ABSTRACT
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.
Keywords
Fetal monitoring - fetal bradycardia - congenital heart block
