The effect of hypoxia on fetal Cardiovascular System

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1) Animal Experiment Fetal heart rate (FHR), EEG, ECG, Tracheal pressure and fetal blood pressure (FBP) recorded continiously by using sheep chronic prepartion model revealed the obvious changes of FBP, FHR, fetal breathing movement (FBM) as well as its quantitative and qualitative differences in each period of sleeping cycles. While the Accerelation (ACC) (amplitude more than 40bpm, duration more than 40sec) coincident with fetal movement, burst of fetal breathing movement (FBM) and increase of FBP were characteristic during low voltage high frequency (LVHF) sleep, the deccerelation (DCC) with fetal movement (FM) were characteristicaly increased in high voltage low frequency (HVLF) sleep and this tendency was more prominent in younger fetuses. Nor epinephrine (NE) and arginine vasopressin (AVP) increased during hypoxia were infused continuously to fetal lamb and abult domestic rabbits t clalify the effects of these hormones on fetal cardiovasuclar system. While Ne resulted in increase … More of FBP and decrease in FHR, AVP resulted in persistent increase in FBP and decrease in FHR and in its variability as well as marked inhibition of FBM.2) Human fetus FM. FBM and FHR were observed by using ultrasound and MT 320 fetal movement recorder during 28-40 gestational weeks. The amplitude and duration of ACC coincident with rolling movent were increased according to progress of gestaional weeks and that type of ACC was characteristic in active sleep. In order to cause a stress situation, 75Hz, 74db vibro-acoustic stimultion (VAST) was performed during the fetal heart rate monitoring. The majority of the fetuses reacted with an ACC in heart rate and the degree of reactivity varied with the weeks of advancement of pregnancy. Our responses were classified into 4 groups, consisting of 5 types. Type-1(ACC type) and type-2(tachycardia type) were in good prognosis. Type-3(triphasic type) was those with cord involvement (group2). Type-4 (DCC type) and type-5 (non-response type) had poor prognosis (group3,4). Less