Volume 135, Issue 5, Pages 1601-1611 (November 2008) Focal Activities and Re-Entrant Propagations as Mechanisms of Gastric Tachyarrhythmias  Wim J.E.P. Lammers, Luc Ver Donck, Betty Stephen, Dirk Smets, Jan A.J. Schuurkes  Gastroenterology  Volume 135, Issue 5, Pages 1601-1611 (November 2008) DOI: 10.1053/j.gastro.2008.07.020 Copyright © 2008 AGA Institute Terms and Conditions

Figure 1 Reconstruction of slow-wave propagation in the canine stomach. Panel A indicates the topographical location of the 240 electrode assembly on the distal corpus and the antrum of the canine stomach (similar representation of the site of recording on the stomach will be used in Figures 2–6). A set of 13 electrograms was selected from the indicated electrode sites and plotted in panel B. The timings of the 13 individual slow waves were manually identified (red bars), and the local activation times (in seconds) were plotted. Panel C: Plot of all the local activation times. The pylorus area (at the left in the map) was not excited by the slow wave. Isochrone lines were drawn around areas activated in time steps of 1 second. Panel D: False colors replace activation times, and an arrow is drawn to indicate the major pathway of slow-wave propagation. Gastroenterology 2008 135, 1601-1611DOI: (10.1053/j.gastro.2008.07.020) Copyright © 2008 AGA Institute Terms and Conditions

Figure 2 Slow-wave propagation during a tachygastric burst. Upper electrogram: Continuous 3-minute recording from the canine antrum, recorded from a site indicated in the maps with the bull mark symbol, demonstrating repeated short bursts of tachygastrias. The box in the middle indicates the burst that was expanded in the lower electrogram and selected for the analysis presented in the 5 propagation maps. Red bars in A–E indicate the periods shown in each of the maps below. N, normal slow-wave propagation; P, premature slow wave; R, slow wave induced by reentry. See text for the description of the propagation maps in A–E. Gastroenterology 2008 135, 1601-1611DOI: (10.1053/j.gastro.2008.07.020) Copyright © 2008 AGA Institute Terms and Conditions

Figure 3 Initiation of premature slow waves and reentry. The upper electrograms display 3 sequences of normal slow-wave propagations (A–C) followed by a premature slow wave in B and a brief burst in C. The lower maps display the slow-wave propagations during these sequences. In all 3 cases, the first slow wave propagated normally from corpus to distal antrum (A, B1, C1). In map B2, a premature slow wave occurred in the antrum, 3.6 seconds after the initiation of the previous slow wave. This premature slow wave (at t = 4.0 seconds) propagated toward the lesser curvature for approximately 2 cm and 2 seconds until a block occurred. The waveforms recorded during this sequence are displayed in the corresponding isochrone colors (blue, red, and brown isochrones in channels 6–14; propagation B). In C2, again a premature wave occurred. This time however, the premature wave was not blocked but continued to propagate, describing a clockwise loop and a counterclockwise loop at t = 8.0 seconds (map C2), both of which reexcited the antrum at t = 9.0 seconds (map C3). Gastroenterology 2008 135, 1601-1611DOI: (10.1053/j.gastro.2008.07.020) Copyright © 2008 AGA Institute Terms and Conditions

Figure 4 Occasional abnormal slow-wave propagation. Upper panel: Tracings recorded from corpus to distal antrum show in A a normal sequence of propagation, whereas, in B, the oral electrograms were slightly delayed. Map A shows a normal propagation pattern. Map B shows the next slow wave propagating from the corpus, together with a second slow wave entering from the greater curvature and a third entering from the lesser curvature. Both additional impulses merged in the middle of the antrum and propagated further toward the distal antrum. Gastroenterology 2008 135, 1601-1611DOI: (10.1053/j.gastro.2008.07.020) Copyright © 2008 AGA Institute Terms and Conditions

Figure 5 Slow-wave propagation during episodes of regular tachygastrias in 2 different dogs (A and B). Electrograms from dog A show regular high-frequency (12.0 cycle/min) slow-wave activity. Two sequential propagations, A1 and A2, are plotted in the right-hand maps and show that activity continuously emerged from the distal end of the greater curvature and propagated uniformly and retrogradely toward the corpus. In dog B (lower panels), a regular high-frequency activity (11.1 c/min) emerged along the middle of the greater curvature but was consistently blocked midway of the antrum and excited an additional area in every other cycle (B2). Gastroenterology 2008 135, 1601-1611DOI: (10.1053/j.gastro.2008.07.020) Copyright © 2008 AGA Institute Terms and Conditions

Figure 6 Slow-wave propagation during irregular tachygastria. Upper traces display continuous variations in waveform amplitudes and directions. Four periods (A–D) were selected, and the corresponding maps are presented in the lower panels. Map A shows a major waveform originating from the distal antrum propagating retrogradely and colliding with a second slow wave descending from the corpus. Map B shows again a slow wave with a distal antral origin and 2 premature waves originating simultaneously close to the corpus (blue isochrone). These 3 waveforms then merged in the middle of the antrum. Map C shows 2 waveforms, one propagating close to the lesser curvature and another one propagating close to the greater curvature; they collided with each other in the distal antrum. In map D, a reentrant wave (red isochrone; t = 34.0 seconds) revolved as a large counterclockwise loop in the middle of the antrum. Gastroenterology 2008 135, 1601-1611DOI: (10.1053/j.gastro.2008.07.020) Copyright © 2008 AGA Institute Terms and Conditions