title: Assessment of ductal blood flow in newborns with obstructive left heart lesions by cardiovascular magnetic resonance.
abstract: BACKGROUND
  Newborns with obstructive left heart lesions often depend on a patent ductus arteriosus to sustain the systemic circulation. Our aims were to validate the direct measurement of ductal flow, and to characterize the magnitude, determinants and hemodynamic effects of patent ductus arteriosus in newborns with obstructive left heart lesions by cardiovascular magnetic resonance (CMR).
  
  
  METHODS
  In this retrospective study, the CMR and clinical information of newborns with obstructive left heart lesions were reviewed. The feasibility and validity of measuring ductal flow and the correlations between ductal flow and ventricular volumes, ascending aortic flow, post-ductal oxygen saturation and Qp:Qs were assessed.
  
  
  RESULTS
  The CMR examinations of 32 newborns were included. It was possible to measure the ductal flow in all of them, with moderate-to-good agreement between measured and calculated ductal flow volume. The flow was bidirectional in all patients, with a net right-to-left shunt in 72%. Net ductal flow correlated inversely with ascending aortic flow (Rho -0.63; p 0.0002), post-ductal oxygen saturation (Rho -0.58; p 0.0004), Qp:Qs (Rho -0.43; p 0.02), and with left ventricular end-diastolic volume index (Rho -0.38; p 0.04). There was no correlation with the diameter of the ductus. The contribution of ductus flow to the systemic circulation correlated with the left ventricular end-diastolic volume index (Rho -0.47; p 0.02).
  
  
  CONCLUSIONS
  Direct measurement of ductal flow in newborns with obstructive left heart lesions is feasible. From these measurements, we were able to demonstrate that patients with smaller left ventricles and lower ascending aortic flow have a greater contribution of ductal flow to the systemic circulation. The size of the ductus arteriosus does not predict net ductal flow. Phase-contrast CMR can be an adjunct method for the assessment of the physiology for very ill neonate patients.
authors.affiliation: Labatt Family Heart Centre in the Department of Paediatrics and Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Marcelo Felipe
authors.initials: MF
authors.lastname: Kozak
authors.forename: Shi-Joon
authors.initials: SJ
authors.lastname: Yoo
authors.forename: Luc
authors.initials: L
authors.lastname: Mertens
authors.forename: Ashley
authors.initials: A
authors.lastname: Ho
authors.forename: Lars
authors.initials: L
authors.lastname: Grosse-Wortmann
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D055424:Cardiac-Gated Imaging Techniques; D004374:Ductus Arteriosus, Patent / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006330:Heart Defects, Congenital / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012189:Retrospective Studies