Pediatric EKG Basics

Why get an EKG in a child?

There are many reasons to check an EKG:

What is the clinical concern?What would raise this concern?What am I looking for on an EKG?
Rhythm– Clinical hx: Palpitations, syncope, maternal history of SSA/SSB Ab, abnormal prenatal rhythm
Exam: Bradycardia/tachycardia, irregular rhythm
– Ectopy
– Heart block
– Tachycardias (afib)
– Sinus pause
Structural heart disease– Clinical hx: Syncope, exercise intolerance, heart failure symptoms, family h/o congenital heart disease
– Exam: Murmur, abnormal pulses, dysmorphic features/genetic syndrome (e.g., trisomy 21), cyanosis, clubbing
– Ventricular hypertrophy/strain
– Atrial enlargement
– Axis deviation
Ischemia or inflammation– Clinical hx: Chest pain, syncope, heart failure symptoms in children <2yo
– Exam: Pericardial rub
– Q waves in I, aVL (ALCAPA)
– ST/T wave changes
– PR prolongation, new RBBB, conduction changes (myocarditis)
Electrolyte disturbances– Clinical hx: Syncope, dehydration illness, medication use
– Exam: Bradycardia/tachycardia
– T wave changes
– Bradycardia/interval prolongation
Interval monitoring– Clinical hx: Syncope, family h/o long QTc, medication use– QTc prolongation
– QRS prolongation

Normal EKG values

Normal EKG values vary significantly by age. Check out the following table used at Texas Children’s Hospital:

Lead placement

EKG lead positioning depends on the number of electrodes being used to perform the study. Adult EKGs are typically 12-lead studies involving 10 electrodes. Pediatric EKGs are ideally 15-lead studies (including the expanded chest leads V3R, V4R, and V7) involving 13 electrodes:

V4R, the most commonly used expanded chest lead, is used in young children to better demonstrate right ventricular potentials. In a 12-lead protocol pediatric EKG, the operator may substitute V4R in place of V3 but the operator must make note of the substitution on the study itself:

EKG Basics

Always be systematic!

  • Rate
  • Rhythm
  • Axis
  • Intervals
  • Deviations
  • Morphologies

Know your patient’s age and the indication for checking an EKG. And end every EKG analysis with a “don’t miss” list, such as the following:

  • Limb lead reversal (the most common cause of a downward P wave in lead I)
  • WPW
  • 2nd, 3rd, or high-degree heart block
  • New complete RBBB
  • SVT, flutter/IART, atrial fibrillation, atrial tachycardia, junctional tachycardia, VT, VF
  • Definitive ischemia or pericarditis
  • Pacemaker non-capture
  • Brugada pattern

In keeping with the above list of alarm issues, there are several issues that tend to differ between pediatric and adult EKGs to consider:

  • Less concerning in pediatric EKGs (versus adults):
    • Higher heart rates
    • RAD, RVH in children <6 months
    • Q waves in inferior leads and lateral precordial leads
    • Concave STE in V2-V3 in teenagers (sometimes all precordial leads)
  • More concerning in pediatric EKGs (versus adults):
    • Q waves in I and aVL
    • New RBBB and PR prolongation
    • Upright T wave in V1 in ages 1 week to 6yo

What is a normal sinus rhythm?

Normal sinus rhythm requires a few criteria:

  • Normal rate (for age)
  • P wave before every QRS, QRS after every P wave
  • P waves look the same
  • P wave axis must be a sinus P wave axis
    • P wave is upright in I and aVF

Benign early repolarization

Benign early repolarization (sometimes called J-point elevation) is a a relatively common finding in young, healthy patients, and thought to be a normal variant. EKG features include widespread concave ST elevation (often most prominent in V2-V5, notching or slurring at the J point, prominent, and slightly asymmetrical T waves that are concordant with the QRS complex.

  • Interestingly, we don’t really know the cause of benign early repolarization, for which there are depolarization and repolarization theories. A 2013 meta-analysis suggested a possible association with sudden cardiac death, but early repolarization will nearly always be an incidental EKG finding given how common it is (affecting 5-18% of children!)

Calculate QTc by hand!

EKG machines aren’t perfect. Calculating the QTc is complicated by a number of issues, including HR and patient age. EKG machines commonly overestimate the QTc at high HRs and underestimate it at low HR. The QTc is slightly longer in newborns and small infants with ULN 470 in first week of life and 450 in the first 6 months of life.

There are a number of formulas available to calculate the QTc. None are perfect, but the most commonly used formula is likely Bazett’s. The QT is best measured in lead II (commonly the rhythm strip) or V5-V6. The maximum slope intercept method is used to
define the end of the T wave.

Blog post based on Med-Peds Forum talk by Chelsea Boyd, MP Class of 2023 & Pediatric Cardiology Fellow at Baylor College of Medicine / Texas Children’s Hospital

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