Methemoglobinemia masquerading as pulmonary hypertension.

Pulmonary arterial hypertension is known to occur postoperatively after closure of VSD. It results in a low cardiac output state with need for ventilation and frequent bagging. Methemoglobinemia, a condition associated with toxic ingestions, has been described in this setting. Methemoglobinemia is known to cause cyanosis and hypotension. We report a critically ill infant with significant methemoglobinemia after VSD closure.