MCQs on Paediatric Cardiology

Written by Dr. Emily Chang (MBBS, FRACP) – Paediatrician

Question 1

A 2-day-old male newborn named Jacob, born at term via normal vaginal delivery, appears well and feeds normally. As part of routine postnatal assessment, pulse oximetry is performed, revealing oxygen saturations of 94% in the right hand and 89% in the right foot. The baby is pink and shows no signs of respiratory distress. Peripheral pulses are palpable and equal.

What is the most appropriate next step in management?

A) Repeat pulse oximetry in 24 hours
B) Start supplemental oxygen and observe
C) Urgently refer for echocardiography
D) Discharge the baby with routine follow-up
E) Administer prostaglandin E1 immediately

Correct Answer: C) Urgently refer for echocardiography

Jacob’s differential oxygen saturations (higher in the right hand compared to the foot) suggest pre-ductal and post-ductal desaturation, which is a red flag for duct-dependent congenital heart disease, such as coarctation of the aorta or transposition of the great arteries. These conditions may be asymptomatic in the early neonatal period due to the presence of a patent ductus arteriosus, but can deteriorate rapidly when the duct closes.

The screening threshold used in Australia for detecting critical congenital heart disease via pulse oximetry is typically saturation <95% in either extremity or a difference >3% between pre- and post-ductal readings. Jacob has both, which warrants urgent echocardiographic assessment to evaluate cardiac anatomy and rule out serious congenital lesions.

Prostaglandin E1 may be needed after the diagnosis is confirmed or if the baby becomes unstable. At this point, since the baby is clinically stable, immediate referral for echocardiography is the safest and most appropriate next step.

Discharging the baby or merely observing without cardiac imaging could result in missed diagnosis and life-threatening deterioration after ductal closure.

Question 2

A 4-month-old infant named Sophie is brought to the clinic with concerns about poor weight gain and frequent respiratory infections. On examination, a loud, harsh pansystolic murmur is heard best at the lower left sternal border. She has mild tachypnea but no cyanosis. Her oxygen saturation is normal.

What is the most likely diagnosis?

A) Atrial septal defect
B) Ventricular septal defect
C) Patent ductus arteriosus
D) Coarctation of the aorta
E) Tetralogy of Fallot

Correct Answer: B) Ventricular septal defect

Ventricular septal defect (VSD) is the most common congenital heart defect. It typically presents in infancy with symptoms of congestive heart failure such as poor feeding, failure to thrive, and frequent respiratory infections due to increased pulmonary blood flow.

The classic murmur is a loud, harsh pansystolic murmur best heard at the lower left sternal border. Patients usually have normal oxygen saturation unless there is significant pulmonary hypertension or Eisenmenger syndrome develops later.

Atrial septal defects tend to have a systolic ejection murmur with a wide fixed split of the second heart sound. Patent ductus arteriosus causes a continuous “machinery” murmur. Coarctation of the aorta presents with differential pulses and hypertension. Tetralogy of Fallot is a cyanotic heart disease with a harsh systolic murmur and central cyanosis.

Question 3

A 3-week-old preterm infant named Ethan is being reviewed in the neonatal clinic. He was born at 32 weeks gestation and has ongoing respiratory distress requiring oxygen. On examination, a continuous “machinery” murmur is heard best at the left infraclavicular area. There is bounding peripheral pulses and a wide pulse pressure.

What is the most appropriate management?

A) Start indomethacin therapy
B) Immediate surgical ligation
C) Begin oral antibiotics
D) Observe and follow up in 6 months
E) Start beta-blockers

Correct Answer: A) Start indomethacin therapy

Patent ductus arteriosus (PDA) is common in preterm infants and can cause left-to-right shunting, leading to pulmonary overcirculation and respiratory distress. The classic murmur is a continuous “machinery” murmur best heard at the left infraclavicular area.

Indomethacin, a nonsteroidal anti-inflammatory drug, promotes closure of the PDA by inhibiting prostaglandin synthesis and is the first-line medical treatment in symptomatic preterm infants.

Surgical ligation is reserved for cases where medical management fails or is contraindicated. Antibiotics and beta-blockers have no role in PDA management. Observation may be considered in asymptomatic term infants with small PDAs but is not appropriate here due to ongoing respiratory symptoms.

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15. Paediatrics Module

15.1 Neonatology

15.2 Growth and Development

15.3 Paediatric Neurology

15.4 Paediatric Cardiology

15.5 Paediatric Respiratory

15.6 Paediatric Gastroenterology

15.7 Paediatric Nephrology

15.8 Paediatric Infections

15.9 Other Paediatric Disorders

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