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QT and JT dispersion in children with long QT syndrome
M J Shah1, T S Wieand, L A Rhodes
1Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine 19104, USA.
Insights
Children with long QT syndrome exhibit increased QT dispersion (QTd) and JT dispersion (JTd), indicating higher arrhythmia risk. Values of 55 msec or greater strongly correlate with critical ventricular arrhythmias.
Area of Science:
- Pediatric Cardiology
- Electrophysiology
- Genetics
Background:
- Long QT syndrome (LQTS) poses a significant risk of sudden cardiac death in children due to ventricular arrhythmias.
- Cardiac electrical heterogeneity, assessed by QT dispersion (QTd) and JT dispersion (JTd), may help identify high-risk LQTS patients.
Purpose of the Study:
- To compare QTd and JTd in children with LQTS versus healthy controls.
- To determine if QTd and JTd can predict critical ventricular arrhythmias in pediatric LQTS.
Main Methods:
- Retrospective analysis of ECG data from 39 children with LQTS and 50 age-matched healthy children.
- Measurement and comparison of QTd and JTd intervals between the LQTS and control groups.
Main Results:
- Children with LQTS showed significantly increased QTd (81 ± 70 msec) and JTd (80 ± 69 msec) compared to controls (QTd: 28 ± 14 msec; JTd: 25 ± 15 msec).
- A QTd or JTd of ≥ 55 msec was correlated with the presence of critical ventricular arrhythmias.
Conclusions:
- Pediatric LQTS patients have elevated QTd and JTd compared to healthy children.
- ECG-derived QTd and JTd measurements are valuable tools for risk stratification in children with LQTS, identifying those prone to life-threatening arrhythmias.
Introduction:
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).
Methods And 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).
Conclusion:
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.