Of Slow Waves and Spike Patches

In the small intestines, the major task of the slow wave is to induce mechanical movements in the intestinal wall by generating local calcium spikes. High resolution electrical mapping reveals fundamental differences in propagation between slow waves and calcium spikes. These differences suggest that slow waves and spikes are propagated by different mechanisms through different cell networks.

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Slow-wave coupling across a gastroduodenal anastomosis as a mechanism for postsurgical gastric dysfunction: evidence for a “gastrointestinal aberrant pathway”

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00002.2019 ◽

2019 ◽

Vol 317 (2) ◽

pp. G141-G146 ◽

Cited By ~ 3

Author(s):

Tim H.-H. Wang ◽

Timothy R. Angeli ◽

Grant Beban ◽

Peng Du ◽

Francesca Bianco ◽

...

Keyword(s):

High Resolution ◽

Slow Wave ◽

Electrical Conduction ◽

Interstitial Cells Of Cajal ◽

Revisional Surgery ◽

Interstitial Cells ◽

Slow Waves ◽

Conduction Pathway ◽

Electrical Mapping ◽

Cells Of Cajal

Postsurgical gastric dysfunction is common, but the mechanisms are varied and poorly understood. The pylorus normally acts as an electrical barrier isolating gastric and intestinal slow waves. In this report, we present an aberrant electrical conduction pathway arising between the stomach and small intestine, following pyloric excision and surgical anastomosis, as a novel disease mechanism. A patient was referred with postsurgical gastroparesis following antrectomy, gastroduodenostomy, and vagotomy for peptic ulceration. Scintigraphy confirmed markedly abnormal 4-h gastric retention. Symptoms included nausea, vomiting, postprandial distress, and reflux. Intraoperative, high-resolution electrical mapping was performed across the anastomosis immediately before revision gastrectomy, and the resected anastomosis underwent immunohistochemistry for interstitial cells of Cajal. Mapping revealed continuous, stable abnormal retrograde slow-wave propagation through the anastomosis, with slow conduction occurring at the scar (4.0 ± 0.1 cycles/min; 2.5 ± 0.6 mm/s; 0.26 ± 0.15 mV). Stable abnormal retrograde propagation continued into the gastric corpus with tachygastria (3.9 ± 0.2 cycles/min; 1.6 ± 0.5 mm/s; 0.19 ± 0.12 mV). Histology confirmed ingrowth of atypical ICC through the scar, defining an aberrant pathway enabling transanastomotic electrical conduction. In conclusion, a “gastrointestinal aberrant pathway” is presented as a novel proposed cause of postsurgical gastric dysfunction. The importance of aberrant anastomotic conduction in acute and long-term surgical recovery warrants further investigation. NEW & NOTEWORTHY High-resolution gastric electrical mapping was performed during revisional surgery in a patient with severe gastric dysfunction following antrectomy and gastroduodenostomy. The results revealed continuous propagation of slow waves from the duodenum to the stomach, through the old anastomotic scar, and resulting in retrograde-propagating tachygastria. Histology showed atypical interstitial cells of Cajal growth through the anastomotic scar. Based on these results, we propose a “gastrointestinal aberrant pathway” as a mechanism for postsurgical gastric dysfunction.

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High-resolution mapping of gastric slow-wave recovery profiles: biophysical model, methodology, and demonstration of applications

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00127.2017 ◽

2017 ◽

Vol 313 (3) ◽

pp. G265-G276 ◽

Cited By ~ 12

Author(s):

N. Paskaranandavadivel ◽

L. K. Cheng ◽

P. Du ◽

J. M. Rogers ◽

G. O’Grady

Keyword(s):

Wave Propagation ◽

Wavelet Transform ◽

High Resolution ◽

Slow Wave ◽

Recovery Phase ◽

Slow Waves ◽

Gastric Slow Wave ◽

High Resolution Mapping ◽

Resolution Mapping ◽

Extracellular Potentials

Slow waves play a central role in coordinating gastric motor activity. High-resolution mapping of extracellular potentials from the stomach provides spatiotemporal detail on normal and dysrhythmic slow-wave patterns. All mapping studies to date have focused exclusively on tissue activation; however, the recovery phase contains vital information on repolarization heterogeneity, the excitable gap, and refractory tail interactions but has not been investigated. Here, we report a method to identify the recovery phase in slow-wave mapping data. We first developed a mathematical model of unipolar extracellular potentials that result from slow-wave propagation. These simulations showed that tissue repolarization in such a signal is defined by the steepest upstroke beyond the activation phase (activation was defined by accepted convention as the steepest downstroke). Next, we mapped slow-wave propagation in anesthetized pigs by recording unipolar extracellular potentials from a high-resolution array of electrodes on the serosal surface. Following the simulation result, a wavelet transform technique was applied to detect repolarization in each signal by finding the maximum positive slope beyond activation. Activation-recovery (ARi) and recovery-activation (RAi) intervals were then computed. We hypothesized that these measurements of recovery profile would differ for slow waves recorded during normal and spatially dysrhythmic propagation. We found that the ARi of normal activity was greater than dysrhythmic activity (5.1 ± 0.8 vs. 3.8 ± 0.7 s; P < 0.05), whereas RAi was lower (9.7 ± 1.3 vs. 12.2 ± 2.5 s; P < 0.05). During normal propagation, RAi and ARi were linearly related with negative unit slope indicating entrainment of the entire mapped region. This relationship was weakened during dysrhythmia (slope: −0.96 ± 0.2 vs −0.71 ± 0.3; P < 0.05). NEW & NOTEWORTHY The theoretical basis of the extracellular gastric slow-wave recovery phase was defined using mathematical modeling. A novel technique utilizing the wavelet transform was developed and validated to detect the extracellular slow-wave recovery phase. In dysrhythmic wavefronts, the activation-to-recovery interval (ARi) was shorter and recovery-to-activation interval (RAi) was longer compared with normal wavefronts. During normal activation, RAi vs. ARi had a slope of −1, whereas the weakening of the slope indicated a dysrhythmic propagation.

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High-resolution electrical mapping of porcine gastric slow-wave propagation from the mucosal surface

Neurogastroenterology & Motility ◽

10.1111/nmo.13010 ◽

2016 ◽

Vol 29 (5) ◽

pp. e13010 ◽

Cited By ~ 16

Author(s):

T. R. Angeli ◽

P. Du ◽

N. Paskaranandavadivel ◽

S. Sathar ◽

A. Hall ◽

...

Keyword(s):

Wave Propagation ◽

High Resolution ◽

Slow Wave ◽

Mucosal Surface ◽

Gastric Slow Wave ◽

Electrical Mapping

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Intraoperative serosal extracellular mapping of the human distal colon: a feasibility study

BioMedical Engineering OnLine ◽

10.1186/s12938-021-00944-x ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Anthony Y. Lin ◽

Chris Varghese ◽

Peng Du ◽

Cameron I. Wells ◽

Niranchan Paskaranandavadivel ◽

...

Keyword(s):

High Resolution ◽

Electrical Activity ◽

Motor Pattern ◽

Distal Colon ◽

Human Colon ◽

Slow Waves ◽

Electrode Spacing ◽

Post Operative Period ◽

Electrical Mapping ◽

Spike Wave

Abstract Background Cyclic motor patterns (CMP) are the predominant motor pattern in the distal colon, and are important in both health and disease. Their origin, mechanism and relation to bioelectrical slow-waves remain incompletely understood. During abdominal surgery, an increase in the CMP occurs in the distal colon. This study aimed to evaluate the feasibility of detecting propagating slow waves and spike waves in the distal human colon through intraoperative, high-resolution (HR), serosal electrical mapping. Methods HR electrical recordings were obtained from the distal colon using validated flexible PCB arrays (6 × 16 electrodes; 4 mm inter-electrode spacing; 2.4 cm2, 0.3 mm diameter) for up to 15 min. Passive unipolar signals were obtained and analysed. Results Eleven patients (33–71 years; 6 females) undergoing colorectal surgery under general anaesthesia (4 with epidurals) were recruited. After artefact removal and comprehensive manual and automated analytics, events consistent with regular propagating activity between 2 and 6 cpm were not identified in any patient. Intermittent clusters of spike-like activities lasting 10–180 s with frequencies of each cluster ranging between 24 and 42 cpm, and an average amplitude of 0.54 ± 0.37 mV were recorded. Conclusions Intraoperative colonic serosal mapping in humans is feasible, but unlike in the stomach and small bowel, revealed no regular propagating electrical activity. Although sporadic, synchronous spike-wave events were identifiable. Alternative techniques are required to characterise the mechanisms underlying the hyperactive CMP observed in the intra- and post-operative period. New findings The aim of this study was to assess the feasibility of detecting propagating electrical activity that may correlate to the cyclic motor pattern in the distal human colon through intraoperative, high-resolution, serosal electrical mapping. High-resolution electrical mapping of the human colon revealed no regular propagating activity, but does reveal sporadic spike-wave events. These findings indicate that further research into appropriate techniques is required to identify the mechanism of hyperactive cyclic motor pattern observed in the intra- and post-operative period in humans.

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Experimental and Automated Analysis Techniques for High-resolution Electrical Mapping of Small Intestine Slow Wave Activity

Journal of Neurogastroenterology and Motility ◽

10.5056/jnm.2013.19.2.179 ◽

2013 ◽

Vol 19 (2) ◽

pp. 179-191 ◽

Cited By ~ 24

Author(s):

Timothy R Angeli ◽

Gregory O'Grady ◽

Niranchan Paskaranandavadivel ◽

Jonathan C Erickson ◽

Peng Du ◽

...

Keyword(s):

Small Intestine ◽

High Resolution ◽

Slow Wave ◽

Automated Analysis ◽

Wave Activity ◽

Slow Wave Activity ◽

Analysis Techniques ◽

Electrical Mapping

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Validation of non-invasive body-surface gastric mapping for detecting electrophysiological biomarkers by simultaneous high-resolution serosal mapping in a porcine model

10.1101/2021.08.01.454685 ◽

2021 ◽

Author(s):

Stefan Calder ◽

Leo K Cheng ◽

Christopher Andrews ◽

Niranchan Paskaranandavadivel ◽

Stephen Waite ◽

...

Keyword(s):

High Resolution ◽

Slow Wave ◽

Body Surface ◽

Porcine Model ◽

Slow Waves ◽

Electrode Spacing ◽

Non Invasive ◽

Gastric Slow Waves ◽

The Relationship ◽

Gastric Mapping

Gastric disorders are increasingly prevalent, but reliable clinical tools to objectively assess gastric function are lacking. Body-surface gastric mapping (BSGM) is a non-invasive method for the detection of gastric electrophysiological biomarkers including slow wave direction, which have correlated with symptoms in patients with gastroparesis and functional dyspepsia. However, no studies have validated the relationship between gastric slow waves and body surface activation profiles. This study aimed to comprehensively evaluate the relationship between gastric slow waves and body-surface recordings. High-resolution electrode arrays were placed to simultaneously capture slow waves from the gastric serosa (32 x 6 electrodes at 4 mm resolution) and abdominal surface (8x8 at 20 mm inter-electrode spacing) in a porcine model. BSGM signals were extracted based on a combination of wavelet and phase information analyses. A total of 1185 individual cycles of slow waves assessed, out of which 897 (76%) were normal antegrade waves, occurring in 10/14 (71%) subjects studied. BSGM accurately detected the underlying slow wave in terms of frequency (r = 0.99, p = 0.43) as well as the direction of propagation (p = 0.41, F-measure: 0.92). In addition, the cycle-by-cycle match between BSGM and transitions of gastric slow waves in terms either or both temporal and spatial abnormalities was demonstrated. These results validate BSGM as a suitable method for non-invasively and accurately detecting gastric slow wave activation profiles from the body surface.

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