Biomagnetic signatures of uncoupled gastric musculature

Abstract  Gastric slow waves propagate in the electrical syncytium of the healthy stomach, being generated at a rate of approximately three times per minute in a pacemaker region along the greater curvature of the antrum and propagating distally towards the pylorus. Disease states are known to alter the normal gastric slow wave. Recent studies have suggested the use of biomagnetic techniques for assessing parameters of the gastric slow wave that have potential diagnostic significance. We present a study in which the gastric syncytium was uncoupled by mechanical division as we recorded serosal electric potentials along with multichannel biomagnetic signals and cutaneous potentials. By computing the surface current density (SCD) from multichannel biomagnetic recordings, we were able to quantify gastric slow wave propagation as well as the frequency and amplitude of the slow wave and to show that these correlate well with similar parameters from serosal electrodes. We found the dominant slow wave frequency to be an unreliable indicator of gastric uncoupling as uncoupling results in the appearance of multiple slow wave sources at various frequencies in external recordings. The percentage of power distributed in specific frequency ranges exhibited significant postdivision changes. Propagation velocity determined from SCD maps was a weak indicator of uncoupling in this work; we believe that the relatively low spatial resolution of our 19-channel biomagnetometer confounds the characterization of spatial variations in slow wave propagation velocities. Nonetheless, the biomagnetic technique represents a non-invasive method for accurate determination of clinically significant parameters of the gastric slow wave.     

Evaluation of Residual Stomach Motility After Proximal Gastrectomy for Gastric Cancer by Electrogastrography

The relationship between the motility and the size of the residual stomach after proximal gastrectomy was evaluated using electrogastrography (EGG). Based on fast Fourier transformation, recorded slow waves could be analyzed to obtain the following parameters: dominant frequency (DF), percentage normal frequency (% 3 cycles per minute [cpm]), and power ratio (PR). EGG parameters, the length of the greater curvature of the residual stomach (LGC), were recorded in 18 gastrectomized patients. Compared to 12 healthy controls, the gastrectomized patients had abdominal EGG parameters including lower %3cpm (43 ± 21% vs 83 ± 7%; P < 0.05), DF (2.2 ± 0.4 vs 3.0 ± 0.2 cpm; P < 0.05), and PR (1.5 ± 0.8 vs 2.5± 0.8; P < 0.05). In relation to LGC and parameters, there was no difference between the patients whose LGC was > 20 cm and controls in PR (2.3± 0.9 vs 2.5± 0.8; n.s.). In conclusion, the motility of the residual stomach would be equal to that of the nonresected stomach as if the volume of the residual stomach was more than half.     

Effect of meal temperature on the frequency of gastric myoelectrical activity

It was hypothesized that the transient postprandial decrease of the dominant frequency in the electrogastrogram (EGG) is related to the temperature of the meal. In a randomized three-period cross-over design, EGG recordings were made in 10 healthy volunteers. A liquid meal (36 kcal, 300 mL) was ingested at either 4, 37 or 55 °C. The changes in the dominant EGG frequency that occurred in the first 25 min postprandial were calculated using running spectrum analysis. After the meal a transient shift in frequency was seen, which was significantly greater after the cold meal than after the other meals (P<0.001), with a greater decrease in the dominant frequency (4 °C:−0.75 [−0.92 ∼ −0.68], 37 °C:−0.34 [−0.51 ∼ −0.18], 55 °C:−0.30 [−0.45 ∼ −0.12] cpm, P = 0.020) and a longer duration (4 °C: 16 [13 ∼ 19], 37 °C: 12 [6 ∼ 14], 55 °C: 5 [3 ∼ 8] min, P = 0.014). No differences were found between the 37 °C and 55 °C meals, the power ratios or the number of dysrhythmias. The magnitude of the postprandial shift in frequency of gastric myoelectrical activity depends on the temperature of the meal. Meal temperature should be taken into account in studies on postprandial gastric motility.     

Effect of single-dose administration of recombinant interferon-alpha2b on gastric myoelectrical activity in patients with chronic hepatitis C

Background Upper abdominal complaints during interferon therapy may result from impaired gastric motility and/or evacuatory function. We examined the effect of acute administration of interferon on gastric myoelectrical activity (GMA) with the use of surface electrogastrography.Methods The study population comprised 25 patients with chronic hepatitis C. All of them were naïve to interferon. On 2 days, after a 25-min basal GMA registration, in group A (5 men, 7 women, aged 44.3 ± 2.8 years) placebo or 5 million i.u. recombinant interferon alpha-2b (IFNA) was administered s.c. and the GMA was recorded in the interdigestive state for two periods (2h and 4h), separated by a 15-min break. In group B (7 men, 6 women, aged 44.7 ± 3.9 years) placebo or 5 million i.u. IFNA was injected s.c. after the ingestion of a semiliquid test meal of 364kcal. Subsequently, the postprandial GMA was recorded for two periods (2h and 4h), separated by a 15-min break.Results A typical flu-like syndrome was observed in 91.7% of patients in group A, and in 92.3% of patients in group B, thus providing evidence of the pharmacodynamic efficiency of the IFNA administration. In the fasted state, IFNA brought about a negligible increase in the rhythmicity and power of the gastric slow waves. IFNA did not elicit any statistically significant effect on gastric slow-wave activity postprandially.Conclusions Acute administration of interferon does not involve any deterioration of GMA that could be linked to the previously reported upper abdominal symptoms in patients undergoing treatment with this drug.     

婴儿期胃电慢波发育的研究

目的研究健康婴儿的胃电慢波发育。方法0～24个月健康婴儿，按3个月的年龄间隔分为9组，每组20例，其中男104例，女76例，无窒息，母乳喂养，无器质性疾病。采用体袁胃电图，分别于记录空腹和餐后体表胃电图各30min。计算出胃电慢波的以下参数：主频、不同慢波节律的百分比、主频不稳定系数、功率比。结果0,6、12、18和24个月健康婴儿餐前主频分别为（2．38&#177;0．5）、（2．54&#177;0．4）、（2．62&#177;0．3）、（2．86&#177;0．3）和（2．97&#177;0．2）cpm，餐后与餐前相比差异无显著性P〉0．05，正常胃电节律百分比分别为（38．6&#177;4．9）、（47．8&#177;3．4）、（55．6&#177;3．6）、（60．4&#177;3．7）、（69．7&#177;3．3），胃动过速节律百分比为（24．6&#177;5．4）、（18．6&#177;4．1）、（15．6&#177;4．9）、（14．7&#177;3．6）、（12．7&#177;4．3），胃动过缓节律百分比为（36．8&#177;5．5）、（33．6&#177;4．3）、（28．8&#177;3．8）、（24．9&#177;3．8）、（17．6&#177;3．7），18个月以上婴儿餐后正常胃电节律百分比较餐前升高（P〈0．05）。12个月以上婴儿餐前、餐后的主频不稳定系数降低（P〈0．05），餐后与餐前相比差异无显著性（P〉0．05），餐后餐前功率比12个月以上较12个月以下增加（P〈0．05）。结论婴儿期的胃电慢波经历一发育成熟阶段，正常胃电节律百分比和主频随年龄的增长逐渐升高，2岁时达到成人水平。     

Effects of trimebutine maleate on gastric motility in patients with gastric ulcer

The effects of trimebutine maleate (TM), a prokinetic drug, on gastrointestinal motility in patients with gastric ulcer were investigated. Twenty patients with active gastric ulcers were allocated to two groups; 10 patients received a proton pump inhibitor alone (PPI group), given orally, and 10 patients received oral TM in combination with a PPI (PPI + TM group), each for a period of 8 weeks. Electrogastrography (EGG) and gastric emptying were measured before and after the treatment period. During the active ulcer stage, tachygastria (more than 0.06 Hz) or bradygastria (less than 0.04 Hz) in the EGG frequency were observed in 9 patients either before or after meals. During the healed ulcer stage, tachygastria or bradygastria was observed in 4 of 10 patients in the PPI group, while in the PPI + TM group, 1 patient had tachygastria and none had bradygastria. Postprandial dip (PD) was observed in 3 of the 20 patients during the active stage, while after treatment, PD was observed in 3 patients in the PPI group and in 6 patients in the PPI + TM group, respectively. Gastric emptying in the PPI group did not show any change between before and after treatment, while that in the PPI + TM group improved significantly after treatment. These results suggest that TM may have an ameliorative effect on abnormal gastric motility in patients with gastric ulcer. (Received Sept. 17, 1997; accepted Apr. 24, 1998)     

脊柱手术对胃功能的影响及相关治疗的疗效研究

目的：研究脊柱手术对胃功能的影响及相关治疗的疗效。方法：６０例脊柱手术患者，２０例四肢手术患者，２０名健康者，脊柱手术组术前及术后的均行胃电图检查，其中２０例行Ｘ线钡餐造影动态胃蠕动波记录，脊柱手术组术后随机分为３组，分别予中药香砂养胃丸、艾灸、吗丁啉治疗，同时观察比较治疗前后胃电图变化，结果：脊柱手术组术后胃电节律有明显异常，频率和振幅与其他两组差异有显著性（Ｐ〈０．０５，Ｐ〈０．０１），胃蠕动     

用计算机技术研究大鼠胃电和胃运动信号

利用体表电极、体内胃肠电极和压力传感器,通过计算机分别同时记录正常对照组和急性应激组 Ｗｉｓｔａｒ 大鼠体表胃电、体内平滑肌慢波和胃平滑肌运动信号,并进行数据处理和统计学分析。结果表明,正常对照组和急性应激组的体表胃电、体内平滑肌慢波和胃平滑肌运动存在差别。这种差别提示：①体表胃电在一定程度能够反映胃的活动,揭示胃的生理和病理规律,有可能应用于临床,作为胃病的诊断和疗效判定的客观标准;②体表胃电不仅反映体内胃平滑肌慢波的电活动,还与胃平滑肌运动有关,反映了有关胃平滑肌运动的一些信息。