Pediatric ECGs: What is Normal?

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10/28/24, Written by Esteban Davila MD and reviewed by Eric Tang MD.

Learning Objectives:

Utilize understanding of anatomical changes of the heart from birth to adulthood and apply it to ECG interpretation
Recognize common patterns of normal pediatric ECGs, and differentiate those that fall out of this pattern

Resources

Free:

Good book but $$

A Guide to Neonatal and Pediatric ECGs

Why do I, an Emergency Physician, need to interpret a pediatric ECG? Can’t I just call Pediatric Cardiology?

Do you have one on speed dial? If not, it can be helpful to know how to interpret normal from abnormal.

I’ve never received any training on this, how would I be expected to interpret these?

That’s what we are here for. Thankfully, pediatric ECGs tend to follow particular rules. Those that don’t usually have some underlying abnormality that you can pick out. Let’s dive in. We’ll use a Rate, Rhythm, Axis, Interval approach with associated rules that ECGs should follow, then discuss more specialized topics

Rate

As we know, pediatric patients have a baseline higher heart rate from an increased metabolic rate and decreased influence of vagal tone; don’t need to belabor this point much

Rhythm

These are general tips for all ECG interpretation

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P waves should be small and one wave

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Upright P waves in inferior leads with constant PR interval

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V1 should be biphasic, then upright by V2

Axis

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Some pediatric specific rules need to be explained here first

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Right axis deviation is ok until around 6 months of age

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There should be no extreme axis deviation after 1st week of life

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Left axis deviation is associated with heart disease, but can be found in a normal heart

Intervals

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All interval are generally shorter the younger the patient

PR Interval

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1st degree heart block and Mobitz I can be normal

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Symptomatic or higher grade blocks warrant investigation

QRS Interval

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Bundle Branch Blocks (BBB) are common post Congenital Heart Disease (CHD) surgeries

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If no history of CHD surgery and new BBB, assume pathology

QT Interval

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Measure your own QT interval

Q Waves

A pediatric specific rule

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Q waves should only be in inferior and lateral leads, not deeper than 10 mV

R Wave Progression

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We need to explain some anatomy and physiology of the pediatric heart as well as what ECGs measure to really understand this rule

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Neonatal (0-1 month) → V1 R wave dominant, V6 S wave dominant

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Infant (Birth - 3 years) → V1 R wave dominant, V6 R wave dominant

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Adult (2-3 years and later) → V1 S wave dominant, V6 R wave dominant

T Waves

Think of abnormal T waves as representing some form of increased pressure (strain). To make things easier, only focus on V1-V3 and V6 separately

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Less than 7 days old → V1-V6 expect T waves to be up, but can be anything

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7 days old - 8-10 years → V1-V3 inverted, V6 upright

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8-10 years or older → V1-V3 inverted or upright, V6 upright

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T Wave Inversions are not normal in the limb leads (exception: isolated T Wave Inversion in III and aVR)