The Fontan procedure, a palliative surgery for single-ventricle heart defects, creates a non-physiological circulation that often leads to complications such as pulmonary arteriovenous malformations (PAVMs), thrombosis, and energy loss. As the number of Fontan patients surviving into adulthood continues to grow, precise understanding and improved monitoring of patient-specific hemodynamics is critical for long-term management. Two key challenges hinder progress: 1) the lack of a reliable method to quantify hepatic flow distribution (HFD) from post-operative imaging, a critical determinant of outcomes, and 2) the absence of a validated, patient-specific computational fluid dynamics (CFD) workflow to guide surgical personalization.

This study addresses these gaps by integrating a novel 4D Flow CMR-based particle tracking algorithm with an image-based CFD workflow to quantify and predict Fontan hemodynamics, including HFD, validated with in-vivo data. The 4D Flow-based particle tracking algorithm offers a precise, non-invasive tool for visualizing HFD, demonstrating excellent agreement with phase-contrast MRI (< 5% deviation). Patient-specific CFD models further predicted flow dynamics with high accuracy, validated against in vivo data (< 8% deviation).

Using this integrated workflow, we uncovered uneven mixing between the inferior vena cava and hepatic blood flow, challenging assumptions of uniform mixing and highlighting the critical role of local flow dynamics in determining long-term outcomes. By enabling non-invasive assessment and improved surgical planning, this validated CFD workflow, combined with 4D Flow particle tracking, offers immediate clinical application. With CFD-based surgical planning gaining traction, this approach establishes a new standard for personalized management for patients undergoing treatment for congenital heart diseases.

Summary This study presents a validated workflow integrating 4D Flow CMR and patient-specific CFD to accurately quantify hepatic flow distribution and enhance surgical planning, addressing key challenges in the treatment and long-term management of Fontan patients with single-ventricle disease.

The authors have declared no competing interest.

VG reports research funding from the NHLBI/NIH (R01HL161507) and in-kind research support from NSF (high-performance computing resources from TACC). AS, EE, DH, PEH, and RR report research funding from the NHLBI/NIH (R01HL161507).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

This study was approved by the Institutional Review Board at Boston Children's Hospital (Protocol Title: Utilizing Patient-Specific Computational Fluid Dynamics Modeling to Optimize the Fontan Procedure). The IRB waived the requirement for informed consent as all data were anonymized and collected as part of routine clinical care.

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Yes

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All data produced in the present study are available upon reasonable request to the authors