Particle image velocimetry analysis of the flow field in the total cavopulmonary connection.

The total cavopulmonary connection (TCPC) is a common operation, meant to restore a proper pulmonary blood flow in heart defects with only one functional ventricle. It consists of the direct connection of the venae cavae to the pulmonary arteries in a cross-shaped disposition which entails a peculiar hemodynamics: Side effects can occur, such as recirculation zones and pressure drop across the connection. Our study is aimed at the quantitative investigation of the flow field of a successful Fontan-type operation, in view of the clinical importance of assuring a nearly physiological pulmonary blood flow, especially if one considers that many pediatric patients are eligible for this operation. A glass-blown TCPC phantom, realized according to nuclear magnetic resonance data, was employed in a steady-flow loop. Thus, a realistic model of this Fontan-type operation was realized using materials which enable advanced measurement techniques such as particle image velocimetry (PIV). The mean flow rates at each branch of the cavopulmonary shunt could be independently varied with a vertical shift of the corresponding upstream reservoir. The PIV technique was used successfully in identifying the flow field characteristics. The flow field in this TCPC topology was shown to be well organized and regulated by the presence of a vortex at the confluence of the venae cavae. The effect of different loading conditions, which realistically can be found in vivo, is studied with a high spatial resolution, showing the possibility to use pulmonary resistance as a parameter in designing the surgical geometry.