Treatment of fetal supraventricular tachycardia with flecainide acetate after digoxin failure

Abstract

Treatment of fetal supraventricular tachycardia with flecainide acetate after digoxin failure To the Editors: After reviewing the interesting case report by Kofinas et al. (Kofinas AD, Simon NV, Sagel H, Lyttle E, Smith N, King K. Treatment of fetal supraventricular tachycardia with flecainide acetate after digoxin failure. AMJ OBSTET GYNECOL 1991;165:6301), readers may be interested in a further case of fetal supraventricular tachycardia treated by maternal administration of flecainide after unsuccessful treatment with digoxin that was reported in the British literature. I A 26-year-old gravida 2, para 1 woman at 28 weeks' gestation had fetal tachycardia >200 beats/min on routine auscultation with a Pinard stethoscope. Fetal Mmode echocardiography showed a ventricular rate of 240 beats/min with a 1: 1 atrioventricular relation. The heart was structurally normal, but moderate pericardial effusion and ascites were noted. The mother was given three oral doses of digoxin 500 IJ-g every 8 hours and then 500 IJ-g daily. Echocardiography showed a persistent supraventricular tachycardia in spite of trough maternal serum digoxin levels of 1.5 IJ-g/L and amniotic fluid levels of 0.2 IJ-g/L. Flecainide 11 0 mg (1.4 mg/kg) was then given intravenously under maternal echocardiography and fetal echocardiographic control. Fetal sinus rhythm at 120 beats/min supervened. Oral flecainide 100 mg every 8 hours was substituted for digoxin treatment. Trough maternal serum flecainide concentration was 656 IJ-g/L (adult therapeutic range 400 to 1000 IJ-g/L). The fetus stayed in sinus rhythm, and all traces of pericardial and ascitic effusion resolved within 10 days. Labor was induced at 38 weeks' gestation. A 12-lead electrocardiogram on the 3450 gm female infant showed sinus rhythm with no evidence of preexcitation. Concentrations of flecainide in maternal and cord plasma obtained simultaneously 5 hours after the last oral dose were 833 and 533 IJ-g/L, respectively, confirming good transplacental passage of flecainide. The baby remained in sinus rhythm without further medication. Martin Mills, MB University Department ofObstetrics & Gynaecology, Bristol Maternity Hospital, Bristol, England