THE PAEDIATRIC ECG
The Heart of Louis XVII, Abbey of St Denis, Paris.
This is the heart of the ten year old Louis XVII of France who was torn from his mother’s arms and died in tragic circumstances at the hands of the French revolutionaries in 1795. It rests in a crystal urn in the abbey of St. Denis in Paris. Was, however, the disease riddled little boy who died in 1795 after years of abuse and solitude in a prison cell, really the son of Louis XVI and Marie Antoinette? Or had royalists managed at the height of the revolution to spirit the young heir from harm after his parents were sent to the guillotine and place an unfortunate substitute boy in his place? This question has intrigued historians for 200 years.
In 2000 the Belgian Professor of Genetics Jean-Jacques Cassiman was able to isolate mt DNA from the heart and from some hair of Marie Antoinette and her sister. In the words of Deborah Cadbury, “…sunlight streaming through the windows, classical music playing softly as he worked, Cassiman could study the result base by base…using the ghostly imprint of the genetic material of mother and son, united again after 200 years as an electronic signal in a 21st century laboratory computer, together they were able to reveal what really happened…the DNA signatures for the critical region of mt DNA were identical. A 200-year-old mystery had been solved, the Dauphin had indeed died in his cell in 1795 and the heart preserved in the Abbey is indeed that of Louis XVII.
The ECG recording given by the heart in life, however, unlike its mt DNA imprint, would have been different from his mother’s. It is important to recognise that the ECG in children has distinctive differences from that of an adult.
THE PAEDIATRIC ECG
Differences from the adult
●To about the age of 2 years a more predominant Right Ventricular pattern is seen.
●At birth the right ventricular wall is almost as thick as the left ventricular wall (and this is most pronounced within the first 12 months of age).
Points to note
1.There is greater individual variation in normal tracings compared to adults. Therefore there is a need to be more wary of declaring a youthful ECG abnormal.
2.Rhythm:
●The resting rate is relatively faster
●Sinus arrhythmia is more pronounced in children
Sinus arrhythmia in a nine year old boy.
3.Right ventricular dominant pattern:
●Right axis deviation
●Dominant R Waves in right pre-cordial leads.
●Deep S waves in left pre-cordial leads
●AVR may have a dominant R wave in the QRS and AVL may have a dominant S wave in the QRS
Therefore a pattern which appears to be RV hypertrophy will be seen, however in the infant / young child this is perfectly normal.
4.Intervals:
●PR is relatively shorter
●QRS is relatively shorter
●Upper limit of normal QTC is slightly greater in younger age groups:
0.45 in young infants.
0.44 in older infants or children.
0.43 in adolescents and adults.
Table of normal values in paediatric ECGs.
5.T wave Changes
T wave inversion in V1 can be normal in adults, but in children T inversion extends further to the left in the precordium:
●0-3 yrs may extend up to V4.
●By 12 yrs may extend up to V3.
Normal 12 lead ECG of a 4 year old. Note the dominant R wave pattern and inverted T waves in the early V leads. Prominent sinus arrhythmia is also seen.
The Dauphin, (later Louis XVII),black and red chalk and graphite. Elisabeth Louise Vigee Le Brun, sketched on the eve of the Revolution, 1789
References:
1.Goodacre S, McLeod K. Paediatric electrocardiography, BMJ volume 324 8 June 2002, p.1382-1385.
2.Marriott H, Practical Electrocardiography 8th Ed 1988,p.496
Dr J Hayes
Reviewed 5 March 2009