A study of systemic blood flow in the fetus with cardiac failure using a sheep fetus model

有两个主要因素，神经学和血清学，参与循环控制胎儿。这些因素在血流的重新分配中起着重要的作用，当胎儿陷入困境时，增加了流向大脑、心脏和肾上腺等重要器官的血流量。这项研究表明，不仅心脏调节，外周调节也应维持胎儿循环。对孕120 ~ 135天的羊胎儿进行胎股动脉、静脉插管。在升主动脉和肺动脉周围放置超音波流量计，然后在心室处缝合起搏导线。脑室间隔内注射10%福尔马林溶液完成房室阻滞。人工A-V阻断使胎儿心率从每分钟168次降至81次，心输出量- l降至正常状态的40%。起搏时胎心率为180 bpm，起搏时胎心率逐步降低，搏量增加至100 bpm。当起搏逐步降低心率时，胎儿动脉压在20-30秒的周期内以特征波波动。这种动脉压波动模式很快消失，但当心率进一步下降时又出现。这种模式不受副交感神经或交感神经阻滞的影响。综上所述，胎儿不仅有自己的心脏和外周血管调节系统来维持血液循环。

There are two main factors, neurological and serological, involved iii circulatory control in the fetus. These factors play an important role in redistribution of blood flow, increasing blood flow to the vital organs such as brain, heart and adrenal gland, when the fetus fell in distress. This study clarified that not only cardiac but peripheral regulation should maintain fetal circulation.Canulation to fetal femoral artery and vein was performed in the sheep fetus in 120-135 gestational days. Transit-time ultrasonic flow meters were placed around ascending aorta and pulmonary artery and then a pacing lead wire was attached with some stitches at the ventricle. Atrio-vetricular block was completed by the injection of 10% formalin solution at intraventricula septum. Artificial A-V block decreased fetal heart rate from 168 to 81 bpm and, -cardiac outpu-L, to 40 % of normal condition. Returning -fetal heart rate at 180 bpm by pacing and the decreasing it stepwise, stroke volume increased up to the period of 100 bpm heart rate. When the heart rate was stepwise decreased by pacing, fetal arterial pressure fluctuated with a characteristic wave in a 20-30 second cycle. This waving pattern of arterial pressure disappeared soon, but reappeared when the heart rate was changed down further. This pattern was not affected by parasympathetic or sympathetic blockades.In conclusion, fetus has own not only cardiac but peripheral vascular regulation to maintain circulation.