Fetal heart rate and umbilical artery velocity variability in fetuses with congenital cardiac defects: a preliminary study

Objective To examine whether variabilities in fetal heart rate and umbilical artery flow velocity are possible markers for hemodynamic dysfunction in fetuses with a congenital heart defect. Methods Doppler studies of the umbilical artery velocity waveform were performed at 20-35 weeks of gestation in 13 patients with a congenital heart defect. We determined absolute and variability values for heart rate and flow velocities from umbilical artery velocity, waveforms of a least 18 s duration. We compared these findings with normal controls matched for gestational age. Results Fetuses with a congenital heart defect displayed decreased umbilical artery peak systolic and time-averaged velocities. However, variability in peak systolic and time-averaged velocities and fetal heart rate variability were increased compared with normal controls. Absolute fetal heart rates were similar between the two groups. Conclusions Marked cardiovascular changes occur in the fetus with a congenital heart defect compared with, the normal healthy fetus. We propose that variability in fetal heart rate and umbilical artery blood flow velocity could be additional markers for impaired homeostasis in the presence of fetal congenital heart disease.