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ECG library

The normal newborn

intro6 days old· newborn

A 6-day-old, feeding well, examined for a soft murmur. The ECG is part of the work-up.

25 mm/s · 10 mm/mV · synthetic tracing
100%
IIIIIIaVRaVLaVFV1V2V3V4V5V6
II (rhythm)
Calipers:2000 ms50.0 small boxes30 bpm if R-RDrag the orange markers. One small box = 40 ms.

Key findings

  • Rate 138, normal for age
  • Short PR and QRS, normal for the size of the heart
  • Right-sided dominance is the newborn norm, described here

Learning points

  • Read every pediatric interval against the age band: PR, QRS and QT all lengthen with age as the heart grows.
  • The newborn is a right-ventricular animal: rightward axis and a tall R in V1 are physiology, not hypertrophy.
  • The T wave in V1 flips to inverted after the first week and stays inverted until adolescence; an upright T in V1 in a 3-year-old is the abnormal finding.

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