Hemodynamic implications of direct sheath insertion through VA-ECMO arterial cannula: an In-Vitro model

In patients supported by venoarterial extracorporeal membrane oxygenation (VA-ECMO), concomitant percutaneous procedures are often limited by difficulty obtaining vascular access. Although prior case reports have described using the ECMO arterial cannula as an access site, the hemodynamic implications are unknown. This in-vitro study examined the effect of direct catheter sheath insertion through the VA-ECMO arterial cannula on circuit hemodynamics. An ECMO circuit was constructed in a water-based bench model with arterial cannula size of 13.5, 15, and 16.5 Fr. We measured flow and pressure changes with the direct Seldinger insertion of 4, 5, 6, and 7 Fr sheaths and catheter into the arterial ECMO cannula, simulating concomitant catheter-based interventions. We demonstrated that sheath insertion consistently reduced circuit flow in a size-dependent manner, requiring higher pump speeds to maintain comparable flow. At the maximum pump speed (3000 rpm), the largest cannula (16.5 Fr) maintained flow rates > 3.0 L/min across all sheath sizes tested, whereas the 15 Fr cannula achieved this only with 4-6 Fr sheaths and the 13.5 Fr cannula only with a 4 Fr sheath. Our findings suggest that certain combinations of ECMO cannula and sheath sizes can preserve adequate perfusion, supporting the feasibility of this simple, reproducible technique under carefully selected conditions. This study provides the first evaluation of flow dynamics for this procedure in a standardized setting. Further studies are warranted to confirm our findings.