We report on a case of methemoglobinemia in conjunction with supraventricular tachycardia. A 6-mo-old infant was admitted to hospital with perioral cyanosis three hours after eating a refrigerated mixed-vegetable puree. The patient developed supraventricular tachycardia (SVT) and had a heart rate of 230 beats/min. The arrhythmia resolved spontaneously. A chemical analysis showed oxygen saturation of 85% and a methemoglobin level of 25%. The infant was treated with oxygen and referred to the Pediatric Intensive Care Unit. The patient had two additional short episodes of SVT, which were resolved spontaneously without treatment. She received oxygen for 8 h until the methemoglobin level dropped to 1%.
Conclusion: Long-term storage of refrigerated vegetables can cause methemoglobinemia in infants. Methemoglobinemia can appear in conjunction with SVT, but it is also possible that in a child with a tendency to develop SVT, methemoglobinemia involved hypoxemia, which then triggers SVT.