Actocardiogram

Abstract

Aims: To objectively study fetal movements, clarify fetal behavior, identify false positive fetal heart rate (FHR), estimate fetal outcome, and study fetal response to external stimuli, using an actocardiogram (ACG). Methods: The ACG is a chart record that simultaneously traces FHR and fetal movements by continuous wave (CW) ultrasonic Doppler signals of fetal heart beats and movements using a single probe. In addition, uterine contraction is recorded in clinical models. Results: Signals from fetal movements are clustered to form bursts and characterized by 5 indices of mean duration, occupancy, frequency, ratio of duration of FHR acceleration to movement bursts (A/B ratio), and the ratio of acceleration count to the bursts; fetal behavior was classified into resting, active, hyperactive and intermediate states; non-reactive FHR was differentiated from fetal resting FHR; sinusoidal FHR was separated from benign physiologic one; and sinus bradycardia was separated from hypoxia. Interval of fetal hiccups was 2 sec, and hiccups lasted for 20 minutes or more and tended to repeat in a day. The severity ranking of fetal central nervous system lesion and fetal disorder outcome were assessed using the A/B ratio. The correlation coefficient of FHR and movement increased if the movement delayed. A fetus responded to sound light stimulation in ACG; fetal sensitivity increased in late pregnancy. Conclusion: The controversial obtained used a cardiotocogram were resolved using the ACG. It opened new objective fields in perinatal medicine. © Kazuo Maeda.