CMR-Flow

1351933 - Suboptimal Hemodynamics Are Correlated With Lower Kinetic Energy and Higher Energy Loss in the Superior Cavopulmonary Connection: A Pre-Fontan Study with MRI and Catheterization

Friday, January 27, 2023

10:20 AM – 11:00 AM

Location: Pacific Jewel

Presenting Author(s)

JC

Jacqueline Contento, BSE

Research Engineer
Children's National Hospital, District of Columbia, United States

Primary Author(s)

JC

Jacqueline Contento, BSE

Research Engineer
Children's National Hospital, District of Columbia, United States

Co-Author(s)

FC

Francesco Capuano, PhD

Assistant Professor
Universitat Politècnica de Catalunya - BarcelonaTech
Barcelona, Catalonia, Spain
NM

Nicholas Mouzakis, RT

MR Technologist
Children's National Hospital, United States
NM

Nicole Toscana Marella, MD

Advanced Imaging Fellow
Children's National Medical Center
Washington, District of Columbia, United States
EB

Elias Balaras, PhD

Professor
George Washington University, District of Columbia, United States
Yue-Hin Loke, MD

Assistant Professor of Pediatrics
Children's National Hospital, Maryland, United States

Disclosure(s):

Yue Loke: No financial relationships to disclose

Background: Pre-Fontan assessment of the single ventricle is performed by either cardiac catheterization and/or cardiac magnetic resonance (CMR). Advanced four-dimensional (4D) flow can also visualize the complex flow fields across the superior cavopulmonary connection (SCPC) that potentially represent inefficient flow.¹^,² 4D flow analysis of Fontan patients has previously demonstrated lower kinetic energy³ and elevated energy loss⁴ compared to controls. However, there have been no 4D flow pre-Fontan studies. This study aimed to use 4D flow to analyze the SCPC and the relationship between flow profile and pre-Fontan hemodynamics.

Methods: Diagnostic-quality, ferumoxytol-enhanced CMR, including volumetry and 4D flow data, were acquired in single ventricle patients before their Fontan (n=35, Table 1). After CMR, these patients also underwent cardiac catheterization in the same anesthetic conditions. The SCPC was segmented into a 3D mask (Mimics, Materialise) that was used to extract the relevant flow fields (Figure 1). 4D flow parameters of kinetic energy, viscous energy loss, and vorticity were calculated and compared against CMR-derived aortopulmonary collateral (%APC) and cardiac index (L/min/m²) using linear regression. Presence of pressure gradients as determined by catheterization was analyzed using an unpaired t-test. P-values were calculated, and scatterplots were generated using Prism Version 9 (GraphPad Software, La Jolla, CA).

Results: 4D flow-derived parameters were correlated to suboptimal pre-Fontan hemodynamics (Figure 2). Kinetic energy within the SCPC was negatively associated with increasing %APC burden (P = 0.03) and positively associated with cardiac index (P < 0.001). Increasing vortical flow was associated with energy loss (P = 0.002). Lastly, the presence of pressure gradients within the SCPC also was associated with larger energy losses (P = 0.002).

Conclusion: Single ventricle patients with lower cardiac index, larger %APC, and pulmonary artery pressure gradients in the SCPC had associated lower kinetic energy, higher vorticity, and high energy losses, as identified by 4D flow. Future work will continue to analyze the SCPC to further explore the clinical implications of 4D flow analysis.