The atrial rate was 400 bpm; the ventricular rate was 200 bpm. The fetus did not have heart failure, but we needed to treat the arrhythmia via the mother, so we admitted her to the hospital. There have been many reports of quinidine crossing the placenta to deliver an adequate dosage to the baby, so we gave the mother quinidine/ After several days of monitoring we noted that the atrial flutter had stopped. When the baby was born his esophageal pacing study revealed that he had WPW syndrome and inducible orthodromic tachycardia. Of course older patients have atrial fibrillation in association with WPW, but I believe that this baby?s atrium was too small to fibrillate, and he had atrial flutter instead.