Management strategy for fetal tachycardia

To develop a management strategy for fetal tachycardia.

Forty-four fetuses (20-40 weeks' gestation) with nonsinus tachycardia were divided into three groups based on duration of tachycardia and degree of heart failure. Fetuses with intermittent tachycardia were treated expectantly. Fetuses with sustained tachycardia were treated with transplacental antiarrhythmic agents alone if heart failure was mild to moderate, and with direct intramuscular therapy if heart failure was severe. Degree of heart failure was determined by echocardiographic variables of ventricular function, atrioventricular valve insufficiency, and hydrops. Fetal well-being and response to treatment were evaluated by daily heart rate surveillance and frequent fetal echocardiograms and ultrasounds.

Fifteen fetuses with intermittent tachycardia (n = 15, group 1) did not progress to sustained tachycardia or heart failure. Fetuses with sustained tachycardia and mild-to-moderate heart failure (n = 14, group 2) were cardioverted or rate controlled with transplacental agents (n = 9); three term fetuses were delivered electively without treatment and two progressed to severe heart failure and were treated in group 3. Seventeen fetuses (15 initially, two progressing) with severe heart failure were cardioverted (in 0. 25-21 days; mean 4.3 days) with fetal intramuscular plus transplacental antiarrhythmic therapy (group 3). Overall, 43 of 44 fetuses were delivered at 32 to 41 (mean 37) weeks with minimal morbidity and a mortality rate of 2.2% (95% confidence interval 0. 06%, 12.0%).

Perinatal mortality and morbidity were low after following a management strategy based on duration of tachycardia, degree of heart failure, and biophysical profile combined with vigilant ongoing fetal surveillance.