MCQ – 33231

A neonate has central cyanosis and short systolic murmur on the 2nd day of birth.The diagnosis is ‑

Correct Answer » B Explanation

• Transposition of the Great Arteries (TGA) is the most common cause of cyanosis presenting within the first few days of life.
• In TGA:
  • The aorta arises from the right ventricle.
  • The pulmonary artery arises from the left ventricle.
  • Systemic and pulmonary circulations run in parallel rather than in series.
• Survival depends on mixing of blood through:
  • Patent foramen ovale (PFO)
  • Atrial Septal Defect (ASD)
  • Ventricular Septal Defect (VSD)
  • Patent Ductus Arteriosus (PDA)
• The murmur is often absent or only a short systolic murmur because there is no significant obstruction in uncomplicated TGA.
• The uploaded notes describe TGA as presenting with:
  • Cyanosis from birth or shortly after birth
  • Single second heart sound (S2)
  • Murmur often absent
  • Egg-on-side appearance on chest X-ray

Why the Other Options Are Incorrect

A. Tetralogy of Fallot (TOF)

• Cyanosis usually develops after several weeks to months, as pulmonary stenosis worsens.
• Neonates with classic TOF are not typically cyanotic on the 2nd day of life, unless pulmonary obstruction is severe.
• TOF usually presents with:
  • Ejection systolic murmur
  • Single S2
  • Hypercyanotic (Tet) spells occurring later in infancy.

C. Atrial Septal Defect (ASD)

• ASD is an acyanotic congenital heart disease.
• Neonates are usually asymptomatic.
• Cyanosis is not an early feature.

D. Ventricular Septal Defect (VSD)

• VSD is also an acyanotic congenital heart disease.
• Symptoms generally begin 6–8 weeks after birth when pulmonary vascular resistance falls.
• Cyanosis develops only after long-standing pulmonary hypertension leading to Eisenmenger syndrome.