High-resolution spatial analysis of slow wave initiation and conduction in porcine gastric dysrhythmia.

BACKGROUND: The significance of gastric dysrhythmias remains uncertain. Progress requires a better understanding of dysrhythmic behaviors, including the slow wave patterns that accompany or promote them. The aim of this study was to use high-resolution spatiotemporal mapping to characterize and quantify the initiation and conduction of porcine gastric dysrhythmias.
METHODS: High-resolution mapping was performed on healthy fasted weaner pigs under general anesthesia. Recordings were made from the gastric serosa using flexible arrays (160-192 electrodes; 7.6mm spacing). Dysrhythmias were observed to occur in 14 of 97 individual recordings (from 8 of 16 pigs), and these events were characterized, quantified and classified using isochronal mapping and animation. KEY
RESULTS: All observed dysrhythmias originated in the corpus and fundus. The range of dysrhythmias included incomplete conduction block (n=3 pigs; 3.9±0.5cpm; normal range: 3.2±0.2cpm) complete conduction block (n=3; 3.7±0.4cpm), escape rhythm (n=5; 2.0±0.3cpm), competing ectopic pacemakers (n=5, 3.7±0.1cpm) and functional re-entry (n=3, 4.1±0.4cpm). Incomplete conduction block was observed to self-perpetuate due to retrograde propagation of wave fragments. Functional re-entry occurred in the corpus around a line of unidirectional block. 'Double potentials' were observed in electrograms at sites of re-entry and at wave collisions. CONCLUSIONS & INFERENCES: Intraoperative multi-electrode mapping of fasted weaner healthy pigs detected dysrhythmias in 15% of recordings (from 50% of animals), including patterns not previously reported. The techniques and findings described here offer new opportunities to understand the nature of human gastric dysrhythmias.