Determining Geometric Predictors of Blood Flow Efficiency in the Tetralogy of Fallot Patient Population
Leslie Louvelle1, Matthew Doyle1, Glen Van Arsdell2, Cristina Amon1.
1University of Toronto, Toronto, ON, Canada, 2Hospital for Sick Children, Toronto, ON, Canada.
Objectives: The objective of this work is to correlate geometric parameters with mechanical efficiency values derived from computational fluid dynamics simulations of Tetralogy of Fallot (TOF) patient anatomies.
Methods: Using SimVascular (open source), 8 TOF patient cardiac MRI scans (12.4 ± 2.4 years after repair) were segmented to include the region from the right ventricular infundibulum to the left and right pulmonary arteries (LPA, RPA). Geometric parameters, including diameters perpendicular to the vessel centreline at key regions, were extracted from each patient-specific anatomy using SolidWorks (Dassault Systèmes, Waltham, MA) and normalized against body surface area. Simulations were completed in ANSYS Fluent (Ansys, Inc., Canonsburg, PA) using patient-specific boundary conditions.
Results: With the exception of the infundibulum diameter, vessel diameters at specific regions such as the main pulmonary artery were poorly correlated with mechanical efficiency. Infundibulum diameter was moderately linearly correlated (R2 = 0.43), with increased diameter associated with increased efficiency. The ratio of the mean of the LPA and RPA diameters to the infundibulum diameter was strongly negatively correlated with efficiency (R2 = 0.80). Although the relationships were weaker, the LPA-infundibulum diameter and RPA-infundibulum diameter ratios were also independently negatively correlated with efficiency (R2 = 0.65 and R2 = 0.66 for the LPA and RPA, respectively).
Conclusions: This work highlights the importance of the diameter of the infundibulum relative to the diameter of the pulmonary arteries and has significance for surgical decision-making related to the location and size of patch enlargement of vessels in surgical TOF repair.
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