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The corrected QT interval in 24 h ECGs in neonates
Thomas Krasemann1, Katrin Bente, Gerhard Burkhardtsmaier
1Department of Paediatric Cardiology, Evelina Children's Hospital, Guy's and St. Thomas' NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK. Thomas.Krasemann@gstt.nhs.uk
Insights
The corrected QT interval (QTc) in neonates may differ between awake and sleep states, particularly in specific ECG lead positions. This study provides guide values for neonatal QTc during different states.
Area of Science:
- Neonatal cardiology
- Electrocardiography
- Sudden infant death syndrome
Background:
- Prolonged corrected QT interval (QTc) in neonates is a suspected risk factor for sudden infant death.
- Previous studies did not differentiate between awake and sleeping neonates.
Purpose of the Study:
- To investigate differences in QTc between awake and sleeping neonates.
- To establish reference values for neonatal QTc in 24-hour ECG recordings.
Main Methods:
- Ambulatory ECG was performed on 100 neonates (age 2-11 days).
- QT interval was continuously measured in three leads, with QTc calculated using Bazett's formula.
- QTc values during sleep were compared to those during wake periods.
Main Results:
- Heart rate was significantly higher in awake neonates and in female neonates when awake.
- No significant QTc difference was found between awake and sleep states in leads 1 and 3.
- A statistically significant difference in QTc was observed in lead 2.
Conclusions:
- Neonatal QTc variations in ambulatory ECGs are lead-position dependent.
- Significant QTc changes between awake and sleep states were identified in one specific lead.
- Reference values for awake and sleeping neonates are provided.
Background:
A prolongation of the corrected QT interval (QTc) in the routine ECG of otherwise healthy neonates has been suspected to be a risk factor for sudden infant death. None of the studies published so far differentiated between awake and sleeping neonates.
Objective:
This study was designed to find possible differences of the QTc when neonates were asleep or awake, and to provide guide values for neonatal QTc in 24-h ECGs.
Methods:
Hundred neonates (51 male, 49 female, age 2-11 days) underwent ambulatory ECG with defined lead positions. The QT interval was measured constantly in three different leads, and the corrected QT interval was calculated using Bazett's formula. We compared the QTc obtained during sleep with the QTc obtained from wake periods.
Results:
The heart rate was significantly higher when the neonates were awake, and when awake higher in girls than in boys. While there was no statistically significant difference between the QTc when the babies were awake or asleep in leads 1 and 3, this reached the level of mathematical significance in the most cranio-caudal lead 2.
Conclusion:
Changes of the corrected QT interval in neonates seems to be dependent on the lead position of ambulatory ECGs, and could be found only in one lead. Guide values for the sleeping and awake neonate are provided.
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