Electrogastrography: its role in managing gastric disorders

Vectorgastrogram: dynamic trajectory and recurrence quantification analysis to assess slow wave vector movement in healthy subjects

Functional gastric disorders entail chronic or recurrent symptoms, high prevalence and a significant financial burden. These disorders do not always involve structural abnormalities and since they cannot be diagnosed by routine procedures, electrogastrography (EGG) has been proposed as a diagnostic alternative. However, the method still has not been transferred to clinical practice due to the difficulty of identifying gastric activity because of the low-frequency interference caused by skin-electrode contact potential in obtaining spatiotemporal information by simple procedures. This work attempted to robustly identify the gastric slow wave (SW) main components by applying multivariate variational mode decomposition (MVMD) to the multichannel EGG. Another aim was to obtain the 2D SW vectorgastrogram VGGSW from 4 electrodes perpendicularly arranged in a T-shape and analyse its dynamic trajectory and recurrence quantification (RQA) to assess slow wave vector movement in healthy subjects. The results revealed that MVMD can reliably identify the gastric SW, with detection rates over 91% in fasting postprandial subjects and a frequency instability of less than 5.3%, statistically increasing its amplitude and frequency after ingestion. The VGGSW dynamic trajectory showed a statistically higher predominance of vertical displacement after ingestion. RQA metrics (recurrence ratio, average length, entropy, and trapping time) showed a postprandial statistical increase, suggesting that gastric SW became more intense and coordinated with a less complex VGGSW and higher periodicity. The results support the VGGSW as a simple technique that can provide relevant information on the "global" spatial pattern of gastric slow wave propagation that could help diagnose gastric pathologies.

Advanced Bioelectrical Signal Processing Methods: Past, Present, and Future Approach-Part III: Other Biosignals

Analysis of biomedical signals is a very challenging task involving implementation of various advanced signal processing methods. This area is rapidly developing. This paper is a Part III paper, where the most popular and efficient digital signal processing methods are presented. This paper covers the following bioelectrical signals and their processing methods: electromyography (EMG), electroneurography (ENG), electrogastrography (EGG), electrooculography (EOG), electroretinography (ERG), and electrohysterography (EHG).

Gastric slow wave rhythm identification using new approach based on noise-assisted multivariate empirical mode decomposition and Hilbert-Huang transform

BACKGROUND

Electrogastrography (EGG) is the method of cutaneous recording of the myoelectrical activity of the stomach. A multi-channel signal is recorded non-invasively by means of electrodes placed outside the epigastric area. The normal electrical rhythm of the stomach (slow wave) may become significantly disturbed due to disorders of gastrointestinal tract. Abnormally fast electrical rhythms are termed tachygastria, while abnormally slow rhythms are known as bradygastria. Because some features of biological signals may go undetected using the classical methods of signal spectral analysis, we propose a new method for EGG rhythm identification.

METHODS

In this study, the calculation of the basic rhythms of multi-channel EGG signals is performed by means of the noise-assisted multivariate empirical mode decomposition (NA-MEMD) and Hilbert-Huang transform (HHT), using EGG data from eight healthy subjects. The results were compared with those obtained using classical spectral analysis.

KEY RESULTS

The mean values of the normogastric index for preprandial and two postprandial stages were found to be 64.78 ± 11.37%, 61.29 ± 15.86%, and 63.80 ± 13.24%, respectively. The obtained values of normogastric index are consistent with the normal human physiological value, which is approximately 70% for healthy subjects.

CONCLUSIONS

This method is able to capture features of the signal which are mostly undetectable by standard EGG processing methods. The EGG dominant rhythm identification using the instantaneous normogastric, bradygastric, and tachygastric indices provides new insights into biological EGG patterns.

Assessment of slow wave propagation in multichannel electrogastrography by using noise-assisted multivariate empirical mode decomposition and cross-covariance analysis

Electrogastrography (EGG) is a noninvasive technique for recording the myoelectrical activity of the stomach. An electrogastrographic signal recorded by using a four-channel system with electrodes placed on the surface of the skin is a mixture of a low-frequency gastric pacesetter potential known as a slow wave, electrical activity from other organs, and random noise. The aim of this work was to investigate the possibility of detecting the propagation of the gastric slow wave from multichannel EGG data. Noise-assisted multivariate empirical mode decomposition (NA-MEMD) and cross-covariance analysis (CCA) are proposed as new detection tools. NA-MEMD was applied to attenuate the noise and extract the EGG signal from four channels, while CCA was performed to assess the time shift between the EGG signal channels. Validation of the method was performed using synthetic EGG signals and the methodology was tested on four young, healthy adults. After validation, the proposed method was applied for two kinds of human EGG data: 10-min (short) EGG data from the preprandial phase and 90-120-min (long) EGG data from the preprandial phase as well as the postprandial phase. The results obtained for both synthetic and human EGG data confirm that the proposed method could be a useful tool for assessing the propagation of slow waves. The time shift calculation from the preprandial phase of the EGG examination yielded more consistent results than the postprandial phase. The mean value of the slow wave time lag between neighbouring channels for synthetic data was found to be 4.99±0.47 s. In addition, it was confirmed that the proposed method, that is, NA-MEMD and CCA together, are robust to noise.

Empirical Mode Decomposition for slow wave extraction from electrogastrographical signals

The aim of this study was to investigate the effectiveness of Empirical Mode Decomposition (EMD) for slow wave extraction from multichannel electrogastrographical signal (EGG) the cutaneous recording of gastric myoelectrical activity. From the pacemaker region of stomach both spontaneous depolarization and repolarization occur generating the myoelectrical waves that are called the gastric pacesetter potentials, or slow waves. The 3 cycles per minute (3pcm) (0.05Hz) slow wave is fundamental electrical phenomenon in stomach responsible for the propagation and maximum frequency of stomach contractions. Appropriate spread of gastric contractions is a key for the correct stomach emptying whereas delay in this action causes various gastric disorders, such as bloating, vomiting or unexplained nausea. Unfortunately the EGG signal is not a pure one but usually a sort of mixture consisting of respiratory signals, cardiac signals, random noise and possible myoelectrical activity from other organs surrounding the stomach, such as duodenum or small intestine. Identify and removal of contaminations from different artifactual sources from the EGG recording is a major task before EGG analysis and interpretation. The use of EMD method and Hilbert spectrum combination for slow wave extraction from raw EGG signal seems to be a good choice, because this adaptive decomposition technique is unique suitable for both nolinear, no-stationary data analysis.

Gastric motility following ingestion of a solid meal in a cohort of adult asthmatics

BACKGROUND/AIMS

Asthmatics have abnormal esophageal motility and increased prevalence of gastroesophageal reflux disease (GERD). The contribution of gastric motility is less studied. We studied gastric myoelectrical activity, gastric emptying (GE) and their association with GERD symptoms and vagal function in adult asthmatics.

METHODS

Thirty mild, stable asthmatics and 30 healthy controls underwent real-time ultrasonography and 1 hour pre- and post-prandial cutaneous electrogastrography, following a test meal (480 kcal, 60% carbohydrate, 20% protein, 20% fat and 200 mL water). The percentage of normal slow waves and arrhythmias, dominant frequency and power, frequency of antral contractions, gastric emptying rate (GER) and antral motility index (MI) was calculated. Twenty-seven asthmatics underwent gastroscopy and in all subjects GERD symptoms were assessed by a validated questionnaire. Vagal function parameters were correlated with gastric motility parameters.

RESULTS

The asthmatics (37% male; 34.8 ± 8.4 years) and controls (50% male; 30.9 ± 7.7 years) were comparable. None had endoscopic gastric pathological changes. Twenty asthmatics described GERD symptoms. Twenty-two (73.3%) asthmatics showed a hypervagal response. Compared to controls, asthmatics had delayed GER and lower MI, lower percentage of normal gastric slow waves, more gastric dysrythmias and failed to increase the post-prandial dominant power. There was no correlation of GE and cutaneous electrogastrography parameters with presence of GERD symptoms or with vagal function.

CONCLUSIONS

Asthmatics showed abnormal gastric myoelectrical activity, delayed GE and antral hypomotility in response to a solid meal compared to controls. There was no association with vagal function or GERD symptom status.

Electrogastrographic characteristics in subjects with stomach remnant

BACKGROUND AND AIMS

Slow wave (SW) is an essential component in mediating stomach motility. The purpose of the present study was to investigate the SW characteristics in subjects with stomach remnant.

METHODS

We consecutively enrolled 58 distal radical subtotal gastrectomy (RSG) patients (male/female: 44/14, age: 33-79 years) to receive an electrogastrographic (EGG) measurement. Their Helicobacter pylori status and dyspeptic score were simultaneously assessed. In addition, EGG data of 58 age- and sex-matched healthy subjects were compared. Based on power spectral analysis, the following EGG parameters were derived: dominant frequency (DF)/power (DP), percentage of normal rhythm (2-4 cpm), power ratio (PR) referring the postprandial power change, etc.

RESULTS

Visual analysis occasionally found a short period of approximately 11 cpm myoelectricity-like rhythm. Distal RSG patients had lower fasting (1.90 +/- 0.69 vs 2.97 +/- 0.58 cpm, P < 0.001) and postprandial (2.03 +/- 0.72 vs 3.35 +/- 0.27 cpm, P < 0.001) DF values, while their fasting (36.2 +/- 22.3% vs 67.1 +/- 23.4%, P < 0.001) and postprandial (33.4 +/- 19.9% vs 82.2 +/- 16.7%, P < 0.001) percentages of normal rhythms were diminished. In contrast, fasting DP, its meal response and PR (2.99 +/- 2.40 vs 2.45 +/- 2.63, NS) were comparable to those of controls. Neither gender, age, type of gastroenterostomy, Helicobacter pylori colonization, dyspeptic score nor elapsed time after surgery had an obvious influence on EGG parameters.

CONCLUSIONS

Distal RSG patients may have decreased SW frequency and less meal ingestion changed EGG parameters in terms of SW frequency, normality and stability, whereas their EGG power remained unchanged irrespective of meal ingestion.

Every slow-wave impulse is associated with motor activity of the human stomach

Using a newly developed high-resolution three-dimensional magnetic detector system (3D-MAGMA), we observed periodical movements of a small magnetic marker in the human stomach at the typical gastric slow-wave frequency, that is 3 min(-1). Thus we hypothesized that each gastric slow wave induces a motor response that is not strong enough to be detected by conventional methods. Electrogastrographies (EGG, Medtronic, Minneapolis, MN) for measurement of gastric slow waves and 3D-MAGMA (Innovent, Jena, Germany) measurements were simultaneously performed in 21 healthy volunteers (10 men, 40.4+/-13.6 yr; 11 women, 35.8+/-11.6 yr). The 3D-MAGMA system contains 27 highly sensitive magnetic field sensors that are able to locate a magnetic pill inside a human body with an accuracy of +/-5 mm or less in position and +/-2 degrees in orientation at a frequency of 50 Hz. Gastric transit time of the magnetic marker ranged from 19 to 154 min. The mean dominant EGG frequency while the marker was in the stomach was 2.87+/-0.15 cpm. The mean dominant 3D-MAGMA frequency during this interval was nearly identical; that is, 2.85+/-0.15 movements per minute. We observed a strong linear correlation between individual dominant EGG and 3D-MAGMA frequency (R=0.66, P=0.0011). Our findings suggest that each gastric slow wave induces a minute contraction that is too small to be detected by conventional motility investigations but can be recorded by the 3D-MAGMA system. The present slow-wave theory that assumes that the slow wave is a pure electrical signal should be reconsidered.

High-resolution mapping of in vivo gastrointestinal slow wave activity using flexible printed circuit board electrodes: methodology and validation

High-resolution, multi-electrode mapping is providing valuable new insights into the origin, propagation, and abnormalities of gastrointestinal (GI) slow wave activity. Construction of high-resolution mapping arrays has previously been a costly and time-consuming endeavor, and existing arrays are not well suited for human research as they cannot be reliably and repeatedly sterilized. The design and fabrication of a new flexible printed circuit board (PCB) multi-electrode array that is suitable for GI mapping is presented, together with its in vivo validation in a porcine model. A modified methodology for characterizing slow waves and forming spatiotemporal activation maps showing slow waves propagation is also demonstrated. The validation study found that flexible PCB electrode arrays are able to reliably record gastric slow wave activity with signal quality near that achieved by traditional epoxy resin-embedded silver electrode arrays. Flexible PCB electrode arrays provide a clinically viable alternative to previously published devices for the high-resolution mapping of GI slow wave activity. PCBs may be mass-produced at low cost, and are easily sterilized and potentially disposable, making them ideally suited to intra-operative human use.

Electrogastrography in the management of pediatric functional dyspepsia and motility disorder

PURPOSE

Electrogastrography (EGG) is a noninvasive investigation for recording gastric myoelectrical activity. We hypothesize that children with functional dyspepsia (FD) and gastrointestinal (GI) motility disorder have abnormal gastric myoelectrical activity. We aim to study the dyspepsia symptom scores and EGG of these children and compare them with those of the normal population.

METHODS

Seventeen children aged 6 to 18 years with persistent dyspepsia symptoms but with normal investigations were recruited as the FD group. Nine children with same age as the FD group with known upper GI motility disorder were recruited as the GI group. Eight normal healthy children were recruited as controls (CL). Dyspepsia symptom score (0-18) was charted, and all had EGG performed. Gastric slow wave frequency of 2 to 4 cycles per minute is defined as normogastria. Electrogastrography is regarded as abnormal when normogastria occurs in less than 70% of recorded time. Wilcoxon rank sum test and Fisher's Exact test were performed with statistical significance at P value equal to .05.

RESULTS

Mean dyspepsia symptom score was significantly different in comparing FD and GI with CL groups (FD, 6.71; GI, 5.54; CL, 0.25; P < .001). Abnormal EGG patterns occur more often in FD than in CL (FD, 58.9%; CL, 12.5%; P = .042). Abnormal EGG patterns were found in 55.6% of GI and 12.5% of CL (P = .131).

CONCLUSIONS

Electrogastrography is a useful and noninvasive armamentarium for evaluating the abnormal myoelectrical activity in children with FD and GI motility disorder.

Development of gastric slow waves and effects of feeding in pre-term and full-term infants

The aims of this study were to investigate the difference in developmental process of gastric slow waves and the effects of feeding in pre-term and full-term infants. Twenty-six pre-term and 31 full-term infants were enrolled in the study. Gastric myoelectrical activity was recorded using electrogastrography (EGG) from birth to month 6. An increase in the % of 2-4 cpm slow waves was noted in both pre-term (P < 0.01) and full-term infants (P < 0.04) from birth to month 4. The pre-term infants showed a reduced dominant EGG power at certain points of the study. (3) Breast or formula feeding resulted in no difference in the EGG in the full-term infants and showed a difference in the postprandial dominant power of the EGG in the pre-term infants only at month 2 after birth (P < 0.05) but not at other times. The gastric slow wave in pre-term infants is of a significantly reduced amplitude but similar rhythmicity. The method of feeding has no effects on the EGG in full-term infants and minimal effects (may be of non-clinical significance) on the EGG in pre-term infants as the difference was noted only at one time point during the 6-month follow-up study.

Electrogastrography in pediatric functional dyspepsia: relationship to gastric emptying and symptom severity

OBJECTIVES

The aims of this study were to determine the electrogastrographic patterns in children with functional dyspepsia and to investigate the correlations among electrogastrogram (EGG), gastric emptying (GE), and pain severity.

METHODS

We studied 30 children (19 F; mean age 11.4 years) with functional dyspepsia. Electrogastrography was performed for 30 minutes fasting and for 1 hour during a GE test after ingestion of an isotope-labeled solid meal. The percent emptying was measured every 10 minutes for 1 hour after the meal. The dominant frequency of the EGG, the change in the postprandial peak power (deltaP), and percent dysrhythmia during each recording session were calculated. Specific symptoms were graded from 0 (none) to 4 (severe) by the patient.

RESULTS

Of 30 patients, 14 (47%) had slow GE, and 15 (50%) had abnormal EGG (dysrhythmia > or = 30% or deltaP < 0). GE was slow in 73% of patients with an abnormal EGG but was slow in only 20% of patients with normal EGG (P = 0.009). GE was negatively correlated with fasting bradygastria (r = -0.383, P = 0.04). Abdominal pain was the most severe dyspeptic symptom, both during fasting and after the meal. Patients with an abnormal EGG had an increased mean pain severity score (3.5 +/- 0.2 vs. 2.5 +/- 0.2, P = 0.002).

CONCLUSIONS

Sixty percent of functional dyspepsia subjects had either slow GE or abnormal EGG. Patients with abnormal EGG were more likely to have slow GE. EGG abnormalities were associated with more severe postprandial pain and should be considered a possible mechanism for dyspeptic symptoms.

Chronic gastritis is not associated with gastric dysrhythmia or delayed solid emptying in children with dyspepsia

To determine if chronic gastritis (CG) is associated with gastric dysrhythmia or delayed solid emptying in children with dyspepsia, 22 patients (7-15 years of age) with dyspepsia and normal gross endoscopies were studied. Antral biopsies were evaluated for chronic gastritis, and immunohistology was performed to determine densities of CD3+, CD20+, CD25+, and tryptase-positive cells. Electrogastrography (EGG) and gastric scintiscan evaluation were performed within 2-7 days of endoscopy. CG and increased immune cell densities were not associated with altered gastric emptying. Mean CD3+ cell counts were positively correlated with the percentage normal slow waves, and patients with a normal EGG had increased CD3+ cell density. In children with dyspepsia, chronic antral inflammation in the setting of a normal gross endoscopy is not associated with EGG abnormalities or delayed solid emptying. Chronic gastritis and gastric dysrhythmia may simply be two separate and distinct mechanisms resulting in the clinical entity of dyspepsia.

Electrogastrography: basic knowledge, recording, processing and its clinical applications

The slow wave (SW) of the gastrointestinal (GI) tract mainly functions to trigger the onset of spike to elicit smooth muscle contraction, which provides the essential power of motility. Smooth muscle myogenic control activity or SW is believed to originate in the interstitial cells of Cajal (ICC). The electrical coupling promotes interaction between muscle cells, and ICC additionally contribute to SW rhythmicity. Stomach SW originates in the proximal body showing the continuous rhythmic change in the membrane potential and propagates normally to the distal antrum with a regular rhythm of approximately 3 c.p.m. A technique using electrodes positioned on the abdominal skin to pick up stomach rhythmic SW refers to electrogastrography (EGG). The stomach SW amplitude is very weak, while many visceral organs also produce rhythmic electricities, for example heartbeat, respiration, other organs of the GI tract and even body movements. Thus noise other than SW should be filtered out during the recording, while motion artifacts are visually examined and deleted. Finally, the best signal among all recordings is selected to compute EGG parameters based on spectral analysis. The latter is done not only to tranform frequency domain to time domain but also to provide information of time variability in frequency. Obtained EGG parameters include dominant frequency/power, % normal rhythm, % bradygastria, % tachygastria, instability coefficient and power ratio. Clinical experience in EGG has been markedly accumulated since its rapid evolution. In contrast, lack of standardized methodology in terms of electrode positions, recording periods, test meals, analytic software and normal reference values makes the significance of EGG recording controversial. Unlike imaging or manometrical studies, stomach motility disorders are not diagnosed based only on abnormal EGG parameters. Limitations of EGG recording, processing, computation, acceptable normal parameters, technique and reading should be known to conduct subjective assessments when EGG is used to resolve stomach dysfunction. Understanding basic SW physiology, recording methodology and indications may open EGG as a new domain to approach the stomach motor dysfunction.

Evolution of gastric electrical features and gastric emptying in children with Duchenne and Becker muscular dystrophy

OBJECTIVES

Although muscular dystrophy (MD) affects primarily striated muscles, smooth muscle cells of the gastrointestinal tract may also be involved. We recorded gastric electrical activity and gastric emptying time (GET) in children with MD at initial presentation and at 3-yr follow-up in order to detect gastric motor abnormalities and study their evolution along the clinical course.

METHODS

Twenty children with MD (median age: 4.6 yr; range age: 3-7 yr) were investigated by means of ultrasonography, for measuring GET, and by electrogastrography (EGG); 70 children served as controls.

RESULTS

Ten patients had Duchenne muscular dystrophy (DMD) and 10 Becker muscular dystrophy (BMD). GET was significantly more delayed in MD patients (DMD, median: 195 min; range 150-260 min; BMD, median: 197 min; range: 150-250 min) than in controls (median: 150 min; 110-180 min; p < 0.05); it markedly worsened at the follow-up in DMD (median: 270 min; range 170-310 min; p < 0.001 vs controls) but not in BMD patients (median: 205 min; 155-275 min; p < 0.05 vs DMD). Baseline EGG showed a significantly lower prevalence of normal rhythm and significantly higher prevalence of dysrhythmias in both groups of patients as compared to controls (% of normal rhythm: DMD 66.7 +/- 8.2, BMB 67.2 +/- 11.5, controls 85.3 +/- 7.2, p < 0.001; % of tachygastria: DMD 28.4 +/- 8.0, BMB 29.8 +/- 12.3, controls 10.6 +/- 5.1, p < 0.001; % of dominant frequency instability coefficient: DMD 36.1 +/- 6.0, BMB 33.2 +/- 2.9, controls 17.9 +/- 7.1, p < 0.001); furthermore, no difference in fed-to-fasting ratio of the dominant EGG power was found between the two groups and controls (DMD 2.84 +/- 1.27, BMB 2.82 +/- 0.98, controls 3.04 +/- 0.85, ns). However, at the follow-up no significant change in the prevalence of normal rhythm and dysrhythmias occurred in both groups (ns vs baseline values), whereas only DMD patients showed a marked reduction in fed-to-fasting power ratio (0.78 +/- 0.59; p < 0.001 vs controls and BMD; p < 0.05 vs baseline), which correlated with the progressive neuromuscular weakness occurring in DMD subjects (r, 0.75; p < 0.001).

CONCLUSIONS

In children with MD, there is an early abnormality in gastric motility that is due to deranged regulatory mechanisms, whereas contractile activity of smooth muscle cells seems to be preserved. At the follow-up, DMD patients exhibited a progressive failure in neuromuscular function, which was accompanied by a gastric motility derangement with worsening in GET and in EGG features suggesting an altered function of gastric smooth muscle cells.

Domperidone is more effective than cisapride in children with diabetic gastroparesis

BACKGROUND

Disorders of gastrointestinal motility are commonly detected in patients with insulin-dependent diabetes mellitus and are associated with significant morbidity. They contribute to poor metabolic control of diabetes.

AIM

To assess the effect of an 8-week course of domperidone or cisapride on gastric electrical activity, gastric emptying time and dyspeptic symptoms in children with insulin-dependent diabetes mellitus and gastroparesis.

METHODS

Dyspeptic symptoms were assessed by a score system, gastric emptying time was measured by ultrasonography and gastric electrical activity was obtained by electrogastrography. Fourteen children received domperidone and 14 received cisapride. The median (range) ages were 11.6 years (5-15 years) and 12 years (6-16.9 years), respectively. Symptom assessment, ultrasonography and electrogastrography were repeated at the end of the trial. Fasting and fed (180 min after feeding) glycaemia and haemoglobin A, C (HbA1c) levels were also measured.

RESULTS

At the end of the trial both groups showed a significant decrease in symptomatic score; however, the score was markedly lower in the domperidone group than in the cisapride group (P < 0.01). Domperidone was significantly more effective than cisapride in reducing the gastric emptying time (P < 0.05), normalizing gastric electrical activity (P < 0.05) and decreasing the prevalence of episodes of gastric dysrhythmia (P < 0.01). Domperidone was also more effective than cisapride in improving diabetic metabolic control. No potentially drug-related adverse effects occurred.

CONCLUSIONS

In children with insulin-dependent diabetes mellitus complicated by dyspeptic symptoms and gastroparesis, domperidone is superior to cisapride in reversing gastric emptying delay and gastric electrical abnormalities, as well as in improving dyspeptic symptoms and diabetic metabolic control.

Gastric electrical activity and gastrointestinal hormones in dyspeptic patients

AIMS

To explore the patterns of gastric electrical activity, gastric emptying and gastrointestinal hormones in dyspeptic patients and relate them to Helicobacter pylori status.

METHODS

Twenty-two patients with functional dyspepsia and 29 healthy volunteers underwent cutaneous electrogastrography and dynamic ultrasound before and after a test meal. All dyspeptic patients underwent endoscopy and biopsy; all subjects were examined for the presence of antibodies to H. pylori, and the plasma levels of gastrin, neurotensin, cholecystokinin, and pancreatic polypeptide were measured.

RESULTS

The area under the curve (AUC) of the normal slow wave percentage was lower in dyspeptic patients than controls (Kruskal-Wallis p = 0.016; Dunn's test: H. pylori-positive patients: 21,235.5 [19,101.0-22,688.8] vs. H. pylori-negative controls: 22,532.0 [20,133.0-23,755.0], p < 0.05). The AUC of the tachygastria percentage was higher in dyspeptic patients than controls (p = 0.0001; H. pylori-positive patients: 2,173.5 [325.8-3,055.3] vs. H. pylori-negative controls: 682.0 [118.5-1,902.4], p < 0.05; H. pylori-negative patients: 1,843.0 [1,107.0-4,277.0] vs. H. pylori-negative controls: 682.0 [118.5-1,902.4], p < 0.05). The AUC of gastrin was higher in H. pylori-positive than H. pylori-negative subjects (p = 0.0002; H. pylori-positive patients: 16,146.5 [11,368.8-33,141.7] vs. H. pylori-negative controls: 11,250.0 [5,674.0-17,448.0], p < 0.05; H. pylori-positive controls: 20,250.0 [12,070.0-64,430.0] vs. H. pylori-negative controls: 11,250.0 [5,674.0-17,448.0], p < 0.05). In the total group of dyspeptic patients and in the H. pylori-positive patients, a negative correlation was found between the AUC of neurotensin and the total score for postprandial fullness (dyspeptic patients r = -0.51, p = 0.01; H. pylori-positive patients r = -0.66, p = 0.02).

CONCLUSIONS

In dyspeptic patients, alterations in gastric electrical activity were not related to H. pylori infection. Nevertheless, H. pylori infection induces higher gastrin levels in both patients and asymptomatic subjects.

Transmission of rectal electric waves: is it through circular or longitudinal smooth muscle layers or both?

The rectum possesses electric activity in the form of pacesetter (PPs) and action potentials (APs). In recent studies we suggested that the waves are not initiated by the extrarectal autonomic innervation but might be triggered by a 'rectosigmoid pacemaker' and are transmitted in the rectal wall through the rectal musculature and not the enteric nerve plexus. To investigate whether the rectal waves are transmitted through the circular or longitudinal muscle layer, the rectum of 18 mongrel dogs was exposed under anesthesia through an abdominal incision. Three electrodes were applied to the rectal wall (longitudinal muscle layer) and another 3 electrodes to the circular muscle; the latter was exposed by splitting apart the fibers of the longitudinal muscle. Rectal electric activity and pressure were recorded from the 6 electrodes before and after performing individual myotomy of the rectal longitudinal (9 dogs), circular (9 dogs), and then the whole muscle layers (18 dogs). The myotomy was performed proximal to and between the electrodes. Pacesetter (PPs) and action potentials (APs) were recorded from the 3 electrodes on the longitudinal muscle but no waves were registered from those on the circular muscle. After longitudinal muscle myotomy was performed between electrodes 1 and 2, PPs and APs were recorded from electrode 1 but not 2 and 3 and when performed proximally to electrode 1, no waves were registered. The rectal pressure increased concomitantly with occurrence of APs. Circular muscle myotomy effected no change in the rectal electric activity recorded from the 3 electrodes applied to the longitudinal muscle. In total muscle myotomy, the electric waves were recorded from the electrodes proximal but not distal to the myotomy. We propose that the motile activity of the rectal longitudinal muscle is initiated by the electric activity which appears to be triggered by the rectosigmoid pacemaker, while that of the circular muscle fibers is believed to be initiated by the stretch reflex induced by rectal distension. This concept is evidenced not only by the current findings but also by the histologic structure of the rectal musculature being of the unitary type of smooth muscles.

Gastric dysrhythmias occur in gastro-oesophageal reflux disease complicated by food regurgitation but not in uncomplicated reflux

AIM

To investigate gastric pacemaker activity in gastro-oesophageal reflux disease using the electrogastrogram.

PATIENTS

Forty patients with gastro-oesophageal reflux disease (20 with acid reflux, 20 with the additional symptom of food regurgitation) and 30 asymptomatic controls.

METHODS

Patients were studied using an electrogastrogram, oesophageal manometry, and 24 hour ambulatory oesophageal pH analysis.

RESULTS

An abnormal electrogastrogram was recorded in two (7%) controls, two (10%) patients with acid reflux, and 10 (50%) patients with food regurgitation. Food regurgitators had significantly more gastric dysrhythmias (tachygastrias) both before (p<0.02) and after (p<0.01) a test meal. Gastric pacemaker activity was also significantly less stable following the test meal in food regurgitators (p<0.003). Patients with food regurgitation and an abnormal electrogastrogram had higher oesophageal acid exposure than those with a normal electrogastrogram (p<0.05).

CONCLUSIONS

The electrogastrogram is usually normal in gastro-oesophageal reflux disease but an abnormal rhythm occurred in half of our patients with the additional symptom of food regurgitation. Furthermore, an abnormal electrogastrogram is associated with increased oesophageal acid exposure.

Vomiting and gastric motility in infants with cow's milk allergy

BACKGROUND

Regurgitation and vomiting are common manifestations of cow's milk protein allergy (CMPA) in infants and are usually ascribed to gastroesophageal reflux (GER). Gastric anaphylaxis can induce antral dysmotility in the rat, and therefore the hypothesis for the current study was that cow's milk in sensitized infants may impair antral motility, thereby promoting GER and reflex vomiting.

METHODS

Seven vomiting infants with CMPA and nine with primary GER underwent a challenge with cow's milk formula. Electrogastrography (EGG) was used to measure the spectral frequency (bradygastria = 1.5-2.4 cycles per minute [cpm], normogastria = 2.5-3.9 cpm, tachygastria = 4.0-9.0 cpm) and the postprandial-to-fasting power ratio of gastric electrical activity, whereas gastric half-emptying time (T1/2) was measured by electrical impedance tomography (EIT).

RESULTS

In CMPA and GER, respectively, during fasting, the frequency distribution (mean +/- SD) of the EGG was as follows: normogastria 47.9%+/-12.5% versus 52.2%+/-9.8%, bradygastria 24.1%+/-5.7% versus 22.8%+/-8.3%, and tachygastria 28.0% 8.5% versus 25.0% 8.3%. In contrast, after the cow's milk challenge, the difference between the two groups was statistically significant: normogastria 33.1%+/-8.8% versus 70.6%+/-8.6% (P < 0.0001). bradygastria 38.0%+/-15.5% versus 15.7%+/-5.2% (P = 0.002), and tachygastria 28.9%+/-10.6% versus 13.4%+/-4.6% (P = 0.001. The postprandial/ fasting power ratio (mean +/- SD) was 3.2+/-1.9 in CMPA and 8.1+/-2.1 in GER (P < 0.0001). Gastric T1/2 (mean +/- SD) of the cow's milk meal was 89.0+/-26.3 minutes versus 54.0+/-12.6 minutes (P = 0.003). In infants with GER all EGG parameters and gastric T1/2 were similar to that in 10 healthy control infants.

CONCLUSIONS

In sensitized infants, cow's milk induces severe gastric dysrhythmia and delayed gastric emptying, which in turn may exacerbate GER and induce reflex vomiting. Electrogastrography and EIT can be useful in the assessment of vomiting, GER, and CMPA in infants.