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Fontan Hemodynamics From 100 Patient-Specific Cardiac Magnetic Resonance Studies: A Computational Fluid Dynamics Analysis | Journal Scan
Study Questions:
What are the hemodynamic consequences of varying Fontan types using cardiac magnetic resonance imaging (CMR)-derived computational fluid dynamics (CFD) analysis?
Methods:
Fontan connection models were created from CMR scans for 100 patients with single-ventricle anatomy. Underlying anatomy was hypoplastic left heart syndrome (HLHS) in 31% of patients. The majority (64%) had intra-atrial Fontan connections, with a smaller proportion with extracardiac connections (33) and a small minority (3) with atriopulmonary Fontan connections. Phase-velocity CMR in the aorta, vena cavae, and pulmonary arteries was used to identify patient-specific time-averaged flow boundary conditions for CFD. In a subset of patients, comparison with four-dimensional CMR velocity data was used to provide additional verification of simulations. Indexed Fontan power loss, connection resistance, and hepatic flow distribution were quantified and correlated with patient characteristics.
Results:
Patient-to-patient variation led to significant differences in indexed power loss (two orders of magnitude). Fontan circuit resistance appears to account for a relatively small proportion of the total resistance, as it was estimated to be 15-20% of published values of pulmonary vascular resistance for patients with single-ventricle anatomy. Increased power loss was associated with lower cardiac output and decreased systemic venous flow. There were no differences between intra-atrial and extracardiac connections. The highest power loss was seen in patients with localized Fontan pathway or pulmonary artery stenosis.
Conclusions:
The authors concluded that Fontan loss varies from patient to patient, and elevated levels are correlated with lower systemic flow and cardiac index.
Perspective:
Strategies for creating the systemic venous to pulmonary arterial connections for patients with single-ventricle anatomy vary from center to center, and from surgeon to surgeon. There has been ongoing debate as to the most efficient Fontan type. Patients with historical repairs (atrial appendage to pulmonary artery types of Fontans) are often referred for Fontan conversion to mitigate arrhythmias and improve efficiency of their Fontan circulation. This study suggests that the type of Fontan is not as important as the patency of the circuit, supporting an aggressive approach to intervening on Fontan pathway or branch pulmonary artery stenosis.
Keywords: Aorta, Arrhythmias, Cardiac, Atrial Appendage, Cardiac Output, Constriction, Pathologic, Hemodynamics, Venae Cavae, Hypoplastic Left Heart Syndrome, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Pulmonary Artery, Pulmonary Circulation, Vascular Resistance
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