An Improved Method for the Estimation and Visualization of Velocity Fields from Gastric High-Resolution Electrical Mapping

Paskaranandavadivel, Niranchan; OrGrady, G.; Du, Peng; Pullan, Andrew J.; Cheng, Leo K.

doi:10.1109/tbme.2011.2181845

Cited by 45 publications

(53 citation statements)

References 24 publications

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“…31 Velocity was calculated using a finite difference method with Gaussian-smoothing filter, and visualized using directional arrows on a color-gradient speed map. 32 In addition, velocity was secondarily averaged across regions of circumferential and longitudinal propagation, to investigate conduction anisotropy. 33 Amplitudes were calculated by applying a peak-to-trough detection algorithm.…”

Section: Methodsmentioning

confidence: 99%

Loss of Interstitial Cells of Cajal and Patterns of Gastric Dysrhythmia in Patients With Chronic Unexplained Nausea and Vomiting

et al. 2015

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Background & Aims Chronic unexplained nausea and vomiting (CUNV) is a debilitating disease of unknown cause. Symptoms of CUNV substantially overlap with those of gastroparesis, so the diseases therefore may share pathophysiologic features. We investigated this hypothesis by quantifying densities of interstitial cells of Cajal (ICCs) and mapping slow wave abnormalities in patients with CUNV vs controls. Methods Clinical data and gastric biopsy specimens were collected from 9 consecutive patients with at least 6 months of continuous symptoms of CUNV, but normal gastric emptying, treated at the University of Mississippi Medical Center, and from 9 controls (individuals undergoing bariatric surgery but free of gastrointestinal disease or diabetes). ICCs were counted and ultrastructural analyses were performed on tissue samples. Slow-wave propagation profiles were defined by high-resolution electrical mapping (256 electrodes; 36 cm2). Results from patients with CUNV were compared to those of controls as well as patients with gastroparesis who were previously studied by identical methods. Results Patients with CUNV had fewer ICCs than controls (mean 3.5 vs 5.6 bodies/field; P<.05), with mild ultrastructural abnormalities in the remaining ICCs. Slow-wave dysrhythmias were identified in all 9 subjects with CUNV vs only 1/9 controls. Dysrhythmias included abnormalities of initiation (stable ectopic pacemakers, unstable focal activities) and conduction (retrograde propagation, wave front collisions, conduction blocks, and re-entry), operating across bradygastric, normal (range 2.4−3.7 cycles/min), and tachygastric frequencies; dysrhythmias showed velocity anisotropy (mean 3.3 mm/s longitudinal vs 7.6 mm/s circumferential, P<.01). ICCs were less depleted in patients with CUNV than those with gastroparesis (mean 3.5 vs 2.3 bodies/field; P<.05), but slow-wave dysrhythmias were similar between groups. Conclusions This study defined cellular and bioelectrical abnormalities in patients with CUNV, including the identification of slow-wave re-entry. Pathophysiologic features of CUNV were observed to be similar to those of gastroparesis, indicating that they could be spectra of the same disorder. These findings offer new insights into the pathogenesis of CUNV and may help to inform future treatments.

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Section: Methodsmentioning

confidence: 99%

Loss of Interstitial Cells of Cajal and Patterns of Gastric Dysrhythmia in Patients With Chronic Unexplained Nausea and Vomiting

et al. 2015

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“…All data analysis was performed in the Gastrointestinal Electrical Mapping Suite (GEMS) software (v1.5) (Yassi, O'Grady et al 2012). Details of filtering (Paskaranandavadivel, O'Grady et al 2013), slow wave event and dysrhythmia detection, and data presentation methods (activation, amplitude and velocity mapping) were reported in detail a previous set of studies (O'Grady, Egbuji et al 2011; O'Grady, Angeli et al 2012; Paskaranandavadivel, O'Grady et al 2012). Unless otherwise mentioned, the data are reported in mean ± SEM.…”

Section: Methodsmentioning

confidence: 99%

A theoretical study of the initiation, maintenance and termination of gastric slow wave re-entry

Paskaranandavadivel

O’Grady

et al. 2014

Math Med Biol

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Gastric slow wave dysrhythmias are associated with motility disorders. Periods of tachygastria associated with slow wave re-entry were recently recognized as one important dysrhythmia mechanism, but factors promoting and sustaining gastric reentry are currently unknown. This study reports two experimental forms of gastric re-entry and presents a series of multi-scale models that define criteria for slow wave re-entry initiation, maintenance, and termination. High-resolution electrical mapping was conducted in porcine and canine models and two spatiotemporal patterns of re-entrant activities were captured: single-loop rotor and double-loop figure-of-eight. Two separate multi-scale mathematical models were developed to reproduce the velocity and entrainment frequency of these experimental recordings. A single-pulse stimulus was used to invoke a rotor re-entry in the porcine model and a figure-of-eight re-entry in the canine model. In both cases, the simulated re-entrant activities were found to be perpetuated by tachygastria that was accompanied by a reduction in the propagation velocity in the re-entrant pathways. The simulated re-entrant activities were terminated by a single-pulse stimulus targeted at the tip of re-entrant wave, after which normal antegrade propagation was restored by the underlying intrinsic frequency gradient. Main findings: (i) the stability of re-entry is regulated by stimulus timing, intrinsic frequency gradient and conductivity; (ii) tachygastria due to re-entry increases the frequency gradient while showing decreased propagation velocity; (iii) re-entry may be effectively terminated by a targeted stimulus at the core, allowing the intrinsic slow wave conduction system to re-establish itself.

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“…The amplitude and velocity of each wavefront were also calculated using methods previously described [8], [14]. …”

Section: Methodsmentioning

confidence: 99%

Automated classification of spatiotemporal characteristics of gastric slow wave propagation

Paskaranandavadivel

Gao

et al. 2013

2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

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Gastric contractions are underpinned by an electrical event called slow wave activity. High-resolution electrical mapping has recently been adapted to study gastric slow waves at a high spatiotemporal detail. As more slow wave data becomes available, it is becoming evident that the spatial organization of slow wave plays a key role in the initiation and maintenance of gastric dsyrhythmias in major gastric motility disorders. All of the existing slow wave signal processing techniques deal with the identification and partitioning of recorded wave events, but not the analysis of the slow wave spatial organization, which is currently performed visually. This manual analysis is time consuming and is prone to observer bias and error. We present an automated approach to classify spatial slow wave propagation patterns via the use of Pearson cross correlations. Slow wave propagations were grouped into classes based on their similarity to each other. The method was applied to high-resolution gastric slow wave recordings from four pigs. There were significant changes in the velocity of the gastric slow wave wavefront and the amplitude of the slow wave event when there was a change in direction to the slow wave wavefront during dsyrhythmias, which could be detected with the automated approach.

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An Improved Method for the Estimation and Visualization of Velocity Fields from Gastric High-Resolution Electrical Mapping

Cited by 45 publications

References 24 publications

Loss of Interstitial Cells of Cajal and Patterns of Gastric Dysrhythmia in Patients With Chronic Unexplained Nausea and Vomiting

Loss of Interstitial Cells of Cajal and Patterns of Gastric Dysrhythmia in Patients With Chronic Unexplained Nausea and Vomiting

A theoretical study of the initiation, maintenance and termination of gastric slow wave re-entry

Automated classification of spatiotemporal characteristics of gastric slow wave propagation

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