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

• Published in: Neurogastroenterology and motility Vol. 23; no. 9; pp. e345 - e355
• Main Authors: O’Grady, G., Egbuji, J. U., Du, P., Lammers, W. J. E. P., Cheng, L. K., Windsor, J. A., Pullan, A. J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-09-2011
• Subjects: Anesthesia; Animals; arrhythmia; bradygastria; Conduction; conduction block; ectopic; Electrodes; Electrophysiology - methods; Gastrointestinal Diseases - physiopathology; Humans; Mapping; Muscle Contraction - physiology; Muscle, Smooth - anatomy & histology; Muscle, Smooth - physiology; Nerve conduction; Pacemakers; Periodicity; Retrograde transport; re‐entry; Rhythms; Stomach - anatomy & histology; Stomach - physiology; Stomach - physiopathology; Swine; tachygastria; Waves
• ISSN: 1350-1925; 1365-2982
• DOI: 10.1111/j.1365-2982.2011.01739.x

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; 7.6 mm 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 ± 0.5 cpm; normal range: 3.2 ± 0.2 cpm) complete conduction block (n = 3; 3.7 ± 0.4 cpm), escape rhythm (n = 5; 2.0 ± 0.3 cpm), competing ectopic pacemakers (n = 5, 3.7 ± 0.1 cpm) and functional re‐entry (n = 3, 4.1 ± 0.4 cpm). 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.