to the right atrium, the recirculation rate increased from 6.93%±1.06% to 21.73%±4.21%. Conclusions The pulsatile fluid external model can accurately quantify the recirculation performance of step-tip catheters. Compared to the steady-state registration standards, the test results are more in line with the real in vivo environment, providing a standardized evaluation method for dialysis catheter registration testing, structural optimization, and clinical catheter placement.
