Quantitative comparisons of pulmonary artery hemodynamics before and after Pulsta valve implantation in patients with Tetralogy of Fallot using computational fluid dynamics

The evaluation of percutaneous pulmonary valve implantation (PPVI) performance has been predominantly confined to assessing changes in the right ventricular volume using magnetic resonance imaging (MRI). This study aimed to evaluate the hemodynamic changes in the pulmonary arteries following PPVI using computational fluid dynamics (CFD) in patients with Tetralogy of Fallot. We conducted CFD analysis based on MRI scans performed before and after PPVI using Pulsta valve in nine patients who underwent PPVI between 2016 to 2021. We constructed patient-specific anatomic models of the pulmonary arteries, prescribed inflow boundary conditions obatined from MRI measurements, and used Windkessel boundary conditions at the outlet of the pulmonary arteries. From CFD data, we measured hemodynamics metrics including energy dissipation and backward velocities at the main, right, left pulmonary artery regions. Statistical analysis, including Wilcoxon rank-sum tests and multivariable linear regression, was performed to examine the associations between CFD data and non-CFD factors, as well as changes in these parameters after PPVI. Before PPVI, the flow velocity in the right pulmonary artery was significantly higher than that in the left pulmonary artery and main pulmonary artery in both the forward and backward directions. Forward and backward velocities decreased after PPVI, leading to an attenuation of the velocity differences among the pulmonary arteries. After PPVI, the vorticity and energy dissipation decreased significantly, whereas changes in the Womersley and Reynolds numbers were not statistically significant. A deeper understanding of the hemodynamics of pulmonary arteries using CFD can aid in evaluating the effectiveness of PPVI and refining its indications in patients with Tetralogy of Fallot.