Which clinical feature is most commonly associated with tetralogy of Fallot in infants?

Tetralogy of Fallot is a congenital heart defect characterized by a combination of four specific cardiac anomalies: ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta. One of the hallmark clinical features associated with this condition, particularly in infants, is cyanosis.

Cyanosis occurs due to the mixing of oxygenated and deoxygenated blood, which leads to a decreased level of oxygen saturation in the peripheral tissues. In infants with tetralogy of Fallot, the right-to-left shunting of blood through the ventricular septal defect and narrowed outflow tract results in a significant degree of desaturation. This is typically observed when the child is crying or during exertion, but can also be present at rest, especially if the infant is in a position that aggravates the right ventricular obstruction.

The other clinical features, while they may be associated with different cardiac conditions or as secondary complications, do not specifically characterize tetralogy of Fallot. Chest pain is uncommon in infants and not a typical presentation. Convulsions could arise from severe hypoxia but are not a direct manifestation of tetralogy itself. Palpitations, typically indicative of arrhythmias, are less relevant in the context of this