Device Specific Aortic Outflow Cannula Jets Studied Using 2D PIV and High-Performance 3D CFD Simulation

In the US, approximately 1 in 100 children are born with a clinically significant congenital heart defect (CHD). The palliative repair of these defects requires complex biventricular and univentricular surgical operations in newborns often smaller than 2 kg. However, recovery after neonatal intervention remains suboptimal ¹. A major component of these surgeries is the cardiopulmonary by-pass (CPB) procedure which if prolonged can potentially lead to neurological complications and developmental defects in a young patient. During CPB, tiny aortic cannulae (2–3 mm inner diameter), with micro-scale blood-wetting features transport relatively large blood volumes (0.3 to 1.0 L/min) resulting in high blood flow velocities. Our recent 3D computational fluid dynamics (CFD) simulations of jet flows in device specific cannulae ² have indicated that the turbulent jet wake at high physiological neonatal extracorporeal life support (ECLS) circuit blood flow rates can potentially have damaging hemolytic effects, when evaluated in a cuboidal flow domain, as well as in in-silico aortic insertion configurations. Such severe flow conditions can result in platelet activation, vascular injuries and blood damage. Despite these risks, cannulation methods have received little attention compared to the effort expended to assure the safety and efficacy of the mechanical circulatory support blood pumps. Qui et al ³ report that cannula problems are the second most frequently reported mechanical complication in ECLS therapy for respiratory cases and the third most frequent complication in cardiac cases. The purpose of this study is to quantitatively evaluate the jet wake region of two popular 8FR pediatric cannulae, DLP Medtronic 77008 and RMI FEM II – 008 – AT (inner diameter ∼1850 microns), using stereo particle image velocimetry (PIV) to validate numerically computed flow fields.