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NICU guideline identifier

ECG - the neonatal electrocardiograph

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  •  AxisReport the rate, rhythm, conduction, p waves, frontal plane axis, QRS complex.
  • Comment on T waves over R chest. Look at QT interval
  • Rate = 1500 / number of little squares or
              = 300 / number of big squares
  • Frontal plane QRS axis

Normal Values

 Click here to open a larger version of the normal values table


P waves
P waves
Peaked (>3mm) = RA hypertrophy
Broad or biphasic = LA hypertrophy
Right Ventricular Hypertrophy Pure RV1 >10mm (no SV1)
RV1 >25 (SV1 present)
Upright TV1 after 3 days (RV strain)
Right axis deviation >+180°
Left Ventricular Hypertrophy RV6 >17mm in 1st week (>25mm in 1st month)
SV1 >20mm
SV1 + RV6 >45mm
QV5 or V6 >5mm with tall symmetric T
Asymmetric T inversion = LV strain
ST depression = LV strain 
Biventricular Hypertrophy  Abnormal voltages over R and L chest leads
Prominent mid-precordial voltages
AV Block 
2° Mobitz Type 1 (Wenkebach)
2° Mobitz Type 2

Prolonged P-R interval
Progressive increase in P-R then dropped beat
Dropped beats without P-R prolongation
Complete heart block

Tachycardias  Atrial flutter - atrial rate 300-400, and regular saw-tooth pattern of P waves in LI and LIII.
Ventricular rate depends on degree of A-V block.
Atrial fibrillation (rare in newborn). Often associated with cardiac abnormalities, especialy if LA enlargement.
Atrial tachycardia.
AV re-entry tachycardia.
WPW: Short P-R paroxysmal tachycardias. Wide QRS with Δ wave re-entry through accessory pathway.
AV Nodal re-entry tachycardia
Sinus tachycardia  
Ventricular Tachycardia   >5 ventricular ectopics in rapid succession
Identify independent atrial activity

Regular, broad complex tachycardia
Concordant pattern over chest leads

(Capture, atrial capture beats with narrow complexes
(Fusion, supraventricular beat with ventricular complex) 
Ventricular Fibrillation   
Prolonged Q-T    
Ectopic Beats  Common: 21-31% of healthy preterm and up to 23% of term infants 

Conditions with Specific ECGs

Preterm Infant

  • Shorter QRS duration, shorter PR and QT interval
  • Less RV dominance than term infant at birth

AV Canal

  • QRS -30 to -90°
  • RA enlargement
  • Prolonged PR

Ebstein's Anomaly

  • QRS low voltage or RBBB or ventricular pre-excitation
  • PR prolonged, RA enlargement

Hypoplastic Right Heart

  • Variable.
  • Absent or diminished RV voltages

Transposition of the Great Arteries

  • Often normal

Tricuspid atresia

  • RA hypertrophy
  • Left axis deviation

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Document Control

  • Document type: Clinical Guideline
  • Services responsible: Neonatology, Paediatric Cardiology
  • Owner: Newborn Services Clinical Practice Committee
  • Editor: Sarah Bellhouse