title: Echocardiographic definition and surgical decision-making in unbalanced atrioventricular septal defect: a Congenital Heart Surgeons' Society multiinstitutional study.
abstract: BACKGROUND
  Although identification of unbalanced atrioventricular septal defect (AVSD) is obvious when extreme, exact criteria to define the limits of unbalanced are not available. We sought to validate an atrioventricular valve index (AVVI) (left atrioventricular valve area/total atrioventricular valve area, centimeters squared) as a discriminator of balanced and unbalanced forms of complete AVSD and to characterize the association of AVVI with surgical strategies and outcomes.
  
  
  RESULTS
  Diagnostic echocardiograms and hospital records of 356 infants with complete AVSD at 4 Congenital Heart Surgeons' Society (CHSS) institutions (2000-2006) were reviewed and AVVI measured (n=315). Patients were classified as unbalanced if AVVI≤0.4 (right dominant) or ≥0.6 (left dominant). Surgical strategy and outcomes were examined across the range of AVVI. Competing risks analysis until the time of commitment to a surgical strategy examined 4 end states: biventricular repair (BVR), univentricular repair (UVR), pulmonary artery banding (PAB), and death before surgery. A prediction nomogram for surgical strategy based on AVVI was developed. The majority of patients had balanced AVSD (0.4<AVVI<0.6) and underwent BVR. Patients with AVVI<0.19 uniformly underwent UVR. Heterogeneous repair strategies were found when 0.19≤AVVI≤0.39 (UVR and BVR), with a disproportionate number of deaths in this range. AVVI≥0.6 (left dominant) was less common. The proportion of subjects predicted for the end states at 12 months after diagnosis are: BVR, 86%; UVR, 7%; PAB, 1%; death without surgery, 1%; alive without surgery, 5%.
  
  
  CONCLUSIONS
  AVVI effectively characterizes the transition between balanced and unbalanced AVSD with important correlation to anatomic substrate and selected surgical strategy.
authors.affiliation: Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, ON, Canada. anusha.jegatheeswaran@utoronto.ca
authors.forename: Anusha
authors.initials: A
authors.lastname: Jegatheeswaran
authors.forename: Christian
authors.initials: C
authors.lastname: Pizarro
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Caldarone
authors.forename: Meryl S
authors.initials: MS
authors.lastname: Cohen
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Baffa
authors.forename: David B
authors.initials: DB
authors.lastname: Gremmels
authors.forename: Luc
authors.initials: L
authors.lastname: Mertens
authors.forename: Victor O
authors.initials: VO
authors.lastname: Morell
authors.forename: William G
authors.initials: WG
authors.lastname: Williams
authors.forename: Eugene H
authors.initials: EH
authors.lastname: Blackstone
authors.forename: Brian W
authors.initials: BW
authors.lastname: McCrindle
authors.forename: David M
authors.initials: DM
authors.lastname: Overman
mesh_terms: D018572:Disease-Free Survival; D004452:Echocardiography; D005260:Female; D006345:Heart Septal Defects, Ventricular / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000401:mortality / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012955:Societies, Medical; D015996:Survival Rate; D013903:Thoracic Surgery; D014481:United States