Congenital Heart Disease - Cases
Catalina Vargas-Acevedo, MD
Research Assistant Congenital Heart Disease Institute
Fundacion Cardioinfantil-LaCardio
Bogota, Distrito Capital de Bogota, Colombia
Carlos-Eduardo Guerrero-Chalela, MD
Cardiac imaging/Adult Congenital Heart Disease
Fundación Cardioinfantil–La Cardio, Bogotá, Colombia, Distrito Capital de Bogota, Colombia
Omar D. López Mejía, PhD
Associate professor
universidad de los andes, Colombia
Juan Andres Rojas, MSc
Mechanical Engineer
Universidad de los Andes, Distrito Capital de Bogota, Colombia
Javier Navarro, PhD
Postdoctoral Fellow
Universidad de los Andes, Colombia
Camila Castro, MSc
Doctoral Student
Universidad de los Andes, Colombia
Camilo Pérez, MSc
Doctoral Student
Universidad de los Andes, Colombia
Julian-Francisco Forero-Melo, MD
Cardiac imaging
Fundación Cardioinfantil–La Cardio, Bogotá, Colombia, Colombia
Juan Carlos Briceño, PhD
Professor
Universidad de los Andes / Fundación Cardioinfantil-LaCardio, Colombia
Miguel Ronderos-Dumir, MD
Pediatric Interventional Cardiologist
Fundación Cardioinfantil-LaCardio, Colombia
A computational fluid dynamics (CFD) model was created based on post-TCPC cardiac magnetic resonance (CMR) acquired in a 1.5T scanner, and pressure data were obtained from cardiac catheterization 5 days after CMR. A post-contrast three-dimensional (3D) balanced steady-state free precession self-navigated sequence (FOV= 300 x 300 x 140 mm, reconstructed Voxel 0.59 x0.59 x 2.0 mm Flip angle 90◦, T2-preparation: 50 ms) covering the chest, was used for the anatomical reconstruction and boundary conditions. Velocities in the system were estimated using phase contrast images at inferior vena cava (IVC), superior vena cava (SVC), TCPC/IVC junction, mid-conduit, left pulmonary artery, and right pulmonary artery. A 3D model of the vascular anatomy was reconstructed, modifying conduit diameter from the original size (20 mm) to 16 mm, 18 mm, and 22 mm (Figure 1). Three outcomes were estimated for each conduit size: mean velocity and pressure within the circuit, rate of energy loss, and residence time. Energy loss was calculated as the difference between energy input and output in the circuit. The rate of energy loss was used to determine hemodynamic efficiency for each variation; efficiency was considered inversely proportional to the rate of energy loss. At larger conduit diameters, there was a greater velocity output through the right pulmonary artery than the left, suggesting unbalanced pulmonary blood flow. Furthermore, larger conduit diameters showed more extensive regions of recirculation regions (Figure 2). There was a tendency towards lower pressure inside the conduit circuit at a smaller diameter. As conduit diameter increased, there was greater energy loss (8.368 mW in the 16 mm versus 15.020 mW in the 22 mm). Similarly, as the diameter increased, there was more residence time within the circuit (0.701s in 16 mm diameter versus 0.913s in the 22 mm diameter) (Figure 3).
Learning Points from this Case: Conduit diameter might impact the hemodynamic efficiency of the TCPC circulation. Our model showed higher recirculation, rate of energy loss, and residence time when using larger conduit diameters. A better understanding of TCPC hemodynamic efficiency might help provide a more efficient conduit to single ventricle patients in a resource-limited setting. Furthermore, CFD modeling can be created from standard CMR imaging protocols.