Some aspects of pediatric ECGs are different from adult ECGs

  Commenting on pediatric ECG should be done according to the patient's age.

  The leads V3R, V4R and V7 may provide additional information in children.

  For pediatric ECGs

            - minimum bandwidth cutoff should be 150 Hz.

            - minimum sampling rate should be 500 Hz.

  Until 31st week of intrauterine life, the left ventricle is more dominant.

      The more premature is the newborn, the less dominant is the right ventricle.

      After 31st week of intrauterine life, the right ventricle becomes more dominant.

      Rapid decrease of pulmonary vascular resistance after birth starts to reverse

      the right ventricular dominance.

      After the 1st month of life, the left ventricle becomes more dominant.

  The ECG intervals of normal children reach adult values at the age of
7 years.



Heart rate

  Heart rate increases from birth to the end of the 1st month; then it starts to decrease again.

  Since they have a high resting heart rate, sinus arrhythmia is rarely seen in NEWBORNs.

  Sinus arrhythmia is more common in children and adolescents.

  In the awake state, the normal range of heart rate in children is

            91-166 /minute in the first week of NEWBORNs.

            107-180 /minute at the end of the first month.

            89-151 /minute at the end of the first year.

  In an agitated or crying newborn, the heart rate may increase up to 220/minute.

  A heart rate
above 220/minute is always abnormal.



P wave

  During sinus rhythm, the P wave must be positive in leads I, II and aVF.

  Right atrial abnormality is present if the P wave amplitude in lead II is

           
> 3 mm in the first 6 months of life

           
> 2.5 mm after the 6th month of life.

  Normal P wave axis in children is
between 0 and 90 degrees.

  The P wave may be biphasic in lead V1 (C1).




PR interval

  The PR interval is best measured at lead II.

  The PR interval increases with the age.

  The PR interval shortens as the heart rate increases.

  Normally the PR interval of a NEWBORN is
between 70 and 140 msec (average 100 msec).



QRS complex

  The normal range for QRS axis in the NEWBORN is 55-200 degrees.

  At the end of the first month, it decreases to
< 160 degrees.

  At the end of the first year, the QRS axis becomes similar to that of the adults.

  In normal NEWBORNs, the QRS width should be
< 80 msec.

  As the age advances, the width of the QRS also increases.




Q wave

  In normal children, small q waves (septal q) may be seen in leads V5 and V6.

  In normal NEWBORNs,

            Q waves with depths of 0.55 mV (
5mm) in lead III,

            and 0.33 mV (
3 mm) in lead aVF may be seen.

  In normal childrenh the width of such Q waves should be
< 20 msec.

  Observation of deep and wide Q waves in leads I and aVL should raise

      the suspicion of anomalous origin of left coronary artery from the pulmonary artery.




R wave

  In NEWBORNs, a prominent R wave may be seen in right precordial leads.

  In NEWBORNs, the amplitude of a normal R wave in lead V1 may even be 26 mm.

  In diagnosing right ventricular hypertrophy in NEWBORNs

     
the R/S ratio in lead V1 is not always sufficient.

      In newborns and infants, close proximity of the heart to the prercordial electrodes

      affects the R/S ratio in lead V1.

  In NEWBORNs, the R wave amplitude in lead V6 is too low. It increases until adulthood.




QT interval

  QT interval is the interval from the beginning of the QRS complex to the end of the T wave.

  Since the heart rate in children is high, the P wave may superimpose on the preceeding T wave

      and may obscure the point where the T wave intersects the isoelectric baseline.

      In this case,
the end of the T wave should be extrapolated by drawing a tangent

      to the downslope of the T wave and considering its intersection with the isoelectric line
.

  QT interval should be corrected according to the heart rate.

      The most common method for this purpose is
the Bazett's formula.

  Bazett's formula may not be correct if the heart rate is too low or too high.

  Inclusion of the U wave is controversial.

 
The lead with the longest QT interval should be chosen.

 
In the presence of sinus arrhythmia, the shortest RR interval should be chosen

      for QT interval measurement.

  In normal children corrected QT interval should be
< 440 msec.

  In children, a corrected QT interval
> 460 msec is considered as abnormal.



T wave

  The T wave in right precordial leads may be positive during the first week of a NEWBORN.

      Afterwards, it becomes negative and usually
stays negative untill 7 years of age.

  If negativity of the T wave in right precordial leads persist into adolescence,

      it is called as
persistant juvenile T pattern.

  In the first 7 years of life (except the first week of life), the presence of
positive T waves

      in right precordial leads
(V1 to V3) suggest the presence of right ventricular hypertrophy.



References

  Chou's Electrocardiography in Clinical Practice.

      Adult and Pediatric. 5th ed. Philadelphia. WB Saunders. 2001.

  Journal of Electrocardiology 2010;43:524-529.

  American Journal of Emergency Medicine 2008;26:221-228

  European Heart Journal 2002;23:1329-1344.

  Am J Cardiol 1995;75:71.

  Circulation 1990;81:730-739.