In the proposed study, we will non-invasively assess the altered hemodynamics of total cavo-pulmonary connection (TCPC) with four-dimensional flow-sensitive (4D Flow) magnetic resonance imaging (MRI), using numerical and physical patient-specific models as reference standards. The major innovations of this study include: 1. In vivo assessment of TCPC performance from dynamic, volumetric velocity fields measured with 4D Flow MRI. 2. Comprehensive hemodynamic assessment of velocities, flow, energy losses and systemic output directly derived from 4D Flow MRI data. 3. The use of 4D Flow MRI to perform measurements in physical models under varying conditions, which would not be possible in vivo; the results will help validate parallel computational fluid dynamics (CFD) models.
Previous studies have simulated TCPC hemodynamics, and have established energy loss as an appropriate metric for describing the efficiency of the TCPC system. These have been primarily based on the use of 2D Flow MR to provide conditions for CFD. We will be using 4D Flow MR to calculate kinetic energy (KE) because it is less computationally challenging and does not require as many assumptions. In addition, we will be comparing the use of 2D Flow to 4D Flow for numerical simulations. Kinetic energy in TCPC will be correlated to systemic ventricle KE and function (ejection fraction). In addition, wall shear stress and pressure drops will be determined from both CFD and 4D Flow MR.