Magnetic vector analysis of gastrointestinal electrical control activity

The electrical control activity (ECA) of the gastrointestinal tract exists as an omnipresent slow wave that characterizes the underlying activity of the smooth muscle. In the presence of mesenteric ischemia, small intestine ECA in animal models decreases over time. One-dimensional, multichannel SQUID magnetometers can noninvasivley record magnetic fields associated with ECA activity. Using vector optimization, we can resolve three orthogonal channels into a single vector corresponding to a single loop of normal or ischemic small intestine. We recorded the magnetic fields associated with the ECA of three male pigs after induction of ischemia using optimized vectors to discern the activity of the affected loop of bowel. A Student´s T-test was performed to determine if the change in ECA frequency after induction of ischemia was significant.