title: Geometry of the Aortic Arch After Initial Hybrid or Norwood Palliation.
abstract: BACKGROUND
  Aortic arch reconstruction is a challenging technical step in the Norwood operation or the comprehensive stage II operation. This study sought to analyze differences in aortic arch geometry and dimensions in patients undergoing Norwood or hybrid palliation.
  
  
  METHODS
  Retrospective data collection included all patients who underwent Norwood or hybrid palliation at the Hospital for Sick Children in Toronto between 2007 and 2014; 139 patients were analyzed. Lateral angiograms obtained before stage II or comprehensive stage II and Fontan completion were measured at the level of the ascending aorta, transverse arch, isthmus, and descending aorta. Reintervention rate and type were assessed.
  
  
  RESULTS
  Before stage II or comprehensive stage II hybrid procedures, patients had significantly larger descending aorta z-scores. Patients undergoing Norwood operations showed a significant increase in descending aorta z-scores before Fontan completion. Comparable dimensions (absolute and z-scores) were found at all points of measurements before Fontan completion. Geometry was similar in both groups but significantly different compared with normal dimensions. Reduction in aortic arch diameter happened almost solely in the segment between the transverse arch and the isthmus. Stent inclusion in patients undergoing hybrid procedures led to similar dimensions. Reintervention rates were very low (Norwood 9.6% vs hybrid 7.6%). Reintervention for excessive dimensions was as common as for recoarctation.
  
  
  CONCLUSIONS
  Aortic arch geometry and growth is not altered by palliation type. The increase in descending aorta diameter seen in patients undergoing Norwood operations is in accord with physiologic changes and may reflect catch-up growth. Reintervention rates are low and are not related to recoarctation alone.
authors.affiliation: Division of Cardiovascular Surgery, The Labatt Family Heart Centre, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Christoph
authors.initials: C
authors.lastname: Haller
authors.affiliation: Division of Cardiovascular Surgery, The Labatt Family Heart Centre, Department of Surgery, University of Toronto, Toronto, Ontario, Canada; Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Devin
authors.initials: D
authors.lastname: Chetan
authors.affiliation: Division of Cardiovascular Surgery, The Labatt Family Heart Centre, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Arezou
authors.initials: A
authors.lastname: Saedi
authors.affiliation: Division of Cardiovascular Surgery, The Labatt Family Heart Centre, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Rachel
authors.initials: R
authors.lastname: Parker
authors.affiliation: Division of Cardiovascular Surgery, The Labatt Family Heart Centre, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Glen S
authors.initials: GS
authors.lastname: Van Arsdell
authors.affiliation: Division of Cardiovascular Surgery, The Labatt Family Heart Centre, Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Caldarone
authors.affiliation: Division of Cardiovascular Surgery, The Labatt Family Heart Centre, Department of Surgery, University of Toronto, Toronto, Ontario, Canada. Electronic address: osami.honjo@sickkids.ca.
authors.forename: Osami
authors.initials: O
authors.lastname: Honjo
mesh_terms: D001013:Aorta, Thoracic / Q000473:pathology*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D018636:Hypoplastic Left Heart Syndrome / Q000473:pathology* / Q000601:surgery*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D058327:Norwood Procedures; D010166:Palliative Care; D012189:Retrospective Studies; D016896:Treatment Outcome