ECG and heart rate variability changes in preterm and near-term fetal lamb following LPS exposure

The aim of this study is to evaluate the myocardial response in the preterm and near-term fetal lamb with infection. Chronically instrumented fetal lambs were exposed to lipopolysaccharide (LPS), and the fetal electrocardiogram (FECG) ST waveform was examined using STAN. Fetal heart rate variability (FHRV) was automatically analyzed by adapting a polynomial function to the RR sequence in the FECG. Preterm fetuses exposed to >90 ng/kg LPS died within 8 hours of LPS administration, a response not seen in near-term fetuses. In both surviving and nonsurviving preterm fetuses, cardiovascular responses were characterized by decreased arterial pressure, negative T waves, and tachycardia accompanied by an increase in FHRV. Similar changes were not observed in the near-term fetuses after LPS. The study shows that preterm lambs are more sensitive to LPS in terms of myocardial/cardiovascular response than the more mature fetuses are. High FHRV and negative ST waveform seem to characterize the LPS-induced stress response in preterm fetuses.