title: Dynamic morphology of the secundum atrial septal defect evaluated by three dimensional transoesophageal echocardiography.
abstract: OBJECTIVE
  To define by three dimensional echocardiography the pattern and potential determinants of contraction of a secundum atrial septal defect through the cardiac cycle, and to evaluate the possibility of using cross sectional transthoracic and transoesophageal imaging to assess the dynamic nature of the defect.
  
  
  METHODS
  Three dimensional echocardiography was performed using a multiplane transoesophageal probe on 50 patients with a secundum atrial septal defect (median age 9.8 years). Nine patients were excluded because of poor images or morphological features that precluded defect measurement. In 41 cases, defect area, long and short axis length, and distance of the attenuated anterior rim were measured in their largest and smallest dimensions.
  
  
  RESULTS
  Defect area changed significantly through the cardiac cycle (mean change 61%, p < 0.0001; range 17% to 86%). The defect contracted symmetrically and was not related to patient age, defect size, heart rate, Qp/Qs ratio, the presence of an aneurysmal atrial septum, or attenuated anterior rim. In all cases with an attenuated anterior rim (n = 13), the length of the rim significantly decreased (p = 0. 001) during atrial systole. Dynamic changes measured by either transthoracic or transoesophageal cross sectional images did not correlate with those obtained by three dimensional imaging.
  
  
  CONCLUSIONS
  Three dimensional echocardiography shows dynamic features of defects in the atrial septum. This information may lead to an improved understanding of the pathophysiology of atrial shunting.
authors.affiliation: Division of Cardiology, The Variety Club Cardiac Catheterization Laboratories, The Hospital for Sick Children, the University of Toronto School of Medicine, Toronto, Ontario, Canada.
authors.forename: Y V
authors.initials: YV
authors.lastname: Maeno
authors.forename: L N
authors.initials: LN
authors.lastname: Benson
authors.forename: P R
authors.initials: PR
authors.lastname: McLaughlin
authors.forename: C
authors.initials: C
authors.lastname: Boutin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D019560:Echocardiography, Three-Dimensional; D017548:Echocardiography, Transesophageal; D006344:Heart Septal Defects, Atrial / Q000000981:diagnostic imaging*; D006801:Humans; D008875:Middle Aged; D009200:Myocardial Contraction; D015588:Observer Variation