A newborn becomes blue and sweaty with feeding. Which congenital heart defect is most likely?

• A. Ventricular Septal Defect
• B. Tetralogy of Fallot
• C. Patent Ductus Arteriosus
• D. Atrial Septal Defect

Answer: (B)

Cyanosis in a newborn that worsens with feeding points to a cyanotic congenital heart defect with reduced pulmonary blood flow. Tetralogy of Fallot fits this pattern because it includes a ventricular septal defect and, crucially, obstruction of the right ventricular outflow tract (pulmonary stenosis). The stenosis shunts blood right-to-left across the VSD, delivering poorly oxygenated blood to the systemic circulation. When a baby feeds, metabolic demand rises and systemic vascular resistance can increase, worsening the right-to-left shunt and triggering a “tet spell”—the child becomes more blue and sweaty as oxygen delivery to tissues drops.

In contrast, other common defects tend to present differently. A VSD typically causes a left-to-right shunt with a harsh holosystolic murmur and signs of heart failure, not early cyanosis. A patent ductus arteriosus usually has a continuous machinery murmur and can lead to heart failure later in infancy. An atrial septal defect often remains asymptomatic for years and does not cause marked cyanosis in the newborn period.