A novel antireflux device based on magnets

Problems with repairing gut sphincters malfunctions

Correcting a gut sphincter malfunction is a difficult problem. Because each sphincter has two opposite functions, that of closure and opening, repairing one there is a risk of damaging the other. Indeed, widening a narrow sphincter, such as lower esophageal sphincter (LES) and anal sphincter, may cause gastroesophageal reflux and fecal incontinence, respectively, whereas narrowing a wide sphincter, may cause a difficult transit. All the corrective treatments for difficult or retrograde transit concerning LES and anal sphincter with their unwanted consequences have been analyzed and discussed. To overcome the drawbacks of sphincter surgical repairs, researchers have devised devices capable of closing and opening the gut lumen, named artificial sphincters (ASs). Their function is based on various mechanisms, e.g., hydraulic, magnetic, mechanical etc, operating through many complicated components, such as plastic cuffs, balloons, micropumps, micromotors, connecting tubes and wires, electromechanical clamps, rechargeable batteries, magnetic devices, elastic bands, etc. Unfortunately, these structures may facilitate the onset of infections and induce a local fibrotic reaction, which may cause device malfunctioning, whereas the compression of the gut wall to occlude the lumen may give rise to ischemia with erosions and other lesions. Some ASs are already being used in clinical practice, despite their considerable limits, while others are still at the research stage. In view of the adverse events of the ASs mentioned above, we considered applying bioengineering methods to analyze and resolve biomechanical and biological interaction problems with the aim to conceive and build efficient and safe biomimetic ASs.

Is magnetic anal sphincter augmentation still an option in fecal incontinence treatment: a systematic review and meta-analysis

PURPOSE

Magnetic anal sphincter (MAS) augmentation is a novel surgical option for the treatment of fecal incontinence. Current clinical evidence is conflicting. The purpose of this meta-analysis was to report the safety profile, potential benefits, and the functional efficacy of this device.

METHODS

The study followed the PRISMA guidelines. Literature databases (Medline, Scopus, Web of Science, CENTRAL) were screened for eligible articles. The primary endpoint was the pooled effect of MAS in the Cleveland Clinic Incontinence Score (CCIS) score. Quality evaluation was based on the ROBINS-I and Risk of Bias 2 tool.

RESULTS

Overall, 8 studies with 205 patients were included. MAS resulted in a significant reduction of CCIS values (p = 0.019), and improvement only in the embarrassment domain of FIQoL scores (p = 0.034). The overall morbidity rate was 61.8%. Postoperative adverse events included MAS explantation in 12%, infection in 5.1%, pain in 10% and obstructed defecation in 5.8% of patients.

CONCLUSION

The application of MAS in patients with fecal incontinence results in the improvement of some clinical parameters with a notable morbidity rate. Due to several study limitations, further, high-quality RCTs are required to delineate the efficacy and safety of MAS.

Artificial sphincters: An overview from existing devices to novel technologies

Artificial sphincters (ASs) are used to replace the function of the biological sphincters in case of severe urinary and fecal incontinence (UI and FI), and gastroesophageal reflux disease (GERD). The design of ASs is established on different mechanisms, e.g., magnetic forces or hydraulic pressure, with the final goal to achieve a implantable and durable AS. In clinical practice, the implantation of in-commerce AS is considered a reasonable solution, despite the sub-optimal clinical outcomes. The failure of these surgeries is due to the malfunction of the devices (between 46 and 51%) or the side effects on the biological tissues (more than 38%), such as infection and atrophy. Concentrating on this latter characteristic, particular attention has been given to the interaction between the biological tissues and AS, pointing out the closing mechanism around the duct and the effect on the tissues. To analyze this aspect, an overview of existing commercial/ready-on-market ASs for GERD, UI, and FI, together with the clinical outcomes available from the in-commerce AS, is given. Moreover, this invited review discusses ongoing developments and future research pathways for creating novel ASs. The application of engineering principles and design concepts to medicine enhances the quality of healthcare and improves patient outcomes. In this context, computational methods represent an innovative solution in the design of ASs, proving data on the occlusive force and pressure necessary to guarantee occlusion and avoid tissue damage, considering the coupling between different device sizes and individual variability.

Magnetic challenge against gastroesophageal reflux

Almost 15 years have passed since the first paper on the possibility of using magnets to prevent gastro-esophageal reflux (GER) was published and so it is time to assess the results obtained with the first magnetic device available on the market, the Linx magnetic sphincter augmentation (MSA) and to consider what other options are forthcoming. MSA demonstrated an anti-reflux activity similar to that of Nissen fundoplication, considered the "gold standard" surgical treatment for GER disease, and caused less gas-bloating and a better ability to allow vomiting and belching. However, unlike Nissen fundoplication, this magnetic device is burdened by complications, which are roughly similar to those of the non-magnetic anti-reflux Angelchik prosthesis, that, after considerable use in the eighties, was shelved due to these complications. It is interesting to note that some of these complications show the same pathophysiological mechanism in both devices. The upcoming new magnetic devices should avoid these complications, as their anti-reflux magnetic mechanism is completely different. The experiments in animals regarding these new magnetic appliances were examined, remarking their advantages and drawbacks, but the way to apply them in surgical practice is long and difficult, although worthy, as they represent the future of magnetic surgery.

Prospective randomized controlled trial of an injectable esophageal prosthesis versus a sham procedure for endoscopic treatment of gastroesophageal reflux disease

BACKGROUND

This study aimed to assess whether endoscopic implantation of an injectable esophageal prosthesis, the Gatekeeper Reflux Repair System (GK), is a safe and effective therapy for controlling gastroesophageal reflux disease (GERD).

METHODS

A prospective, randomized, sham-controlled, single-blinded, international multicenter study planned final enrollment of 204 patients in three groups: up to 60 lead-in, 96 GK, and 48 sham patients. The sham patients were allowed to cross over to the GK treatment arm or exit the study at 6 months. The primary end points were (1) reduction in serious device- and procedure-related adverse device effects compared with a surgical composite complication rate and (2) reduction in heartburn symptoms 6 months after the GK procedure compared with the sham procedure. The secondary end point was improved esophageal pH (total time pH was <4) 6 months after the GK procedure compared with baseline.

RESULTS

A planned interim analysis was performed after 143 patients were enrolled (25 lead-in, 75 GK, and 43 sham patients), and the GK study was terminated early due to lack of compelling efficacy data. Four reported serious adverse events had occurred (2 perforations, 1 pulmonary infiltrate related to a perforation, and 1 severe chest pain) at termination of the study with no mortality or long-term sequelae. Heartburn symptoms had improved significantly at 6 months compared with baseline in the GK group (p < 0.0001) and the sham group (p < 0.0001), but no significant between-group difference in improvement was observed (p = 0.146). Esophageal acid exposure had improved significantly at 6 months compared with baseline in the GK group (p = 0.021) and the sham group (p = 0.003), but no significant between-group difference in improvement was observed (p = 0.27).

CONCLUSIONS

The GK procedure was associated with some serious but infrequent complications. No statistically significant difference in outcomes was observed between the treatment and control groups at 6 months compared with baseline.

A novel endoesophageal magnetic device to prevent gastroesophageal reflux

BACKGROUND

Endoscopic methods to prevent gastroesophageal reflux (GER) show scarce effectiveness and may narrow the esophageal lumen more or less stiffly, sometimes impairing bolus transit and leading to dysphagia. The aim of this study was to demonstrate the possibility of reinforcing lower esophageal sphincter (LES) tone by implanting endoluminally a magnetic device.

MATERIALS AND METHODS

The device consists of two small magnetic plaques to be implanted in the submucosa close to LES with opposite polarities facing so that they attract one other, closing the esophageal lumen. The magnets were implanted by means of a special endoluminal device in five esophageal-gastric ex vivo specimens taken from swine. Variation in endoluminal pressure at the LES level was measured by means of slow pull-through of a thin side-hole manometric catheter in each specimen, before and after insertion of the magnets.

RESULTS

The new high-pressure zone exhibited a length of about 2 cm and a pressure of 14.2+/-1.27 mmHg [mean +/- standard deviation (SD)], significantly (p<0.001) higher than that measured before insertion of the magnetic valve (1.5+/-0.26 mmHg).

CONCLUSIONS

The present research demonstrates that it is possible to create at the LES level a dynamic closure of a value considered sufficient to prevent GER, by implanting in the esophageal submucosa of anatomical specimens a magnetic device by means of a special endoluminal probe. Once effectiveness and tolerability of magnets covered by a biocompatible sheath have been demonstrated in vivo, this device could become a simple and effective nonsurgical solution to GER.

A novel magnetic device to prevent fecal incontinence (preliminary study)

BACKGROUND AND AIMS

In this research we propose an original magnetic device to strengthen the hypo-atonic anal sphincter and prevent fecal incontinence.

METHODS

The device consists in a couple of small magnetic plaques to be surgically inserted in the wall of the anal canal between the external and internal anal sphincters with the opposite polarities face to face, so that, attracting themselves, close the anal lumen. Three couples of magnets made of materials of different magnetic force (neodymium>ferrite>plastoferrite) were evaluated in each of three swine anatomical preparations by measuring the endoanal pressure with a manometric catheter, both before and after magnet implantation. The mean pressures obtained before and after magnet insertion were statistically compared with Student t test.

RESULTS

The endoanal pressure after the insertion of neodymium magnets was 79.7+/-13.1 (mean+/-SD), after ferrite magnets was 42.1+/-5.6 mmHg and after plastoferrite magnets was 21.6+/-4.6 mmHg, all of them significantly higher than the pressure recorded in basal conditions (1.72+/-0.71 mmHg).

CONCLUSION

This research demonstrated that the implantation of a couple of magnets in the wall of the anal canal is able to create a high pressure zone of a value sufficient to prevent fecal incontinence and that the strength of this "dynamic closure" can be modulated by using magnets of various attraction force, so allowing a "tailored correction" of the anal sphincter hypotension.