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

Abstract

Background The significance of gastric dysrhythmias remains uncertain. Progress requires a better understanding of dyrshythmic behaviors, including the slow wave patterns that accompany or promote them. The aim of this study was to use high-resolution (HR) spatiotemporal mapping to characterize and quantify the initiation and conduction of porcine gastric dysrhythmias. Methods HR 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 out 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.

Effect of Ethanol Exposure on Slow Wave Activity and Smooth Muscle Contraction in the Rat Small Intestine

“…In the remainder, a small circuit was discovered whereby the impulse propagated along five electrode sites with an average revolution time of 2620 ms. b A similar event occurred along six electrode sites (average revolution time: 2275). In both panels, the first electrogram is also displayed at the bottom of the panel to illustrate the continuity in propagation from one electrode to the next Dig Dis Sci the pig stomach [27], and the rat pregnant uterus [28]. Furthermore, since the circuits were revolving in the absence of an anatomical obstacle, this was classified as functional reentry, the behavior of which is determined by local electrophysiological properties [29,30].…”

Functional reentry and circus movement arrhythmias in the small intestine of normal and diabetic rats

“…Previously, reentrant activity and circus movements in smooth muscle organs have been shown in the canine stomach (17), the pig stomach (19), and the rat pregnant uterus (13). Furthermore, since the circuits were revolving in the absence of an anatomical obstacle, we may classify this type of reentrant activity as functional reentry, i.e., determined by local electrophysiological properties (1,26).…”

Gastric Arrhythmias in Gastroparesis

“…44 A surprising complexity to gastric arrhythmias is being revealed, necessitating new terms and classification schemes adapted from cardiology, including focal events and re-entry as mechanisms of tachygastria, and conduction block and retrograde escape rhythms as mechanism of bradygastria. 19,46 It has also been possible to assess the dynamic evolution of arrhythmic patterns through time, including defining wavefront interactions and collisions.…”

“…10,19 Under this schema, it can be surmised that disorders of slow wave initiation result from abnormalities to intrinsic ICC frequencies, whereas disorders of conduction result from disruption to slow wave entrainment through ICC networks. 20 …”