Comparison of symmetrical tip dialysis catheters using computational flow dynamics.

Purpose: Over 25% of prevalent U.S. hemodialysis patients receive renal replacement through catheters. Symmetrical tip dialysis catheters have become alternatives to split tip and step tip designs owing to low solute recirculation and ease of positioning. We compared flow characteristics and recirculation of two symmetrical tip dialysis catheters using computational flow dynamics (CFD). Materials and Methods: We compared the VectorFlow catheter (with helically contoured distal lumens which offset the vectors of blood entering and leaving the device) with the Palindrome catheter (with symmetrically cross-cut tips within a dual-D configuration). A previously validated CFD model was used to compare these catheters for recirculation (as percent blood flow), Platelet Activation State (PAS) (a computational metric of thrombogenicity) and Helical Flow Index (HFI, to quantify the helical content of the streaming blood) using a steady-state superior vena model assuming catheter flow rates of 400 mL/min. Results: Both catheters were associated with a recirculation close to zero. Arterial and venous lumen outflow Platelet Activation State (PAS) (70th percentile) of VectorFlow catheter vs. Palindrome was 1.88 x 10-6 vs. 2.09 x 10-6 (arterial); and 5.08 x 10-6 vs. 1.14 x 10-5 (venous), respectively. Both catheters exhibited a symmetrical venous flow structure away from the catheter tip and coherent helical trajectories entering the arterial lumen, but transitioning rapidly in the VectorFlow catheter to fully developed flow. HFI analysis showed that both the Palindrome and VectorFlow catheters exhibited helical flow, with HFI of 0.032 and 0.024, respectively; the helically contoured lumens of the VectorFlow were also effective in deflecting the venous flow away from the arterial lumen. Conclusion: Both VectorFlow and Palindrome catheters showed minimal recirculation rates compared to conventional step tip and split tip alternatives. The VectorFlow catheter was associated with lower Platelet Activation State (PAS) levels and helical deflection of blood from the venous lumen away from the arterial lumen. [Copyright &y& Elsevier]