title: Differentiation of Impaired From Preserved Hemodynamics in Patients With Fontan Circulation Using Real-time Phase-velocity Cardiovascular Magnetic Resonance.
abstract: OBJECTIVE
  Progressive impairment of hemodynamics in patients with Fontan circulation is common, multifactorial, and associated with decreased quality of life and increased morbidity. We sought to assess hemodynamic differences between patients with preserved (preserved Fontans) and those with impaired circulation (impaired Fontans) after pulmonary vasodilation using oxygen and under forced breathing conditions.
  
  
  METHODS
  Real-time phase-contrast cardiovascular magnetic resonance was performed using non-ECG triggered echo-planar imaging (temporal resolution=24 to 28 ms) in the ascending aorta (AAo) and superior vena cava (SVC)/inferior vena cava (IVC) on room air, after 100% oxygen inhalation (4 L/min; 10 min) and on forced breathing in 29 Fontan patients (17.2±7.3 y) and in 32 controls on room air (13.4±3.7 y). The simultaneously recorded patients' respiratory cycle was divided into 4 segments (expiration, end-expiration, inspiration, and end-inspiration) to generate respiratory-dependent stroke volumes (SVs). The imaging data were matched with physiological data and analyzed with home-made software.
  
  
  RESULTS
  The mean SVi (AAo) was 46.1±11.1 mL/m in preserved Fontans versus 30.4±6.2 mL/m in impaired Fontans (P=0.002) and 51.1±6.9 mL/m in controls (P=0.107). The cutoff value for differentiation of Fontan groups was SVi (AAo, end-expiratory) of 32.1 mL/m. After hyperoxygenation, the mean SVi (AAo) increased to 48.7±12.7 mL/m in preserved Fontans (P=0.045) but remained unchanged in impaired Fontans (31.1±5.8 mL/m, P=0.665). Simultaneously, heart rates decreased from 75.2±15.9 to 70.8±16.4 bpm (preserved; P=0.000) but remained unchanged in impaired circulation (baseline: 84.1±9.8 bpm, P=0.612). Compared with physiological respiration, forced breathing increased the maximum respiratory-related cardiac index difference (ΔCImax) in preserved Fontans (SVC: 2.5-fold, P=0.000; and IVC: 1.8-fold, P=0.000) and to a lower extent in impaired Fontans (both veins, 1.5-fold; P(SVC)=0.011, P(IVC)=0.013). There was no impact on mean blood flow.
  
  
  CONCLUSIONS
  Oxygen affected the pulmonary vascular system by vasodilation and increased SVi in preserved Fontans but had no effect on impaired Fontans. Forced breathing increased ΔCImax but did not change the mean blood flow by sole activation of the ventilatory pump. End-expiratory aortic SVi represents a valuable measure for classifying the severity of Fontan hemodynamics impairment.
authors.affiliation: *Institute for Radiology, Nuclear Medicine and Molecular Imaging †Department for Congenital Heart Defects, Heart and Diabetes Centre North Rhine Westphalia Ruhr University Bochum, Bad Oeynhausen ‡Department of Radiology, University of Bonn, Bonn §Department for Pediatric Cardiology and Pediatric Intensive Care, Ludwig Maximilians University, Medical Hospital of the University of Munich, Campus Grosshadern, Munich, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Körperich
authors.forename: Katja
authors.initials: K
authors.lastname: Müller
authors.forename: Peter
authors.initials: P
authors.lastname: Barth
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gieseke
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Haas
authors.forename: Ingram
authors.initials: I
authors.lastname: Schulze-Neick
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Burchert
authors.forename: Deniz
authors.initials: D
authors.lastname: Kececioglu
authors.forename: Kai T
authors.initials: KT
authors.lastname: Laser
mesh_terms: D000293:Adolescent; D000328:Adult; D001011:Aorta / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002648:Child; D003937:Diagnosis, Differential; D017352:Echo-Planar Imaging / Q000379:methods; D005260:Female; D018729:Fontan Procedure; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011446:Prospective Studies; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014683:Vena Cava, Superior / Q000000981:diagnostic imaging / Q000503:physiopathology*; D055815:Young Adult