[Acute cyanosis after transcatheter balloon valvuloplasty: toxic methemoglobinemia due to local prilocaine use].

Methemoglobinemia is characterized by varying degrees of cyanosis due to increased hemoglobin concentrations containing oxidized iron. Prilocaine is a widely used local anesthetic and can cause methemoglobinemia in infants even in therapeutic doses. We present two female infants (younger than 2 months) who developed severe cyanosis after transcatheter pulmonary balloon valvuloplasty and were diagnosed with toxic methemoglobinemia. Both infants were anesthetized with local prilocaine application before balloon valvuloplasty. Methemoglobin levels of the patients were measured as 49.6% and 37.7%, respectively. Both were successfully treated with intravenous methylene blue and ascorbic acid.