title: QT and JT dispersion in children with long QT syndrome.
abstract: BACKGROUND
  Abnormalities of ventricular repolarization leading to ventricular arrhythmias place children with long QT syndrome at high risk for sudden death. Dispersion of the QT (QTd) and JT (JTd) intervals, as markers of cardiac electrical heterogeneity, may be helpful in evaluating children with long QT syndrome and identifying a subset of patients at high risk for development of critical ventricular arrhythmias (ventricular tachycardia, torsades de pointes, and/or cardiac arrest).
  
  
  RESULTS
  The QTd and JTd intervals in 39 children with long QT syndrome were compared to those of 50 normal age-matched children. In the long QT syndrome group, QTd measured 81 +/- 70 msec compared to 28 +/- 14 msec in the control group (P < 0.05), and JTd in the long QT syndrome group was 80 +/- 69 msec compared to 25 +/- 15 msec in the control group (P < 0.05).
  
  
  CONCLUSIONS
  Children with long QT syndrome have an increased QTd and JTd when compared to normal controls. A QTd or JTd > or = 55 msec correlates with the presence of critical ventricular arrhythmias. These ECG measures of dispersion can be useful in stratifying children with the long QT syndrome who are at higher risk for developing critical ventricular arrhythmias.
authors.affiliation: Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine 19104, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Shah
authors.forename: T S
authors.initials: TS
authors.lastname: Wieand
authors.forename: L A
authors.initials: LA
authors.lastname: Rhodes
authors.forename: C I
authors.initials: CI
authors.lastname: Berul
authors.forename: V L
authors.initials: VL
authors.lastname: Vetter
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D012189:Retrospective Studies; D012680:Sensitivity and Specificity