Basic study of fetal heart ischemia by using a multi-electrodes fetal electrocardiogram via maternal abdomen for all gestational period fetuses

方法：用妊娠C57BL/6N小鼠和17只DPC胎鼠进行实验。这些测量是在东北大学流体力学实验室进行的，以利用他们的动物超声实验设备。麻醉后剖宫产，将电极固定在胎鼠身上，测量胎儿超声图像。结果：胎心电势低至几微伏(μV)，胎儿心电信号的提取十分困难。为了克服这个问题，我们开发了一种针状电极，它包含一个信号放大机制，能够将噪声降低到最低水平。据我们所知，我们是世界上第一个报告成功测量胎儿el…的组织。更多的心电图示。此外，基于这些研究，我们能够从胎儿心电图中识别出到目前为止被认为在小鼠身上不存在的“T波”。接下来，我们研究了由于子宫动脉分支的周期性限制和释放(每支5分钟，重复3次)而引起的心电图和胎心率的变化。结果显示，夹闭动脉分支时T波升高，并伴有频发心律失常，导致胎心率减慢。松开夹闭后，再次出现频发心律失常，心率逐渐恢复到正常水平。此外，在这些分析中，我们能够从胎儿大脑提取超声图像，显示大脑中动脉分支的血流。然而，由于母亲的呼吸，很难从超声图像中获得显示大脑感兴趣区域的清晰图像。由于这一障碍，我们无法产生子宫动脉分支限制和释放时脑内血流的实时图像。讨论：我们的分析表明，胎儿心电和超声可以作为监测胎儿缺血的有用工具。较少

Methods: Experiments were performed with pregnant C57BL/6N mice and 17 dpc fetuses. The measurements were carried out in the Fluid Dynamics Laboratory of the Tohoku University to take advantage of their ultrasonogram experimental facilities for animals. Caesarean section was carried out in pregnant mice after anesthesia and electrodes were attached to the fetuses to measure fetal ultrasonogram. 5 minute clipping and 5 minute release of the branches of the uterine artery was performed three times in tandem and the results were monitored by ultrasonogram.Results: The fetal heart potential was as low as a few microvolts (μV) and because of this low signal extraction of the fetal electrocardiogram proved to be very troublesome. To overcome this problem, we developed a needle electrode that contained a signal amplification mechanism and were able to reduce the noise to a minimal level. To our knowledge, we are the first group in the world to report the successful measurement of the fetal el … More ectrocardiogram. Moreover, based on these investigations, we were able to identify the characteristic "T-wave" from the fetal electrocardiogram that had been so far believed to be nonexistent in mice. Next, we investigated the alterations in the electrocardiogram pattern and fetal heart rate because of the periodic constraint and release (5 minutes each, 3 times repeated) of the branches of the uterine artery. The results showed increase of the T-wave during constraint by clipping of the branches of the artery, accompanied with frequent arrhythmia, which lead to a reduction of fetal heart rate. After release of the clipping, frequent arrhythmia was again observed and the heart rate gradually improved to a normal level. Furthermore, during these analyses we were able to extract an ultrasonogram from the fetal brain that showed the blood flow in the branches of the middle cerebral artery. However, due to the breathing of the mother, it was difficult to obtain a clear image from the ultrasonogram that showed the area of interest in the brain. Because of this hindrance, we were unable to produce a real-time image of the blood flow in the brain during constraint and release of the branches of the uterine artery.Discussion: Our analysis shows that fetal electrocardiogram and ultrasonogram can be a useful tool to monitor fetal ischemia. Less