Uterine EMG Analysis And Research On The Mechanism Of Uterine Contraction

Derived from the electrical activity generated at the muscle fiber lever, uterine EMG provides complementary information on the muscle. During the last 60 years, uterine EMGs have been extensively investigated at the cell and tissue levels, at whole-organ myometrial and abdominal levels. However, the relationship between uterine EMGs and synchronization or polarity of the contractility of the uterus remains uncertain. Since synchronization and polarity are significant characteristics of uterine contraction, the research on the relationship will help to find out the mechanism of uterine contraction, and will help to provide a very promising technique for clinical or physiologic investigations of uterine activity, compared with current invasive monitoring.A new mathematical model to simulate the uterine EMG by computer is proposed in the paper. In this model, the uterine EMG is generated by the electrical potential produced by an annular band polarized by electric dipoles and moving from horns to cervix. The model is consistent with the function of the uterus and reproduces all the morphological characteristics (waveform, amplitude, duration, frequency) of the uterine EMG as obtained by experiments in vivo. It is easy to simulate by computer.To pick up multi-channel uterine EMGs exactly, a novel multi-channel biopotential amplifier is presented. The proposed circuit has many interesting characteristics regarding simplicity and cost, while achieving high CMRR and effective dc interference suppression without any trimming. In this paper, the multi-electrodes are fixed on the rat's uterine in the new way, and the spread and propagation of stimulate electrical signal are observed in vivo. The results are compared with impulse conduction experiments down by Melton, and draw the conclusion that uterine muscle fiber is different from skeletal muscle fiber since it isn't sensitive to electrical stimulates. To overcome the shortcoming of cross correlation, in this paper, two new methods are proposed to distinguish the initiation of uterine contraction. The first one is based on statistical characteristics of uterine EMGs; the second one we developed is a wavelet transform-based method. With the two algorithms, we can estimate the electrical wave propagation along the uterus.