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OCCASIONAL REVIEW
Twelve instructiveelectrocardiograms for thepaediatricianDarren Hutchinson
Andrew Davis
AbstractPaediatric arrhythmias have diverse presentations and unique features.
Arrhythmia diagnosis depends on knowing the possibilities, examining
the relationship between the P waves and QRS complexes and pattern
recognition. Ten clinical cases together with a dozen instructive electro-
cardiograms are presented to highlight important principles that all
paediatricians should be aware of.
Keywords Belhassen tachycardia; Long QT Syndrome; Paediatric
arrhythmia; Paediatric electrocardiography; Supraventricular tachycardia;
Wolff Parkinson White syndrome
Case 1
Syncope
A 10-year-old boy was brought to the Emergency Department
after fainting whilst sprinting at school. He had been previously
well. The episode was brief and he was immediately alert after
the event. His ECG is shown in Figure 1. His corrected QT
interval is significantly prolonged and after exclusion of
myocardial and electrolyte abnormalities, is diagnostic of Long
QT syndrome. He subsequently proved to have a mutation in
KCNQ1 (Long QT 1).
Long QT syndrome is an important cause of syncope and
sudden death in childhood as the individual is prone to
‘Torsades de Pointes’, a form of ventricular tachycardia which
may deteriorate to ventricular fibrillation. Most long QT
syndromes are caused by mutations in genes that encode the
ion channels of the myocyte. The QT measurement is taken
from the beginning of the q wave to end of the T wave. The end
of the T wave can be determined by drawing a tangent from the
steepest part of the T wave to the baseline. The QT interval is
corrected (QTc) for heart rate by using Bazett’s formula: QTc ¼QT/square root of previous RR interval (both in seconds). The
QTc is normally distributed in the normal population and this
Darren Hutchinson MBBS is in the Department of Cardiology, Royal
Children’s Hospital, Melbourne, Victoria, Australia. Conflict of interests:
none.
Andrew Davis MBBS MD FRACP FCSANZ FHRS is a Department of Cardiology,
Royal Children’s Hospital and Department of Paediatrics, Melbourne,
Victoria, Australia. Conflict of interests: none.
PAEDIATRICS AND CHILD HEALTH 20:12 577
distribution overlaps substantially with the QTc values of the
afflicted population.
Syncope during physical activity is an important ‘warning
bell’ symptom that requires cardiac assessment. In those with
borderline measurements examining the QTc in the recovery
phase of exercise can assist greatly in making the diagnosis. It is
important to make the diagnosis because the untreated mortality
in prolonged QT syndrome after the first syncope is high.
However for most patients, with simple treatments (especially
beta blockade), the outlook is good. After the diagnosis is made,
comprehensive screening of the family including anyone who
may be afflicted is obligatory.
Case 2
Palpitations and dizzy episodes
A 10-year-old girl presents after a 10-min episode of sudden
onset, sudden offset palpitations associated with dizziness and
chest discomfort. Her ECG is shown in Figure 2a. She has Wolff
Parkinson White Syndrome. Figure 2b, from a different patient
has the same diagnosis but the findings are considerably more
subtle and could be missed with a cursory examination of the
ECG.
Case 3
Collapse
A 15-year-old previously well girl collapsed a school whilst
playing sport. She was taken to her local Emergency Department.
She was drowsy, pale and diaphoretic. Her pulse was thready,
fast and irregular.
Her 12-lead ECG is shown in Figure 3. She had an irregular
wide complex tachycardia. The patient was anaesthetised and
a synchronized biphasic DC shock cardioverted her to sinus
rhythm. A repeat 12-lead ECG revealed a short PR interval and
pre-excitation consistent with Wolff Parkinson White syndrome.
Her presenting ECG shows rapid and irregular conduction of
atrial fibrillation down her accessory pathway.
Wolff Parkinson White syndrome results from eccentric
activation of the ventricle via an accessory atrioventricular
connection. This results in the pre-excitation pattern seen in
sinus rhythm. The pathway is the substrate for supraventric-
ular tachycardia that usually travels down the AV node and
retrograde up the accessory pathway causing symptoms as in
case 2.
Rarely, but importantly, supraventricular tachycardia may
beget atrial fibrillation as in case 3. A small percentage of path-
ways can conduct atrial fibrillation very rapidly which can lead
to ventricular fibrillation and sudden death. The presence of
subtle pre-excitation as in Figure 2b does not preclude the
pathway being dangerous. Assessment by or in conjunction with
a paediatric electrophysiologist is warranted. Ablation is usually
indicated in symptomatic children, once they have reached an
appropriate size. Anti-arrhythmic drugs are used in the interim.
Controversy remains regarding the management of children who
have incidentally been found to have pre-excitation. Sudden and
definitive loss of pre-excitation on exercise testing usually
implies the pathway is unlikely to be dangerous. Electrophysi-
ology study can, to an extent, risk stratify those patients with
rapidly conduction accessory pathways.
Crown Copyright � 2010 Published by Elsevier Ltd. All rights reserved.
Figure 2 a The ECG shows sinus rhythm with pre-excitation. The PR interval is short with delta waves, a widened QRS complex and abnormal repolar-
ization consistent with Wolff Parkinson White Syndrome. b This ECG also shows pre-excitation but its presence is much more subtle. A good clue to the
presence of pre-excitation is the absence of a q wave in lead V6 or V7. The normal septal q wave is a manifestation of normal septal activation from left to
right, which may be perturbed when pre-excitation is present.
Figure 1 The ECG shows sinus rhythm with a prolonged QT interval. The corrected QT interval in lead II is 0.53 s.
OCCASIONAL REVIEW
PAEDIATRICS AND CHILD HEALTH 20:12 578 Crown Copyright � 2010 Published by Elsevier Ltd. All rights reserved.
Figure 3 Irregular wide complex tachycardia from extremely rapidly conducted pre-excited atrial fibrillation in a child with WPW syndrome. The differential
diagnosis includes ventricular tachycardia.
OCCASIONAL REVIEW
Case 4
Unwell neonate
A 2-week girl presented to the emergency department pale,
breathless and refusing feeds. A tachycardia was noted
(Figure 4). She has supraventricular tachycardia with obvious
retrograde P waves. Adenosine was administered converting the
babe to sinus rhythm. No pre-excitation was present.
The ECG is consistent with supraventricular tachycardia.
The mechanism is the same as in Wolff Parkinson White
syndrome however the pathway in this case was only unidi-
rectional and does not conduct downwards in sinus rhythm, so
the interval ECG was normal. The likelihood of recurrence is
high; many patients are successfully treated with beta-blockers
with more complex anti-arrhythmic medications usually
reserved for treatment failures. There is a good chance of
spontaneous cure.
Figure 4 Regular narrow complex tachycardia with clearly seen retrograde P w
PAEDIATRICS AND CHILD HEALTH 20:12 579
Case 5
Screening ECG
A 4-day-old infant with Trisomy 21 had a screening ECG per-
formed (Figure 5). The automated report read: ‘Sinus rhythm.
Right axis deviation. Consider anterior ischaemia. Abnormal
ECG’. The ECG however is normal for age.
The ECG of the newborn is very different to that of an adult in
a number of ways and will progressively change from newborn
to childhood to adolescence and then adulthood. Automated ECG
reports may not have paediatric algorithms or the algorithm is
not used if the date of birth is not entered; the ECG is then
reported as if the patient is an adult resulting in confusion. The
average heart rate of a newborn infant is approximately 125 bpm.
This will peak at around 1e2months of age when the average
heart rate is approximately 150 bpm. The overall vector of the
QRS complex in the frontal plane is much more rightward in the
aves.
Crown Copyright � 2010 Published by Elsevier Ltd. All rights reserved.
Figure 5 Normal ECG for a day 4 newborn.
Figure 6 Atrial ectopic tachycardia with Wenckebach atrioventricular conduction. The P waves have an abnormal morphology. Arrows indicate P waves.
Figure 7 Long RP tachycardia with inverted P wave inferiorly. Chest lead Voltages are large consistent with biventricular hypertrophy. Diagnosis was the
persistent form of junctional reentry tachycardia (‘PJRT’).
OCCASIONAL REVIEW
PAEDIATRICS AND CHILD HEALTH 20:12 580 Crown Copyright � 2010 Published by Elsevier Ltd. All rights reserved.
OCCASIONAL REVIEW
newborn. This is normal for age and should not be described as
right axis deviation. The mean QRS vector in a newborn infant is
approximately þ135 degrees. This compares to þ60 degrees in
a 15-year-old.
T wave evolution throughout childhood is important. It is
normal for an infant to have inverted T waves in the right pre-
cordium after the first week of life. The inverted T waves may
progress throughout childhood with T inversion from V1 up to
Figure 8 a Ventricular tachycardia followed by probable sinus rhythm with first
some premature beats. b Sinus rhythm, right axis deviation and a wide QRS co
QRS complex has a ‘Brugada’ like morphology.
PAEDIATRICS AND CHILD HEALTH 20:12 581
V4 being accepted as normal. There is progressive change from
inverted to upright T waves across the precordial leads from left
to right with growth. In the majority of children, all T waves in
the precordial leads will be upright by 8 years of age excluding
V1. Persistence of an inverted T wave in lead V1 until late teens
in common. Importantly an upright T wave in V1 prior to 8 years
and after 8 days of age likely indicates right ventricular
hypertrophy.
degree atrioventricular block, with a right bundle branch block pattern and
mplex that is alternating every second beat. In lead V1 the first and third
Crown Copyright � 2010 Published by Elsevier Ltd. All rights reserved.
OCCASIONAL REVIEW
Whilst ECG screening for congenital heart disease in Trisomy
21 is highly specific it is not sensitive enough to be of value and
echocardiography is indicated in all infants with Trisomy 21
because of the high incidence of associated congenital heart
disease.
Case 6
Lethargy and malaise
A 6-year-old boy sees a paediatrician for lethargy and malaise
and a baseline tachycardia with irregularity is noted. An ECG is
performed (Figure 6).
Atrial ectopic tachycardia (also called focal atrial tachycardia)
originates in the either atrium from a focus other than the sinus
node. The P waves usually have an abnormal axis. The tachy-
cardia has an ‘automatic’ basis and often has wide variation in
rate (‘warm up’ e ‘cool down’). There may be varying degrees of
atrioventricular block. The essential feature of Wenckebach
conduction is that the pre-block PR interval is longer than the
post block PR interval as above. Sometimes the incessant
tachycardia ‘tires’ the heart and causes a tachycardia-induced
cardiomyopathy, which usually resolves with control of the
arrhythmia. Children less than 3 years of age usually respond
well to anti-arrhythmic therapy with a good chance of resolution,
whereas those greater than three are less likely to resolve. Atrial
ectopic tachycardia is amenable to catheter ablation.
Case 7
Shortness of breath
A 2-year-old boy came to the emergency Department because of
laboured breathing. He had clinical evidence of cardiac failure
and a baseline tachycardia between 130e150 bpm. His ECG is
shown in Figure 7.
Whilst not diagnostic, this ECG is typical for the so-called
‘permanent form of junctional reciprocating tachycardia’ (‘PJRT’).
ThePwaveshaveanabnormalaxisandare inverted in leads II, III and
Figure 9 Complete atrioventricular block. The atrial rate is 125/min. The ventr
a ventricular, rather than a junctional escape mechanism.
PAEDIATRICS AND CHILD HEALTH 20:12 582
aVF. The differential diagnosis is atrial ectopic tachycardia arising
from the low right atrium. The distinction can sometimes bemade on
Holter monitoring or may require electrophysiology study. The
tachycardia involves retrograde conduction from the ventricles via
a slowly conducting accessory pathway usually located near the
mouth of the coronary sinus. This makes the R to P interval long.
The retrograde P wave is then conducted down the AV node to the
ventricle and the cycle can commence again. The label ‘PJRT’ is
amisnomerbecause theoriginal predictedmechanismwas incorrect.
As ‘PJRT’ is often incessant the result can be a tachycardia-induced
cardiomyopathy. ‘PJRT’ is difficult to treat with anti-arrhythmic
medication but may resolve spontaneously. It can be cured with
ablation of the pathway. After rate control or ablation ventricular
function can usually be expected to return to normal.
Case 8
Seizure
A 3-year-old girl was taken to a local hospital via ambulance after
a seizure at home. There was no significant past history and no
known history of drug ingestion. She was lapsing in and out of
consciousness. Her presenting ECG is shown in Figure 8a. It
shows ventricular tachycardia and then probable sinus rhythm
with first degree atrioventricular block, a broad QRS complex with
a right bundle branch block pattern and some premature beats.
After intubation a second ECG was obtained (Figure 8b). It
shows sinus rhythm, right axis deviation and a wide QRS complex
that is alternating every second beat. In lead V1 the first and third
QRS complex has a ‘Brugada’ like morphology with ST elevation.
Brugada syndrome is a genetic condition that can predispose
to life threatening ventricular arrhythmias. Typically there is
a right bundle branch pattern in the anterior precordial leads
together with ST elevation. This pattern may be only present
intermittently. Differential diagnosis of this pattern includes
pericarditis, myocardial ischaemia or infarction, mediastinal
tumour, arrhythmogenic right ventricular dysplasia and over-
dose of tricyclic antidepressants. Close questioning of the family
icular escape rate is 50/min. The QRS complex is wide; indicating
Crown Copyright � 2010 Published by Elsevier Ltd. All rights reserved.
Figure 10 Belhassen’s ventricular tachycardia. Wide complex (but relatively narrow) tachycardia with a leftward axis and a right bundle branch block.
Arrows on lead V3 indicate P waves. There is ventriculo-atrial dissociation with the ventricular rate being faster than the atrial rate. Arrows show P waves.
OCCASIONAL REVIEW
revealed her grandmother who lived in the house was taking
tricyclic antidepressants and drug screen revealed a high blood
level of the same. After a period of intensive care she made an
uneventful recovery.
Case 9
Incidental bradycardia
A5-year-old boywho is admitted to hospital after fracturing his arm
after a fall from his bike. Routine observations note heart rate of
approximately50bpm.Observationsareotherwisenormal.AnECG
was performed showing complete atrioventricular block (Figure 9).
In retrospect his parents commented that he is more tired of an
evening than his brothers and that he sleeps poorly. His asymp-
tomatic mother was positive for anti-Ro/SSA antibodies and it was
presumed he had undiagnosed congenital atrioventricular block.
Congenital heart block is most commonly associated with
lupus maternal antibodies, especially anti-Ro/SSA or anti-La/
SSB, which can cross the placenta. Other causes of later pre-
senting congenital heart block include structural heart defects,
especially congenitally corrected transposition of the great
arteries. Detailed, evidence based indications for pacing are
published and include for paediatric atrioventricular block;
symptomatic bradycardia, wide complex escape rhythm, long QT
interval and ventricular rate in an infant less than 55 bpm. It is
now widely accepted that all patients with congenital heart block
should be paced by their teenage years.
Case 10
Palpitations and pre-syncope
A 9-year-old boy had sudden onset of palpitations and pre-
syncope whilst sitting in math class. He was transferred to the
PAEDIATRICS AND CHILD HEALTH 20:12 583
closest Emergency Department. His ECG is shown in Figure 10.
The diagnosis of supraventricular tachycardia was made,
however adenosine was given but failed to revert him to sinus
rhythm. After the diagnosis was appreciated he was reverted to
sinus rhythm using intravenous verapamil.
Belhassen’s ventricular tachycardia is a relatively narrow
complex (but still broad complex), with features that include
a right bundle branch block/left axis deviation morphology and
verapamil sensitivity. As it is relatively narrow complex it is
frequently confused with supraventricular tachycardia. It is also
known as posterior fascicular ventricular tachycardia as its origin
is reentry within that region of the left bundle branch. The
tachycardia is amenable to catheter ablation. A
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