Influence of side-hole configuration on recirculation in dual-lumen cannulas for veno-venous extracorporeal membrane...

Veno-venous extracorporeal membrane oxygenation (VV-ECMO) increasingly utilizes dual-lumen cannulas (DLCs) to facilitate single-site cannulation. However, challenges such as recirculation and elevated wall shear stress (WSS) continue to impede their efficacy. The influence of the geometric configuration of drainage side holes on these hemodynamic parameters remains inadequately characterized.

In this study, we performed transient, non-Newtonian computational fluid dynamics (CFD) simulations on eight distinct DLC configurations subjected to pulsatile venous inflow. These simulations were conducted within an idealized model of the vena cava and right atrium (RA), developed in accordance with ISO 18193:2021 standards. The study systematically varied the axial spacing between drainage holes and the infusion port (denoted as H₁/H₂), as well as the circumferential and axial arrangement of side holes in the superior vena cava (SVC) and inferior vena cava (IVC).

Results indicate that the recirculation fraction (RF) is influenced by two geometric factors. First, among six configurations with fixed axial spacing, the peak RF (RF_max) was positively associated with the SVC drainage fraction (R ² = 0.87, n = 6). Given the limited number of configurations and the narrow range of SVC drainage fractions examined, this association should be considered exploratory. Second, reducing axial spacing increased the time-averaged RF (RF_ave) from 2.73% in the baseline configuration to 6.48%. Circumferential distribution of the IVC side holes was associated with a lower RF_ave (2.10%-2.34%) and with reduced stagnation volume, without increased WSS exposure or impaired washout.

These results suggest that considering circumferential side-hole placement could be a useful and underexamined parameter for DLC design optimization in VV-ECMO within the investigated geometric range.