Isopower mapping of electrogastrograms in short-bowel syndrome

Local differences in electrogastrographic indices associated with total gastrectomy, total colectomy, distal gastrectomy and colonic replacement

The electrogastrographic indices of spectral frequency, instability factor (IF), power amplitude, and power content (%) were compared between control subjects (C), and subjects following either total gastrectomy (TG), total colectomy (TC), distal gastrectomy (DG) or colonic replacement surgery (CR). In the fasting state, both the spectral frequency and IF of the epigastric 3-cycle per minute (cpm) group of the TC subjects were significantly lower than those indices in C, TG, DG, and CR subjects. In contrast, the power amplitude and power content of the epigastric 3-cpm group of both TG and DG subjects were significantly lower than those of C and TC subjects. The original epigastric waves of TG had remarkably high amplitudes. Furthermore, the absolute power of the epigastric 3-cpm of the TC subjects was 10 times higher than that in either the C or TG subjects. These results may be partially explained by the assumption that the recorded epigastric electrogastrography (EGG) is mainly contributed to by the 3-cpm myoelectric activity of the stomach and colon, while the infraumbilical EGG is mainly contributed to by the 3-cpm myoelectric activity of the colon. Topographic EGG maps visually supported these assumptions.

Local differences in electrogastrograms recorded from 16 locations on the human thoraco-abdominal surface

Local differences in the electrogastrographic (EGG) indices were studied. The indices include the spectral frequency, the instability factor (IF) of the spectral frequency, and the power content in addition to the usual power amplitude of 5 frequency groups as follows: the 1-cpm group (0-2.4), the 3-cpm group (2.5-4.9), the 6-cpm group (5.0-7.4), the 8-cpm group (7.5-9.9), and the 10-cpm group (10.0-12.9). In general, the infraumbilical frequency and the IF of both of the 3- and 6-cpm groups were higher than those of the epigastric frequencies. In contrast, both the epigastric power amplitude and the power content of the 3- and 6-cpm groups were higher than those of the infraumbilical ones. Mapping of the absolute power amplitude and superimposing the maximal power foci further visualized and clarified the local differences in the epigastric and infraumbilical myoelectrical activity, especially of gastric and colonic activity.

Correlations between the responses of electrogastrograms, heart rate and respiratory rate to the stress of the mirror drawing test in human subjects

An electrogastrogram (EGG) recorded on the skin is believed to reflect the electrical activity of the gastrointestinal tract. In this study, linear correlations were calculated for the EGG spectral frequencies and the power ratios, changes in heart and respiratory rate before and during mirror drawing test (MDT) stress and after having meals, with the changes in the sympathetic tone indicator (LF/HF) and HADS anxiety and depression scores in human subjects (n=48). Depression scores had a negative linear correlation with the EGG resting frequencies of the epigastric and supraumbilical 6 cpm groups (5.0-7.4 cpm). Anxiety scores had a positive linear correlation with the EGG area power ratio of the resting to MDT stress responses of the epigastric and infraumbilical 6 cpm groups (6 cpm area during MDT/that during fasting rest). The resting LF/HF had a positive linear correlation with the EGG area power ratio of the resting to MDT stress responses of the epigastric and infraumbilical 3 cpm groups (2.5-4.9 cpm). The resting LF/HF ratio had a negative correlation with the area power ratio of the resting to postprandial responses (postprandial power/resting power) in the epigatric, supraumbilical and infraumbilical 6 cpm groups. The resting LF/HF ratio had a positive linear correlation with the heart rate at rest and during MDT-stress. In contrast, the resting LF/HF ratio had a negative linear correlation with the respiratory rate at rest and during MDT-stress. EGGs of the surface electrical activities of the gastrointestinal tract were influenced by acute MDT-stress and their frequencies and their response power ratios were correlated linearly with anxiety scores, depression scores and the sympathetic tone indicator, the LF/HF ratio.

Electrogastrographic activity in patients who received proximal gastrectomy plus jejunal interposition or total gastrectomy plus jejunal interposition

Electrogastrograms (EGGs) were recorded in patients both before and after receiving proximal gastrectomy plus jejunal interposition (PGJI) or just after receiving total gastrectomy plus jejunal interposition (TGJI). Intraluminal pressure was also recorded in some postoperative patients. The EGG 3 cpm component (2.5-4.9 cpm) remained after PGJI, but subsequently decreased with a significant reduction in the preoperative to postoperative ratio of the 3 cpm components (P<0.05). The mean frequency of the 3 cpm components increased significantly after PGJI (P<0.05) and its instability factor increased. The EGG 10 cpm components became relatively dominant compared to other frequency components in 2 out of 8 of patients having PGJI but the mean amplitude of 10 cpm decreased. In TGJI patients, only the 10 cpm component was conspicuous in EGG as in the case of total gastrectomy and Roux en Y anastomosis procedures. The spectral frequencies of intraluminal pressure in the interposed jejunum were similar to the EGG of 10 cpm components both in the case of PGJI and TGJI patients. In conclusion, surface EGG could record the electrical activities of the interposed jejunum more easily in patients having had TGJI than in PGJI.

Motor and electrogastrographic activity of the gastric tube formed after esophagectomy

In order to characterize the motor activity of a surgically constructed gastric tube, several hours of ambulatory intraluminal pressure recordings were performed in 6 patients following esophagectomy and gastric tube construction. Whole pressure waves were spectrally analyzed by Fast Fourier Transform (FFT). Simultaneous abdominal and thoracic electrogastrograms (EGGs) were recorded for about 20 min both before and after meals during ambulatory pressure recording. The pressure waves and EGGs for each 20 min recording were analyzed by the maximal entropy method (MEM). While the motility index of the pressure waves decreased after a meal, the 3 cpm component of these waves (2.4-3.7 cpm) increased significantly (n=6, P<0.05). Both bradygastria (0-2.4 cpm) and the duodeno-respiratory component (10-15 cpm) decreased, while the tachygastria component (3.7-10 cpm) increased, although these differences were not significant. The peak power of the gastric tube abdominal EGGs was significantly larger than that of control abdominal or thoracic EGGs in each of the 1 cpm (0-2.4 cpm), 6 cpm (5.0-7.4) and 8 cpm components (7.5-9.9). The thoracic EGG consisted mainly of the 3 cpm component, while the spectral amplitudes of the 1, 6, 8 and 10 cpm components were below 6% of the 3 cpm component. The peak spectral frequency both of the intraluminal pressure waves by FFT and of the thoracic EGGs by MEM occurred within the 3 cpm component. A cross correlation of about 0.2-0.3 occurred between the thoracic EGGs and the intraluminal pressure waves. Thus the gastric tube seems to preserve most of the original gastric motor characteristics and to contribute as a substitute for the original esophagus and stomach.

The effects of stress in response to mirror drawing test trials on the electrogastrogram, heart rate and respiratory rate of human subjects

Electrogastrograms (EGGs), heart and respiratory rates were recorded simultaneously from human subjects and analyzed spectrally by the maximal entropy method. The stress of the mirror drawing test (MDT) significantly increased both the heart and respiratory rates with an associated increase in LF/HF ratios. MDT stress, however, increased (excited groups) or decreased (inhibited groups) the power amplitude and the power ratio, (peak power during MDT)/(peak power during rest), of the 1-cpm (0-2.4 cpm), 3-cpm (2.5-4.9), 6-cpm (5.0-7.4), 8-cpm (7.5-9.9) and 10-cpm (10.0-12.9) spectral group components of the EGG recording of the electrical activity of the gastrointestinal tract. The depression scores of the subjects in the MDT stress excited group were higher and their resting frequencies were significantly lower than those of the MDT stress inhibited groups in each of the epigastric, supra-umbilical and infra-umbilical 6-cpm frequency groups but not in the epigastric 1-cpm frequency group. Anxiety scores of the MDT stress excited groups were significantly higher and their power ratios were also significantly higher than those of the inhibited groups in each of the epigastric 10-cpm, the supra-umbilical 6-cpm and the infra-umbilical 1- and 3-cpm frequency groups. Therefore, depression scores appeared to have inhibitory effects on the resting EGG frequencies, while anxiety scores appeared to have facilitatory effects on the EGG power ratio during MDT stress. It is suggested that analysis of EGG under MDT stress would provide a measure of the stress sensitivity of the electrical activity of the human gastrointestinal tract.

The herbal medicine Rikkunshi-to stimulates and coordinates the gastric myoelectric activity in post-operative dyspeptic children after gastrointestinal surgery

Rikkunshi-to (TJ-43), a gastroprotective herbal medicine, has been used for the symptomatic relief of adult patients with dyspepsia. However, its mechanism has yet to be fully elucidated. The aim of this study is to evaluate the effect of TJ-43 on the gastric myoelectric activity in post-operative dyspeptic patients, whose symptoms persisted for over 1 year after gastrointestinal surgery. Electrogastrography (EGG) recordings were performed to calculate the biomechanical parameters on the dominant peak frequency (DPF). Eight pediatric patients with dyspeptic symptoms after gastrointestinal surgery were examined and six age-matched children without any dyspeptic symptoms were used as controls, and they were compared with nine age-matched children without any dyspeptic symptoms after gastrointestinal surgery as subcontrols. All patients exhibited symptomatic relief after the administration of TJ-43, and the mean symptom score decreased significantly after the treatment of TJ-43 over a 1-month period ( P<0.0001). The variability index (VI) and the percentage of normal waves (PNW) were calculated as irregularity parameters of DPF. The power ratio (PR) was calculated as a parameter of the gastric contractile activity. There were no significant differences in the VI and PNW between the controls and patients during the postprandial state after therapy, even though significant differences existed regarding those parameters between the controls and patients before the therapy. There were no significant differences in the DPF, VI, and PNW between the controls and subcontrols. Furthermore, PR exhibited a significant increase after therapy ( P<0.05). However, there was a significant difference in the PR between the controls and subcontrols ( P<0.05). Postprandial dip was observed in all control subjects, eight patients in the subcontrols, and two patients after administration of TJ-43, respectively. An abnormal gastric electrical activity therefore seems to be an important factor in the pathophysiology of post-operative dyspeptic children. The coordinating and stimulating effect of TJ-43 on the gastric myoelectric activity therefore seems to play an important role in the reduction of dyspeptic symptoms.