High-resolution Mapping of Hyperglycemia-induced Gastric Slow Wave Dysrhythmias

BACKGROUND/AIMS: It is now recognised that gastric dysrhythmias are best characterised by their spatial propagation pattern. Hyperglycemia is an important cause of gastric slow wave dysrhythmia, however, the spatiotemporal patterns of dysrhythmias in this context have not been investigated. This study aims to investigate the relationship between hyperglycemia and the patterns of dysrhythmias by employing high-resolution (multi-electrode) mapping simultaneously at the anterior and posterior gastric serosa. METHODS: High-resolution mapping (8 × 16 electrodes per serosal) was performed in 4 anesthetized hounds. Baseline recordings (21 ± 8 minutes) were followed by intravenous injection of glucagon (0.5 mg per dose) and further recordings (59 ± 15 minutes). Blood glucose levels were monitored manually using a glucose sensing kit at regular 5-minute intervals. Slow wave activation maps, amplitudes, velocity, anisotropic ratio, and frequency were calculated. Differences were compared between baseline and post glucagon injection. RESULTS: Baseline slow waves propagated symmetrically and antegrade. The blood glucose levels were increased by an average of 112% compared to the baseline by the end of the recordings. All subjects demonstrated elevated incidence of slow wave dysrhythmias following injection compared to the baseline (48 ± 23% vs 6 ± 4%, P < 0.05). Dysrhythmias arose simultaneously or independently on anterior and posterior serosa. Spatial dysrhythmias occurred before and persisted after the onset and disappearance of temporal dysrhythmias. CONCLUSIONS: Infusion of glucagon induced gastric slow wave dysrhythmias, which occurred across a heterogeneous range of patterns and frequencies. The spatial dysrhythmias of gastric slow waves were shown to be more prevalent and persisted over a longer period of time compared to the temporal dysrhythmias.

Measuring Gastrointestinal Electrical Activity With Extracellular Electrodes

No abstract available.

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

BACKGROUND/AIMS: Small intestine motility is governed by an electrical slow wave activity, and abnormal slow wave events have been associated with intestinal dysmotility. High-resolution (HR) techniques are necessary to analyze slow wave propagation, but progress has been limited by few available electrode options and laborious manual analysis. This study presents novel methods for in vivo HR mapping of small intestine slow wave activity. METHODS: Recordings were obtained from along the porcine small intestine using flexible printed circuit board arrays (256 electrodes; 4 mm spacing). Filtering options were compared, and analysis was automated through adaptations of the falling-edge variable-threshold (FEVT) algorithm and graphical visualization tools. RESULTS: A Savitzky-Golay filter was chosen with polynomial-order 9 and window size 1.7 seconds, which maintained 94% of slow wave amplitude, 57% of gradient and achieved a noise correction ratio of 0.083. Optimized FEVT parameters achieved 87% sensitivity and 90% positive-predictive value. Automated activation mapping and animation successfully revealed slow wave propagation patterns, and frequency, velocity, and amplitude were calculated and compared at 5 locations along the intestine (16.4 +/- 0.3 cpm, 13.4 +/- 1.7 mm/sec, and 43 +/- 6 microV, respectively, in the proximal jejunum). CONCLUSIONS: The methods developed and validated here will greatly assist small intestine HR mapping, and will enable experimental and translational work to evaluate small intestine motility in health and disease.