The Neonatal Electrocardiograph

 

Reviewed by David Knight and Clare O'Donnell
October
1998
Clinical Guidelines Back Newborn Services Home Page
Normal Values Interpretation Conditions with Specific ECGs

 

 
  • Report 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

Age

Ht Rate

/min

QRS vector

o

PR interval

sec

QIII

mm

QV6

mm

RV1

mm

SV1

mm

RSV1

sec

RV6

mm

SV6

mm

R/S V6

sec

SV1+ RV6

mm

R + S V4

mm 

<1
day

93-154
(123)

+59 to -163
(137)

0.08-.16 (0.11)

4.5

2

5-26
(14)

0-23
(8)

0.1- ?
(2.2)

0-11
(4)

0-9.5
(3)

0.1 - ?
(2.0)

28

52.5

1-2
days

91-159
(123)

+64 to -161
(134)

0.08-.14
(0.11)

6.5

2.5

5-27
(14)

0-21
(9)

0.1 - ?
(2.0)

0-12
(4.5)

0-9.5
(3)

0.1 - ?
(2.5)

29

52

3-6
days

91-166
(129)

+77 to -163
(132)

0.07-.14
(0.10)

5.5

3

3-24
(13)

0-17
(7)

0.2 - ?
(2.7)

0.5-12
(5)

0-10
(3.5)

0.1 -?
(2.2)

24.5

49

1-3
weeks

107-182
(148)

+65 to -161
(110)

0.07-.14
(0.01)

6

3

3-21
(11)

0-11
(4)

1.0- ?
(2.9)

2.5-16.5
(7.5)

0-10
(3.5)

0.1 - ?
(3.3)

21

49

(mean), ? = undefined

Interpretation

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

Prolonged P-R interval
2° Mobitz Type 1 (Wenkebach) Progressive increase in P-R then dropped beat
2° Mobitz Type 2 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
Direct
Indirect (Capture, atrial capture beats with narrow complexes
(Fusion, supraventricular beat with ventricular complex)
Regular, broad complex tachycardia
Concordant pattern over chest leads

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