title: Improving left ventricular outflow tract obstruction repair in common atrioventricular canal defects.
abstract: BACKGROUND
  Left ventricular outflow tract obstruction (LVOTO) is the second most frequent reason for reoperation after atrioventricular canal (AVC) defect repair. Limited data are available on the mechanisms of LVOTO, their treatment, and outcomes.
  
  
  METHODS
  Between 1998 and 2010, 56 consecutive children with AVC underwent 68 LVOTO procedures. The AVC was partial in 4, transitional in 9, and complete in 43. The LVOTO procedure was required in 21 patients at the primary AVC repair, and the initial LVOTO procedure in 35 patients was a late reoperation after AVC repair.
  
  
  RESULTS
  During a mean follow-up of 50±41 months, 5 patients (24%) with LVOTO repair at AVC repair required a reoperation for LVOTO, and 7 patients (20%) whose initial LVOTO repair was a reoperation required a second reoperation for LVOTO repair. Overall freedom from LVOTO reoperation was 98.5% at 1 year, 92.5% at 3 years, 81% at 5 years, 72.2% at 7 years, and 52.5% at 10 and 12 years. The freedom from reoperation was neither significantly different between partial, transitional, and complete AVC (p=0.78) nor between timing of the LVOT procedure (p=0.49). Modified single-patch AVC repair was associated with a higher LVOTO reoperation rate (p=0.04). Neither the mechanisms leading to LVOTO nor the surgical techniques used were independent predictors of reoperation.
  
  
  CONCLUSIONS
  LVOTO in AVC is a complex and multifactorial disease. Aggressive surgical repair has improved late outcomes; however, risk factors for reoperation and the ideal approach for repair remain to be defined.
authors.affiliation: Department of Cardiovascular Surgery, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA. patrick.myers@childrens.harvard.edu
authors.forename: Patrick O
authors.initials: PO
authors.lastname: Myers
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: del Nido
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Marx
authors.forename: Sitaram
authors.initials: S
authors.lastname: Emani
authors.forename: John E
authors.initials: JE
authors.lastname: Mayer
authors.forename: Frank A
authors.initials: FA
authors.lastname: Pigula
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Baird
mesh_terms: D000293:Adolescent; D006348:Cardiac Surgical Procedures; D002648:Child; D002675:Child, Preschool; D006343:Heart Septal Defects; D006801:Humans; D007223:Infant; D008944:Mitral Valve Insufficiency / Q000150:complications* / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014694:Ventricular Outflow Obstruction / Q000209:etiology* / Q000601:surgery*