Delayed Presentation of Tetralogy of Fallot with Isolated Cyanosis

Table 1

Differential diagnosis of hypoxia or cyanosis in an infant [7, 8, 13].

Congenital heart disease	Shock states	Hematologic causes	Neurologic causes
(i) Tetralogy of Fallot	(i) Cardiogenic	(i) Methemoglobinemia	(i) Seizures
(ii) Transposition of the great arteries	(ii) Hypovolemic	(ii) Anemia	(ii) Phrenic nerve palsy
(iii) Total anomalous pulmonary venous connection	(iii) Obstructive	(iii) Polycythema
(iv) Tricuspid atresia	(iv) Distributive
(v) Truncus arteriosus
Acquired respiratory disease	Infectious respiratory disease	Congenital respiratory disease	Miscellaneous causes
(i) Trauma	(i) Laryngotracheitis	(i) Laryngomalacia	(i) Cold exposure
(ii) Foreign body	(ii) Epiglottitis	(ii) Choanal atresia	(ii) Breath-holding spells
(iii) Pneumothorax	(iii) Bacterial tracheitis	(iii) Micrognathia
(iv) Asthma	(iv) Pneumonia	(iv) Pulmonary hypoplasia
(v) Pulmonary edema	(v) Bronchiolitis	(v) Pierre Robin sequence
		(vi) Cystic fibrosis