ECG9

16/12/2008 ECG Diag 9 /ghazi

Principles of ECG Diagnosis9

Pediatric electrocardiography

Dr Ghazi Ahmad RadaidehMD, FRCP

Rashid HospitalDubai - UAE


Reading 12-Lead ECG step-by-step (RAWIHI)

1. Rate, Rhythm and Regularity2. Determine the QRS Axis3. Evaluate the Waves (P,QRS,T ),

Intervals (PR,ST,QT)4. Evaluate for chamber Hypertrophy5. Look for myocardial Infarction and Ischemia6. Interpret the ECG


Introduction The basic principles of cardiac conduction and

depolarisation in infants and children are the same as for adults,

Age related changes in the anatomy and physiology of infants and children produce normal ranges for ECG features that differ from adults and vary with age.

Awareness of these differences is the key to correctinterpretation of pediatric ECG


Indications for paediatric ECG

Syncope or seizure Exertional

symptoms Drug ingestion Tachyarrhythmia Bradyarrhythmia

Cyanotic episodes Heart failure Hypothermia Electrolyte disturbance Kawasaki disease Rheumatic fever Myocarditis Myocardial contusion Pericarditis Post cardiac surgery Congenital heart defects


Paediatric electrocardiographicfindings that may be normal

Heart rate >100 beats/min QRS axis >90 Right precordial T wave inversion Dominant right precordial R waves Short PR and QT intervals Short P wave and short duration of QRS complexes Inferior and lateral Q waves


right axis deviation,

dominant R wave in leads V1,

Right precordial T wave inversion


Age related changes in normal ECG Right and Left Ventricles:

At birth the RV is larger than the LV. the LV increasing in size until it is larger than

the RV by age 1 month. By age 6 months, the ratio of the RV to the LV

is similar to that of an adult.


Age related changes in normal ECG

Age Range 1 wk-1mo +110 (+30 to +180) 1-3mo +70 (+10 to +125) 3mo-3yr +60 (+10 to +110) Older than 3yr +60 (+20 to +120) Adults +50 (-30 to +105

Mean and ranges of Normal QRS AxesThe axis changes gradually from Rt axis to normal


Age related changes in normal ECG The PR interval decreases from birth to age

1 year and then gradually increases throughout childhood.

The P wave duration and the QRS durationincrease with age.

The QT interval depends on heart rate and age, increasing with age while decreasing with heart rate.


P wave amplitude and duration: Mean P amplitude: 1.5mm, max. 3mm. Normal P wave duration: 0.06 0.02s. Max. P wave duration;

< 1 year 0.08sec Child 0.10sec


PR interval varies with age and heart rate

Age Lower limit Upper limit< 3 yr. 0.08sec 0.15 (HR < 100)3 - 16 yr. 0.10sec 0.16 (HR < 100)> 16 yr. 0.12sec 0.18 (HR < 100)


QRS durationAge Range

Premature infants 0.04sec Full term 0.05sec 1 - 3 yr. 0.06sec Child > 3 yr 0.07sec Adult 0.08sec


T wave

The T wave in lead V1 inverts by 7 daysand typically remains inverted until at least age 7 years. Upright T waves in the right precordial leads

(V1 to V3) between ages 7 days and 7 years are a potentially important abnormality and usually indicate RVH.

Upright T waves in V1-V3 are normal in the neonate up to 7 days.


Heart Rate

The resting heart rate decreases with age from about: 140 beats/min at birth to 120 beats/min at age 1 year, to 100 at 5 years, to adult values by 10 years.


Normal values in pediatric ECG

9-26 (0-4)1-12 (3-25)


Prolongation of the QRS complex Wide QRS complex may be due to:

bundle branch block, ventricular hypertrophy, metabolic disturbances, or drugs


Criteria for RVH

A qR complex or an rSR' pattern in lead V1, upright T waves in the right precordial leads

between ages 7 days and 7 years, marked right axis deviation (particularly

associated with right atrial enlargement), complete reversal of the adult precordial pattern

of R and S waves


Criteria for RVH RV1 > 20mm at all ages SV6 > 14mm (0-7days); > 10mm (1wk-6mth);

> 7mm (6mth-1yr); > 5mm (>1yr) R/S V1 6.5 (0-3mth); 4.0 (3-6mth);

2.4 (6mth-3yr); 1.6 (3-5yr); 0.8 (6-15yr) T wave upright in V4R or V1 after 72 hrs. Presence of Q wave in V1


RVH in the newborn S waves in lead I, 12mm R waves in aVR, 8mm Important abnormalities in V1 such as:

Pure R waves (without S) in V1, 10mm R waves in V1, 25mm QR pattern in V1 (also seen in 10% of normal

newborns) Upright T waves in V1 in newborns > 7days old

QRS axis greater than +180


LVH Left ventricular hypertrophy may be indicated

by: deep Q waves in the left precordial leads or the typical adult changes of lateral ST depression and

T wave inversion


Criteria for LVH

SV1 > 20mm RV6 > 20mm > 26mm in older child SV1 + RV6 > 40mm over 1yr of age;

> 30mm if < 1yr Q wave of 4mm or more in V 5-6 T wave inversion in V 5-6


The QT interval Approach to QT interval in children is the same as in

adults except for the fact that it is highly variable inthe first three days of life)

QT prolongation may be seen in association with: hypokalaemia, hypocalcaemia, hypothermia, drug treatment,

cerebral injury, and the congenital long QT syndrome. Other features of the long QT syndrome include:

notching of the T waves, abnormal U waves, relative bradycardia for age, and T wave alternans.


T waves T waves may be inverted OR or biphasic in strain

pattern due to ventricular hypertrophy, T waves may be inverted as a result of myocardial

disease (inflammation, infarction, or contusion). Flat T waves are seen in association with

hypothyroidism. Abnormally tall T waves occur with hyperkalaemia.


Abnormalities of rate and rhythm The wide variation in children's heart rate with age

and activity. Systemic illness must be considered in any child presenting

with an abnormal HR or Rhythm. Sinus tachycardia in babies and infants can result in rates of

up to 240 beats/min, hypoxia, sepsis, acidosis, or intracranial lesions may cause

bradycardia. Sinus arrhythmia is a common feature .

Its relation to breathing slowing on expiration and speeding up oninspiration allows diagnosis.


Electrocardiogram from 9 year old boy

marked sinus arrhythmia


Tachyarrhythmias The approach to ECG diagnosis of

tachyarrhythmias in children follows the same principles as for adults, Most narrow complex tachycardias in children are due to

(AVRT) secondary to an accessory pathway. (AVNRT) is rare in infants but may be seen in later

childhood and adolescence. Atrial flutter and fibrillation are rare in childhood and are

usually associated with underlying structural heart disease or previous cardiac surgery.


Extrasystoles Atrial extrasystoles are very common and

rarely associated with disease Ventricular extrasystoles are also common

and, are almost always benign, in the context of the structurally normal heart Typically, atrial and ventricular extrasystoles

are abolished by exercise


Ventricular Tachycardia Although all forms of ventricular tachycardia are

rare, broad complex tachycardia should be considered to be ventricular tachycardia until proved otherwise. Monomorphic ventricular tachycardia may occur

secondary to surgery for congenital heart disease. Polymorphic ventricular tachycardia, or torsades de

pointes, is associated with the long QT syndrome Bundle branch block (usually right bundle) often

occurs after cardiac surgery, and a previous electrocardiogram can be helpful.


ECG from 6 year old girl with congenital heart block secondary to maternal

antiphospholipid antibodies;

there is complete atrioventriculardissociation, and the ventricular escape rate is about 50 beats/min

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