Presurgical planning using image-based in silico anatomical and functional characterization of Tetralogy of Fallot...

The ideal vascular reconstruction strategy for anomalies associated with Tetralogy of Fallot (ToF) is often driven by observations made at the operating table. A method to conduct accurate studies to assess the virtues of a certain surgical technique to guide surgical decisions is found wanting. We hypothesize that patient-specific computed tomography (CT)-based morphometry followed by in silico reconstruction of viable surgical options with haemodynamic function assessment using computational fluid dynamics (CFD) can guide surgical decisions and help forecast functional outcomes without invasive measurements.

A ToF patient associated with additional left pulmonary artery (LPA) stenosis and a patent ductus arteriosus (PDA) who underwent a successful correction using a single pericardial patch (SPP) was selected as a reference for morphological characterization after 3D anatomical reconstruction from CT images. A second patient with morphological similarities established after scaled, co-registration with the reference patient was selected for virtual correction using the same strategy (i.e. SPP repair). CFD was employed for functional analysis of pulmonary artery (PA) pressure gradients in the baseline preoperative and virtually corrected models, using patient-specific cardiac output and Qp/Qs information.

SPP repair was modelled in silico following surgical steps of PDA ligation, creation of an incision along the LPA and main PA (MPA) and finally suturing a rectangular SPP, effectively reducing MPA to LPA angle. Analysis of SPP repair revealed significant reduction in right ventricular outflow tract-LPA pressure gradient with improved left-right PA flow distribution in both patients.

In silico surgery followed by CFD evaluation has the potential in augmenting morphology-guided decisions on surgical strategy and holds promise in preoperatively determining optimal intervention strategy. This is a paradigm-shifting concept to evaluate patient-specific anomalies in a manner more objective than mere visual inspection of anatomical traits from radiology images. Present studies are focused on an analysis with a larger patient cohort to establish a library of ToF patients' successful surgical outcomes to inform morphology-based selection of surgical strategy.