Patient‐Specific Atrial Hemodynamics of a Double Lumen Neonatal Cannula in Correct Caval Position

Abstract

Clinical success of pediatric veno‐venous (VV) extracorporeal membrane oxygenation (ECMO) is associated with the double lumen cannula cardiovascular device design as well as its anatomic orientation in the atrium. The positions of cannula ports with respect to the vena cavae and the tricuspid valve are believed to play a significant role on device hemodynamics. Despite various improvements in ECMO catheters, especially for the neonatal and congenital heart patients, it is still challenging to select a catalogue size that would fit to most patients optimally. In effect, the local unfavorable blood flow characteristics of the cannula would translate to an overall loss of efficiency of the ECMO circuit. In this study, the complex flow regime of a neonatal double lumen cannula, positioned in a patient‐specific right atrium, is presented for the first time in literature. A pulsatile computational fluid dynamics (CFD) solver that is validated for cardiovascular device flow regimes was used to perform the detailed flow, oxygenated blood transport, and site‐specific blood damage analysis using an integrated cannula and right atrium model. A standard 13Fr double lumen cannula was scanned using micro‐CT, reconstructed and simulated under physiologic flow conditions. User defined scalar transport equations allowed the quantification of the mixing and convection of oxygenated and deoxygenated blood as well as blood residence times and hemolysis build‐up. Site‐specific CFD analysis provided key insight into the hemodynamic challenges encountered in cannula design and the associated intra‐atrial flow patterns. Due to neonatal flow conditions, an ultra high velocity infusion jet emanated from the infusion port and created a zone of major recirculation in the atrium. This flow regime influenced the delivery of the oxygenated blood to the tricuspid valve. Elevated velocities and complex gradients resulted in higher wall shear stresses (WSS) particularly at the infusion port having the highest value followed by the aspiration hole closest to the drainage port. Our results show that, in a cannula that is perfectly oriented in the atrium, almost 38% of the oxygenated blood is lost to the atrial circulation while only half of the blood from inferior vena cava (IVC) can reach to the tricuspid valve. As such, approximately 6% of venous blood from superior vena cava (SVC) can be delivered to tricuspid. High values of hemolysis index were observed with blood damage encountered around infusion hole (0.025%). These results warrant further improvements in the cannula design to achieve optimal performance of ECMO and better patient outcomes.

Heart valve inspired and multi‐stream aortic cannula: Novel designs for cardiopulmonary bypass improvement in neonates

“…This obviously shows that a turbulent outflow is more favorable in aortic cannulas if optimal perfusion characteristics are desired. Another important issue which can be frequently faced in the literature, especially during the computational simulations is the decision on whether the outflow of aortic cannula should be treated as laminar or turbulent . Our results confirmed that even for relatively low Reynolds flows, the outflow shows strong turbulence which builds as early as 3‐4 jet diameters downstream of the exit tip.…”

Hemodynamics of neonatal double lumen cannula malposition

“…The 3D reconstructions of the DLC and atrium were combined in the computer as reported in our previous study. 12 Here, clinical malpositioned configurations are generated to simulate clinical scenarios and numerical algorithm was adapted to allow for site-specific determination of the hemodynamic parameters. As shown in Figure 1, a total of six cases of malposition were simulated, consisting of two rotations (antero-atrial and atrio-septal) and four translations (two retrograde movements inside the IVC, two dislodgements in the atrium).…”

“…This solver has been recently applied to neonatal aortic cannulas 19 as well as DLC by our group and validated experimentally. 12,20 The discrete system of Reynolds-averaged Navier–Stokes (RANS) equation was solved using Semi-Implicit Pressure Linked Equation (SIMPLE) solver and each simulation took around 8 hours on a Dell Precision T7600 desktop computer with dual core Xeon processors. Second-order accuracy for diffusive and convective fluxes was used.…”

“…11 Our recent computational fluid dynamics (CFD) study showed that for one DLC design, even in the recommended orientation, neonatal hemodynamics is less than optimal, resulting in significantly high values of recirculation (up to 38%). 12 In this article, we extend this approach to study the hemodynamic performance at clinical malposition configurations oriented inside the right atrium. It is hoped that this systematic analysis will help us in understanding the malposition-related hemodynamics.…”

Artificial Organs 2018: A Year in Review

“…Jamil Muhammad et al of Koç University, Sarıyer, Turkey, investigated the complex flow regime of a neonatal double lumen cannula in veno‐venous extracorporeal membrane oxygenation (ECMO) with the double lumen cannula positioned in a patient‐specific right atrium. A pulsatile computational fluid dynamics (CFD) solver was used to perform the detailed flow, oxygenated blood transport, and site‐specific blood damage analysis using an integrated cannula and right atrium model.…”