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

Objective To examine whether variabilities in fetal heart rate and umbilica l 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 perf ormed at 20-35 weeks of gestation in 13 patients with a congenital heart de fect. We determined absolute and variability values for heart rate and flow velocities from umbilical artery velocity, waveforms of a least 18 s durat ion. We compared these findings with normal controls matched for gestationa l age. Results Fetuses with a congenital heart defect displayed decreased umbilica l artery peak systolic and time-averaged velocities. However, variability i n peak systolic and time-averaged velocities and fetal heart rate variabili ty 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 congeni tal heart defect compared with, the normal healthy fetus. We propose that v ariability in fetal heart rate and umbilical artery blood flow velocity cou ld be additional markers for impaired homeostasis in the presence of fetal congenital heart disease.