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Dynamic QT Interval Changes from Supine to Standing in Healthy Children
Audrey Dionne1, Anne Fournier1, Nagib Dahdah1
1Division of Cardiology, CHU mère-enfant Sainte-Justine, Université de Montréal, Montréal, Québec, Canada.
The Canadian Journal of Cardiology
|December 26, 2017
Summary
A standing test significantly alters corrected QT intervals (QTc) in children, with changes exceeding adult responses. Current adult criteria may misdiagnose long QT syndrome (LQTS) in children, necessitating pediatric-specific standards.
Area of Science:
- Pediatric Cardiology
- Electrophysiology
- Clinical Diagnostics
Background:
- QT-interval variations are crucial for diagnosing long QT syndrome (LQTS) in children and adults.
- A standing challenge test is a proposed alternative provocative test for LQTS in adults, but pediatric data are lacking.
Purpose of the Study:
- To characterize corrected QT (QTc) interval changes in healthy children during a standing challenge test.
- To evaluate the applicability of adult LQTS diagnostic criteria to pediatric populations using standing test data.
Main Methods:
- 100 healthy children underwent a standing test with continuous electrocardiographic monitoring.
- QT intervals were measured at baseline, during standing, and during a 5-minute recovery period.
- Measurements were corrected for heart rate (QTc) and analyzed in leads II/V5.
Main Results:
- Heart rate increased by 29 ± 10 bpm upon standing.
- QTc intervals significantly increased from baseline (426 ± 21 ms) to standing (509 ± 41 ms; P < 0.001).
- QTc intervals returned to baseline within 1 minute of recovery.
Conclusions:
- Standing test elicits substantial QTc alterations in children, greater than those observed in adults.
- Two-thirds of children would be misclassified as having LQTS if adult criteria were applied.
- Development of child-specific QTc standards for the standing test is essential for accurate LQTS diagnosis.
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