DISTURBANCES IN THE PROPAGATION OF THE SLOW-WAVE DURING ACUTE LOCAL ISCHEMIA IN THE FELINE SMALL-INTESTINE

Objective and design: The normal aborad propagation of the slow wave i n the small intestine is easily distorted by pacing, hypoxia or transe ction. We studied whether acute local ischaemia would also induce seri ous conduction disturbances and ectopic pacemaking. Methods: After gen eral anaesthesia and a mid-abdominal incision, a multi-electrode array of 240 extracellular electrodes was positioned on the serosal surface of an exteriorized intestinal loop. Simultaneous recordings of all 24 0 surface electrodes was performed during a control period and for 5-1 0 min following local acute arterial occlusion. After the experiments, activation maps were constructed describing the pattern of propagatio n of the slow waves. Results: During control periods, the activation m aps showed homogeneous aborad conduction of the slow wave. During acut e ischaemia, local areas of inexcitability developed rapidly, merging together to form lines of conduction block. This in turn often provoke d the appearance of subsidiary ectopic pacemakers. The location of the conduction blocks as well as that of ectopic pacemakers was highly va riable and could disappear and reappear at other sites. Conclusion: Wi thin minutes, acute ischaemia disturbed the organized homogeneous abor ad propagation of the slow wave leading to pronounced inhomogeneous de pression of conduction, local inexcitability, conduction block and the appearance of subsidiary pacemakers.