A modular magnetic anastomotic device for minimally invasive digestive anastomosis: proof of concept and preliminary data in the pig model

A Novel Deformable Self-Assembled Magnetic Anastomosis Ring (DSAMAR) for Esophageal Stenosis Recanalization without Temporary Gastrostomy in Beagle Dogs

BACKGROUND

To assess the feasibility of a deformable self-assembled magnetic anastomosis ring (DSAMAR) in the treatment of esophageal stenosis in beagle dogs via transoral access without temporary gastrostomy.

METHODS

Experimental esophageal stenosis was created in 10 beagle dogs by partial cervical esophageal ligation. The DSAMAR was inserted into the distal esophagus via the narrow section of the esophagus using a gastroscope. A circular DSAMAR was placed in the proximal esophagus. The magnetic rings on both sides of the experimental stenosis automatically attracted each other. We then recorded the operation time, postoperative complications, anastomotic formation time, and magnetic ring discharge time. The dogs were euthanized 4 weeks postoperatively; subsequently, we obtained the esophageal anastomotic specimens and observed the anastomotic formation via the naked eye and by light microscopy.

RESULTS

Our esophageal stenosis model produced reproducible stenoses in all dogs, which was confirmed via endoscopy and esophagography. DSAMAR was successfully implanted in all experimental animals under endoscopic and X-ray monitoring, and all linear DSAMARs were successfully transformed into rings. The magnets at both ends of the esophageal stenosis were automatically attracted. All animals survived until euthanasia. No complications, including esophageal perforation, bleeding, and gastrointestinal obstruction, were noted during the perioperative period. The mean operation time of endoscopic magnetic anastomosis was 15.6 ± 2.41 (range, 12-19) min. The mean esophageal anastomotic formation time was 8.8 ± 1.03 (range, 7-10) days, and the mean expulsion time of DSAMAR was 13.94 ± 2.88 (range, 10-19) days. Gastroscopy and esophagography were performed at 4 weeks postoperatively; the esophageal patency was good. Macroscopic observation of the esophageal anastomotic specimens revealed that the esophageal mucosal layer of the anastomosis had good continuity and the anastomosis was smooth.

CONCLUSION

DSAMAR is a feasible option for magnetic recanalization of esophageal stricture via transoral access without temporary gastrostomy.

An experimental study on long term outcomes after magnetic esophageal compression anastomosis in piglets

BACKGROUND/PURPOSE

Previous studies have shown that a patent, watertight esophageal anastomosis can be accomplished safely using specially-shaped magnets in piglets. However, it is unclear whether such a magnetic esophageal compression anastomosis (MECA) remains patent in the long-term. The purpose of this study was to evaluate the long-term outcome of MECA in an experimental pig model over an observation period of 2 months.

METHODS

Ten piglets underwent creation of an MECA with custom-made 8 mm magnets and a U-shaped esophageal bypass loop to allow peroral nutrition at eight weeks of life. Two weeks later, the bypass loop was closed surgically, requiring the pigs to swallow via the newly created magnetic compression anastomosis. The pigs were fed soft chow for 2 months. They were monitored for weight gain and signs of dysphagia. At the endpoint of two months, esophagoscopy and contrast esophagography was performed. After removal of the esophagus, the tissues were macroscopiocally and histologically assessed.

RESULTS

Six piglets survived until the endpoint. In two pigs, closure of the bypass loop failed, these demonstrated mean weight gain of 792 gs/day [95% Confidence interval 575 to 1009 gs/day]. Weight gain in four pigs that exclusively fed via the magnetic anastomosis averaged 577 gs/day [95% confidence interval 434 to 719 gs/day (p = 0.18)]. There were no signs of dysphagia. All magnets passed with the stool within 16 days. After 2 months, a well-formed magnetic compression anastomosis was visible and easily negotiated with a 6.5 mm endoscope. Esophogram and macroscopic findings confirmed patentency of the esophageal anastomoses. Histopathology showed a circular anastomosis lined with contiguous epithelium.

CONCLUSION

MECA creates a long-term functional and patent anastomosis in pigs. This concept may facilitate minimally-invasive esophageal atresia repair by obviating a technically challenging and time-consuming hand-sewn anastomosis.

Effects of Warmed and Humidified CO2 Surgical Site Insufflation in a Novel Experimental Model of Magnetic Compression Colonic Anastomosis

Background. Pneumoperitoneum insufflation with warmed and humidified carbon dioxide (WH-CO2) can prevent heat loss and increase tissue oxygenation. We evaluated the impact of localized WH-CO2 insufflation on the anastomotic healing process. Methods. Sixty male Wistar rats were randomized: Group 1 (control, n = 12), Group 2 (cold and dry CO2, CD-CO2, n = 24), and Group 3 (WH-CO2, n = 24). A magnetic compression side-to-side colonic anastomosis was performed under 60-minute local abdominal CO2 flow insufflation. Animal temperature was recorded. IL-1, IL-6, and CRP levels were assessed before and after insufflation and on postoperative day (POD) 7 and POD 10. Endoscopic follow-up was performed on POD 7 and POD 10. A burst pressure (BP) test of the specimen was performed on POD 10, and histopathological analysis was then performed. Metabolomics of the anastomotic site was determined. Results. Seven rats (5 CD-CO2 group, 1 WH-CO2 group, and 1 control group) died during the survival period. Necropsies revealed intestinal occlusions (n = 2). One additional rat from the CD-CO2 group was sacrificed on POD 7 due to intestinal perforation. The postoperative course was uneventful in the remaining cases. There was no difference in BP among the groups. Thermal monitoring confirmed that WH-CO2 insufflation was effective to reduce heat loss. IL-1 levels were statistically and significantly lower on POD 10 in the WH-CO2 group than the CD-CO2 group but not lower than the control group. CRP levels, histopathology, and metabolomics did not show any difference between the 3 groups. Conclusions. WH-CO2 was effective to preserve core temperature. However, it did not improve anastomotic healing.

An experimental study on magnetic esophageal compression anastomosis in piglets

INTRODUCTION

Fashioning a patent, watertight anastomosis in patients with esophageal atresia is a challenging task in pediatric surgery, particularly when performed under tension. A reproducible suture-less alternative would decrease operative time. We evaluated magnetic esophageal compression anastomoses in a novel bypass-loop swine model.

METHODS

Eight-week-old piglets underwent thoracotomy to mobilize the esophagus at the carina to create a U-shaped loop. Custom-made 8 mm diameter Neodymium Magnets were inserted into the esophagus proximal and distal to the loop, then mated side-to-side at the future anastomosis site. Pigs were observed for 8 (n = 4), 10 (n = 6), and 12 (n = 2) days and then sacrificed. The magnetic compression anastomosis was evaluated macroscopically, by radiography, burst pressure testing, and histology.

RESULTS

All 12 pigs survived until the endpoint. Separation of the magnets occurred at a median of 9 days. Contrast esophagrams showed patency and no leak. All anastomoses withstood pressures well over 13 kPa without leak. Histopathology showed epithelialized circular scar tissue.

CONCLUSION

Magnetic compression anastomoses of the esophagus using our specially-designed magnets are formed between the 8th and 10th postoperative day, are patent and mechanically resistant to supraphysiologic intraluminal pressures. These data lay the basis for a potential clinical application in patients born with esophageal atresia.

LEVEL OF EVIDENCE

Not applicable (experimental animal study).

The effect of three different surgical techniques for colon anastomosis on regional postoperative microperfusion: Laser Doppler Flowmetry study in pigs

BACKGROUND

The optimal surgical approach to reconnecting bowel ends safely after resection is of great importance.

OBJECTIVES

This project is focused on assessment of the perianastomotic microcirculation quality in the short postoperative period when using three different anastomosis techniques in experimental animal.

METHODS

The experimental study involved 27 young female domestic pigs divided into three subgroups of 9 animals according to each surgical method of anastomosis construction in the sigmoid colon region: by manual suture, by stapler, or by gluing. Blood microcirculation in the anastomosis region was monitored using Laser Doppler Flowmetry (LDF). Anastomosis healing was evaluated by macroscopic and histological examination.

RESULTS

Evaluation of the microcirculation in the anastomosis region showed the smallest decrease in perfusion values in animals reconstructed by suturing (Δ= -38.01%). A significantly more profound drop was observed postoperatively after stapling or gluing (Δ= -52.42% and Δ= -59.53%, respectively). All performed anastomoses healed without any signs of tissue and function pathology.

CONCLUSIONS

Sewing, stapling, and gluing techniques for bowel anastomosis each have a different effect on regional microcirculation during 120 min. postoperatively. Nevertheless, the final results of anastomosis healing were found without of any pathology in all experimental animals managed by above mentioned anastomotic techniques.

Experimental Procedure of Compression Anastomosis Using Fragmented Rings: A Porcine Model

BACKGROUND

Compression anastomosis has been recently abandoned because of a nonsuperiority compared to stapling anastomosis. Nonremoval of the rings has frequently been reported and this technique does not support a routine use. The aim of this experimental study was to assess the feasibility of anastomosis using compression with a device consisting of fragmented rings.

METHODS

A new compression device, the "Anastocom," was compared to standard double-stapled colocolonic anastomosis in 2 groups of 8 pigs. In each group, colocolonic anastomosis was performed with a circular stapler (DST Series EEA Staplers) in 4 pigs and with the Anastocom device for the other 4 pigs.

RESULTS

The anastomotic rings were expelled between postoperative day 7 and day 13 from the 4 animals sacrificed at day 30. The anastomosis was clean and intact in all pigs. After sacrifice, there was no difference in the bursting pressure at day 7 ( P = .226) or at day 30 ( P = .885) between the 2 types of anastomosis. After sacrifice at day 7, the mean bursting pressure values for the Anastocom and EEA anastomoses were 128.6 mm Hg (range 119-143 mm Hg) and 218.9 mm Hg (range 84-240 mm Hg), respectively. After sacrifice at day 30, the mean bursting pressure values for the Anastocom and EEA anastomoses were 111 mm Hg (range 59-234 mm Hg) and 105 mm Hg (range 81-130 mmHg), respectively.

CONCLUSION

No bowel obstruction was observed with Anastocom. This fragmentation mechanism should better prevent nonexpulsion compared to basic compression anastomosis.

Modelling side to side intestinal anastomosis

Side-to-side intestinal anastomosis is a surgical procedure where an incision is performed between two parallel segments of gut and then they are sutured together. The purpose of this paper is to investigate if the standard surgical practice diameter used in anastomosis leads to undesirable closed circulatory flows which may be harmful to the gut tissue. A finite element model for the chyme flow in a side by side anastomosis with realistic user configurable parameters is developed and solved in a wide range of situations. We analyze the flow crossing the anastomosis, the normalized pressure difference in the gut section and the streamlines that show the presence or absence of closed flow regions for a set of surgically feasible anastomosis diameter values. In contrast with the findings of simpler analytical models, closed flows do not appear in any of these cases. The study shows that the current standard surgical practice where the anastomosis diameter is similar to the gut diameter does not lead to undesirable effects predicted by some simple analytical models.

Experimental Evaluation of the Optimal Suture Pattern With a Flexible Endoscopic Suturing System

BACKGROUND

The ability to perform reliable, secure endoluminal closure of the gastrointestinal tract wall, is a prerequisite to support the progress of the emerging field of endoluminal surgery. Along with advanced clipping systems, flexible endoscopic suturing devices are commercially available. Current systems can replicate traditional surgical suturing patterns in the endoluminal environment. The aim of this study was to evaluate the optimal endoluminal suturing technique using a flexible endoscopic suturing device.

MATERIALS AND METHODS

Procedures were performed on bench-top simulators containing 20 explanted porcine stomachs. A standardized 3-cm full-thickness incision was created on the anterior wall of each stomach using monopolar cautery. The gastrotomy was closed endoscopically using an over-the-scope suturing device (OverStitch, Apollo Endosurgery; Austin, TX). Three different techniques were used: single stitches, figure-of-8 pattern, and running suture. Material consumption and operation time were recorded and bursting pressure measurement of the closure was performed.

RESULTS

No statistically significant differences were identified in suturing time. Suturing time (minutes) was slightly shorter with the figure-of-8 technique (41.14 ± 4.6) versus interrupted (45.75 ± 1.1) versus continuous (51.44 ± 10.0), but the difference was not statistically significant. The number of sutures required was greater in the interrupted group. No significant difference was found in the burst pressure (mm Hg): figure-of-8 (45.85 ± 26.2) versus interrupted (30.5 ± 22.89) versus continuous (32.0 ± 26.5). In the figure-of-8 group, 85.5% of cases were leakproof above 30 mm Hg, while in the other groups only 50% of cases were so.

CONCLUSION

A figure-of-8 suturing pattern seems to be the preferable suturing technique with the endoscopic suturing device.