title: Determinants and clinical significance of flow via the fenestration in the Fontan pathway: a multimodality study.
abstract: BACKGROUND
  The use of a fenestration in the Fontan pathway remains controversial, partly because its hemodynamic effects and clinical consequences are insufficiently understood. The objective of this study was to quantify the magnitude of fenestration flow and to characterize its hemodynamic consequences after an intermediate interval after surgery.
  
  
  METHODS
  Twenty three patients with a fenestrated extracardiac conduit prospectively underwent investigation by cardiac magnetic resonance (CMR), echocardiography, and invasive manometry under the same general anesthetic 12 ± 4 months after Fontan surgery. Fenestration flow was determined using phase contrast CMR by subtracting flow in the Fontan pathway above the fenestration from Fontan flow below the fenestration.
  
  
  RESULTS
  Fenestration flow constituted a mean of 31 ± 12% (range 8-50%) of ventricular preload. It was associated with a lower Qp/Qs (r = -0.64, p=0.001) and oxygen saturation (r = -0.74, p<0.0001). Fenestration flow volume was correlated with pulmonary vascular resistance (r = 0.45, p = 0.04) and markers of ventricular diastolic function (early diastolic strain rate r = 0.57, p = 0.008 and ventricular untwist rate r = 0.54, p = 0.02). In 14 patients (61%) all of the net inferior vena cava flow and part of the superior vena cava flow were diverted into the systemic atrium and did not reach the lungs.
  
  
  CONCLUSIONS
  Fenestration flow can be measured accurately with CMR. In two-thirds of the patients not only all of the inferior vena cava flow, but also some of the superior vena cava flow is diverted through the fenestration. Fenestration flow is driven by a balance between pulmonary vascular resistance and early diastolic ventricular function.
authors.affiliation: The Labatt Family Heart Centre and Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, Canada. Electronic address: lars.grosse-wortmann@sickkids.ca.
authors.forename: Lars
authors.initials: L
authors.lastname: Grosse-Wortmann
authors.forename: Andreea
authors.initials: A
authors.lastname: Dragulescu
authors.forename: Christian
authors.initials: C
authors.lastname: Drolet
authors.forename: Rajiv
authors.initials: R
authors.lastname: Chaturvedi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kotani
authors.forename: Luc
authors.initials: L
authors.lastname: Mertens
authors.forename: Katherine
authors.initials: K
authors.lastname: Taylor
authors.forename: Gustavo
authors.initials: G
authors.lastname: La Rotta
authors.forename: Glen
authors.initials: G
authors.lastname: van Arsdell
authors.forename: Andrew
authors.initials: A
authors.lastname: Redington
authors.forename: Shi-Joon
authors.initials: SJ
authors.lastname: Yoo
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology*; D002675:Child, Preschool; D003326:Coronary Circulation / Q000502:physiology*; D004452:Echocardiography / Q000379:methods; D005260:Female; D018729:Fontan Procedure / Q000379:methods*; D006330:Heart Defects, Congenital / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007223:Infant; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D008365:Manometry / Q000379:methods; D064847:Multimodal Imaging / Q000379:methods*; D011446:Prospective Studies