Among cyanotic congenital heart diseases, which is considered the most common?

• A. Transposition of the great arteries
• B. Tetralogy of Fallot
• C. Tricuspid atresia
• D. Pulmonary atresia

Answer: (B)

Cyanotic congenital heart diseases are those where deoxygenated blood mixes into the systemic circulation, causing blue-tinged skin and lips. Among these, Tetralogy of Fallot is the most common lesion seen in children. It’s the classic cyanotic defect because it includes four anatomical changes that promote right-to-left mixing: a ventricular septal defect, obstruction of the right ventricular outflow tract, an overriding aorta, and right ventricular hypertrophy. The amount of cyanosis depends on how severe the outflow obstruction and the VSD are, which explains why patients can have varying degrees of color change and occasional spells. While transposition of the great arteries is also a well-known cyanotic defect requiring urgent treatment, and other conditions like tricuspid atresia and pulmonary atresia exist, Tetralogy of Fallot occurs more frequently and is the prototypical cyanotic lesion in pediatric practice.