No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Effects of water ingestion on gastric electrical activity and heart-rate variability in healthy human subjects
Abstract
Electrogastrography (EGG) is a method to record electrical activity of the stomach using cutaneous electrodes. Power ratio (PR) is one of the parameters and means the relative change of EGG power of gastric activity from before to after certain stimulations (e.g., meals, water or drugs). Autonomic nervous function is an important modulator of gastric activity, but its relation with the EGG parameters has not been well clarified. We recorded EGG and the R-R interval simultaneously both before and after drinking 150 ml water for 400 s, and spectrally analyzed them using the maximum entropy method in 12 healthy volunteers. We calculated PR from before to after water ingestion, and the power of the high-frequency component of R-R interval variability before (pre-HF) and after water ingestion (post-HF), and their ratio (rHF = post-HF/pre-HF). PR was positively correlated with rHR (r = 0.727; P < 0.05) and negatively correlated with pre-HF (r = 0.706; P < 0.05), and rHF was negatively correlated with pre-HF (r = 0.776; P < 0.05). These results suggest that simultaneous recording of EGG and ECG for frequency domain analysis is necessary to estimate the vagal nervous activity.
... The relative change of EGG power from before to after certain stimulation is thought to be of clinical significance (5,10) and may correspond to vagal nerve activity. Although there have been a few reports on the relationship between the EGG parameters and autonomic nervous system (ANS) functions (19,36), it is still a debate whether EGG power is well associated with ANS functions before and after water intake. ...
... The power of EGG between 0.042 and 0.058 Hz (2.5-3.5 cpm) was determined as EGG-3 cpm power. The ratio of EGG-3 cpm power in the postwater state to that in the prewater state was defined as power ratio (PR) (36). Similarly, the ratio of HF in the postwater state to that in the prewater state was defined as rHF. ...
... Kaneko et al. (19) demonstrated that liquid food intake enhances the cardiac vagal activity (HF component). Our results were consistent with what was found by Watanabe et al. (36), who, using water ingestion, did not show a significant difference in the HF but demonstrated that the change of EGG power (PR) correlated well with the change of cardiac vagal nervous activity (rHF). It is likely that power spectral analysis of HRV is able to reflect the linearity between changes of HRV and gastric myoelectrical activity in response to water intake. ...
We utilized transfer function analysis of heart rate variability (HRV) and respiration to investigate the effect of water intake on gastric myoelectrical activity and its relationship to vagal activity. The electrogastrography (EGG) and HRV were recorded simultaneously before and after drinking 500 ml of water in 10 healthy subjects. We observed good linearity between lung volumes and HRV signals at a ventilatory rate between 0.2 and 0.4 Hz before and after water intake. The EGG power of 3 cycles/min increased remarkably after the water intake. We found that there was a significant increase in the magnitude of the respiration-HRV transfer function after water intake (P < 0.05). The EGG 3 cycles/min power was positively correlated with the transfer magnitude throughout the study (r = 0.54, P = 0.01). These results confirm that transfer function analysis of HRV sensitively identifies subtle changes in the respiratory sinus arrhythmia that occurs with water intake. The present findings suggest that transfer function analysis of HRV and respiration after water intake can be used to evaluate vagal nervous activity in the human gut.
... 25,26 To date, the relationship between EGG parameters and autonomic nervous system (ANS) functions have only been assessed in healthy adults after liquid meal or water ingestion. 11,27,28 The normal postprandial autonomic response as assessed by HRV spectral analysis and its relation to gastric myoelectrical activity after a solid meal or water ingestion in children has not yet been elucidated. The aims of this two-part study were to investigate the patterns of myoelectrical and autonomic activities, and their interactions, following both a solid meal and water loading challenge in healthy children. ...
... To our knowledge, simultaneous recordings of ECG and EGG were performed in three previous studies to investigate the relationship between postprandial EGG parameters and HRV parameters following ingestion of liquids. 11,27,28 Keneko et al. showed liquid food (250 mL Ensure) intake significantly increased the HF amplitude only during the first 5 min and this vagal activation disappeared thereafter. 27 No changes in the LF-to-HF ratio and no significant correlation between postprandial EGG power change and HRV parameters were observed in that study. ...
... Watanabe et al. investigated the effect of water ingestion on the power ratio (PR: the relative change of EGG power after and before water ingestion) and HRV parameters and reported that PR was negatively correlated with the HF power in the preprandial state (r ¼ )0.706, P ¼ 0.0192) and had no significant correlations with other HRV parameters. 28 Chen et al. reported a positive correlation for the postprandial power change following water ingestion and the HF power ratio (but not the HF itself). 11 In summary, a solid meal results in a significant increase in EGG-dominant frequency, dominant power and the percentage normal slow waves, and sympathovagal balance, in healthy children. ...
The aim of this study was to investigate the correlation of gastric myoelectrical and autonomic activities in healthy children. Simultaneous recordings of electrogastrography (EGG) and electrocardiogram (ECG) were performed in healthy children before and after a solid meal and water loading respectively. The autonomic activity was assessed by spectral analysis of the heart rate variability (HRV). The solid meal resulted in an increase in EGG-dominant frequency (2.92 cpm vs 3.16 cpm, P < 0.05), dominant power (46.9 dB vs 53.7 dB, P < 0.05) and percentage normal slow waves (81.9%vs 89.0%, P < 0.05), while only dominant power increased following water loading. Power in the low-frequency band of HRV (LF) was significantly increased and power in the high-frequency band of HRV (HF) significantly decreased following the solid meal. Postprandial LF was positively and HF negatively correlated with the postprandial increase in EGG-dominant power. Water loading was not associated with any significant changes in HRV parameters. These results suggest that both vagal and sympathetic pathways are involved in modulation of gastric myoelectrical activity.
... [29][30][31][32] In addition to the aforementioned pharmacological tools to induce variations in GI motility, food ingestion is known to induce changes in gastric motility and the very early stages of these changes are not thought to be controlled by the vagus, 33 although HF-HRV responses to water, liquid food, and solid meals have provided dissonant results. [34][35][36][37][38] The second aim of the present study was to test the hypotheses that the correlation between HF-HRV power and proximal antrum motility can be altered by treatments that affect gastric motility via recognized vagal pathways. ...
... [29][30][31][32] In addition to the aforementioned pharmacological tools to induce variations in GI motility, food ingestion is known to induce changes in gastric motility and the very early stages of these changes are not thought to be controlled by the vagus, 33 although HF-HRV responses to water, liquid food, and solid meals have provided dissonant results. [34][35][36][37][38] The second aim of the present study was to test the hypotheses that the correlation between HF-HRV power and proximal antrum motility can be altered by treatments that affect gastric motility via recognized vagal pathways. ...
Background
Cardiac vagal tone can be monitored non‐invasively via electrocardiogram measurements of the high‐frequency power spectrum of heart rate variability (HF‐HRV). Vagal inputs to the upper GI tract are cumbersome to measure non‐invasively. Although cardiac and GI vagal outputs arise from distinct brainstem nuclei, the nucleus ambiguus, and the dorsal motor nucleus of the vagus, respectively, we aim to test the hypotheses that in freely moving rats HF‐HRV power is correlated to proximal antral motility and can be altered by high levels of circulating estrogen and vagal‐selective treatments known to affect antral motility.
Methods
Male and female Sprague‐Dawley rats were implanted with a miniaturized strain gauge on the proximal gastric antrum and ECG electrodes to collect simultaneous antral motility and electrocardiogram. After recovery, male rats underwent baseline recordings before and after administration of saline (N = 8), cholecystokinin (CCK; N = 7), ghrelin (N = 6), or food (N = 6). Female rats (N = 6) underwent twice‐daily recordings to determine baseline correlations during estrous cycle stages.
Key Results
There was a significant positive correlation between HF‐HRV and proximal antral motility at baseline in males and females with low, but not high, estrogen levels. In male rats, the significant positive correlation was maintained following CCK, but not ghrelin or food administration.
Conclusions and Inferences
Our data suggest that in rodents, HF‐HRV positively correlates to proximal antral motility at baseline conditions in males and low‐estrogen females or following interventions, such as CCK, known to affect vagal tone. This correlation is not observed when antral motility is influenced by more complex events.
... Electrogastrography (EGG) is a method to record electrical activity of the stomach which oscillates at a frequency of about 3 cycles/min (0.05 Hz) towards distal antrum. Though there have been a few reports on the relationship between the parameters of ECG, EGG and autonomic nervous function [7], the relation between PRV, EGG in the fasting and postprandial state has not been well assessed in relation to autonomic nervous function, which is thought to be an important modulator of gastric activity. The spectral analysis of the PPI and EGG was carried out and the existence of rhythmic oscillations was revealed. ...
Photoplethysmography (PPG) is typically used to extract cardiac-related information like heart rate and cardiac output, though extra-cardiac information like respiratory rate can also be extracted from PPG. The aim of the current study is to advance this approach further and investigate existence of gastric-related activity in PPG. To this end, we consider pulse rate variability (PRV), which provides information analogous to heart rate variability (HRV). Finger PPG and electrogastrography (EGG) signals were recorded from 8 healthy volunteers in fasting and postprandial state for 30 minutes. Peak-to-peak interval (PPI) analysis shows that the power of high frequency (HF) component in fasting and postprandial state changes significantly. The power ratio (PR), which is the ratio between powers of low frequency band (LF, 0.04-0.15 Hz) to that of high frequency band (HF, 0.15-0.4 Hz) and the EGG power were calculated in fasting and postprandial state. PR was positively correlated with EGG power (r = 0.46; P< 0.05). PR indicates the balancing sympathovagal modulation and vagal nervous activity. The significance of this study is that PR from PRV analysis could be used as a tool for diagnosing gastric system instead of the present invasive/cumbersome methods.
... The appropriateness of using cardiac autonomic regulation as a surrogate of gastric autonomic innervation has been supported by previous studies. Researchers from our and other laboratories have demonstrated that ingestion of water or food provoked a parallel change in cardiac vagal and gastric myoelectrical activities Kaneko et al., 1995;Watanabe et al., 1996). In studying the effect of stress on GMA, Yin et al. (2004) also used HRV to infer gastric autonomic innervation. ...
The gastric myoelectrical activity (GMA) fluctuates across sleep-wake states as a result of modulation by the brain-gut axis. The role of the autonomic nervous system in this phenomenon, however, was not elucidated fully. Through simultaneous recording and subsequent continuous power spectral analysis of electroencephalogram, electromyogram, electrocardiogram and electrogastromyogram (EGMG) in 16 freely moving Wistar rats, the sleep-wake states of the animals were defined and indices of cardiac autonomic regulation and GMA were calculated. We found that both cardiac autonomic regulation and GMA fluctuated through sleep-wake cycles. Correlation analysis further revealed significant correlations between EGMG power and each of the R-R interval, high-frequency power, low-frequency power, very-low-frequency power, low-frequency power to high-frequency power ratio and normalized low-frequency power of heart rate variability with respect to their trend of change across different sleep-wake states. These results suggest that the sleep-wake-related change of GMA was related to sympathovagal balance. The sympathetic nerve may play a more important role in the central modulation of GMA than perceived previously.
... Previous studies have indicated that autonomic nervous system and hormones contributed to EGG change. 25,26 Normal, post-prandial increase of EGG amplitude was suppressed in patients who had undergone surgical vagotomy. 27 Post-prandial EGG changes correlated with high-amplitude components of ECG change, which is an indicator of parasympathetic nervous activity of the heart. ...
Eating disorders are common psychiatric disorders in young women. The aim of the present study was to evaluate the gastric electrical activity of patients with eating disorders and its relation to their symptoms. The electrogastrography (EGG) was performed before and after a water load test for outpatients with eating disorders (n = 36; 14 anorexia nervosa, 14 bulimia nervosa, eight eating disorder not otherwise specified) and healthy women (n = 19). A structured interview (Eating Disorder Examination) was used to assess clinical symptoms. The percentage of normal gastric myoelectrical power was significantly smaller in the eating disorder patients (44.5% vs 74.2%; P < 0.05), while the percentage of bradygastric power was significantly greater, both before and after the water load test compared with the control subjects (30.4% vs 10.4%; P < 0.05). In addition, moderate correlation was found between the duration of illness and the percentage of bradygastria (P < 0.05). In conclusion, it is suggested that longstanding abnormal eating in patients with eating disorders may induce disturbances to gastric motor function, resulting in their abnormal, eating-related behavior, and form a symptomatic vicious circle. The EGG may be a promising method for determining the pathophysiology of eating disorders and for developing effective therapeutic approaches.
The clinical utility of autonomic function tests in pediatric gastroenterology is steadily evolving. The current tests available evaluate cardiac and sudomotor responses and not direct gastrointestinal responses. Therefore, the results are interpreted and extrapolated (in the appropriate clinical setting) to the abnormality of the gastrointestinal tract. The tests are divided into those of autonomic cardiovascular function (cardiac response to deep breathing, Valsalva maneuver, head-up tilt (HUT) table test, handgrip, and cold pressor test) and those of sudomotor function (quantitative sudomotor test and thermoregulatory sweat test). Together, these two groups of tests evaluate the sympathetic adrenergic, sympathetic cholinergic, and parasympathetic cholinergic function in several organ systems from which one infers the presence of absence of an autonomic disorder, whether it is primarily affecting central or peripheral nervous systems, and whether it appears focal or generalized.
Background
Women with chronic pelvic pain (CPP) have poor cardiovagal modulation. It is unclear whether this finding reflects a broader abnormality across many systems such as gastro‐vagal modulation.
Aim
To determine if maladaptive cardiovagal activity in females with CPP is accompanied by maladaptive gastric myoelectric activity.
Methods
A total of 36 health controls (HC) and 75 CPP underwent supine (10 min), then upright (tilted 70° head up; 30 min), and back to supine (10 min) positions. High‐frequency heart rate variability (HF‐HRV; 0.15‐0.4 Hz) was measured as an index of cardiovagal activity. Cutaneous electrogastrography (EGG) assessed gastric myoelectric activity pre‐ and during‐upright tilt. EGG measures from 16 HC and 31 CPP patients were available for analysis and included relative percentage of gastric activity within the normal (2‐4 cpm) and tachygastria (4–10 cpm) ranges, plus ratio of normal/tachygastria.
Results
HF‐HRV was lower in CPP individuals at all time points (each p < .05). CPP individuals showed lesser decrease in HF‐HRV from supine to upright, and poorer HF‐HRV recovery from upright back to supine (F[1, 106] = 4.62, p = .034). HC showed increase in tachygastria activity (t[15] = −2.09, p = .054) while the CPP group showed no change in tachygastria activity from pre‐upright to upright (t[30] = −0.62, p = .537).
Conclusions
Individuals with CPP going from supine to upright demonstrate an impairment in both tachygastria and the parallel decrement in HRV. These results support the hypothesis of a generalized blunting in the physiological modulation in CPP individuals affecting both cardiovascular and gastric systems.
Humans show individual differences of biological rhythm phase, and can be classified into the “morning type” (peak performance being achieved in the early part of the day) or the “evening type” (peak performance towards the end of the day) . We therefore hypothesized that evening-type individuals would show different daytime variations of autonomic nervous activity, gastric motility and appetite sensations, which are under the control of the biological clock. In this study, 34 young women began fasting at 22:00 h on the previous night and ate test meals at a pre-determined time on the test day. Electrogastrography, electrocardiography (cardiac autonomic nerve activity) , appetite sensations, sleepiness, and core (eardrum) temperature were measured from 8:00 to 20:00 h at 1-hour intervals. After completion of all measurements, the subjects completed a morningness-eveningness questionnaire, and were divided into morning- or evening-preference types. Evening-preference individuals demonstrated a higher heart rate, a predominance of sympathetic nerve activity and greater sleepiness in the daytime. Moreover, they had a significantly lower hunger score during the morning, and did not show a significant shift in the frequency of postprandial gastric motility as compared with morning-preference individuals. Our results suggest that an evening-preference lifestyle may be associated with attenuation of appetite and vitality during the morning.
Objective: To record gastric myoelectrical activity (EGG) of healthy subjects as preliminary study. Methods: Fourteen normal subjects participated in the study. The electrogastrogram (EGG) was recorded in fasting state for ten minutes followed by ten minutes recording after drinking water. Results: Visual analysis of EGG data demonstrated gastric slow wave frequency in the range of 2.5 - 3.1 cycles per min (mean = 2.98) in fasting state. Eighty five percent of normal subjects showed decrease in slow wave frequency to 2.2 - 3.0 cycles per min (mean = 2.65) after drinking water. However, post-water amplitude was increased in all the subjects when compared to pre-water amplitude. Conclusion: It appears that gastric electrical activity can be successfully measured noninvasively using electrodes placed on abdomen.
The purpose of this study is to clarify the relationship among the viscosity of fluid diet and mechanism of the gastric myoelectrical activity with simultaneous measurements of electrogastrography (EGG) and heart rate variability (HRV). We studied for 8 healthy male volunteers, EGG and electrocardiogram (ECG) were measured simultaneously. And indexes of EGG and HRV for the periods of fasting and postprandial obtained by the analysis using Short-time Fourier transform (STFT) to assess gastric myoelectrical activity and autonomic nervous activity respectively on the intakes of three kinds of test meals which were different in viscosities. In relation to indexes of EGG, dominant power (DP) of CH3 and CH4 changed significantly (p < 0.05, 0.01) on the intake of low or high viscosity meal. In addition, dominant frequency deviation (DFD) of CH1 and CH2 changed significantly (p < 0.05, 0.01) only on the intake of low viscosity meal. In relation to indexes of HRV, LF/HF of only 15-20 min on postprandial period changed significantly (p < 0.05) on the intake of high viscosity meal. These results may express that distal stomach has a main role in gastric emptying of high viscosity meal similar to known mechanism of gastric emptying, whereas the intake of low viscosity meal lead to irregular activity on proximal stomach.
Aim of this paper is to study the effect of Gastric Myoelectric Activity (GMA) in finger PPG signal. To this end, Pulse Rate Variability (PRV) analysis in combination with Poincare plots was selected. In PRV, the power of High Frequency (HF) component significantly changes in fasting and postprandial state and positively correlated between Power Ratio (PR) of PRV and electrogastrography (EGG) power (r = 0.46; P < 0.05). The results of this study explored that the combination of Poincare plots and PR value could show a new insight into the assessment of gastrointestinal system between different body conditions of a healthy group.
The aim of this research is to evaluate the change in gastric myoelectrical activity (GMA) and autonomic nervous function (ANF) on ingesting different viscosity grades of fluid diet for the 10 healthy subjects with simultaneous measurements of EGG and HRV. Results suggested that (1) Gastric emptying related to function of distal stomach may be promoted by ingestion of high viscosity fluid diet, and (2) Receptive relaxation related to function of proximal stomach may not function on ingesting of low viscosity fluid diet.
Beyond the fundamental pathogenetic importance of Helicobacter Pylori a possible additional role of vagal innervation in favouring or modulating the clinical history of duodenal ulcer (DU) has been suggested by old studies employing invasive methodologies. Aim of this study was to assess whether vagal prevalence in autonomic modulation was present in healed DU patients (n=20) as compared to controls,(n=50), using a validated non-invasive methodology, based on spectral analysisis of cardiovascular variability. This approach provides markers of the sympathetic and vagal modulations of the SA node, respectively by way of the normalized low frequency (LFRR) and high frequency (HFRR) components of RR interval variability; LF/HF ratio furnishes a marker of sympatho-vagal balance. In addition, sham feeding (SF) provided a means to assess, in DU patients, neurally mediated acid secretion, as the SF acid output (SAO) to basal acid output (BAO) ratio (SAO/BAO). Results showed that LFRR was smaller in DU patients than in controls (40.3±3.9 vs. 52.3±2.3 normalized units, nu; P
This paper is an experimental study to examine the possibility of extracting gastric myoelectric activity (GMA) from photoplethysmographic (PPG) signals. Diagnosing GMA is a clinically challenging task because of its invasive/cumbersome methods. It is known that the PPG consists of information related to heart rate, respiratory rate and phenomena. Here we take this thread further and see whether GMA can be extracted from PPG in a simpler way and without discomfort to the patients. Since PPG and GMA signals are nonstationary, we choose discrete wavelet transform (DWT) to separate the different frequency components. PPG and Electrogastrog- -ram (EGG, a method of measuring GMA) signals were acquired simultaneously at the rate of 100 Hz from 8 healthy subjects for 30 minutes duration in fasting and postprandial states. Both the signals were decomposed using DWT up to the frequency range (0 - 0.1) Hz. A lower frequency oscillation (≈ 0.05 Hz) called slow wave was extracted from PPG signal which looks similar to the slow wave of GMA in both shape and frequency. Normalized cross-correlation technique was used for comparing the two signals. Cross-correlation values were found to be high (R ≥ 0.73, R = 1.0 indicates exact agreement) for all subjects without any significant change between fasting and postprandial states. The results suggest that there is a possibility of extracting gastric related information from PPG signals using appropriate signal processing techniques. In future this novel technique could be used as a diagnostic tool for gastrointestinal system disorders.
Electrogastrography (EGG) is a noninvasive technique for the cutaneous recording of gastric myoelectrical activity. Since the first measurement of the electrogastrogram (EGG), a great deal of research has investigated its validation, interpretation, and application. Recently, EGG has received more and more attention. EGG has become an attractive tool to study the electrophysiology of the stomach and pathophysiology of gastric motility disorders. It is currently used in both research settings and clinical settings. The following areas are discussed: the refined methods of EGG, the advanced techniques for processing and analyzing the EGG, and the physiological and clinical applications of EGG.
Because various mastication-related factors influence gastric activity, the functional relationship between mastication and gastric function has not been fully elucidated. To investigate the influence of mastication on gastric emptying and motility, we conducted a randomized trial to compare the effects of mastication on gastric emptying and gastric myoelectrical activity under conditions that excluded the influences of food comminution, taste, and olfaction. A (13)C-acetate breath test with electrogastrography and electrocardiography was performed in 14 healthy men who ingested a test meal with or without chewing gum. Autonomic nerve activity was evaluated by fluctuation analysis of heart rate. Gastric emptying was significantly delayed in the 'ingestion with mastication' group. Gastric myoelectrical activity was significantly suppressed during mastication and increased gradually in the post-mastication phase. A decrease in the high-frequency power of heart rate variability was observed coincidentally with gastric myoelectrical activity suppression. These findings suggest that initial gastric emptying is suppressed by mastication, and that the suppression is caused by mastication-induced inhibition of gastric activity (UMIN Clinical Trial Registration no. UMIN000005351).
Relationship between lumbar kyphotic deformity and gastroesophageal reflux disease has been indicated in recent years. But it remains unclear whether kyphotic deformity of the lumbar vertebrae affects gastric motility. Healthy young adults (n = 20) were analyzed by recording the electrogastrography (EGG) and heart rate variability (HRV) before and after meal with flexion and neutral postures. Dominant power (DP) and dominant frequency (DF) of EGG and low frequency (LF) and high frequency (HF) of HRV were analyzed in blocks of 10 minutes' duration. In neutral posture, DPs of all postprandial durations were significantly higher than those during fasting in two channels (P < 0.05, P < 0.01). However, in flexion posture, only DP at postprandial 20 (10-20 minutes after eating) in a channel was significantly higher than that during fasting (P < 0.05). DF in neutral posture was significantly higher than that in flexion posture at postprandial 20 in a channel (P < 0.05). The standard deviation of DF at postprandial 10 in flexion posture was significantly higher than that during fasting in a channel (P < 0.05). LF/HF in neural posture was significantly higher than that in flexion posture at postprandial 10 (P < 0.05). These findings suggest that inhibition of stomach myoelectrical activity was induced in the flexion posture in this lumbar kyphotic model, and autonomic activity as assessed by HRV did not accord with that expected from EGG.
Irritable bowel syndrome (IBS) patients usually manifest autonomic nerve dysfunctions and abnormal psychological behaviors. This study was to assess autonomic nervous system (ANS) response to different stressor as well as evaluate effects of antidepressive treatment of Saint John's Wort Extract in women with IBS.
Thirty women with IBS and 20 healthy women underwent serial ANS function tests. Five-minute-short-time heart rate variability (HRV) spectral analysis were assessed at a stress or resting recording period. Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) were used to measure their anxiety and depression conditions. After 8-weeks' antidepressant treatment, groups of IBS repeated the tests above. Subjects also completed a GI symptom diary once daily during the 2 weeks before therapy and for 2 weeks in the last scheduled therapy session.
IBS-group showed a higher score in HAMA and HAMD (p < 0.01) and showed a significant increase in the low frequency band/high frequency band ratio (L/H) during the period in different stimuli (p <0.01), which was significantly different from controls. After 8-weeks' antidepressive treatment, L/H showed a significant decrease (p < 0.05) response to different stressor, which was significantly different from pre-treatment. Gastrointestinal (GI) symptoms of IBS were also relieved significantly.
Antidepressive treatment can improve the conditions of psychology and the ANS reactivity to stress in patients with IBS.
It is not clear whether the power increase in electrogastrography (EGG) after meal or water ingestion reflects increases in gastric motility or gastric distension bringing the stomach closer to the electrodes on the abdominal skin surface. We recorded EGG and real-time ultrasonography simultaneously before and after 150-ml water ingestion in 17 healthy volunteers. We calculated gastric power, by spectral analysis of EGG by the maximum entropy method, for 400 s before and after water ingestion, and calculated their ratio (power ratio). We calculated, using sonography, the number of antral contractions before and after water ingestion, the motility index after water ingestion, the distance between the antrum and the abdominal skin surface before and after water ingestion, and the ratio of these distances (distance ratio). The number of contractions was positively correlated with gastric power before water ingestion, and the antrum-skin distance was negatively correlated with gastric power both before and after water ingestion. The motility index after water ingestion was positively correlated with both gastric power after water ingestion (Spearman's rank correlation r = 0.492; P = 0.0498) and the power ratio (r = 0.615; P = 0.0141). There was no correlation between the distance ratio and the power ratio. These results suggest that the power increase in EGG induced by water ingestion does not reflect the approach of the antrum to the abdominal surface, but rather, reflects antral motility after water ingestion.
The autonomic nervous system (ANS) function in hyperthyroidism has been so far investigated mainly from the cardiovascular point of view. The aim of this study is to show that the ANS dysfunction in hyperthyroidism is also expressed in gastric myoelectrical activity disturbances and gastric emptying disorders and to search for a correlation between the severity of clinical manifestation and free thyroid hormone levels and the degree of the ANS dysfunction. The analyzed group included 50 recently diagnosed patients with hyperthyroidism who were examined twice: before and after 3 months of thyrostatic treatment. Results were compared with those of a sex-, age- and BMI-matched control group of 50 healthy volunteers. The study included: heart rate variability analysis in time and frequency domain, at rest and during a deep-breathing test, surface electrogastrography in preprandial and postprandial periods measured simultaneously with the ultrasound assessment of gastric emptying time by Bolondi method. In patients with hyperthyroidism in comparison with the control group, the following significant differences were observed: a sharp reduction of the high-frequency component and a decrease of heart rate variability, a high incidence of dysrhythmia with dominant bradyarrhythmia, and a delay of gastric emptying. The degree of disorders related to the degree of clinical manifestation of hyperthyroidism's symptoms and free triiodothyronine serum concentration both. All the disorders were functional and disappeared in a stable euthyroidism. To conclude, the ANS dysfunction in hyperthyroidism results not only in withdrawal of vagal inhibitory effect on sinoatrial node, but in impaired mutual neuro-hormonal regulation (decrease of vagal influence) of gastric myoelectrical activity followed by delay of gastric emptying.
Helicobacter pylori (Hp) infection in diabetic patients has been related to impaired gastric clearance of bacteria due to autonomic neuropathy. Gastrointestinal dysfunction has been described in primary autonomic failure (AF). The aim of the study was to evaluate, for the first time, the presence of Hp infection and gastric function in patients with primary AF.
Twelve patients with primary AF (aged 58–78), 31 healthy controls (aged 48–75) and 31 patients affected by type 2 diabetes (aged 46–75) were studied. A 13C-urea breath test was performed to assess the presence of Hp infection. To evaluate gastric function, AF patients underwent two non-invasive tests: 1) 13C-octanoic acid breath test (OBT) to evaluate gastric emptying, and 2) electrogastrogram (EGG) to evaluate gastric electrical activity.
Hp infection was found in 100 % of AF patients, in 48 % of controls and in 71 % of diabetic patients (p = 0.02 between groups). Electrical or mechanical gastric function was altered in 50 % of AF patients. In particular, 1) after OBT, half-time gastric emptying was delayed in 6 out of 12 patients, and 2) EGG showed the presence of gastric dysrhythmias in 6 out of 12 patients. In conclusion, Hp infection was detected in all AF patients studied; as previously demonstrated in diabetes, such a finding might be related to autonomic neuropathy causing mechanical or electrical gastric dysfunction. Hp detection might be important for the gastrointestinal and extradigestive complications of such infection.
Although extensively investigated throughout the gastrointestinal tract, the influence of alcohol on gastric motility is still unclear. Our aim was to investigate the effect of wine on gastric myoelectrical activity and vagal activity. Ten healthy subjects were studied in two sessions with the electrogastrogram (EGG) for 30 min at baseline, 30 min after ingesting the test liquid [white wine (12.5% alcohol) or matched juice], and 60 min after a standard test meal. Spectral analysis was performed to compute EGG parameters and their postprandial changes. The vagal activity was assessed based on spectral analysis of the heart rate variability (HRV) signal derived from the ECG recording. White wine preload significantly diminished the postprandial increase in EGG dominant power compared to juice preload (1.16 +/- 1.57 vs 5.48 +/- 1.01 dB, P < 0.001). A significant decrease in vagal activity was observed after wine (23.40 +/- 4.30 vs 17.43 +/- 3.40%, P < 0.005), which remained unchanged after the test meal (23.40 +/- 4.30 vs 16.77 +/- 4.40%, P < 0.05). This decrease was not noted in the juice session. A correlation was established between changes after wine consumption in EGG dominant power and in the percentage of the vagal activity (r = 0.89, P < 0.05). In conclusion, white wine preload inhibits the postprandial EGG dominant power, suggesting a possible inhibition of postprandial gastric contractions. This effect may be associated with diminished vagal activity.
This study compared women with irritable bowel syndrome who had a history of an anxiety or depressive disorder to those without symptoms of either disorder on indicators of cardiac parasympathetic activity, autonomic nervous system balance, and general autonomic activity. The Diagnostic Interview Schedule was used to determine anxiety or depressive disorders, and a Holter monitor was used to record R-R intervals over 24 hr. A similar comparison was done with healthy controls. Among women with irritable bowel syndrome, those with a positive history had lower parasympathetic and general activity throughout the 24-hr period than did women without a diagnosis. Indicators of autonomic balance were slightly higher in women with a positive history compared to those without a history. Similar differences were seen in controls. Thus, a history of anxiety and depressive disorders is associated with lower parasympathetic activity, both in women with IBS and healthy controls. Further exploration is needed to understand if lower parasympathetic activity influences the pain and stool pattern changes seen in persons with irritable bowel syndrome.
In 57 normal subjects (age 20-60 years), we analyzed the spontaneous beat-to-beat oscillation in R-R interval during control recumbent position, 90° upright tilt, controlled respiration (n = 16) and acute (n = 10) and chronic (n = 12) β-adrenergic receptor blockade. Automatic computer analysis provided the autoregressive power spectral density, as well as the number and relative power of the individual components. The power spectral density of R-R interval variability contained two major components in power, a high frequency at ~ 0.25 Hz and a low frequency at ~ 0.1 Hz, with a normalized low frequency: high frequency ratio of 3.6 ± 0.7. With tilt, the low-frequency component became largely predominant (90 ± 1%) with a low frequency: high frequency ratio of 21 ± 4. Acute β-adrenergic receptor blockade (0.2 mg/kg IV propranolol) increased variance at rest and markedly blunted the increase in low frequency and low frequency: high frequency ratio induced by tilt. Chronic β-adrenergic receptor blockade (0.6 mg/kg p.o. propranolol, t.i.d.), in addition, reduced low frequency and increased high frequency at rest, while limiting the low frequency: high frequency ratio increase produced by tilt. Controlled respiration produced at rest a marked increase in the high-frequency component, with a reduction of the low-frequency component and of the low frequency: high frequency ratio (0.7 ± 0.1); during tilt, the increase in the low frequency: high frequency ratio (8.3 ± 1.6) was significantly smaller. In seven additional subjects in whom direct high-fidelity arterial pressure was recorded, simultaneous R-R interval and arterial pressure variabilities were examined at rest and during tilt. Also, the power spectral density of arterial pressure variability contained two major components, with a relative low frequency: high frequency ratio at rest of 2.8 ± 0.7, which became 17 ± 5 with tilt. These power spectral density components were numerically similar to those observed in R-R variability. Thus, invasive and noninvasive studies provided similar results. More direct information on the role of cardiac sympathetic nerves on R-R and arterial pressure variabilities was derived from a group of experiments in conscious dogs before and after bilateral stellectomy. Under control conditions, high frequency was predominant and low frequency was very small or absent, owing to a predominant vagal tone. During a 9% decrease in arterial pressure obtained with IV nitroglycerin, there was a marked increase in low frequency, as a result of reflex sympathetic activation. Bilateral stellectomy prevented this low-frequency increase in R-R but not in arterial pressure autospectra, indicating that sympathetic nerves to the heart are instrumental in the genesis of low-frequency oscillations in R-R interval.
The ability of transcutaneous recordings of gastric electrical activity to detect gastric electrical abnormalities was determined by simultaneous measurements of gastric electrical activity with surgically implanted serosal electrodes and cutaneous electrodes in six patients undergoing abdominal operations. Transient abnormalities in gastric electrical activity were seen in five of the six patients during the postoperative period. Recognition of normal gastric electrical activity by visual analysis was possible 67% of the time and with computer analysis 95% of the time. Ninety four per cent of abnormalities in frequency were detected by visual analysis and 93.7% by computer analysis. Abnormalities involving a loss of coupling, however, were not recognised by transcutaneous recordings. Transcutaneous recordings of gastric electrical activity assessed by computer analysis can usually recognise normal gastric electrical activity and tachygastria. Current techniques, however, are unable to detect abnormalities in electrical coupling.
Power spectrum analysis of heart rate fluctuations provides a quantitative noninvasive means of assessing the functioning
of the short-term cardiovascular control systems. We show that sympathetic and parasympathetic nervous activity make frequency-specific
contributions to the heart rate power spectrum, and that renin-angiotensin system activity strongly modulates the amplitude
of the spectral peak located at 0.04 hertz. Our data therefore provide evidence that the renin-angiotensin system plays a
significant role in short-term cardiovascular control in the time scale of seconds to minutes.
Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.
Gastric electrical activity was recorded from twenty-six patients at celiotomy. The human gastric pacemaker was localized to an area in the midcorpus along the greater curve. Pacesetter potentials were generated regularly by the pacemaker at a mean frequency of 3.2 cycles/min and were propagated circumferentially and aborally from the pacemaker, increasing in amplitude and velocity as they approached the pylorus. The pattern of pacesetter potentials in patients with gastric ulcer, gastric cancer, and duodenal ulcer was similar to that of patients without such diseases. Complete transection of the gastric corpus isolated the distal stomach from the natural pacemaker and resulted in the appearance of a new pacemaker in the distal stomach with a slower frequency. The fact that proximal gastric vagotomy did not greatly alter the frequency of generation or the pattern of propagation of the pacesetter potential provided further evidence that both are myogenic phenomena.
A conceptually simple method for power estimation in maximum entropy spectral analysis, based on evaluation of complex residues of the spectral density estimator, is suggested. Numerical integration of the peaks of the power density function is thus avoided. The agreement in simple cases with conventional estimates is demonstrated, and the explicit performance is analyzed in detail in a series of examples. The close connection between the residue power estimate and the estimate proposed recently by Pisarenko is pointed out. The method is particularly suitable for spectral decomposition of low noise time series with several harmonic components, because it allows a direct listing of frequency and power estimates, provides an indication of the purity of the obtained harmonic components and enhances the resolution of the maximum entropy spectral density estimator.
Changes in gastric myoelectrical activity following highly selective vagotomy were studied in 12 patients by means of electrogastrography (EGG) using cutaneous electrodes. Measurements were made before, 10 days after, and six months after operation. Eight patients undergoing cholecystectomy served as controls. Preoperatively all controls and patients had normal recordings. In the cholecystectomized patients no significant changes were found postoperatively. Ten days after highly selective vagotomy the normal initial postprandial dip in gastric ECA frequency and the subsequent increase in frequency and power were not seen. Tachygastrias were observed in three patients. Six months after operation the normal frequency and power responses to a test meal had returned, but both the fasting and postprandial ECA frequencies were raised significantly. It is concluded that highly selective vagotomy is associated with abnormalities in myoelectrical activity, in particular in the postprandial state, most of which are reversible with time.
Unlabelled:
The relationship between the cutaneously recorded electrogastrogram (EGG) and gastric contractions in man is unclear. We investigated: (1) the relationship between the electrogastrogram (EGG) signals and gastric contractions elicited by barium meals and (2) the effects of barium meals on frequency and amplitude of EGG signals. As documented by fluoroscopy in four healthy subjects, barium meals stimulated three per minute gastric peristalsis which corresponded with simultaneously recorded three cycle per minute (cpm) EGG waves. Eighteen other healthy volunteers ingested 45% (w/v) or 60% barium suspensions. As determined by Fourier analysis, the dominant EGG frequency before barium was 3 cpm in 16 subjects; two subjects had no distinct frequency peaks. After barium ingestion, the mean amplitude or power at 3 cpm and 1 cpm increased, but the increase was significant only after 45% barium.
In conclusion:
(1) individual EGG waves after barium reflect gastric peristaltic sequences, which are reflected in increases in amplitude or power of 3 cpm EGG activity; (2) density or viscosity of the barium meal affects the gastric myoelectric response; and (3) mechanical correlates of 1 cpm EEG activity are unknown.
The effects of sham feeding on gastric motility of human subjects have not previously been studied. The amplitude of 3-cpm electrogastrogram (EGG) waves increases after the ingestion of food. We hypothesized that sham feeding would stimulate a similar, but briefer gastric myoelectric response. Healthy human subjects chewed and expectorated a hot dog on a roll and later ate a second hot dog. EGGs were continuously recorded before, during, and after sham feeding and eating. The results of experiment I (N=27) showed that the hand-scored amplitude of the 3-cpm waves increased significantly (P< 0.05="" and="">
The unit activity of vagal efferent fibers suspected to be involved in the nervous control of gastric motility was studied on dogs in which the central end of the left vagus had been sutured to the peripheral end of the left phrenic nerve. In such preparations, the activity of the motor units of the reinnervated diaphragm became an indicator of the activity of vagal efferent fibers. This activity was recorded using electromyography in unanesthetized dogs after part of the left diaphragm had been transplanted to a subcutaneous site. These fibers fired spontaneously at low frequency (from 0.1 to 5 spikes/s). In the fasted dog, this discharge frequency fluctuated with the various phases of the migrating myoelectric complexes (MMC) occurring on the gastric antrum: mean frequencies of about 0.1-1.5 spikes/s during phase I; 1.5-5 spikes/s in phase III; intermediate values for phases II and IV (for phases definition, see C.F. Code and J.A. Marlett. The interdigestive myoelectric complex of the stomach and small bowel of dogs. J. Physiol. London 246: 289-309, 1975). AFter feeding, the discharge frequency was as high as during phase III of a MMC, and this sustained activity lasted several hours. In addition, vagal discharges were increased by distending the gastric walls and decreased by a slight general anaesthesia or duodenal distension. These data suggest that vagal fibers synapse with intramural neurons, which in turn excite smooth muscle of the gastric antrum.
Simultaneous measurement of plasma motilin concentration and gastrointestinal contractile activity was make in 12 healthy dogs. Plasma motilin concentration was measured by radioimmunoassay and gastrointestinal contractile activity was monitored by means of chronically implanted force transducers. During the interdigestive state, it was found that the plasma motilin concentration increased in complete accordance with the cyclical interdigestive contractions of the stomach. Furthermore, plasma motilin concentration was lowered by the ingestion of food, and it reamined low as long as the gastric motor activity was in the digestive pattern. Since, as reported previously the interdigestive contractions can be induced by tthe exogenous administration of motilin, we concluded that (1) motilin is released at constant intervals during the interdigestive state, and this release is suppressed by the ingestion of food; (2) motilin induces the interdigestive contractions of the stomach and duodenum; and (3) motilin is an interdigestive hormone and is the only known polypeptide hormone of the gut whose release is not induced by a meal.
Gastric electrical activity was recorded from twenty-six patients at celiotomy. The human gastric pacemaker was localized to an area in the midcorpus along the greater curve. Pacesetter potentials were generated regularly by the pacemaker at a mean frequency of 3.2 cycles/min and were propagated circumferentially and aborally from the pacemaker, increasing in amplitude and velocity as they approach the pylorus. The pattern of pacesetter potenitals in patients with gastric ulcer, gastric cancer, and duodenal ulcer was similar to that of patients without such diseases. Complete transection of the gastric corpus isolated the distal stomach from the natural pacemaker and resulted in the appearance of a new pacemaker in the distal stomach with a slower frequency. The fact that proximal gastric vagotomy did not greatly alter the frequency of generation or the pattern of propagation of the pacesetter potential provided further evidence that both are myogenic phenomena.
Electrical recordings have been made from cutaneous electrodes placed on the trunk with a view to establishing the source
of the slow potential changes which can be recorded. Cutaneous recordings have been made on 16 normal subjects in both the
fasted and fed states, and in some cases simultaneous recordings have been made from electrodes attached to the end of a naso-gastric
tube and sucked onto the stomach wall. Frequency and correlation analyses have been used to help interpret the potential changes.
A significant frequency component at approximately 3 cycles/min (average 3·02±0·21/min) was found in 88% of the stretches
of record analysed. It is shown that this is the basic electrical rhythm of the stomach. In a smaller number of recordings
(28%), a significant frequency component at 10–12 cycles/min was found. The source of these rhythms has not been proven, but
is likely to be from either the small or large bowel.
This study investigated the effect of food ingestion on motion sickness severity and its physiological mechanisms. Forty-six fasted subjects were assigned either to a meal group or to a no-meal group. Electrogastrographic (EGG) indices (normal 3 cpm activity and abnormal 4-9 cpm tachyarrhythmia) and respiratory sinus arrhythmia (RSA) were measured before and after a meal and during a subsequent exposure to a rotating drum in which illusory self-motion was induced. The results indicated that food intake enhanced cardiac parasympathetic tone (RSA) and increased gastric 3 cpm activity. Postprandial effects on motion sickness severity remain equivocal due to group differences in RSA baseline levels. During drum rotation, dysrhythmic activity of the stomach (tachyarrhythmia) and vagal withdrawal were observed. Furthermore, high levels of vagal tone prior to drum rotation predicted a low incidence of motion sickness symptoms, and were associated positively with gastric 3 cpm activity and negatively with tachyarrhythmia. These data suggest that enhanced levels of parasympathetic activity can alleviate motion sickness symptoms by suppressing, in part, its dysrhythmic gastric underpinnings.
The gastric electric activity paces the contractions of the stomach and can be measured noninvasively using surface electrodes placed on the abdomen. In this paper, response of the gastric electric activity to water and a solid meal was investigated using surface electrodes. Applying an improved recording technique, power spectral analysis and statistical analysis methods, the gastric electric activity in preprandial, postwater and postprandial states was measured and analysed from ten healthy volunteers. To more convincingly show the effect of water and the solid meal on the gastric slow wave and gastric motility, simultaneous recordings of the cutaneous EGG and manometric activities in the stomach were performed in three gastroparetic patients. It was found that water does not induce contractions of the stomach, but the gastric slow wave amplitude increases (p less than 0.05) and frequency decreases (p less than 0.05). The solid meal results in an increase in both the amplitude (p less than 0.01) and the frequency (p less than 0.02) of the gastric slow wave. It appears that the postprandial EGG amplitude increases because of a combination of stomach contractions and gastric distension bringing the stomach closer to the recording electrodes. The slow wave frequency, however, correlates well with stomach contractions.
We investigated the effects of age and obesity on the fasting cutaneous electrogastrogram (EGGc) by studying both young and aged, healthy men. All subjects underwent an electrogastrographic recording lasting 1 h, and frequency and power data were obtained by means of spectral analysis. In order to make a precise comparison of the data, each subject's body mass index (BMI) was calculated and each age group was subdivided into nonobese subjects, those with a BMI of less than 24.9 kg/m2, and obese subjects, those with a BMI of more than 25 kg/m2. Comparison of the mean frequency values of the gastric spectral peak did not reveal statistically significant differences among the groups (young vs. old, nonobese vs. obese). Comparison of the mean power values of the gastric spectral peak, on the other hand, showed that there was a statistically significant reduction in spectral power in the aged subjects compared with the young (p = 0.017 in the aged vs. young nonobese subjects and p = 0.009 in the aged vs. young obese subjects), and in the obese subjects compared with the nonobese (p = 0.00021 in the young and p = 0.00029 in the aged). Frequency, therefore, is the parameter of gastric electrical activity which may best be studied by means of EGGc as it is only very slightly affected by physiological parameters, such as age and the adiposity of subjects. EGGc, therefore, could be useful in the study of those gastric diseases associated with disorders in gastric electrical rhythm and rate.
The electrical and motor activities of the stomach were studied in the early postoperative phase after abdominal surgery by means of surface recording techniques: electrogastrography (EGG) and impedance gastrography (IGG). EGG and IGG recordings were made pre-operatively and on the first and second postoperative days. Physical signs and symptoms related to gastrointestinal motility were assessed. Two patient groups were studied; a group of patients undergoing cholecystectomy (n = 9) was compared with a group with major colonic surgery (n = 14). After colonic surgery, resumption of a normal oral diet was later and nausea and vomiting were seen more frequently than after cholecystectomy. Other physical signs concerning intestinal motility did not differ between the groups. Gastric myo-electrical activity (0.04-0.06 Hz), recorded electrogastrographically, tended to decrease in the postoperative phase in both groups, and return to pre-operative values later in the colonic surgery group. However, none of the differences reached statistical significance. Abnormal gastric activity (tachyarrhythmia) was observed in one pre-operative patient but in 6 patients (2 cholecystectomy, 4 colonic surgery) after operation. IGG variables were not significantly affected by the operation and were not significantly different between the groups. No correlation between the symptoms nausea and vomiting in the postoperative phase and the incidence of tachyarrhythmias could be demonstrated in this study. It is concluded that antral myo-electrical and motor activity, measured with non-invasive techniques (EGG and IGG), are not grossly abnormal on the first and second postoperative day after abdominal surgery. It is further concluded that abnormal gastric frequencies do not appear to play a major role in the genesis of postoperative nausea and vomiting.
Fifty-two subjects were exposed to a rotating optokinetic drum. Ten of these subjects who became motion sick during the first session completed two additional sessions. Subjects' symptoms of motion sickness, perception of self-motion, electrogastrograms (EGGs), heart rate, mean successive differences of R-R intervals (RRI), and skin conductance were recorded for each session. The results from the first session indicated that the development of motion sickness was accompanied by increased EGG 4-9 cpm activity (gastric tachyarrhythmia), decreased mean successive differences of RRI, increased skin conductance levels, and increased self-motion perception. The results from the subjects who had three repeated sessions showed that 4-9 cpm EGG activity, skin conductance levels, perception of self-motion, and symptoms of motion sickness all increased significantly during the drum rotation period of the first session, but increased significantly less during the following sessions. Mean successive differences of RRI decreased significantly during the drum rotation period for the first session, but decreased significantly less during the following sessions. In conclusion, we have demonstrated that the development of motion sickness is accompanied by an increase in gastric tachyarrhythmia, and an increase in sympathetic activity and a decrease in parasympathetic activity, and that adaptation to motion sickness is accompanied by the recovery of autonomic nervous system balance.
Changes in gastric myoelectrical activity following highly selective vagotomy were studied in 12 patients by means of electrogastrography (EGG) using cutaneous electrodes. Measurements were made before, 10 days after, and six months after operation. Eight patients undergoing cholecystectomy served as controls. Preoperatively all controls and patients had normal recordings. In the cholecystectomized patients no significant changes were found postoperatively. Ten days after highly selective vagotomy the normal initial postprandial dip in gastric ECA frequency and the subsequent increase in frequency and power were not seen. Tachygastrias were observed in three patients. Six months after operation the normal frequency and power responses to a test meal had returned, but both the fasting and postprandial ECA frequencies were raised significantly. It is concluded that highly selective vagotomy is associated with abnormalities in myoelectrical activity, in particular in the postprandial state, most of which are reversible with time.
The effects of sham feeding on gastric motility of human subjects have not previously been studied. The amplitude of 3-cpm electrogastrogram (EGG) waves increases after the ingestion of food. We hypothesized that sham feeding would stimulate a similar, but briefer gastric myoelectric response. Healthy human subjects chewed and expectorated a hot dog on a roll and later ate a second hot dog. EGGs were continuously recorded before, during, and after sham feeding and eating. The results of experiment I (N = 27) showed that the hand-scored amplitude of the 3-cpm waves increased significantly (P less than 0.01) during sham feeding. Two minutes after sham feeding, the mean amplitude of 3-cpm EGG waves returned to baseline level. The increase in EGG amplitude during eating was also significant (P less than 0.01), and remained increased for approximately 30 min after ingestion. The procedure used in experiment II (N = 20) was similar to experiment I, but EGGs were computer analyzed and power, ie, spectral intensities, at 3 cpm were obtained. The increase in power at 3 cpm during sham feeding and during eating was significant (P less than 0.05 and P less than 0.02, respectively). Similar to experiment I, the duration of increase in power at 3 cpm was brief during sham feeding compared to the postprandial increase. Four vagotomized subjects failed to show an increase in power at 3 cpm in response to sham feeding. We conclude: (1) The cephalic-vagal stimulation of sham feeding increases briefly the amplitude and power of 3-cpm gastric myoelectric activity in healthy subjects but not vagotomized patients.(ABSTRACT TRUNCATED AT 250 WORDS)
In 57 normal subjects (age 20-60 years), we analyzed the spontaneous beat-to-beat oscillation in R-R interval during control recumbent position, 90 degrees upright tilt, controlled respiration (n = 16) and acute (n = 10) and chronic (n = 12) beta-adrenergic receptor blockade. Automatic computer analysis provided the autoregressive power spectral density, as well as the number and relative power of the individual components. The power spectral density of R-R interval variability contained two major components in power, a high frequency at approximately 0.25 Hz and a low frequency at approximately 0.1 Hz, with a normalized low frequency:high frequency ratio of 3.6 +/- 0.7. With tilt, the low-frequency component became largely predominant (90 +/- 1%) with a low frequency:high frequency ratio of 21 +/- 4. Acute beta-adrenergic receptor blockade (0.2 mg/kg IV propranolol) increased variance at rest and markedly blunted the increase in low frequency and low frequency:high frequency ratio induced by tilt. Chronic beta-adrenergic receptor blockade (0.6 mg/kg p.o. propranolol, t.i.d.), in addition, reduced low frequency and increased high frequency at rest, while limiting the low frequency:high frequency ratio increase produced by tilt. Controlled respiration produced at rest a marked increase in the high-frequency component, with a reduction of the low-frequency component and of the low frequency:high frequency ratio (0.7 +/- 0.1); during tilt, the increase in the low frequency:high frequency ratio (8.3 +/- 1.6) was significantly smaller. In seven additional subjects in whom direct high-fidelity arterial pressure was recorded, simultaneous R-R interval and arterial pressure variabilities were examined at rest and during tilt. Also, the power spectral density of arterial pressure variability contained two major components, with a relative low frequency:high frequency ratio at rest of 2.8 +/- 0.7, which became 17 +/- 5 with tilt. These power spectral density components were numerically similar to those observed in R-R variability. Thus, invasive and noninvasive studies provided similar results. More direct information on the role of cardiac sympathetic nerves on R-R and arterial pressure variabilities was derived from a group of experiments in conscious dogs before and after bilateral stellectomy. Under control conditions, high frequency was predominant and low frequency was very small or absent, owing to a predominant vagal tone. During a 9% decrease in arterial pressure obtained with IV nitroglycerin, there was a marked increase in low frequency, as a result of reflex sympathetic activation.(ABSTRACT TRUNCATED AT 400 WORDS)
We present a useful technique for analyzing the various functional components that comprise the cardiovascular control network. Our approach entails the imposition of a signal with broad frequency content as an input excitation and the computation of a system transfer function using spectral estimation techniques. In this paper, we outline the analytical methods involved and demonstrate the utility of our approach in studying the dynamic behavior of the canine cardiac pacemaker. In particular, we applied frequency-modulated pulse trains to either the right vagus or the cardiac sympathetic nerve and computed transfer functions between nerve stimulation rate and the resulting atrial rate. We found that the sinoatrial node (and associated automatic tissue) responds as a low-pass filter to fluctuations in either sympathetic or parasympathetic tone. For sympathetic fluctuations, however, the filter has a much lower corner frequency than for vagal fluctuations and is coupled with a roughly 1.7-s pure delay. We further found that the filter characteristics, including the location of the corner frequency and rate of roll-off, depend significantly on the mean level of sympathetic or vagal tone imposed.
A method to record the gastric basic electrical rhythm (BER) using skin electrodes is described. Correlation is made with mucosal suction electrodes in 20 volunteers. Successful simultaneous recording from surface electrodes and mucosal electrodes is made in 16/20 subjects (80%). An increase in amplitude of the recorded gastric BER with gastric contractions is demonstrated and discussed. Five patients with gastric motility disturbances and chronic nausea are also investigated. Four of these patients had diabetic gastroparesis. Each had preservation of the gastric BER. The rate was usually normal at three per minute, but during acute nausea episodes which occurred in three of the four, an abnormally increased rate of the BER (tachygastria) was seen. This finding was also seen in a subject with atrophic gastritis and delay of gastric emptying. The surface electrogastrogram may prove to be a useful tool for the investigation of patients with suspected gastric arrhythmias.
In this review we present some current applications of electrogastrography, relationships between the electrogastrogram (EGG) and electrical and contractile activity of the stomach, EGG recording technique, and the current status of electrogastrography. The authors conclude the following: (1) The 3 cpm frequency of the EGG reflects the frequency of pacesetter potentials occuring at the serosal and mucosal surfaces of the stomach. (2) An increase in the contractile activity of the corpus-antrum is associated with an increase in the amplitude of the 3 cpm EGG signal. (3) Tachygastria (5-9 cpm waves) recorded with the EGG reflects identical frequencies recorded with mucosal electrodes from the gastric antrum. (4) Low frequency componets (approximately 1 cpm) appear in the EGG signal but their physiological significance is unknown at this time.
Using cutaneous electrodes an electrogastrographic study was made of gastric myoelectrical activity in both the fasting and postprandial states in 48 patients with unexplained nausea and vomiting and in 52 control subjects. A gastric emptying study, using a radio-labelled solid phase meal, was carried out in 30 of these 48 patients. A follow up study was done after one year. In 48% of the patients abnormal myoelectrical activity was found which was characterised by: instability of the gastric pacemaker frequency; tachygastrias in both the fasting and postprandial states; the absence of the normal amplitude increase in the postprandial electrogastrogram. This last characteristic was correlated with a delayed gastric emptying of solids. The present study shows that with electrogastrography in a heterogeneous group of patients with unexplained nausea and vomiting a subgroup can be discerned with abnormal myoelectrical activity. Our findings suggests that this abnormal myoelectrical activity is related to these symptoms.
Most of the gastrointestinal tract and the biliary tract have a cyclic motor activity. The electric counterpart of this motor activity is called cyclic myoelectric activity. A typical motor cycle in the LES, stomach, and small intestine is composed of a quiescent state, followed by progressively increasing amplitude and frequency of contractions culminating in a state of maximal contractile activity. The colonic motor cycle has only the quiescent and the contractile states. In the small intestine, these motor complexes migrate in an aborad direction, and in the colon in both orad and aborad directions. The mechanisms of initiation and migration of these complexes are best understood in the small intestine. Both the initiation and migration of these complexes seem to be controlled by enteric neural mechanisms. The functions of the enteric mechanisms may be modulated by the central nervous system and by circulating endogenous substances. The mechanisms of initiation of these complexes are not completely understood in the rest of the gastrointestinal tract and in the biliary tract. The physiologic function of these motor complexes that occur only after several hours of fast in the upper gastrointestinal tract of nonruminants may be to clean the digestive tract of residual food, secretions, and cellular debris. This function is aided by a coordinated secretion of enzymes, acid, and bicarbonate. In ruminants, phase III activity is associated with the distal propulsion of ingested food. The function of colonic motor complexes that are not coordinated with the cyclic motor activities of the rest of the gastrointestinal tract may be only to move contents back and forth for optimal absorption.
The role of the vagus nerves in the control of postprandial motility in the upper gastrointestinal tract was investigated in four dogs by use of a bilateral cervical cooling blockade technique. On administration of food, the fasting migrating motor complex (MMC) was replaced by the postprandial (feeding) pattern. Feeding pattern duration varied in a dose-dependent manner with either total volume or calories of food. During the feeding pattern, oscillations in lower esophageal sphincter (LES) pressure occurred at time intervals equivalent to the MMC cycle period. Twenty-one control feeding experiments and 17 postprandial vagal blockade experiments were performed, with a minimum of three of each type in each dog. Vagal blockade, initiated at times ranging from 15 min to 4 h after feeding and maintained for up to 5 h, abolished the postprandial activity in the upper gastrointestinal tract. During postprandial vagal blockade, LES pressure was abolished and bursts of contractions were observed only in the upper small bowel, a pattern resembling that observed during vagal blockade in the fasted state. These bursts occurred at the expected times relative to, and their cycle period was not significantly different from, that of the MMCs recorded prior to feeding. Vagal blockade started prior to feeding prevented initiation of the fed pattern, which appeared immediately on termination of the blockade. We conclude that initiation and maintenance of the postprandial pattern in the upper gastrointestinal tract with concurrent inhibition of the fasting MMC normally require vagal integrity. The "clock" controlling the MMC cycle period is not reset by feeding, but its effect on motility is suppressed.
Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.
The objective of this study was to improve recording techniques for the recognition of gastric electrical dysrhythmias, and to explore the potential of pharmacologic agents to "evoke" gastric dysrhythmias. Eighteen healthy volunteers participated in 22 individual recordings, divided into two separate studies--a dose-response study and a randomized, double-blind study. The internal or mucosal electrogastrogram was recorded with a novel approach, using magnetic force to maintain internal electrodes in apposition with the gastric wall, whereas the external or cutaneous electrogastrogram, manometric activity, and respiration were measured by conventional methods. Analysis of simultaneous internal and external electrogastrographic signals, including both dysrhythmia and dysrhythmia-free intervals, revealed a good correspondence between the internal and external signals. In the dose-response study, 5 of the 6 volunteers intravenously infused with glucagon, in doses ranging from 3 to 22 micrograms/kg, developed gastric electrical dysrhythmias. In the randomized, double-blind study, 4 of 5 volunteers intravenously infused with glucagon (7 micrograms/kg) developed gastric dysrhythmias that were recognized by our improved techniques. Dysrhythmias, defined by visual analysis, consisted either of "tachygastria" (greater than or equal to 6 cycles/min for greater than or equal to 1 min) or "bradygastria" (greater than or equal to 1 cycle/min for greater than or equal to 1 min) and were evident on both internal and external electrogastrograms. Dysrhythmias were usually associated with absence of antral phasic pressure activity and frequently with nausea.
Fasting gastrointestinal motor and hormone patterns were studied in 11 healthy volunteers. Cyclic motor activity was present in all subjects during fasting, but the duration and site of onset of each cycle were variable, even in the same subject. Fasting gastrin, GIP, and glucagon levels remained low and constant during the 8-hr study, while plasma motilin levels exhibited cyclic variation in 7 of the 11 subjects. Achlorhydria (induced with cimetidine in 5 of the 11 subjects) did not alter the pattern of fasting motor activity or plasma motilin. In the remaining six subjects, the effect of liquid nutrient meals was examined. Ingestion of a sodium chloride bolus failed to disrupt fasting cyclic activity, while all nutrient-containing solutions inhibited gastric phase-2 motor activity, the duration of inhibition being longest for the mixed and lipid meals. All nutrient meals released GIP, while only protein and mixed meals released gastrin, and the lipid meal released motilin. Our study confirms the rhythmicity of interdigestive motor cycles in man and demonstrates their lack of dependence on gastric acid secretion and some relationship to motilin cycles in certain individuals as determined by radioimmunoassay. Transition from fasting to fed pattern (after liquid meals) is characterized by the inhibition of phasic gastric pressure changes in the antrum and the development of irregular activity in the intestine, similar in pattern to fasting phase 2. Because the duration of interruption of the gastric interdigestive pattern by meals depends on their nutrient content, we conclude that dietary composition may be a major determinant of the fasting-fed motor balance in man.
The object of this study was to elucidate what is actually measured in electrogastrography. Comparison of gastric signals simultaneously recorded from serosal and cutaneous electrodes in the conscious dog led to the following findings: 1. In the absence of phasic contractile activity and electrical response activity (ERA), the cutaneous recordings contained a frequency corresponding to the fundamental frequency of the electrical control activity (ECA) of the stomach (about 0.08 Hz). 2. Tachygastrias gave rise to cutaneous signals containing the tachygastric frequency (about 0.25 Hz). 3. The amplitude of the electrogastrogram increased when ERA occurred. It is concluded that both ECA and ERA are reflected in the electrogastrogram. A model is proposed that describes the electrogastrogram as the result of field potentials generated by depolarization and repolarization dipoles.
To investigate changes in postprandial electrogastrography (EGG) from the neurohormonal mechanisms.
We measured EGG indices [frequency amplitude of normal 3-cpm (EGG-3 cpm)], high frequency amplitude of heart rate variability which has reflected cardiac parasympathetic tone, and several serum immunoreactive (ir)-hormone levels in 12 fasted male volunteers (mean age 25.3 yr).
Immediately after the liquid food intake (250 kcal), a transient decrease in EGG-3 cpm frequency (from 0.045 +/- 0.001 Hz to 0.040 +/- 0.001 Hz; p < 0.05) accompanied by an increase in high frequency amplitude (from 31.05 +/- 3.45 ms to 39.10 +/- 4.08 ms; p < 0.05), and a serum immunoreactive gastrin level increase (from 38.72 +/- 4.92 pmol/L to 54.00 +/- 10.45 pmol/L; p < 0.05) and an immunoreactive somatostatin level decrease (from 15.00 +/- 0.43 pmol/L to 13.70 +/- 0.46 pmol/L; p < 0.01) were observed, suggesting vagal excitement. EGG-3 cpm amplitude and serum immunoreactive human pancreatic polypeptide (hPP) levels significantly increased soon after ingestion, and these changes lasted for 30 min. Furthermore, there was a positive correlation between changes in EGG-3 cpm amplitude and those in serum immunoreactive hPP levels during the postprandial periods (r = 0.55, p < 0.001).
Considering the reports that a cholinergic, nonvagal pathway is of major importance in food-stimulated hPP release, the present results suggest that postprandial changes in EGG-3 cpm frequency and amplitude might be a good tool for evaluating not only vagal but also nonvagal cholinergic activity in the human gut.
The objective of this study was to investigate whether gastric contractions in the fasting and fed state can be identified from the cutaneous electrogastrogram.
Simultaneous measurements of gastric myoelectrical and manometric activities were made in 10 healthy female volunteers from 1:00 AM to 9:45 AM. For manometric recording, a catheter incorporating solid state transducers was used. Cutaneous electrogastrography (EGG) was used for myoelectrical recording. All EGG data from 1:00 AM to 7:30 AM that occurred during motor quiescence, all EGG data that occurred during antral contractions, and 2-h EGG data after breakfast given at 7:30 AM were quantitatively analyzed and compared with each other. The EGG in three specific periods (fasting without antral contractions, fasting with contractions, and postprandial) was characterized by four parameters that include frequency, power, and stabilities of the frequency and power.
1) the peak power of the postprandial EGG was, respectively, 12.5 dB (about 2-fold increase in amplitude) and 6.8 dB (about 1-fold increase in amplitude) higher than that during motor quiescence (p < 0.05) and motor activity in the fasting state; 2) the dominant frequency of the postprandial EGG was, respectively, 6% and 13% higher than that during motor quiescence and motor activity (p < 0.05) in the fasting state; 3) the peak power of the fasting EGG was 48% more unstable during motor activity than motor quiescence (p < 0.05); 4) the stability of the EGG frequency was not significantly different during the three different periods.
The EGG provides important and useful information for the assessment of gastric motility. An unstable EGG peak power is indicative of gastric contractions in the fasting state. An increase in EGG peak power and/or dominant frequency after a solid test meal suggests a normal postprandial gastric motility.
This study was undertaken to determine the accuracy of cutaneous electrogastrography (EGG).
The ability of EGG to assess gastric contractions and electrical frequency, phase lag, and waveform was studied in 4 healthy volunteers with cutaneous electrodes before and after eating, 4 healthy fasting volunteers with intraluminal pressure recording tubes and cutaneous electrodes, 1 patient with surgically implanted gastric serosal electrodes, and 4 anesthetized dogs with serosal force transducers and implanted and cutaneous electrodes. In 2 of the dogs, an intragastric distending balloon was introduced.
The use of long-distance serosal electrodes allowed direct comparison of internal and cutaneous signals. Cutaneous electrodes recognized 80%-85% of changes in frequency with spectral analysis. Only 30%-40% of increases in EGG amplitudes were associated with gastric contractions. Gradual distention of the canine stomach after blocking contractions with atropine and glucagon increased the EGG amplitudes. No appreciable phase lag could be discerned with EGG. The descending portion of the EGG waveform was predominant.
Frequency dynamics is currently the only reliable cutaneous EGG parameter.
A summary of many of the new techniques developed in the last two decades for spectrum analysis of discrete time series is presented in this tutorial. An examination of the underlying time series model assumed by each technique serves as the common basis for understanding the differences among the various spectrum analysis approaches. Techniques discussed include the classical periodogram, classical Blackman-Tukey, autoregressive (maximum entropy), moving average, autotegressive-moving average, maximum likelihood, Prony, and Pisarenko methods. A summary table in the text provides a concise overview for all methods, including key references and appropriate equations for computation of each spectral estimate.
Regional differentiation of sympathetic efferents under various natural and experimental conditions
- Iriki
Iriki, M., Regional differentiation of sympathetic efferents under various natural and experimental conditions, Shinkei Kenkyu no Shinpo, 33 (1989) 196-206.
Effects of cold stress on gastric myoelectric activity
- Stem
Sham Feeding: cephalic-vagal influences on gastric myoelectric activity
- Stem
Acquisition and analysis of electrogastrographic data: the Dutch experience
- Smout