A technique for intrapartum monitoring of fetuses with congenital bradycardias.

Our objective was to construct from readily available components a system that would allow determination of P-wave to P-wave intervals in fetuses with congenital heart block. Using a fetal monitor, bedside patient monitor, spiral electrode, and a special cable described herein, we obtained direct fetal electrocardiograms from two fetuses with autoimmune heart block. Measurement of the atrial rate was made by determining the P-wave to P-wave interval. These determinations were compared to atrial rates measured by M-mode echocardiography in utero and neonatal electrocardiograms. Atrial rates determined by direct fetal electrocardiogram were identical to rates obtained by M-mode echocardiography and within 10 beats/min of rates calculated from neonatal electrocardiograms. Premature ventricular contractions in one fetus were also detected. It is possible to perform continuous and accurate assessments of sinoatrial node activity in fetuses with congenital heart block using components readily available to most obstetricians.