title: Authors' reply.
authors.affiliation: Department of Pediatric Cardiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Wittlieb-Weber
authors.affiliation: Department of Pediatric Cardiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Meryl S
authors.initials: MS
authors.lastname: Cohen
authors.affiliation: Department of Pediatric Cardiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Michael G
authors.initials: MG
authors.lastname: McBride
authors.affiliation: Department of Pediatric Cardiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Paridon
authors.affiliation: Department of Pediatric Cardiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Paul
authors.initials: P
authors.lastname: Stephens
mesh_terms: D000293:Adolescent / Q000502:physiology*; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging*; D003951:Diagnostic Errors / Q000517:prevention & control*; D015150:Echocardiography, Doppler / Q000379:methods*; D005080:Exercise Test; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging*