CET Pediatric ECG Considerations 2 — Questions and Answers
Question 1: A 6-month-old infant's ECG shows right axis deviation. This finding is considered:
- A pathological sign requiring immediate cardiology referral
- Normal for this age due to right ventricular dominance (Correct answer)
- Indicative of left bundle branch block
- A sign of hypocalcemia
Correct answer: Normal for this age due to right ventricular dominance
Right axis deviation is normal in infants due to right ventricular dominance, which persists until the left ventricle gradually takes over in early childhood.
Question 2: When performing an ECG on a crying infant, the technician should FIRST:
- Proceed with the recording and note the artifact
- Attempt to calm the infant before recording (Correct answer)
- Increase the paper speed to 50 mm/s
- Apply additional electrodes to reduce noise
Correct answer: Attempt to calm the infant before recording
Muscle artifact from crying significantly degrades ECG quality, so calming the infant first—using a pacifier, feeding, or parental soothing—produces a more accurate tracing.
Question 3: The P-wave amplitude in pediatric patients is considered abnormal if it exceeds:
- 1.5 mm
- 2.5 mm (Correct answer)
- 3.5 mm
- 4.0 mm
Correct answer: 2.5 mm
A P-wave exceeding 2.5 mm in amplitude suggests right atrial enlargement and is abnormal in pediatric patients just as in adults.
Question 4: Which congenital heart defect classically produces a 'dome-shaped' or 'boot-shaped' heart on chest X-ray and right ventricular hypertrophy on ECG?
- Atrial septal defect
- Patent ductus arteriosus
- Tetralogy of Fallot (Correct answer)
- Coarctation of the aorta
Correct answer: Tetralogy of Fallot
Tetralogy of Fallot causes right ventricular hypertrophy on ECG and the classic 'boot-shaped' heart (coeur en sabot) on X-ray due to RV enlargement and a small pulmonary artery.
Question 5: In a 10-year-old, the normal PR interval range is approximately:
- 60–80 ms
- 100–200 ms (Correct answer)
- 200–240 ms
- 240–280 ms
Correct answer: 100–200 ms
The normal PR interval in children aged 10 is approximately 100–200 ms (0.10–0.20 s), similar to adults but with the lower bound reflecting faster conduction.
Question 6: A neonate's ECG shows a QTc of 500 ms. The most appropriate next step is:
- Repeat the ECG in 1 week
- Notify the ordering provider immediately (Correct answer)
- Document as a normal finding in neonates
- Increase the ECG paper speed and repeat
Correct answer: Notify the ordering provider immediately
A QTc of 500 ms is markedly prolonged and associated with risk of life-threatening arrhythmias including torsades de pointes; the ordering provider must be notified immediately.
Question 7: Sinus arrhythmia in children—where the heart rate increases with inspiration and decreases with expiration—is considered:
- A sign of sick sinus syndrome
- Normal and related to vagal tone (Correct answer)
- Indicative of atrial fibrillation
- A pathological finding requiring Holter monitoring
Correct answer: Normal and related to vagal tone
Sinus arrhythmia is a normal physiological variation in children reflecting respiratory modulation of vagal tone and does not require further evaluation.
CET Pediatric ECG Considerations 2
A 6-month-old infant's ECG shows right axis deviation.
This finding is considered: