Magnamosis II: Magnetic compression anastomosis for minimally invasive gastrojejunostomy and jejunojejunostomy

Magnamosis combined with endoscopy: A new endoscopic technique in digestive surgery

Conventional hand-sewn technique is the basic method for anastomosis in the gastrointestinal tract. However, with the rapid development of minimally invasive surgery and the spread of fast track surgery, hand-sewn technique cannot satisfy the requirements of modern surgery. The common goal that the majority of surgeons seek to achieve has changed: to reduce surgical invasion and operative time as minimally as possible, on the premise that therapeutic and anastomotic effects can be guaranteed. Therefore, after more than 30 years of exploration and development, magnamosis as a novel anastomosis technique shows its significant superiority in anastomosis or recanalization in the gastrointestinal tract. Furthermore, the combination of magnamosis and endoscopy may transform part of the surgical procedures into endoscopic procedures. This review aims to elucidate the application and future development of magnamosis combined with endoscopy in anastomosis or recanalization in the gastrointestinal tract.

Magnetic gastrointestinal anastomosis in pediatric patients

BACKGROUND/PURPOSE

To describe 17 patients who underwent magnetic, non-surgical gastrointestinal (GI) anastomoses.

METHODS

Patients with GI obstruction, stenosis, or atresia were treated with image-guided and/or endoscopically placed discoid magnet pairs or catheter-based bullet-shaped magnet pairs.

RESULTS

Anastomosis was achieved in 7 days in an 11-year-old with gastric outlet obstruction due to metastatic colon cancer. Anastomosis was achieved in 8 and 10 days in 2 patients (age 2.0 years and 3.4 years) who had rectocolonic stenosis. Re-anastomosis was achieved in an average of 6 days (range 3 to 7 days) in 5 patients (age 6 months to 5.9 years) with severe recurrent postsurgical esophageal stenosis refractory to dilatation. Primary esophageal anastomosis was achieved in an average of 4.2 days (range 3 to 6 days) in 9 patients with esophageal atresia (Type A or Type C surgically converted to Type A) with a gap length of 4 cm or less. The average age of these esophageal atresia patients was 3 months (range 23 days to 5 months).

CONCLUSION

Minimally invasive magnet placement was feasible and achieved anastomosis in all patients.

Magnetic compression in gastrointestinal and bilioenteric anastomosis: how much force?

AIM

The concept of compression alimentary anastomosis is well established. Recently, magnetic axial alignment pressures have been encompassed within such device constructs. We quantify the magnetic compression force and pressure required to successfully achieve gastrointestinal and bilioenteric anastomosis by in-depth interrogation of the reported literature.

METHODS

Reports of successful deployment and proof of anastomotic patency on survival were scrutinized to quantify the necessary dimensions and strengths of magnetic devices in (a) gastroenteral anastomosis in live porcine models and (b) bilioenteric anastomosis in the clinical setting. Using a calculatory tool developed for this work (magnetic force determination algorithm, MAGDA), ideal magnetic force and compression pressure were quantified from successful reports with regard to their variance by intermagnet separation.

RESULTS

Optimized ranges for both compression force and pressure were determined for successful porcine gastroenteral and clinical bilioenteric anastomoses. For gastroenteral anastomoses (porcine investigations), an optimized compression force between 2.55 and 3.57 kg at 2-mm intermagnet separation is recommended. The associated compression pressure should not exceed 60 N/cm(2). Successful bilioenteric anastomoses is best clinically achieved with intermagnet compression of 18 to 31 g and associated pressures between 1 and 3.5 N/mm(2) (at 2-mm intermagnet separation).

CONCLUSION

The creation of magnetic compression anastomoses using permanent magnets demonstrates a remarkable resilience to variations in magnetic force and pressure exertion. However, inappropriate selection of compression characteristics and magnet dimensions may incur difficulties. Recommendations of this work and the availability of the free online tool (http://magda.ucc.ie/) may facilitate a factor of robustness in the design and refinement of future devices.

Magnamosis III: delivery of a magnetic compression anastomosis device using minimally invasive endoscopic techniques

PURPOSE

Magnamosis creates a secure sutureless anastomosis through magnetic compression. In this study, we further develop and test delivery devices capable of creating a secure duodeno-colonic anastomosis using available minimally invasive endoscopic techniques.

METHODS

Eight pigs underwent general anesthesia. Colonoscopy was used to deliver 1 magnetic ring to the hepatic flexure. Simultaneously, upper endoscopy delivered the other magnetic ring into the duodenum using a variety of techniques. The 2 magnetic rings were brought into magnetic proximity under laparoscopic guidance. The pigs were recovered and examined daily followed by sacrificing at 1, 2, 4, and 6 weeks.

RESULTS

The device designed to deliver and release each magnetic ring evolved from using a guide wire and balloon devices to redesigning the magnetic ring casing with a groove to accommodate an endoscopic snare. Laparoscopic visualization assured safe magnet mating of intestinal segments. The duodeno-colonic anastomoses created with the snare yielded widely patent anastomoses. In vitro testing revealed excellent burst pressure. Histology revealed complete healing as early as 1 week.

CONCLUSION

We redesigned the magnamosis device to facilitate delivery by endoscopic techniques. The snare technique allows endoscopic positioning and controlled release of the magnetic rings for a secure side-to-side duodeno-colonic anastomosis.

Magnetic compression gastrostomy in the rat

PURPOSE

Magnetic compression anastomosis is used for gastrointestinal, biliary, and urinary anastomoses. We have developed a simple magnetic compression gastrostomy technique in rats.

METHODS

Animals were randomized into two groups (n = 12 each): magnetic gastrostomy (MG) and surgical gastrostomy (SG) (control). In the MG group, a magnetic insertion catheter was coupled with the first magnetic ball and introduced transorally into the stomach. A second magnetic ball was placed subcutaneously into the left upper quadrant. The two magnetic balls (4 mm) were strongly coupled together. On postoperative day (PD) 20 (MG group) and PD10 (SG group), rats were killed, gastrostomies were evaluated macroscopically and histopathologically, and mechanical burst testing was performed.

RESULTS

Two animals died due to suspected leaks. Macroscopic evaluation indicated no gastrostomy canal in one rat in each group. Mild adhesion was observed in two rats in the MG group. Moderate adhesion was observed in all rats in the SG group. No significant differences were observed in burst pressure between the two groups (means: MG group, 143 mmHg, n = 9; SG group, 159 mmHg, n = 8).

CONCLUSIONS

Magnetic compression gastrostomy can be performed easily in rats, and may be developed in future as a simple alternative to some gastrostomy procedures in humans.

Compression anastomoses in colorectal surgery: a review

The main serious risks of anastomotic construction in the colon and rectum include dehiscence and stricture formation. There is a resurgence of interest in sutureless anastomoses formed by compression elements since the introduction of shape memory alloy (SMA) systems, which evoke minimal early inflammatory response whilst maintaining anastomotic integrity. Currently, the most commonly used SMA is the nickel-titanium (NiTi) alloy that is highly biocompatible, returning to its pre-deformed stable (austenite) shape under different mechanical and thermal loads for use in humans. Pre-clinical data for shape memory alloy systems in colorectal anastomoses are limited, but it appears to be safe in porcine and canine models with limited leakage and reduced stricture formation. There does not appear to be any difference in tissue biochemistry of inflammatory markers when compared with conventional stapled techniques, although the few studies available show a markedly reduced early inflammatory response at the anastomotic site with the NiTi device. The majority of the clinical data concerning compression anastomoses are derived from the biofragmentable anastomotic ring device. This device has fallen out of use because of reported leaks, instrumental failure and problems with device expulsion. A novel SMA device, the NiTi anastomotic ring, permits construction of a low rectal anastomosis construction during open or laparoscopic procedures. The preliminary data demonstrate a safety comparable to conventional staple technology. This device also provides the potential of benefit of reduced anastomotic inflammation, because the compression ring results in direct serosa-to-serosa (or alternatively serosa-to-muscularis propria) apposition without the persistence of residual foreign material. This type of construction could lead to a reduced incidence of early anastomotic leakage and/or the development of anastomotic stenosis. Randomized clinical trials employing a NiTi arm for elective, emergency and high-risk colorectal anastomoses are required to determine its indications and clinical profile as well as to assess whether such technology may selectively obviate the need for proximal diversion in low colorectal anastomoses.

An original endoluminal magnetic anastomotic device allowing pure NOTES transgastric and transrectal sigmoidectomy in a porcine model: proof of concept

INTRODUCTION

While experimental natural orifice transluminal endoscopic surgery (NOTES) sigmoid colectomies have been reported, pure NOTES anastomoses are restricted by the limited reach of commercially available circular staplers. MAGNAMOSIS is a set of self-orienting magnetic rings that can be delivered endoluminally throughout the colon to generate a compression anastomosis. Aim. To assess the feasibility of a pure NOTES transrectal (TR) and transgastric (TG) approach to perform any segmental colectomy.

MATERIALS AND METHODS

One pig (50 kg) underwent the experimental procedure as follows: (a) creation of the TG access to the peritoneal cavity, (b) precise transluminal placement of the proximal MAGNAMOSIS ring, (c) creation of the TR access with the TEO and transrectal dissection of the sigmoid mesentery, (d) resection of the surgical specimen, (e) transrectal extraction of the specimen, (f) delivery and mating of the distal MAGNAMOSIS ring, and (g) closure of the TG and TR viscerotomies. The animal survived for 14 days at which time burst pressure and histology were performed.

RESULTS

A pure NOTES TR and TG segmental colectomy was performed in 139 minutes. The postoperative course was uneventful. The animal had a formed bowel movement including the magnetic rings on postoperative day 5. Endoscopic examination at postoperative day 14 revealed a patent anastomosis. Necropsy revealed no abscess or signs of peritonitis. Burst pressure was >198 mm Hg. The histology showed a sealed anastomosis with mild inflammation.

CONCLUSIONS

MAGNAMOSIS enabled a totally NOTES partial colectomy with combined TG and TR access. The flexible delivery options and low cost of manufacturing could make MAGNAMOSIS an attractive alternative to circular staplers.