Revista de Gravidez e Saúde Infantil

Abstrato

Fetal Heart Rate Changes are the Fetal Brain Response to Fetal Movement in Actoardiogram: The Loss of Fhr Variability is the Sign of Fetal Brain Damage

Kazuo Maeda

Aims To study fetal brain response to fetal movements with fetal heart rate (FHR) changes. Methods FHR changing mechanism was investigated by simultaneously recorded FHR and fetal movements detected directly at fetal thorax with Doppler ultrasound in act cardiogram (ACG). FHR changing process was confirmed by electronic and physiologic simulations. Results and conclusion As recorded movement spike height was parallel to fetal movement amplitude in ACG, FHR increased when the fetus moved, and triangular FHR acceleration developed at fetal movement burst by the integral function of midbrain. Moderate fetal movements developed moderate FHR increase, and periodically changing fetal movements developed physiologic sinusoidal FHR separating pathologic sinusoidal one. FHR variability developed by minor fetal movements. FHR acceleration was lost in early stage of hypoxia, and then the loss of variability comparable to anencephaly appeared in severe hypoxic fetal brain damage, followed by cerebral palsy. Thus, early delivery is recommended before the loss of variability, instead of C-section after the loss of variability. Rabbit heart rate reduced along PaO2 drop, where parasympathetic centre was excited in medulla oblongata by low PaO2 developing fetal bradycardia, which showed environmental hypoxia, whereas the loss of variability was full brain damage due to severe hypoxia, where fetal brain could not respond fetal movements as anencephaly.