[Fetal heart rate and Doppler flow parameters in fetal blood vessels--evaluation of 2,517 individual signals].

Analysis of more than 2500 doppler flow signals in three patients was performed to evaluate the influence of fetal heart rate (fhr) variation on S/D-ratio in fetal vessels. Little differences of S/D-ratio in fetal vessels (descending aorta, umbilical arteries) were detected within the physiological variations of fhr (120-160 bpm) (envelope of regression line -0.007, -0.006). Analysing inter- as well as intraindividual variation only minor effects of fhr alteration can be observed in clinical application of doppler flow velocimetry. Dopplersonographic measurements, however, should be performed for at least a three minute period (for each vessel) to avoid false-positive or false-negative interpretation of short term changes of doppler signals. This is especially important in distressed fetuses.