A COMPUTER-MODEL OF UTERINE CONTRACTIONS BASED ON DISCRETE CONTRACTILE ELEMENTS

Objective: To predict uterine contraction waveforms using a microcompu ter-based model of uterine activity based on discrete contractile elem ents, varying the shape of the model, total number of cells, and pacem aker locations. Methods: The model is a hallow ovoid composed of discr ete contractile elements (cells) that propagate electrical impulses, g enerate tension, and have defined contracting and refractory periods. Each cell contacts eight surrounding cells and propagates impulses ite ratively from cell to cell. Contraction pressure is the sum of the ten sion contributions by contracting cells. sample contraction waveforms were generated based on various numbers of cells organized in ovoids w ith long:short axis ratios of 1:1, 3:2, and 2:1, with one or two pacem akers at varying positions. Results: Contraction waveforms are altered by altering the shape of the matrix, but not by increasing the number of contractile elements. The Vertical placement of the pacemaker has a dramatic effect on the shape and symmetry of contractions, including the development of patterns characteristic of ''dysfunctional'' uteri ne contractions. Conclusion: Abnormal uterine contraction patterns may result from pacemaker activity in unusual locations, such as mid-uter us. Further refinement of this computer model of uterine activity may contribute to a better understanding of the genesis of normal and abno rmal intrauterine pressure waveforms and their relationship to the pro gress of labor.