Implantable electrical gastric stimulation to treat morbid obesity in the human: operative technique

Gastric stimulation for weight loss

The prevalence of obesity is growing to epidemic proportions, and there is clearly a need for minimally invasive therapies with few adverse effects that allow for sustained weight loss. Behavior and lifestyle therapy are safe treatments for obesity in the short term, but the durability of the weight loss is limited. Although promising obesity drugs are in development, the currently available drugs lack efficacy or have unacceptable side effects. Surgery leads to long-term weight loss, but it is associated with morbidity and mortality. Gastric electrical stimulation (GES) has received increasing attention as a potential tool for treating obesity and gastrointestinal dysmotility disorders. GES is a promising, minimally invasive, safe, and effective method for treating obesity. External gastric pacing is aimed at alteration of the motility of the gastrointestinal tract in a way that will alter absorption due to alteration of transit time. In addition, data from animal models and preliminary data from human trials suggest a role for the gut-brain axis in the mechanism of GES. This may involve alteration of secretion of hormones associated with hunger or satiety. Patient selection for gastric stimulation therapy seems to be an important determinant of the treatment’s outcome. Here, we review the current status, potential mechanisms of action, and possible future applications of gastric stimulation for obesity.

The effect on gastric tone of gastric electrical stimulation with trains of short pulses varies with sites and stimulation conditions

BACKGROUND

Gastric electrical stimulation (GES) can improve symptoms in patients with gastroparesis and induce weight loss in obese subjects.

AIMS

To evaluate the effect on gastric tone of GES under different conditions at different sites of the stomach.

METHODS

Eleven dogs were implanted with a gastric cannula and two pairs of stimulation electrodes (in the middle of the lesser curvature and of the greater curvature, 10 cm from the pylorus). Gastric tone was assessed with a barostat. GES was applied using: (1) Enterra conditions (14 Hz, 5 mA, 0.3 ms, 0.1 s on, 5 s off); (2) modified Enterra conditions (40 Hz, 5 mA, 0.3 ms, 0.1 s on, 5 s off); and (3) implantable gastric stimulation (IGS) conditions (40 Hz, 5 mA, 0.3 ms, 2 s on, 3 s off). Six sessions were performed randomly with each animal on six separate days.

RESULTS

(1) At the lesser curvature, GES with modified Enterra conditions significantly elevated gastric volume from 96.9 +/- 8.3 ml at baseline to 133.9 +/- 11.7 ml (P = 0.015) and a similar effect was observed with IGS (91.3 +/- 7.1 ml vs. 186.3 +/- 27.1 ml, P = 0.013). GES with Enterra conditions had no such an effect. (2) At the greater curvature, GES with Enterra conditions significantly increased gastric volume from basal 94.1 +/- 4.4 ml to 122.1 +/- 11.3 ml (P = 0.032); modified Enterra conditions had the opposite effect (96.5 +/- 9.0 ml vs. 77.4 +/- 11.7 ml, P = 0.025) and no significant effect was observed with IGS conditions.

CONCLUSION

The effects of GES on gastric tone vary with the conditions and sites of stimulation. These findings may help to explain the distinct effects of GES therapy in patients with gastroparesis and obesity.

A new laparoscopic technique for weight reduction with implanted gastric banding basket

BACKGROUND

Nowadays, obesity is frequently an indication for implantation of an adjustable stomach or gastric band. Among the side effects, in addition to band erosion and port chamber complications, pouch dilation in the sense of increasing enlargement of the forestomach and resulting insufficiency of initial surgical measures consistently occurs. Implantation of a soft basket band will prevent this. The objective of this study was to investigate the practical feasibility of the soft basket band.

METHODS

Ten patients were investigated in an observation study over a period from November 2006 to June 2007. Seven patients were women and three patients were men, with an average age of 43.6 years (25-66 years).

RESULTS

The average body mass index (BMI) at the time of the operation was 47.4 +/- 5.5 kg/m(2), with an average body weight of 134.5 +/- 24.6 kg. After a median follow-up period of 1 month, an average BMI of 44.9 +/- 5.8 kg/m(2) was achieved, and after 3 months, an average BMI of 41.4 +/- 4.8 kg/m(2). The excessive weight loss was 7.4 +/- 4.3 kg after 1 month and 17.9 +/- 6.4 kg after 3 months. A local wound infection occurred as a complication in one patient.

CONCLUSION

Laparoscopy procedures enable mortality to be lowered compared to bypass operations with minimal complications and substantial reduction of weight.

Gastric/intestinal electrical stimulation modulates appetite regulatory peptide hormones in the stomach and duodenum in rats

BACKGROUND

Gastric/intestinal electrical stimulation (GIES) has been used to suppress appetite in the treatment of obesity with promising results. However, the mechanisms by which GIES benefits obese patients are not completely understood. This study investigated the acute effects of GIES on gastric and intestinal tissue levels of peptide hormones related to satiety and appetite in rats.

METHODS

32 rats were divided into 4 groups: 1) sham stimulation, 2) gastric electrical stimulation (GES) with pulse trains, 3) GES with long pulse, and 4) duodenal electrical stimulation (DES) with pulse trains. After 2 hours of GIES, the rats were sacrificed immediately, and gastric fundus, duodenum and distal colon were harvested and extracted. Hormone levels of ghrelin, obestatin, cholecystokinin-8 (CCK-8) and peptide YY (PYY) were measured by radioimmunoassay (RIA).

RESULTS

1) The mean gastric fundus ghrelin level was 1789.04+/-362.81 pg/mg in the sham stimulation and significantly decreased with GES of pulse trains (597.85+/-195.33 pg/mg, P=0.012), GES of long pulse (754.6+/-282.6 pg/mg, P=0.039) and DES (731.69+/-110.84 pg/mg, P=0.037). 2) The mean duodenal CCK-8 concentration was 413.27+/-42.14 pg/mg in the sham stimulation and significantly increased by DES (762.6+/-98.75 pg/mg, P=0.013) but not in others. 3) Neither gastric obestatin nor distal colonic PYY was altered by any of GES or DES.

CONCLUSIONS

GIES significantly impacts appetite-related peptide hormones in gastric and duodenal tissues. Acute GIES-induced manipulation of gut peptide hormones related to appetite and satiety is a nonpharmacologic, well-tolerated clinical procedure that could substantially contribute to the successful treatment and long-term management of obesity.

Effects of gastric electrical stimulation on hippocampus gastric distension responsive neurons and the expression of motilin and neuronal nitric oxide synthase in rats

AIM: To explore the effects of gastric electrical stimulation (GES) on gastric distension (GD) responsive neurons in rat hippocampus, and study the expression of neuronal nitric oxide synthase (nNOS) and motilin (MTL) in rat brain for exploring the central mechanism of GES.

METHODS: Fifty adult Wistar rats were used in this experiment. The effects of GES on GD responsive neurons in hippocampus CA1 area were observed by recording extracellular potentials of single neuron. GD responsive neurons were classified as GD-excitatory (GD-E) and GD-inhibitory (GD-I) neurons according to their responses to GD. GES with 3 sets of parameters were applied for 1 minute respectively: GES-A (6 mA, 0.3 ms, 40 Hz, 2 s-on, 3 s-off) with standard pulse trains; GES-B with increased wave width to 3 ms and GES-C with decreased frequency to 20 Hz. Two hours after GES-A was applied, we observed the expression of nNOS immunoreactive positive neurons in hippocampus by fluorescent immunohistochemistry and the content of motilin in rat brain by radioimmunoassay.

RESULTS: Eighty-seven neurons in hippocampus CA1 area were recorded and 79 responded to gastric distension (GD, 3-5 mL, 10-30 s). Of the 79 GD responsive neurons, 40 (50.6%) were GD-E neurons and 39 (49.4%) were GD-I ones. 62.5%, 100% and 62.3% of GD-E neurons were excited by GES-A, -B, and -C respectively. GES-B excited more GD-E neurons than GES-C (P = 0.016). Among the GD-I neurons, 63.6%, 85.7% and 50.0% neurons were excited by GES-A, -B and -C respectively. GES-C was noted to be less effective comparing with GES-A (P = 0.041) or GES-B (P = 0.021). Two hours after GES-A was used, the expressions of nNOS positive neurons significantly decreased in the CA1 and CA2-3 area of hippocampus (16.75 ± 0.91 cells/mm²vs 20.46 ± 1.30 cells/mm², P < 0.05; 14.91 ± 1.17 cells/mm²vs 18.73 ± 1.10 cells/mm², P < 0.05) and the content of motilin peptide decreased obviously in the hypothalamus (48.93 ± 6.98 fmol/mg vs 96.23 ± 12.93 fmol/mg, P < 0.01), mesencephalon (53.17 ± 8.96 fmol/mg vs 30.96 ± 4.86 fmol/mg, P < 0.05), medulla oblongata (46.27 ± 7.83 fmol/mg vs 73.86 ± 9.37 fmol/mg, P < 0.05) and hippocampus (32.23 ± 6.51 fmol/mg vs 62.72 ± 10.07 fmol/mg, P < 0.05) by radioimmunoassay.

CONCLUSION: GES may activate the gastric distension responsive neurons in hippocampus CA1 area and the excitatory effect of GES is related to the frequency and wave width of stimulation. Decreased expression of nNOS and motilin in the brain may also take part in the central mechanism of GES.

Laparoscopically Implanted Gastric Pacemaker after Kidney-Pancreas Transplantation: Treatment of Morbid Obesity and Diabetic Gastroparesis

Combined kidney-pancreas transplantation is the treatment of choice for end-stage diabetic nephropathy. Weight gain post-transplant increases the risk for post-transplant complications and death due to cardiovascular events. Gastric pacemakers have been used for therapy of diabetic gastropathy and for the treatment of moderate morbid obesity. We report a patient who experienced significant weight gain following successful kidney-pancreas transplantation and was thereafter successfully treated for diabetic gastroparesis and morbid obesity by use of a laparoscopically implanted gastric pacemaker.

Effect of acute gastric electrical stimulation on the systemic release of hormones and plasma glucose in dogs

This study evaluated the effect of gastric electrical stimulation (GES) with various parameters on plasma concentrations of satiety-related peptides and glucose. GES was performed in nine healthy dogs via electrodes implanted in the middle of the lesser curvature. Four sessions were performed in each animal: control, stimulation with IGS (implantable gastric stimulation for obesity, 0.3 m sec), modified IGS (2 msec), and long pulses (300 msec). Blood samples were collected at 15 and 0 min before the meal and at 15, 30, and 60 min after the meal. GES was initiated 30 min before the first blood sample and maintained throughout collection. Plasma ghrelin, leptin, insulin and glucose were measured. The total AUCs of plasma ghrelin and leptin were not significantly affected by GES. The total AUC of plasma insulin was significantly lower with IGS and long pulse parameters (P < 0.05). The total AUC for plasma glucose was significantly lower in sessions with long pulses and modified IGS parameters (P < 0.05). We conclude that acute GES is able to change the release of some satiety-related peptides. Whether this is associated with the changed eating behavior and weight loss in obese patients needs further investigation.

Update on obesity surgery

The prevalence of obesity in the United States has reached epidemic proportions. With more than 30 million Americans clinically obese, the younger population has also been affected. Surgical therapy should be offered to the severely obese patient who is refractory to nonsurgical therapy, as established by the 1991 NIH Consensus Conference on Gastrointestinal Surgery for Severe Obesity. Surgery is currently the most effective therapy for weight loss. It is far more effective than any other treatment modality, both in terms of the amount of weight loss and in terms of durability in maintaining weight loss.

Effects of gastric electrical stimulation on responsive neurons to gastric distension and expression of orexin in rats

AIM: To investigate the effects of gastric electri-cal stimulation (GES) on responsive neurons to gastric distension (GD) in ventromedia hypotha-lamus (VMH) and the expression of orexin in rat brain.

METHODS: Fifty-two adult Wistar rats were used in this experiment. The effects of GES on GD responsive neurons in VMH were observed by recording extracellular potentials of single neuron. GD responsive neurons were classified as GD-excitatory (GD-E) and GD-inhibitory (GD-I) ones according to their responses to GD. GES with three sets of parameters were applied for one minute respectively: GES1 (6 mA, 0.3 ms, 40 Hz, 2 s-on, 3 s-off) with standard pulse trains; GES2 with reduced on-time to 0.1 s and GES3 with decreased frequency to 20 Hz. After GES1 was using for 2 h, we observed the expression of orexin-A immunoreactive (orexin-A-IR) positive neurons in lateral hypothalamus area (LHA) by fluorescent immunohistochemistry and the content of orexin in rat brain by radioimmunoassay.

RESULTS: Ninety neurons in VMH were recorded, of which 82 (85.41%) responded to GD (3-5 mL, 10-30 s). Of the 82 GD responsive neurons, 31 (37.8%) were GD-E neurons and 51 (62.2%) were GD-I neurons. 55.0%, 17.6%, and 14.3% of GD-E neurons were excited by GES1, GES2, and GES3 respectively. More GD-E neurons were excited by GES1 than by GES2 and GES3 (P = 0.002 and 0.016, respectively). Of the GD-I neurons, 63.6%, 37.9%, and 51.9% neurons were excited by GES1, GES2, and GES3, respectively. GES2 was noted to be less effective in comparison with GES1 (P = 0.043). After GES1 was in application for 2 h, the levels of orexin-A-IR positive neurons were significantly decreased in LHA as comopared with those in control group (6.97 ± 1.51/0.1 mm2 vs 26.62 ± 8.30/0.1 mm2, P < 0.01), and the content of orexin peptide was decreased obviously in the hypothalamus (112.54 ± 11.58 fmol/mg vs 185.23 ± 15.22 fmol/mg, P < 0.01), mesencephalon (71.95 ± 8.45 fmol/mg vs 98.48 ± 12.02 fmol/mg, P < 0.05), medulla oblongata (72.36 ± 6.58 fmol/mg vs 101.29 ± 15.22 fmol/mg, P < 0.05), solitary tract nucleus (69.12 ± 4.99 fmol/mg vs 89.21 ± 9.23 fmol/mg, P < 0.05) by radioimmunoassay. However, the content of orexin peptide had no significant change in pons.

CONCLUSION: GES may activate the GD responsive neurons in VMH and the excitatory effect of GES is related to the frequency and time of stimulation. Decreased expression of orexin in the brain may also take part in the central mechanism of GES.

Gastric pacing for morbid obesity: plasma levels of gastrointestinal peptides and leptin

OBJECTIVE

A gastric pacemaker has been developed to treat morbid obesity. Patients experience increased satiety, the ability to reduce food intake, and a resultant weight loss. However, the mechanism behind the changed eating behavior in paced patients is still under investigation.

RESEARCH METHODS AND PROCEDURES

This study was performed on 11 morbidly obese patients (mean BMI, 46.0 kg/m2) treated with gastric pacing. The peripheral blood levels of satiety signals of cholecystokinin (CCK), somatostatin, glucagon-like peptide-1 (GLP-1), and leptin were studied 1 month before gastric pacer implantation, 1 month after implantation, and 6 months after activation of electrical stimulation. Blood samples were drawn 12 hours after fasting and in response to a hypocaloric meal (270 kcal). Patients were followed monthly for vital signs and weight level.

RESULTS

Gastric pacing resulted in a significant weight loss of a mean of 10.4 kg (4.4 BMI units). No negative side effects or complications were observed during the treatment. After activation of the pacemaker, meal-related response of CCK and somatostatin and basal levels of GLP-1 and leptin were significantly reduced (p < 0.05) compared with the tests before gastric pacing. The weight loss correlated significantly with a decrease of leptin levels (R = 0.79, p < 0.01).

DISCUSSION

Gastric pacing is a novel and promising therapy for morbid obesity. Activation of the gastric pacer was associated with a decrease in plasma levels of CCK, somatostatin, GLP-1, and leptin. More studies are necessary to elucidate the correlations between satiety, weight loss, and digestive neuro-hormone changes.

Laparoscopic surgical concepts of morbid obesity

BACKGROUND

According to the WHO, obesity and obesity with associated morbidity constitute a chronic, multi-factorial condition requiring treatment. Conservative treatment has been shown in long-term studies to be ineffective in morbid obesity. Surgical treatments break down into restrictive, malabsorptive, combined restrictive and malabsorptive or motility-reducing procedures.

METHOD AND RESULTS

Laparoscopic implantation of an adjustable gastric band is an efficient restrictive measure for treating the majority of patients with this condition. The adjustable gastric band enables weight loss and food intake to be adapted to the individual patient's need. Of these patients, 80-90% can expect to lose 55-70% of their excess weight. Vertical banded gastroplasty is losing ground among the restrictive options. Preliminary experiences are encouraging, but the long-term results are disappointing when assessed by the standard criteria. Gastric bypass is gaining ground in Europe and is a standard procedure in the USA. This operation is estimated to give a 70-80% loss in excess weight, and provides a better quality of life than do restrictive procedures. The biliopancreatic diversion with duodenal switch combines a sleeve gastrectomy with a duodeno-ileal switch to achieve maximum weight loss. Consistent excess weight loss of between 70% and 80% is achieved, with acceptable decreased long-term nutritional complications. The laparoscopic approach to this procedure has successfully created a surgical technique with optimum benefit and minimal morbidity, especially in the super-obese patient. Intra-gastric stimulation is the least invasive surgical procedure at present. However, the excess weight loss is lowest with this method, at only 32% in the first 2 years after the operation.

CONCLUSION

Provided that safety recommendations are observed, laparoscopic operations for obesity have a fairly low risk. The mortality rate in centres with experienced staff is less than 0.3%. The death rate due to untreated morbid obesity is significantly higher than in a comparable group of patients after surgery.