Creation of compression gastroenterostomy by means of the oral, percutaneous, or surgical introduction of magnets: feasibility study in swine

Endoscopic gastrointestinal bypass anastomosis using deformable self-assembled magnetic anastomosis rings (DSAMARs) in a pig model

BACKGROUND

To investigate the feasibility of a deformable self-assembled magnetic anastomosis ring (DSAMAR), designed and developed by us, for endoscopic gastrointestinal bypass anastomosis.

METHODS

Ten experimental pigs were used as model animals. The DSAMAR comprises 10 trapezoidal magnetic units, arranged in a straight line under the constraint of a guide wire. When the desired anastomosis site is reached under the guidance of an endoscope, the catheter pushes the magnetic unit along the guide wire. The linear DSAMAR can be assembled into a circular DSAMAR. Two DSAMARs were inserted, one at the end of the duodenum and the other into the stomach successively. They attracted each other and compressed the wall of the stomach and duodenum to establish gastrointestinal bypass anastomosis. The experimental pigs were euthanized 4 weeks after the operation, and the gastrointestinal bypass anastomosis specimens were obtained. The anastomosis formation was evaluated by the naked eye and histology.

RESULTS

Gastrointestinal bypass anastomosis with DSAMARs was successfully performed. The average operation time under an endoscope was 70.30 ± 19.05 min (range: 43-95 min). The DSAMARs were discharged through the anus 10-17 days after surgery. There were no complications such as gastrointestinal bleeding, perforation, anastomotic fistula, and gastrointestinal obstruction during and after the operation. Gastroscopy and gross specimen of the anastomosis showed a well-formed magnetic anastomosis. Histological observation showed good continuity of the serous membrane and the mucosa of magnetic anastomosis.

CONCLUSION

The DSAMAR is a safe and feasible device for fashioning gastrointestinal bypass anastomosis in this animal model.

The Evolving Use of Magnets in Surgery: Biomedical Considerations and a Review of Their Current Applications

The novel use of magnetic force to optimize modern surgical techniques originated in the 1970s. Since then, magnets have been utilized as an adjunct or alternative to a wide array of existing surgical procedures, ranging from gastrointestinal to vascular surgery. As the use of magnets in surgery continues to grow, the body of knowledge on magnetic surgical devices from preclinical development to clinical implementation has expanded significantly; however, the current magnetic surgical devices can be organized based on their core function: serving as a guidance system, creating a new connection, recreating a physiologic function, or utilization of an internal–external paired magnet system. The purpose of this article is to discuss the biomedical considerations during magnetic device development and review the current surgical applications of magnetic devices.

Tracheoesophageal fistula treated with magnetic compression technique in canines

There are various surgical methods for tracheoesophageal fistula; however, there is presently no unified standard. Based on the magnetic compression technique, we designed a novel method for the treatment of tracheoesophageal fistula. The purpose of this study was to verify its feasibility in an animal experiment. Six beagle dogs underwent surgical repair after constructing a tracheoesophageal fistula model. After the tracheal and esophageal spaces were freed during the operation, two magnets were used to clamp the fistula. The operation time, intraoperative blood loss, postoperative complications, and wound healing were monitored. Samples were obtained 14 days after the operation, and fistula repair was observed. The tracheoesophageal fistula repair operation was successfully completed for all six beagles. The average operation time was 23.67 ± 4.50 min. The average intraoperative blood loss was less than 10 mL. One dog had a postoperative wound infection, and the rest had no postoperative complications. The wound healed well. In all dogs, after specimen collection, it was observed that the fistula was successfully closed and the mucosal layer was smooth and flat. Histological observation showed that the anastomosis was slightly inflamed, the mucosal layer and surrounding tissues were arranged neatly, and the structure was slightly disordered. Magnetic compression technique can be effectively used to repair tracheoesophageal fistula, shorten the operation time, and simplify the operation procedure, and thus, it has the potential for clinical application.

Endoscopic gastrointestinal anastomosis: a review of established techniques

Technologic advancements in the field of therapeutic endoscopy have led to the development of minimally invasive techniques to create GI anastomosis without requiring surgery. Examples of the potential clinical applications include bypassing malignant and benign gastric outlet obstruction, providing access to the pancreatobiliary tree in those who have undergone Roux-en-Y gastric bypass, and relieving pancreatobiliary symptoms in afferent loop syndrome. Endoscopic GI anastomosis is less invasive and less expensive than surgical approaches, result in improved outcomes, and therefore are more appealing to patients and providers. The aim of this review is to present the evolution of luminal endoscopic gastroenteric and enteroenteric anastomosis dating back to the first compression devices and to describe the clinical techniques being used today, such as magnets, natural orifice transluminal endoscopic surgery, and EUS-guided techniques. Through continued innovation, endoscopic interventions will rise to the forefront of the therapeutic arsenal available for patients requiring GI anastomosis.

Magnetic Anastomosis Rings to Create Portacaval Shunt in a Canine Model of Portal Hypertension

PURPOSE

This study evaluated a novel magnetic compression technique (magnamosis) for creating a portacaval shunt in a canine model of portal hypertension, relative to traditional manual suture.

METHODS

Portal hypertension was induced in 18 dogs by partial ligation of the portal vein (baseline). Six weeks later, extrahepatic portacaval shunt implantation was performed with either magnetic anastomosis rings, or traditional manual suture (n = 9, each). The two groups were compared for operative time, portal vein pressure, and serum biochemical indices. Twenty-four weeks post-implantation, the established anastomoses were evaluated by color Doppler imaging, venography, and gross and microscopic histological examinations.

RESULTS

Anastomotic leakage did not occur in either group. The operative time to complete the anastomosis for magnamosis (4.12 ± 1.04 min) was significantly less than that needed for manual suture (24.47 ± 4.89 min, P < 0.01). The portal vein pressure in the magnamosis group was more stable than that in the manual suture group. The blood ammonia level at the end of the 24-week post-implantation observation period was significantly lower in the magnamosis group than in the manual suture group. Gross and microscopic histological examinations revealed that better smoothness and continuity of the vascular intima had been achieved via magnamosis than with manual suture.

CONCLUSION

Magnamosis was superior to manual suture for the creation of a portacaval shunt in this canine model of portal hypertension.

Endoscopic ultrasound in pancreatic cancer treatment: Facts and hopes

Pancreatic ductal adenocarcinoma is one of the most common causes of cancer-related deaths. Since most patients present with advanced disease, its prognosis is dismal. New and more effective therapeutic strategies are needed. Endoscopic ultrasound is currently an indispensable tool for the diagnosis and staging of pancreatic ductal adenocarcinoma. In recent years, endoscopic ultrasound has evolved to become also a therapeutic procedure. On one hand, the role of endoscopic ultrasound in the management of pancreatic cancer-related symptoms (pain, obstructive jaundice, and gastric outlet obstruction) is now well established. On the other hand, its use as a mean to the delivery of anti-tumor therapies (injecting anti-tumor agents, assisting in radiotherapy, and guiding ablative therapies) is still mostly experimental, despite growing evidence supporting its feasibility, safety and efficacy.

Further Development of Magnetic Compression for Gastrojejunostomy in Rabbits

BACKGROUND

Technical improvement of gastrojejunostomy is critical in bariatric and metabolic surgery. In this study, a novel magnetic compression approach for gastrojejunostomy was evaluated.

MATERIALS AND METHODS

Both cylindrical and rectangular magnets were used in rabbits, and the magnets were named according to their location. All the magnets were perorally introduced into the stomach. The position of the jejunal magnet was controlled by a connecting line. When the jejunal magnet spontaneously entered the jejunum, the gastric magnet was introduced into the stomach. An extracorporeal magnet was used to guide these two magnets together, and the magnet pair was left to create a side-to-side anastomosis. The state of the animals and extrusion time of the magnets were observed. The anastomoses were evaluated by burst pressure and histology.

RESULTS

Gastrojejunostomy was successfully established in all animals. Cylindrical and rectangular magnets spontaneously entered the jejunum through the pylorus within 2.4 ± 0.5 and 6.0 ± 0.8 d, respectively (P < 0.01). The cylindrical and rectangular magnet pairs fell off within 15.3 ± 0.8 and 11.9 ± 1.1 d, respectively (P < 0.01). The burst pressures were statistically similar between the two types of magnets (P > 0.05). Histological examination showed sealed anastomoses with mild inflammation of the mucosa and fibrosis within the submucosa.

CONCLUSIONS

The feasibility and efficacy of establishing gastrojejunostomy by guidewire introduction of magnets, which were guided together with an extracorporeal magnet, were confirmed in rabbits. In humans, with the clinical use of this procedure, surgery would be greatly simplified.

Repair of esophageal atresia with proximal fistula using endoscopic magnetic compression anastomosis (magnamosis) after staged lengthening

We describe the treatment of a patient with long-gap esophageal atresia with an upper pouch fistula, mircogastria and minimal distal esophageal remnant. After 4.5 months of feeding via gastrostomy, a proximal fistula was identified by bronchoscopy and a thoracoscopic modified Foker procedure was performed reducing the gap from approximately 7-5 cm over 2 weeks of traction. A second stage to ligate the fistula and suture approximate the proximal and distal esophagus resulted in a gap of 1.5 cm. IRB and FDA approval was then obtained for endoscopic placement of 10-French catheter mounted magnets in the proximal and distal pouches promoting a magnetic compression anastomosis (magnamosis). Magnetic coupling occurred at 4 days and after magnet removal at 13 days an esophagram demonstrated a 10 French channel without leak. Serial endoscopic balloon dilation has allowed drainage of swallowed secretions as the baby learns bottling behavior at home.

Endoscopic intestinal bypass creation by using self-assembling magnets in a porcine model

BACKGROUND AND AIMS

A purely endoluminal method of GI bypass would be desirable for the treatment of obstruction, obesity, or metabolic syndrome. We have developed a technology based on miniature self-assembling magnets that create large-caliber anastomoses (Incisionless Anastomosis System [IAS]). The aim of this study was to evaluate procedural characteristics of IAS deployment and long-term anastomotic integrity and patency.

METHODS

We performed a 3-month survival study of Yorkshire pigs (5 interventions, 3 controls). Intervention pigs underwent simultaneous enteroscopy/colonoscopy performed with the animals under intravenous sedation. The IAS magnets were deployed and coupled with reciprocal magnets under fluoroscopy. Every 3 to 6 days pigs underwent endoscopy until jejunocolonic anastomosis (dual-path bypass) creation and magnet expulsion. Necropsies and histological evaluation were performed. The primary endpoints were technical success; secondary endpoints of anastomosis integrity, patency, and histological characteristics were weight trends.

RESULTS

Under intravenous sedation, endoscopic bypass creation by using IAS magnets was successfully performed in 5 of 5 pigs (100%). Given porcine anatomy, the easiest dual-path bypass to create was between the proximal jejunum and colon. The mean procedure time was 14.7 minutes. Patent, leak-free anastomoses formed by day 4. All IAS magnets were expelled by day 12. All anastomoses were fully patent at 3 months with a mean diameter of 3.5 cm. The mean 3-month weight was 45 kg in bypass pigs and 78 kg in controls (P = .01). At necropsy, adhesions were absent. Histology showed full re-epithelialization across the anastomosis without fibrosis or inflammation.

CONCLUSION

Large-caliber, leak-free, foreign body-free endoscopic intestinal bypass by using IAS magnets can be safely and rapidly performed in the porcine by model using only intravenous sedation.

Minimally invasive entero-enteral dual-path bypass using self-assembling magnets

BACKGROUND

A minimally invasive method of entero-enteral bypass may be desirable for treatment of obstruction, obesity, or metabolic syndrome. We have developed a technology based on miniature self-assembling magnets which create large-caliber anastomoses (incisionless anastomosis system or IAS). The aim of this study was to assess (a) procedural characteristics of IAS deployment and (b) long-term integrity and patency of the resulting jejuno-ileal dual-path bypass.

METHODS

Endoscopic jejuno-ileal bypass creation using IAS magnets was performed in 8 Yorkshire pigs survived 3 months.

PROCEDURE

The jejunal magnet was endoscopically deployed. However, the ileal magnet required surgical delivery given restraints of porcine anatomy. A 5-mm enterotomy was created through which the ileal magnet was inserted using a modified laparoscopic delivery tool. Magnets were manually coupled. Pigs underwent serial endoscopies for anastomosis assessment. Three-month necropsies were performed, followed by pressure testing of anastomoses and histological analysis.

RESULTS

Jejuno-ileal bypass creation using self-assembling IAS magnets was successful in all 8 pigs (100 %). Patent, leak-free bypasses formed in all animals by day 10. All IAS magnets were expelled by day 12. Anastomoses were widely patent at 3 months, with mean maximal diameter of 30 mm. At necropsy, adhesions were minimal. Pressure testing confirmed superior integrity of anastomotic tissue. Histology showed full epithelialization across the anastomosis with no evidence of submucosal fibrosis or inflammation.

CONCLUSIONS

Entero-enteral bypass using self-assembling IAS magnets is safe and technically feasible in the porcine model. IAS magnets can be rapidly delivered endoscopically or through a modified laparoscopic device. Expulsion of fused magnets avoids retention of prosthetic material. Anastomoses are widely patent and fully re-epithelialized. Three-month pressure testing reveals anastomotic tissue to be as robust as native tissue, while necropsy and histology suggests minimal/absent tissue inflammation. In human anatomy, a fully endoscopic jejuno-ileal bypass using IAS magnets may be feasible.

Endoscopic ultrasound-guided endotherapy

Over the last 2 decades, endoscopic ultrasound (EUS) has evolved from a noninvasive diagnostic tool to a combined diagnostic and therapeutic modality. The use of EUS complementary to endoscopic retrograde cholangiopancreatography (ERCP) has made possible biliary and pancreatic drainage in situations where conventional ERCP is unsuccessful or unlikely to be feasible. The degree of proximity to the pancreas achieved during the procedure has enabled therapeutic interventions such as drainage of peripancreatic fluid collections, pancreatic cyst ablation, and pancreatic cancer therapy. Real-time visualization of flow in adjacent blood vessels using Doppler ultrasound has allowed endovascular therapy for ablation of gastric varices and feeding vessels. Furthermore, the role of EUS is evolving in a multitude of applications such as bilioenteric and enteroenteric anastomosis in a minimally invasive manner, potentially reducing the need for surgery. This article reviews the role of EUS as an alternative to surgery in selective situations and provides an overview of future directions and evolving uses of EUS.

Magnetic compression anastomosis for treatment of benign biliary stricture

Endoscopic and percutaneous procedures have shown high success rates when used to treat benign biliary stricture. However, cases in which a guidewire cannot be passed through a refractory stricture or a complete obstruction are difficult to treat using conventional methods. Magnetic compression anastomosis (MCA) has emerged as a non-surgical alternative avoiding operational mortality and morbidity. The feasibility and safety of MCA have been experimentally and clinically verified in cases of biliobiliary and bilioenteric anastomosis. However, no pre-MCA assessment modality capable of predicting outcomes is as yet available, and no universally effective magnet delivery method has as yet been established, rendering it difficult to identify patients for whom MCA is appropriate. Various experimental studies seeking to overcome these limitations are underway. Such work will improve our in-depth understanding of MCA, which has been trialed in various fields. Upon further development, MCA may become a ground-breaking option for treatment of benign strictures that are difficult to resolve using conventional methods, and MCA may be expected to be minimally traumatic and highly effective. The aim of the present study was to discuss the current status of MCA and the direction of MCA development by reviewing clinical and experimental MCA data.

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.

Magnetic instrumentation and other applications of magnets in NOTES

Modern surgery is developing towards a minimally invasive approach. To minimize the trauma the number of ports is either limited as in single incision laparoscopic procedures or ports are introduced through natural orifices as in natural orifice translumenal endoscopic surgery (NOTES). To provide surgeons with appropriate instrumentation novel technologies are employed involving magnets. This article summarizes the theoretical background, technology and currently developed magnetic instrumentation for NOTES, laparoscopic surgery and endoscopy. Moreover, current limitations and future goals are addressed to outline the prospects for use of magnetic instrumentation in the surgery of tomorrow.

EUS-guided anastomosis

Although some technical challenges in the development of dedicated devices need to be overcome, endoscopic ultrasonography (EUS)-guided anastomosis is promising as a minimally invasive technique for pancreatobiliary diseases.

Smart Self-Assembling MagnetS for ENdoscopy (SAMSEN) for transoral endoscopic creation of immediate gastrojejunostomy (with video)

BACKGROUND

Gastrojejunostomy is important for palliation of malignant gastric outlet obstruction and surgical obesity procedures. A less-invasive endoscopic technique for gastrojejunostomy creation is conceptually attractive. Our group has developed a compression anastomosis technology based on endoscopically delivered self-assembling magnets for endoscopy (SAMSEN) to create an instant, large-caliber gastrojejunostomy.

OBJECTIVE

To develop and evaluate an endoscopic means of gastrojejunostomy creation by using SAMSEN.

SETTING

Developmental laboratory and animal facility.

DESIGN

Animal study and human cadaveric study.

SUBJECTS

Yorkshire pigs (7 cadaver, 5 acute); human (1 cadaver).

INTERVENTIONS

A transoral procedure for SAMSEN delivery was developed in porcine and human cadaver models. Subsequently, gastrojejunostomy creation by using SAMSEN was performed in 5 acute pigs. The endoscope was advanced into the peritoneal cavity through the gastrotomy, and a segment of the small bowel was grasped and pulled closer to the stomach. An enterotomy was created, and a custom overtube was advanced into the small bowel for deployment of the first magnetic assembly. Next, a reciprocal magnetic assembly was deployed in the stomach. The 2 magnetic systems were mated under fluoroscopic and endoscopic guidance. Contrast studies assessed for gastrojejunostomy leak. Immediate necropsies were performed.

MAIN OUTCOME MEASUREMENTS

Technical feasibility and complications.

RESULTS

Gastrojejunostomy creation by using SAMSEN was successful in all 5 animals. Deep enteroscopy was performed through the stoma without difficulty. No leaks were identified on contrast evaluation. At necropsy, the magnets were properly deployed and robustly coupled together, resistant to vigorous tissue manipulation.

LIMITATIONS

Acute animal study.

CONCLUSIONS

Endoscopic creation of immediate gastrojejunostomy by using SAMSEN is technically feasible.

Using external magnet guidance and endoscopically placed magnets to create suture-free gastro-enteral anastomoses

BACKGROUND

To facilitate endolumenal and natural orifice procedures, this study evaluated a novel technique using external and endoscopically placed magnets to create suture-free gastroenteral anastomoses.

METHODS

Seven anesthetized adult swine underwent endoscopic placement of magnets into the small bowel and stomach. Using external magnets, the endoscopically placed internal magnets were brought into opposition under endoscopic view. After 1-2 weeks, the pigs were killed and analyzed. At laparotomy and under sterile conditions, peritoneal cultures were obtained. The anastomoses were evaluated endoscopically and tested using an air insufflation test. Finally, the anastomoses were resected and evaluated microscopically.

RESULTS

The average operative time for endoscopic placement of the magnets was 34.3 +/- 14.8 min. Successful placement and creation of anastomoses occurred in six of the pigs. One pig did not form an anastomosis because the magnets were too large to pass through the pylorus at the time of attempted magnet placement. Six swine experienced uncomplicated postoperative courses. One pig's postoperative course involved constipation for several days, requiring additional fluids and fiber supplementation. The findings at endoscopy showed that the magnets were adhered to the anastomosis, which were easily freed, or within the stomach. The air insufflation test results were negative for all the pigs. At laparotomy, there was no evidence of infection, abscess, or leak, but two peritoneal culture results were positive with scant growth of Staphylococcus aureus and coagulase-negative staphylococcus, presumably contaminants. Microscopically, the anastomoses illustrated granulation and fibrous connective tissue without evidence of infection or leak.

CONCLUSION

Endoscopically placed magnets with external magnet guidance is a feasible and novel approach to creating patent gastroenteral anastomoses without abdominal incisions or sutures.

Magnetic compression anastomosis as a nonsurgical treatment for esophageal atresia

BACKGROUND

We describe a unique technique to promote a nonsurgical esophageal anastomosis with magnets in children with esophageal atresia.

OBJECTIVE

To evaluate the efficacy of magnetic lengthening of atretic esophageal ends to produce an anastomosis and to communicate our results after more than 2 years of follow-up.

MATERIALS AND METHODS

Between September 2001 and March 2004, five children were selected for treatment. Two of the children had esophageal atresia without fistula (type A) and three had atresia with fistula converted to type A surgically; however, surgeons failed to achieve an anastomosis because of the width of the gap. Neodymium-iron-boron magnets were used. Daily chest radiographs were taken until union of the magnets was observed. They were then replaced with an orogastric tube.

RESULTS

Anastomosis was achieved in all patients in an average of 4.8 days. One patient, with signs of early sepsis, was successfully treated with antibiotics. In four of the five patients, esophageal stenosis developed. At the time of this report, two patients were free of treatment and on an oral diet (after 26 months), two patients required periodic balloon dilatation, and one patient had recently undergone surgery due to recurrent esophageal stenosis not amenable to balloon dilatation.

CONCLUSION

Magnetic esophageal anastomosis is a feasible method in selected patients with esophageal atresia. Esophageal anastomosis was achieved in all patients. The only observed complication of significance was esophageal stenosis. One patient needed surgery because of stenosis.

A hinged metalloplastic anastomotic device: a novel method for choledochoduodenostomy

BACKGROUND

In biliary obstruction, the creation of a large-diameter permanent fistula between the bile duct and the duodenum would be attractive.

OBJECTIVE

To invent, prototype, and test a new method of forming a biliary duodenal anastomosis.

DESIGN

Survival and nonsurvival porcine model.

SETTING

An animal laboratory with general anesthesia.

INTERVENTION

A novel hybrid metalloplastic 7F anastomosis device that consisted of a central ferrous metallic tube sandwiched between 2 tapered flexible plastic end pieces was used. The device was hinged on either side of the metal insert so that a magnetic force could form an anastomosis and then the plastic components of the device could deform to fall through the compression anastomosis. These devices were inserted into the bile duct of the pigs over a 0.035-inch guidewire with a pusher tube. Cylindrical-shaped magnets were then positioned over the intraduodenal bile duct so that they exerted compressive ischemic force on the duodenum and bile duct above the papilla.

MAIN OUTCOME MEASUREMENTS

Choledochoduodenal anastomoses created were inspected at subsequent endoscopy and postmortem for patency and size.

RESULTS

Seven anastomosis devices were placed in the bile duct of pigs (weight 22-54 kg). All 4 survival animals were well and eating as soon as they were awake. Anastomoses were successfully accomplished in all survival animals. The supra-ampullary opening into the bile duct ranged from 5 to 10 mm.

LIMITATION

The small number of animals.

CONCLUSIONS

A new method for achieving larger-diameter biliary drainage was developed. Four animals were euthanized after 2 to 7 days. Our best anastomosis resulted from 2 magnets left in the animals for 4 days.

Creation of transcatheter aortopulmonary and cavopulmonary shunts using magnetic catheters: feasibility study in swine

Surgical shunts are the basic form of palliation for many types of congenital heart disease. The Glenn shunt (superior cavopulmonary connection) and central shunt (aortopulmonary connection) represent surgical interventions that could potentially be accomplished by transcatheter techniques. We sought to investigate the efficacy of using neodymium iron boron (NdFeB) magnetic catheters to create transcatheter cavopulmonary and aortopulmonary shunts. NdFeB magnets were machined and integrated into catheters. "Target" catheters were placed in the pulmonary arteries (PAs), and radiofrequency "perforation" catheters were placed in either the descending aorta (DAo) for central shunts or the superior vena cava (SVC) for Glenn shunts. The magnet technique or "balloon target" method was used to pass wires from the DAo or the SVC into the PA. Aortopulmonary and cavopulmonary connections were then created using Atrium iCAST covered stents. Magnet catheters were used to perforate the left pulmonary artery from the DAo, thereby establishing a transcatheter central shunt. Given the orientation of the vasculature, magnetic catheters could not be used for SVC-to-PA connections; however, perforation from the SVC to the right pulmonary artery was accomplished with a trans-septal needle and balloon target. Transcatheter Glenn or central shunts were successfully created in four swine.

Magnamosis: magnetic compression anastomosis with comparison to suture and staple techniques

PURPOSE

An ideal anastomosis between hollow viscera should be easily performed, strong, and operator independent. We hypothesized that transluminal attraction between magnets in the intestine could be harnessed to create an intestinal compression anastomosis (magnamosis) with these characteristics. We further hypothesized that variation of attraction force and geometry of compression would affect the quality of the intestinal anastomosis.

METHODS

We designed a self-orienting device composed of 2 neodymium-iron-boron magnets affixed to polytetrafluoroethylene moldings. Two topologies were evaluated: one designed with 'uniform' compression and the other with 'gradient' compression. Sixteen young adult pigs (Sus scrofa) underwent laparotomy with creation of a magnetic side-to-side anastomosis: 8 with the uniform device and 8 with the gradient device. Each also had a stapled anastomosis, and 5 had an additional hand-sutured anastomosis. Animals were euthanized at 1, 2, and 3 weeks after operation, then anastomoses were compared on the basis of gross appearance, histology, functional radiography, and mechanical integrity.

RESULTS

All magnetic devices formed patent anastomoses without leak. One stapled anastomosis resulted in a contained leak. Mechanical integrity of magnetic anastomoses was not statistically significantly different from staple or suture counterparts, and there was a trend toward greater strength with magnetic anastomoses. Comparison between device types revealed the gradient device trended toward greater strength and earlier patency (67% vs 33% at 1 week). There was no evidence of stenosis, and histologic examination demonstrated tissue remodeling with mucosal and serosal apposition across the magnamoses.

CONCLUSIONS

The magnetic compression anastomosis (magnamosis) device is a safe and effective means of sutureless full-thickness intestinal anastomosis with serosal apposition in a pig model. Gradient compression is superior to uniform compression. This technique is compatible with endoscopic and natural orifice approaches.

Malignant gastroenteric obstruction: therapeutic options

Malignant gastric outlet obstruction is a complication of advanced pancreatic cancer, manifesting endoscopically or radiographically as a stricture of the proximal duodenum. Until recently, management consisted of surgical gastroenteric bypass with or without associated biliary bypass. Over the past decade, the endoscopic deployment of self-expanding metal stents (SEMS) emerged as a new option for restoration of enteric patency. Compared with surgical bypass, SEMS placement is less invasive with good clinical outcomes. Aside from SEMS placement and surgical bypass, recent reports of magnetic gastroenteric anastamosis have emerged. This article critically examines each of the different therapeutic options for malignant gastric outlet obstruction, defines their clinical utility, and provides the exact recommendations as to how they may be usefully employed.

Endoluminal and transluminal surgery: current status and future possibilities

The field of minimally invasive surgery has seen tremendous growth since the first laparoscopic cholecystectomy was performed in 1987. The key question is not how successful these techniques are currently, but rather where may they lead in the future? New technologies promise to usher in an era of even less invasive procedures. The terms being coined in the literature include "incisionless," "endoluminal," "transluminal," and "natural orifice" transluminal endoscopic surgery. These techniques certainly have the potential to become the next wave of minimally invasive procedures. A recent editorial in Surgical Endoscopy by Macfadyen and Cuschieri highlighted the ongoing developments in endoscopic surgery and stressed the critical importance of surgeons being involved in future applications and permutations of these techniques [1]. There are early signs of such involvement. The work of numerous investigators in the field was presented recently at the 2005 Digestive Disease Week. The American Society for Gastrointestinal Endoscopy and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES), in collaboration with the American College of Surgeons, recently organized a postgraduate course in endoluminal therapy at the spring 2005 meeting held in Hollywood, Florida. The course is being offered again at the 2006 SAGES annual meeting. Similar courses are being offered at other regional and national meetings. This review attempts to highlight some of the available and evolving endoluminal therapies reviewed at that forum, including techniques for the management of gastroesophageal reflux disease, endoscopic mucosal resection, endoluminal bariatric surgery, transanal endoscopic microsurgery, and transgastric endoscopic surgery, as well as new technologies and possible future directions in luminal access surgery.

Transluminal endosurgery: single lumen access anastomotic device for flexible endoscopy

BACKGROUND

Forming anastomoses between two hollow organs at flexible endoscopy might reduce the need for surgery for obstructing malignancy. Current methods require access to both lumens. The aim of this work was to develop methods of forming an anastomosis at flexible endoscopy, such as a gastrojejunostomy or cholecystoduodenostomy, when access to only one lumen is feasible.

METHODS

A modified needle was passed through a large-channel echoendoscope from the accessible lumen into the target hollow organ. An anastomotic device was formed by using two 7F catheter segments, which were pushed over a guidewire into the target, the less accessible lumen. When released, by withdrawing the guidewire, the catheters formed a cross shape and created an anastomosis when compressed against a plate from the accessible side.

OBSERVATIONS

These devices were tested in live animal experiments. With an echoendoscope in the stomach, it was repeatedly possible to place needles, threaded tags, and guidewires into the small intestine and gallbladder. In 4 to 7 days, anastomoses were formed in 16 pigs between the small intestine and the stomach, and between the gallbladder and the stomach. The initial diameter of the anastomoses ranged from 3 to 9 mm. No complication occurred.

CONCLUSIONS

It is feasible to form anastomoses at flexible endoscopy when access is limited to a single side.

Percutaneous radiologic gastrostomy

Gastrostomy is a preferred method of nutrition in patients with impaired ability to eat. Although surgical gastrostomy is a well-established method and has been widely performed in the last century, beginning with early 1980s, percutaneous gastrostomy techniques, either endoscopic or radiologic, has widely gained acceptance. As percutaneous methods have been shown to be an effective, safe, easy to perform and low-cost techniques with low morbidity and mortality rates, nowadays percutaneous gastrostomy is the first method of choice in need of nutrition in patients with functioning gut. In this article authors review the technique of percutaneous radiologic gastrostomy, as well as indications, contraindications, variations of technique, ethical considerations, controversies and comparison with surgical and endoscopic methods.

Long-term patency of experimental magnetic compression gastroenteric anastomoses achieved with covered stents

BACKGROUND

Our aim was to evaluate the efficacy of a prototype "YO-YO"-shaped covered stent for keeping experimental magnetic compression gastroenteric fistulas patent for 6 months.

METHODS

Magnets were introduced perorally with endoscopic and fluoroscopic guidance and were mated across the gastric and jejunal walls of 5 dogs. After a mean of 5.5 days a 12-mm diameter YO-YO stent was placed perorally in the resulting fistula. The gastroenteric anastomosis (GEA) with stent was observed endoscopically and gastrographically at 1- to 2-month intervals.

RESULTS

There was no morbidity and there were no significant weight changes. The GEA was widely patent at necropsy at 6 months (n = 4); partial membrane separation occurred at 5 months in the fifth dog. There was minor breakage of the stent prongs in 2 animals.

CONCLUSION

Peroral creation of a stented magnetic compression GEA is safe and provides long-term patency. This technique may be potentially useful for managing gastric outlet obstruction caused by malignancy.

Stent placement of gastroenteric anastomoses formed by magnetic compression

PURPOSE

To evaluate the use of stents for prolonging the patency of gastroenteric anastomoses (GEA) induced by magnet compression.

MATERIALS AND METHODS

Rare earth magnets were inserted perorally and serially in 15 dogs so as to mate across the gastric and jejunal walls. After magnet excretion, the resulting GEA was identified endoscopically, dilated (n = 1), and stented with bare (n = 2) or partially covered (n = 6) flared 10-mm or 12-mm Z stents. The GEA was followed at 2-4-week intervals for patency; malfunctioning shunts were irrigated, or dilated with angioplasty balloons. Gross and histologic examination of the anastomotic tissues was performed in 14 animals.

RESULTS

Magnet pairs were excreted in 5-7 days. Of the 19 magnet placements in 15 animals, stent placement was not possible because of early GEA closure (n = 6), failure to locate (n = 2), pancreatic abscess (n = 1), and magnet perforation with peritonitis (n = 1). Estimated duration of GEA patency was 19 days after balloon dilation, 40-64 days with bare Z stents, and 58-147 days (mean, 90 days) with partially covered Z stents. Shunt function was commonly hindered by bezoars. Stent narrowing or occlusion was caused by tissue overgrowth through bare stents (n = 2), between covered stent struts and through partially detached membrane (n = 2). Serious morbidity (n = 2) was due to malpositioned magnets across the pancreas in one animal and gastric perforation in the other. One dog was euthanized because of unsuspected kidney infection.

CONCLUSION

Partially covered stents significantly extend the anatomic patency rate of magnetic GEA to 7 weeks or more. Functional patency is frequently impaired by bezoars. Ongoing improvements in covered stent design should provide longer-term GEA patency.

Evaluation of compression cholecystogastric and cholecystojejunal anastomoses in swine after peroral and surgical introduction of magnets

PURPOSE

To assess the efficacy of rare-earth magnets for creating a cholecystogastrostomy (CG) or cholecystojejunostomy (CJ) in nine swine.

MATERIALS AND METHODS

Neodymium-iron-boron magnets or rare-earth cobalt magnets of various configuration and strength were coupled in pairs to form four CGs and five CJs. Magnets were implanted surgically in the gallbladder and jejunum, and perorally in the stomach. Gross and histologic examinations of anastomoses were performed 8-16 days later.

RESULTS

All anastomoses showed good adhesion with no leakage and minimal inflammation. Anastomoses were fully patent in four CJs and one CG (mean, 12 days), partially patent in one CJ and one CG (mean, 15 days), and not patent in two CGs. Best results were noted with jacketed disc magnets with cutting rims and a 400-600-g pull. The rare-earth magnets were significantly weakened by gas sterilization in the first four CG experiments. Two of four magnets used in CJ were retained despite a fully patent anastomosis.

CONCLUSION

Leak-free patent or partially patent cholecystenteric anastomoses were created by magnet compression in 9-16 days. This technique may have clinical interventional applications.