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Pediatric ECGs

Introduction to Pediatric ECGs

Thomas R. Burklow, MDAsst C, Pediatric Cardiology

Walter Reed Army Medical Center

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Pediatric ECGs

Electrophysiology and Anatomy

SA Node

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Pediatric ECGs

Mechanics of tracing

Small box = 1 x 1 mm

Large box = 5 x 5 mm

Paper speed (horizontal boxes) Standard = 25 mm/sec

Voltage calibration (vertical boxes)

Standard = 10 mm/mV (2 big boxes) Half standard = 5 mm/mV (1 big box)

May have 10/5: standard for chest leads, half-standard for precordialleads

NOTE THE CALIBRATION!!

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Pediatric ECGs

ECG basics: grid paper

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Basic electrocardiogram

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Pediatric ECGs

Interpretation

Be systematic!!

Rhythm

Rate Axis

Intervals

Atrial enlargement Ventricular hypertrophy

ST/T wave evaluation

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Pediatric ECGs

Rhythm

Sinus rhythm

Subsidiary pacemaker

Tachyarrhythmia

Bradyarrhythmia

Atrioventricular block

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Pediatric ECGs

Normal sinus rhythm

P wave before every QRS

QRS following every P wave

Normal P wave axis

Normal PR interval is NOT required

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Pediatric ECGs

P wave axis

Atrial depolarization occurs from SA node

Wave passes right to left, top to bottom

Positive deflections in leads I (right to left) and aVF(top to bottom)

Normal P wave axis = 0-90 degrees

Abnormal axis implies ectopic pacemaker

Coronary sinus or low right atrial rhythm is commonbenign finding, especially in teens

Positive in lead I, negative in aVF

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Pediatric ECGs

Rate

Measured in beats per minute

60 / RR interval (in seconds)

300 / number of big boxes betweenconsecutive QRS complexes

1500 / number of little boxes between

consecutive QRS complexes

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Pediatric ECGs

Heart rate

Known time interval

Beats in 6 seconds (30 big boxes) x 10

Beats in 3 seconds (15 big boxes) x 20

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Heart rate

Rate approximation

Rate estimate: 300 - 150 - 75 - 60 - 50

Easy to memorize No calculator needed

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Pediatric ECGs

Normal resting heart rates

Newborn: 110 - 150 bpm

2 years: 85 - 125 bpm

4 years: 75 - 115 bpm

> 6 years: 60 - 100 bpm

Adult: 50 - 100 bpm

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Pediatric ECGs

Axis

Hexaxial reference system Bipolar limb leads

I, II, III Augmented unipolar leads

aVR, aVL, aVF

Horizontal reference system Precordial leads

V1 - V7

Right sided leads (e.g. rV3)

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Pediatric ECGs

Reference systems

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Axis determination

Successive approximation Locate quadrant with leads I and aVF

Narrow down by using leads within quadrant

Use most equiphasic lead

Axis is perpendicular to that lead, in the quadrant previouslyidentified

Equal amplitudes If two leads with equal net QRS amplitudes exist, the mean axislies midway between the axis of these two leads

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Pediatric ECGs

Quadrant determination

Normal axis

Left axisBoston

Right axis

Extreme R/L axisSeattle

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Successive approximation

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Axis determination

Amplitude vector

Add net R-S in lead I, R-S in aVF

Plot in mm on grid (lead I horizontal, lead aVFvertical)

Draw vector from origin to net amplitude

Angle of vector = axis

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Pediatric ECGs

Right axis deviation

Axis > 100 degrees

Normal for age: rightward axis > 100

degrees, but within normal limits for age(e.g. 2 week old with axis of +140)

Suggestive of RVH

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Pediatric ECGs

Left axis deviation

Axis < -5 degrees

Q waves in leads I and aVL

Conduction abnormality

Associated with atrioventricular septaldefect

No correlation with LVH

Occurs in 5% of normal population

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Pediatric ECGs

Causes of left axis deviation

Normal variant

AV septal defect (including primum ASD)

Perimembranous inlet VSD Tricuspid atresia

Single ventricle

Double outlet right ventricle Noonan syndrome

Left anterior hemiblock after MI

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Pediatric ECGs

PR Interval

Onset of atrial contraction to onset ofventricular contraction (measures

cumulative time of depolarization throughatria, AV node, and His-Purkinje system)

Varies between leads

Increases with age Decreases with heart rate

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Long PR interval

= First degree AV block

Drugs

Atrial surgery (scar tissue) Acute rheumatic fever (minor Jones criteria)

Kawasaki disease

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Short PR interval

Etiologies

Wolff-Parkinson-White

Glycogen storage disease type IIa (Pompes) Fabry disease

GM1 gangliosidosis

Friedrichs ataxia Duchennes muscular dystrophy

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Pediatric ECGs

QRS Duration

Beginning of Q wave to end of S wave

Use a lead where a Q wave is visible

Normal = 0.04 - 0.08 (may be up to 0.09 inadolescents)

> 0.12 = bundle branch block

0.10-0.12: evaluate morphology

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Pediatric ECGs

RSR Morphology

Seen in right precordial leads: V1, rV3

Common: occurs in 7% of kids

R and R both small and of short duration

S wave larger than R and R

R is less than 10 mm (15 mm in infants)

Abnormal RSR may reflect RBBB or RVH

(volume overload type)

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Pediatric ECGs

QT Interval

Onset of ventricular depolarization (Q wave) to end ofventricular repolarization (T wave)

Do NOT include U waves

Varies inversely with heart rate Best leads: II, V5, V6

QTC (Bazetts formula) = QT/square root RR Normal < 0.44 sec

May be as high as 0.45 sec in adol/adult females

May be as high as 0.49 sec in newborns (to 6 mo.)

QT ruler

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Pediatric ECGs

QT Abnormalities

Short QT

Digoxin

Hypercalcemia

Long QT - Congenital

Jervell-Lange-Nielsen

AR, deafness

Romano-Ward

AD, normal hearing

Long QT - Acquired Metabolic

Hypocalcemia

Hypomagnesemia

Malnutrition (anorexia)

Drugs Ia and III antiarrhythmics

Phenothiazines

TCA

CNS trauma

Myocardial Ischemia

Myocarditis

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Pediatric ECGs

Atrial enlargement

Right atrialenlargement

P wave amplitude >2.5 mm in II

Deep negativedeflection in first 0.04seconds in chest leads

Left atrial enlargement

Terminal portion of Pwave

Negative deflection inV1 beyond 0.04 sec

Duration of negativedeflection > 0.04 sec

Total duration > 0.10sec

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Atrial enlargement

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Right ventricular hypertrophy

Mild

R > 15 mm (< 1 year) or > 10 mm (> 1 year)

Abnormal RSR of normal to slightlyprolonged duration in right chest leads

Moderate

Definite right axis deviation (non-RBBB) rR or pure R in right chest leads

Significant S in left chest leads

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Pediatric ECGs

Right ventricular hypertrophy

Severe

Marked RAD

qR pattern V3R or V1 Tall pure R wave > 15 mm (any age) in right

chest

Upright T wave > 3-5 days of age Very tall R wave with ST depression and T

wave inversion in V1 (strain)

Deep S wave V6

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Pediatric ECGs

Left ventricular hypertrophy

Criteria

LAD for age (more useful in neonates/infants)

R in V5/V6 or I, II, III, aVF, aVL above normal S in V1/V2 above normal

Abnormal R/S ratio (R/S in V1/V2 below

normal) Deep/wide q wave in V5/V6 above fmm

Tall symmetric T waves = LV diastolic overload

With LVH, inverted T waves in I/aVF = strain

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Pediatric ECGs

Combined ventricular hypertrophy

Criteria

Positive voltage criteria for LVH andRVH

In absence of BBB, preexcitation Positive voltage criteria for LVH orRVH with

relatively large voltages for the other ventricle

Large equiphasic QRS complexes in > 2 limbleads and midprecordial (V2 - V5) leads

Katz-Wachtel phenomenon

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QRS morphologies

Normal RBBB Preexcitation(delta wave)

IV block

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Conduction disturbances: RBBB

Prolongation in terminal phase of QRS(terminal slurring

Delayed conduction through RBB prolongs

depolarization of RV Slurring is to the rightand anterior

RAD

QRS above ULN for age

Wide/slurred S in I, V5, V6 Terminal slurred R in aVR and V1, V2, V3r

ST segment shift, T wave inversion (in adults)

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RBBB

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Bundle branch block

RBBB: Etiologies

ASD/PAPVR

Right ventriculotomy

Ebsteins

Coarctation (< 6 months)

LBBB

Rare in children Seen in adults with ischemic and hypertensive heart

disease

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Pediatric ECGs

Intraventricular block

Slowing throughout QRS complex

Etiologies

Metabolic disorders (hyperkalemia) Myocardial ischemia (CPR, quinidine toxicity)

Diffuse myocardial disease

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Wolff-Parkinson-White

Preexcitation: initial slurring of QRS

Accessory conduction pathway

Premature depolarization of part of themyocardium

Slow conduction delta wave

Criteria: Short PR interval for age

Delta wave

Wide QRS for age

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Preexcitation syndromes

Lown-Ganong-Levine

Short PR interval

Normal QRS duration

Fibers bypass upper AV node, but conduct normally

Mahaim fiber

Normal PR interval

Long QRS duration Delta wave

Fiber bypasses His bundle, enters RV myocardium