OBJECTIVES To evaluate the hemodynamicdynamic advantage of a new Fontan surgical template that is intended for complex single-ventricle patients with interrupted inferior vena cava-azygos and hemi-azygos continuation. The new technique has emerged from a comprehensive pre-surgical simulation campaign conducted to facilitate a balanced hepatic flow and somatic Fontan pathway growth after Kawashima procedure. METHODS For 9 patients, aged 2 to18 years, majority having poor preoperative oxygen saturation, a pre-surgical computational fluid dynamics customization is conducted. Both the traditional Fontan pathways and the proposed novel Y-graft templates are considered. Numerical model was validated against in vivo phase-contrast magnetic resonance imaging data and in vitro experiments. RESULTS The proposed template is selected and executed for 6 out of the 9 patients based on its predicted superior hemodynamic performance. Pre-surgical simulations performed for this cohort indicated that flow from the hepatic veins (HEP) do not reach to the desired lung. The novel Y-graft template, customized via a right- or left-sided displacement of the total cavopulmonary connection anastomosis location resulted a drastic increase in HEP flow to the desired lung. Orientation of HEP to azygos direct shunt is found to be important as it can alter the flow pattern from 38% in the caudally located direct shunt to 3% in the cranial configuration with significantly reversed flow. The postoperative measurements prove that oxygen saturation increased significantly (P-value = 0.00009) to normal levels in 1 year follow-up. CONCLUSIONS The new Y-graft template, if customized for the individual patient, is a viable alternative to the traditional surgical pathways. This template addresses the competing hemodynamic design factors of low physiological venous pressure, high postoperative oxygen saturation, low energy loss and balanced hepatic growth factor distribution possibly assuring adequate lung development. Date and number of IRB approval 25 October 2019, 280011928-604.01.01.

Congenital heart diseases (CHDs), especially complex ventricular-arterial (VA) relationships (double outlet right ventricle [DORV], complex types of transposition of the great arteries [TGA], and congenitally corrected TGA [c-TGA]) are a heterogeneous and complex group of cardiac malformations. The planning of an optimal surgical repair of some of these pathologies requires a clear and complete understanding of spatial relationships; hence, they sometimes require advanced diagnostic imaging (1). It is important to reveal the anatomy and three-dimensional (3D) spatial relationships of cardiac structures before the ultimate decision is reached on whether to perform a single ventricular or biventricular repair.Before surgical procedures, the primary noninvasive and widely used diagnostic tool is echocardiography (2-4). While most decisions for treatment can be made with echocardiography (5), it may not be sufficient for decision-making in some complex CHDs, especially with complex VA relationships. In particular, the spatial relationship of great vessels and ventricular septal defects (VSD) is difficult to determine with echocardiography (6). Computed tomography angiography (CTA) has been widely used for the diagnosis of CHDs, and PURPOSEThis study was planned to assess the application of three-dimensional (3D) cardiac modeling in preoperative evaluation for complex congenital heart surgeries. METHODSFrom July 2015 to September 2019, 18 children diagnosed with complex congenital heart diseases (CHDs) were enrolled in this study (double outlet right ventricle in nine patients, complex types of transposition of the great arteries in six patients, congenitally corrected transposition of the great arteries in two patients, and univentricular heart in one patient). The patients' age ranged from 7 months to 19 years (median age, 14 months). Before the operation, 3D patient-specific cardiac models were created based on computed tomography (CT) data. Using each patient's data, a virtual computer model (3D mesh) and stereolithographic (SLA) file that would be printed as a 3D model were generated. These 3D cardiac models were used to gather additional data about cardiac anatomy for presurgical decision-making. RESULTSAll 18 patients successfully underwent surgeries, and there were no mortalities. The 3D patient-specific cardiac models led to a change from the initial surgical plans in 6 of 18 cases (33%), and biventricular repair was considered feasible. Moreover, the models helped to modify the planned biventricular repair in five cases, for left ventricular outflow tract obstruction removal and ventricular septal defect enlargement. 3D cardiac models enable pediatric cardiologists to better understand the spatial relationships between the ventricular septal defect and great vessels, and they help surgeons identify risk structures more clearly for detailed planning of surgery. There was a strong correlation between the models of the patients and the anatomy encountered during the operation. CONCLUSION3D cardiac models accura...

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