Hemodynamic effects of hemodialysis catheter tip position on recirculation and thrombosis-related flow indices in a...

Hemodialysis catheter dysfunction remains a major challenge in end-stage renal disease because thrombogenesis and elevated recirculation can reduce access performance. Catheter tip location in the superior vena cava (SVC), cavoatrial junction (CAJ), or right atrium (RA) affects local hemodynamics, but the optimal position remains uncertain in physiologically realistic models. In this study, a high-fidelity right atrial computational fluid dynamics model was developed to evaluate stepped-tip catheters at three placement locations and five arteriovenous (A/V) offsets (20-30 mm). Recirculation ratio was quantified using particle tracking, and thrombosis-related hemodynamic descriptors, including time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), blood stasis volume, and platelet activation state (PAS), were assessed. Recirculation varied with A/V offset and increased with decreasing dialysis flow rate, rising from 13.11% at 20 mm to 14.21% at 30 mm and from 12.81% at 400 mL/min to 13.04% at 300 mL/min. SVC placement produced the lowest recirculation ratio (10.96%), whereas RA placement produced the highest (13.53%). However, CAJ placement showed the most balanced hemodynamic profile, with near-physiological TAWSS, the lowest high-OSI burden among catheterized cases, and intermediate RRT. These results suggest that catheter tip position should be evaluated by balancing dialysis efficiency against thrombosis-related flow disturbance rather than by minimizing recirculation alone. Within the present model, CAJ provided the most favorable overall compromise.