Changes in intestinal electrical activity during ischaemia correlate to pathology

The gastrointestinal tract possesses an omnipresent electrical slow wave called the basic electrical rhythm (BER). It has been shown that the frequency of the BER falls during intestinal ischaemia. The correlation between changes in the BER and pathology that occur during acute ischaemia are not completely understood. To study this, the electrical activity of the ileum in 14 adult male rabbits was recorded during ischaemia. At baseline, 60, 120 and 210 minutes of ischaemia, segments of bowel were resected for histopathologic evaluation. The BER frequency was determined using the Fast Fourier Transformation (FFT) spectral analysis. The BER amplitude and FFT spectral power were also determined. The results showed significant decrease (p<0.05, Student's T-test) in the BER frequency, amplitude, and spectral power at all time points. Between 60 and 120 minutes, while there was a decrease in BER activity the pathologic grade remained the same (focal loss of surface epithelium). By 210 minutes of ischaemia when the BER could not be recorded, there was diffuse mucosal infarction. The results indicate that changes in the electrical activity of the bowel during acute mesenteric ischaemia occurred prior to the pathologic changes. The presence of electrical activity indicates that there was viable bowel. Thus it should be possible to use recordings of electrical activity to evaluate bowel viability during acute ischaemia.