MRI Phase-Contrast Blood Flow in Fasting Pediatric Patients with Fontan Circulation Correlates with Exercise Capacity

Christopher Z Lam; Dawn David; Laura Acosta Izquierdo; Parneyan Pezeshkpour; Anne I Dipchand; Emilie Jean-St-Michel; Rajiv R Chaturvedi; Simon C Ling; Rachel M Wald; Govind B Chavhan; Michael Seed; Shi-Joon Yoo

doi:10.1148/ryct.210303

MRI Phase-Contrast Blood Flow in Fasting Pediatric Patients with Fontan Circulation Correlates with Exercise Capacity

Radiol Cardiothorac Imaging. 2022 Apr 21;4(2):e210303. doi: 10.1148/ryct.210303. eCollection 2022 Apr.

Affiliation

¹ Department of Diagnostic Imaging (C.Z.L., D.D., L.A.I., P.P., G.B.C., M.S., S.J.Y.), Division of Cardiology, Department of Paediatrics (A.I.D., E.J.S.M., R.R.C., R.M.W., M.S., S.J.Y.), and Division of Gastroenterology, Department of Paediatrics (S.C.L.), Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON, Canada M5G 1X8; Department of Medical Imaging, University of Toronto, Toronto, Canada (C.Z.L., L.A.I., G.B.C., S.J.Y.); Joint Department of Medical Imaging, University Health Network, Toronto, Canada (R.M.W.); and Peter Munk Cardiac Centre, University Health Network, Toronto General Hospital, Toronto, Canada (R.M.W.).

Abstract

Purpose: To assess regional blood flow in fasting pediatric patients with Fontan circulation by using MRI and to explore associations with clinical parameters.

Materials and methods: In this retrospective study, pediatric patients who had undergone the Fontan procedure (<18 years of age) and had undergone clinical cardiac MRI, performed after at least 4 hours of fasting, between 2018 and 2021 were included. Regional blood flow was compared with published healthy volunteer data (n = 19) and assessed in relation to hemodynamic parameters and clinical status. Data are presented as medians, with first to third quartiles in parentheses. Mann-Whitney U, Kruskal-Wallis, χ², and Spearman rank correlation tests were used.

Results: Fifty-five patients (38 boys) with median age at MRI of 14 years (IQR, 11-16 years) and median time from Fontan procedure to MRI of 10 years (IQR, 8-12 years) were included. Patients after Fontan procedure had lower ascending aortic, inferior vena cava, and total systemic blood flow compared with healthy volunteers (3.00 L/min/m² [IQR, 2.75-3.30 L/min/m²] vs 3.61 L/min/m² [IQR, 3.29-4.07 L/min/m²]; 1.73 L/min/m² [IQR, 1.40-1.94 L/min/m²] vs 2.24 L/min/m² [IQR, 2.06-2.75 L/min/m²]; 2.78 L/min/m² [IQR, 2.45-3.10 L/min/m²] vs 3.95 L/min/m² [IQR, 3.20-4.30 L/min/m²], respectively; P < .001). Portal vein flow was greater than hepatic vein flow in 25% of patients. Fontan blood flow was inversely correlated with pre-Fontan mean pulmonary artery pressure (Spearman rank correlation coefficient [r_s ]= -0.42, P = .005) and ventricular end diastolic pressure (r_s = -0.33, P = .04) and positively correlated with post-Fontan percent predicted oxygen consumption at peak workload (r_s = 0.34, P = .02).

Conclusion: Reference ranges are provided for regional systemic blood flow derived by using MRI in fasting pediatric patients with Fontan circulation, who had lower systemic blood flow compared with healthy volunteers. Lower fasting Fontan blood flow correlated with lower exercise capacity.Keywords: Pediatrics, Heart, Congenital, MR Imaging, Hemodynamics/Flow Dynamics, Cardiac Supplemental material is available for this article. © RSNA, 2022.

Keywords: Cardiac; Congenital; Heart; Hemodynamics/Flow Dynamics; MR Imaging; Pediatrics.