title: Comparison of invasive and non-invasive pressure gradients in aortic arch obstruction.
abstract: BACKGROUND
  Aortic arch obstruction can be evaluated by catheter peak-to-peak gradient or by Doppler peak instantaneous pressure gradient. Previous studies have shown moderate correlation in discrete coarctation, but few have assessed correlation in patients with more complex aortic reconstruction.
  
  
  METHODS
  We carried out retrospective comparison of cardiac catheterisations and pre- and post-catheterisation echocardiograms in 60 patients with native/recurrent coarctation or aortic reconstruction. Aortic arch obstruction was defined as peak-to-peak gradient ⩾25 mmHg in patients with native/recurrent coarctation and ⩾10 mmHg in aortic reconstruction.
  
  
  RESULTS
  Diastolic continuation of flow was not associated with aortic arch obstruction in either group. Doppler peak instantaneous pressure gradient, with and without the expanded Bernoulli equation, weakly correlated with peak-to-peak gradient even in patients with a normal cardiac index (r=0.36, p=0.016, and r=0.49, p=0.001, respectively). Receiver operating characteristic curve analysis identified an area under the curve of 0.61 for patients with all types of obstruction, with a cut-off point of 45 mmHg correctly classifying 64% of patients with arch obstruction (sensitivity 39%, specificity 89%). In patients with aortic arch reconstruction who had a cardiac index ⩾3 L/min/m², a cut-off point of 23 mmHg correctly classified 69% of patients (71% sensitivity, 50% specificity) with an area under the curve of 0.82.
  
  
  CONCLUSIONS
  The non-invasive assessment of aortic obstruction remains challenging. The greatest correlation of Doppler indices was noted in patients with aortic reconstruction and a normal cardiac index.
authors.affiliation: 1Department of Pediatrics,Division of Pediatric Cardiology,Seattle Children's Hospital,Seattle,Washington,United States of America.
authors.forename: Bethany L
authors.initials: BL
authors.lastname: Wisotzkey
authors.affiliation: 2Department of Pediatrics,Division of Pediatric Cardiology,Duke University Medical Center,Durham,North Carolina,United States of America.
authors.forename: Christoph P
authors.initials: CP
authors.lastname: Hornik
authors.affiliation: 3Department of Pediatrics,Division of Pediatric Cardiology,Miami Children's Hospital,Miami,Florida,United States of America.
authors.forename: Amanda S
authors.initials: AS
authors.lastname: Green
authors.affiliation: 2Department of Pediatrics,Division of Pediatric Cardiology,Duke University Medical Center,Durham,North Carolina,United States of America.
authors.forename: Piers C A
authors.initials: PC
authors.lastname: Barker
mesh_terms: D001013:Aorta, Thoracic / Q000601:surgery*; D001017:Aortic Coarctation / Q000000981:diagnostic imaging* / Q000601:surgery*; D062186:Arterial Pressure; D006328:Cardiac Catheterization; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014656:Vascular Surgical Procedures
keywords: Arch reconstruction; Doppler; coarctation; pressure gradient