*4.1.1 Maestro rechargeable system*

Vagal blocking therapy (VBloc therapy) has been suggested as a new approach to tackle morbid obesity. Instead of performing a permanent truncal vagotomy, it blocks the vagal nerves in an intermittent manner using electrical pulses generated by the Maestro Rechargeable System (Enteromedics, St Paul, MN).

#### *4.1.1.1 Technique*

The maestro rechargeable system is an FDA approved implant device that is implanted with minimally invasive laparoscopic techniques. The system is provided with two leads which are placed around both the anterior and posterior vagal trunks at the level of the esophageal junction. Each lead delivers high-frequency, low energy, intermittent electrical pulses to its respective intra-abdominal vagal trunk for a predetermined period each day. This intermittent interruption of vagus nerve signaling leads to delayed gastric emptying which reduces feelings of hunger and promotes satiety [44]. A rechargeable neuroregulator is placed subcutaneously on the thoracic wall.

### *4.1.1.2 Efficacy and safety profile*

Several feasibility studies have shown that VBloc therapy has a desirable safety profile and results in clinically important weight loss [45]. However, in the first randomized controlled trial comparing VBloc therapy with sham control, results were disappointing [46]. VBloc therapy was regarded safe, but weight loss was no greater in treated compared to control patients. Authors reported that the system electrical safety checks could have accounted for the weight loss in the control group. Another randomized controlled trial demonstrated 24.4% EWL in the VBloc group compared to 15.9% in the sham control group after a period of 12 months [47]. An open label follow-up study of the VBloc arm showed maintenance of weight loss in the majority of patients [48]. Adverse events were more frequently reported in the VBloc group and mostly involved heartburn or dyspepsia. Stronger evidence is needed to determine the place of VBloc therapy in the treatment of obesity.

#### **4.2 Gastric electrical stimulation**

Based on growing knowledge about gastrointestinal physiology, gastric electrical stimulation (GES) has been identified as a potential treatment modality for obesity [49, 50]. As early as 1995, the concept of GES was demonstrated in a series of animal experiments [51]. The exact mechanism of action of GES is still relatively unknown. However, it is thought that GES impairs gastric electrical activity, induces gastric distension, reduces gastric accommodation, and inhibits stomach peristalsis, thereby leading to delayed gastric emptying and increased satiety [52].

### *4.2.1 The transcend implantable gastric stimulator*

A novel gastric electrical stimulator is the Transcend Implantable Gastric Stimulator (IGS, Transneuronix Inc., Mt Arlington, NJ, USA).

### *4.2.1.1 Technique*

The device consists of one lead with two electrodes which is laparoscopically implanted on the lesser curvature near the pes anserinus and approximately 6 cm away from the pylorus. Proximally, the lead is fixed using an endostitch suture, and distally fixation is secured with the use of two clips. One electrode is positioned near the pes anserinus, while the other is placed near the esophagogastric junction. After adequate lead and electrode placement, the electrical pulse generator, which is connected to the lead, is implanted in a supra-fascial pocket and anchored with two sutures. Intraoperative gastroscopy is used to diagnose iatrogenic gastric perforation. After implantation, the device will be in off-mode for a period of 30 days, to allow the gastric tissue to heal before stimulation is initiated.

**47**

43.2 kg/m<sup>2</sup>

*4.2.2.1 Technique*

*Endoluminal Techniques to Treat Obesity DOI: http://dx.doi.org/10.5772/intechopen.82733*

*4.2.1.2 Efficacy and safety profile*

20 patients with a mean BMI of 40.9 kg/m<sup>2</sup>

meaningful weight loss and maintenance.

*4.2.2 Tantalus gastric electrical stimulatory device*

A safety and feasibility study of the Transcend IGS implanted in 12 patients demonstrated a technically feasible and safe procedure [53]. In 25% of the patients, lead dislodgement occurred which required replacement. After 9 months, patients had lost a mean weight of 16 ± 12 kg. Another study conducted in 2002, in which

of 10.6 ± 1.8 at 1 month, 1.5 ± 3.5 at 6 months, and 23.8 ± 5.0 at 10 months. Three intraoperative gastric penetrations were observed by gastroscopy. No further adverse events or complications were reported during the study period [54]. However, in a prospective double-blinded randomized sham-controlled trial, no difference was observed between the treatment and control group after a treatment period of 12 months [55]. Contributing to this was an investigator-initiated substudy designed to assess whether IGS affects plasma levels of ghrelin and peptide YY which resulted in the conclusion that IGS does not prevent increase in fasting plasma levels of ghrelin that are associated with weight loss [56]. In conclusion, further studies are needed to determine whether changes in technology can provide

The Tantalus Electrical Stimulatory Device (Metacure, Israel) is a pulse generator accommodated with three bipolar leads. The device is designed to create an early activation of physiological satiety by enhancing physiological signals of gastric distensions and contractions. The system is capable of delivering gastric contractility modulation (GCM) signals triggered by food. The device senses spontaneous electrical activity of the smooth muscles and then delivers signals to enhance them. With the use of a specialized algorithm of electro-mechanical parameters in the gut, the system can detect the onset of a meal. It is hypothesized that enhancing of spontaneous gastric contractions in a very early stage of the meal, before reaching full gastric distension, induced early satiety by stimulation of stretch receptors. These elicit an increased input to the CNS, thereby promoting a feeling of fullness.

The system is implanted with the use of a laparoscope, whereby the three bipolar

leads are placed in the sub-serosa of the gastric wall. One lead is placed in the fundus area to detect the intake of food, while the other two are positioned in the antrum for slow-wave detection and signal delivery. Nonabsorbable sutures and two clips are to ensure proper fixation at, respectively, the proximal and distal part of the lead. The procedure is carried out under both laparoscopic and gastroscopic visualization to prevent perforation of the gastric wall. After successful lead placement, the leads are connected to the implantable pulse generator which is placed in

In the first open-label single center trial, 12 patients with a mean BMI of

 underwent the implantation with the Tantalus system [57]. After 6 weeks of "off"-mode, the system got activated, which resulted in 17.6 ± 4.3% of EWL after a period of 20 weeks. Furthermore, a significant decrease in hunger, assessed with the three-factor eating questionnaire (TFEQ ), was observed. Apart from two SAE including one case of rhabdomyolysis and one case of pulmonary

a subcutaneous pocket at the left side of the abdomen.

*4.2.2.2 Efficacy and safety profile*

received the device, showed a % EWL
