The MUSE™ system includes the endostapler and a console connected with the endostapler, containing a controller for the camera, ultrasonic range finder and various sensors, a pump for insufflation and irrigation, a suction system, and power and controls for the LED.

The endostapler has:
The anvil, alignment pin, anvil screw, and ultrasound are all designed to ensure proper alignment and positioning of the device during stapling. The distal tip may be articulated in one direction to align with the rigid section and cartridge, with a bending radius of 26 and 40 mm.

Details of the device are illustrated in Fig. 7.4.

The procedure can be performed by one operator in experienced hands. The patient is placed in the supine position, under general anesthesia with endotracheal intubation. Positive end-expiratory pressure (PEEP) of at least 5 mmHg (7.5-cm H₂O) is administered. After a preliminary endoscopic assessment of the esophagus and stomach and once no contraindications are found, an overtube is placed. Then, the endostapler is inserted transorally through the overtube and gently advanced into the stomach under direct vision; passing the rigid section across the pharyngoesophageal junction may encounter some resistance. In order to avoid applying excessive force and risk to injure the esophagus, the overtube may be withdrawn approximately 5 cm and then advanced with the endostapler as a unit. This maneuver can be repeated until the system reaches the esophageal midbody. Flexing the neck may make passage easier.

Once into the stomach, distended by insufflation of air or CO2, the stapler is advanced until the tip is approximately 5 cm past the EGJ and then retroflex by 180° to obtain an adequate vision of the gastric fundus and EGJ to select stapling location.

The most important stapling location is the leftmost location, which is typically performed first. This is the anchoring point for the fundus and should be placed as far to the left of the esophagus as possible. At times, depending on anatomy, it may be easier to perform the first stapling in a more central location. The additional stapling locations should be within 60–180° as long as the rightmost stapling should not be done on the lesser curve, because stapling in the lesser curve may attach the antrum to the esophagus and open the esophagogastric junction rather than close it. Additional staplings may be placed between the leftmost and rightmost. Once the correct location for stapling has been identified, all the procedures are performed under ultrasound guidance. Subsequent phases of the procedure include clamping tissue, deploying alignment pin, advancing anvil screw, stapling, and retrieving anvil screws [29]. Details of the MUSE^TM device’s technique are shown in Fig. 7.5. Endoscopic pre- and post-procedural findings after TIF with MUSE^TM system are reported in Fig. 7.6.

Antiemetic prophylaxis with at least two drugs (according to the ASA recommendations for interventions with high risk of post-procedure nausea and vomiting) and full muscle relaxation throughout the procedure are mandatory for TIF. Antiemetic prophylaxis is maintained i.v. for 24 h, while broad-spectrum antibiotic therapy is maintained i.v. for 48 h and then by oral route over a 5-day period.

Almost all patients complain of transient pharyngeal irritation, as a result of insertion and manipulation of the device, and some have mild to moderate epigastric pain in 6 h after the procedure. Pain persisting for 2–4 days may require analgesics and should be considered for esophageal or gastric leak; CT scan and hydrosoluble contrast X-ray investigation should be carried out in these cases. Dysphagia and gas bloating are generally not reported by patients. White blood cell count may be slightly increased after the procedure. At discharge, patients are instructed to follow a liquid diet for the first 2 weeks and a soft diet for the next 4 weeks. PPIs are discontinued 7 days after the procedure. Patients are also asked to refrain from vigorous exercise for 4 weeks.

To date, 20 prospective studies and one retrospective study, most of them observational and carried out in a limited number of patients, have been published on short- and medium-term follow-up (1–3 years) after TIF using EsophyX^® device [38–58]. One study evaluated patients’ outcomes up to 6 years after the procedure [56]. Sixteen studies assessed symptoms by means of the GERD health-related quality of life (HRQL); 11 evaluated pre- and post-procedure pH ± impedance recordings. A multicenter prospective study compared the efficacy of TIF versus omeprazole in a randomized controlled trial [59].

Overall, in 17 studies TIF was proven to discontinue antireflux medications or markedly decrease their dose; three studies arose concerns about the effectiveness of the procedure [45, 46, 49].

In the observational, nonrandomized studies, 6- and 12-month outcomes after TIF showed that 75–84 % and 53–85 % of patients had either discontinued PPI use or halved the dose of PPI therapy. Normalization of esophageal acid exposure, in terms of total acidic refluxes, number of refluxes, and DeMeester score, was reported in 37–89 % of patients.

Twenty-four months after TIF, daily high-dosage PPI dependence was eliminated in 75–93 % of patients. Endoscopic findings comparing fundoplication immediately after the procedure and 2 years later are reported in Fig. 7.7. In the two series reporting a 3-year follow-up, persistent discontinuation of daily PPI ranged from 74 to 84 % of cases [54, 56].

Only one study evaluated outcomes 6 years after TIF in 14/50 patients who underwent the procedure. High-dosage PPI dependence was eliminated in 86 % of patients, and approximately half of them completely stopped PPI use [56], providing evidence of the long-lasting effect of TIF on symptoms and PPI usage. Results are summarized in Fig. 7.8. Unsuccessful outcomes of TIF occurred mainly between 6 and 12 months after the procedure, while between 12 and 36 months, the results did not substantially differ. Six-year results were substantially similar to those reported at 36 months. These findings show that an appropriate patient selection plays a pivotal role in achieving clinical success after TIF and confirm that factors negatively affecting postoperative outcomes play a role early in the postoperative period in most patients. Operator’s experience plays an important role in TIF outcomes, too. All TIF failures observed in our series occurred in patients who underwent the procedure early in the operator’s learning curve. A retrospective study in 124 unselected patients carried out in two community hospitals and reporting, respectively, 75 and 80 % of patients free of typical and atypical GERD symptoms over a mean follow-up of 7 months confirmed that the operator’s experience plays a major role in successful outcomes [52].

Only three prospective, randomized controlled trials have been so far published. Two assessed the 6-month efficacy of TIF versus omeprazole therapy: one showed TIF more effective than PPI therapy in treating regurgitation and extraesophageal symptoms (97 % vs 50 % of patients, respectively; P = 0.006) [58]; the second one proved at intention-to-treat analysis TIF more effective than PPI in eliminating GERD symptoms (67 % vs 45 %, respectively; P = 0.023) [59]. These data show different outcomes and require additional randomized studies to clarify the efficacy of TIF in treating GERD. The third study compared 3- and 12-month results of TIF and Nissen fundoplication, showing TIF as effective and safe as Nissen fundoplication but with significantly lower hospital stay (2.9 ± 0.8 days vs 6.4 ± 0.7 days, respectively; P < 0.0001) [60].

Outcomes of TIF, with regard to the effects on PPI usage, are reported in Tables 7.1 and 7.2.