Magnetic Compression Technique for Esophageal Anastomosis in Rats

Effect of tissue tension on magnetic compression anastomosis of digestive tract

With the increasing application of magnetic compression anastomosis (MCA) in gastrointestinal anastomosis, we identified an interesting phenomenon that an anastomosis is more prone to stenosis after endoscopic gastrointestinal MCA. We hypothesized that the increase in tissue tension during endoscopic procedures is the cause of anastomotic stenosis. In this study, we investigated the effect of tissue tension on gastroduodenal bypass MCA in Sprague-Dawley (SD) rats. Twenty SD rats were divided into the study group (high-tension group, n = 10) and control group (no tension group, n = 10), wherein the rats underwent complete gastroduodenal bypass magnetic anastomosis under high tension and no tension of the digestive tract, respectively. Anastomotic specimens were obtained 4 weeks after the operation, and anastomotic diameters of the two groups were observed and measured. The histological difference was observed by hematoxylin & eosin and Masson staining. The operation was successfully completed in all rats, and all survived until 4 weeks postoperatively. Anastomotic measurements revealed that the anastomosis diameter was significantly smaller in the study group than in the control group, and there were three cases of severe anastomotic stenosis. Histological observation showed that the amount of collagen fibers in the anastomosis was greater in the study group than in the control group. The results suggest that the high-tension state of the digestive tract is an important factor leading to anastomotic stenosis, and thus, we put forward the Yan-Zhang's Tissue Tension Theory of MCA to explain this phenomenon.

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.

Feasibility experiment of a novel deformable self-assembled magnetic anastomosis ring (DSAMAR) for gastrointestinal anastomosis through a natural orifice

Although the application of magnetic compression anastomosis is becoming increasingly widespread, the magnets used in earlier studies were mostly in the shape of a whole ring. Hence, a deformable self-assembled magnetic anastomosis ring (DSAMAR) was designed in this study for gastrointestinal anastomosis. Furthermore, its feasibility was studied using a beagle model. The designed DSAMAR comprised 10 trapezoidal magnetic units. Twelve beagles were used as animal models, and DSAMARs were inserted into the stomach and colon through the mouth and anus, respectively, via endoscopy to achieve gastrocolic magnamosis. Surgical time, number of failed deformations, survival rate of the animals, and the time of magnet discharge were documented. A month later, specimens of the anastomosis were obtained and observed with the naked eye as well as microscopically. In the gastrocolic anastomosis of the 12 beagles, the procedure took 65-120 min. Although a deformation failure occurred during the operation in one of the beagles, it was successful after repositioning. The anastomosis was formed after the magnet fell off 12-18 days after the operation. Naked eye and microscopic observations revealed that the anastomotic specimens obtained 1 month later were well-formed, smooth, and flat. DSAMAR is thus feasible for gastrointestinal anastomosis under full endoscopy via the natural orifice.

Application of Y-Z deformable magnetic ring for recanalization of transanal single-access rectal stricture

Magnetic compression anastomosis has been reported to have remarkable clinical outcomes. Here, we tested the applicability of a Y-Z deformable magnetic ring (DMR) for non-surgical manipulation of rectal stenosis (RS) in a beagle dog model under a transanal single-access condition. RS was modeled in 8 beagle dogs using partial ligation with silk thread. Under X-ray guidance, the Y-Z DMR was positioned at the proximal and distal ends of the RS, and the magnetic ring was bent into an "O" shape, such that the two rings were magnetically attracted. Operation time, complications during or after operation, and discharge time of the magnetic rings were recorded. The anastomosis bursting pressure was measured two weeks after removing the rings, and its formation was assessed through gross and histological examination. Partial ligation with a silk thread successfully established the canine RS model. After Y-Z DMR installation, the magnetic ring was successfully reconfigured from an "S" to an "O" shape. Strong attraction existed between the rings. The operation time was 9-15 min (average: 11.75 ± 1.98 min). No rectal bleeding or perforation occurred during or after operation. The ring was naturally expelled 7-10 days after surgery. A pressure of > 300 mmHg was recorded at the point of anastomosis rupture. The rectal anastomosis appeared to have healed properly on the surface, which was confirmed histologically, signifying the success of this procedure. A Y-Z DMR facilitated the successful recanalization of transanal single-channel RS without needing surgery in an animal model.

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.

Value of a novel Y-Z magnetic totally implantable venous access port in improving the success rate of one-time needle insertion

Background and objectives

A totally implantable venous access port (TIVAP) is a commonly used intravenous infusion device for patients receiving chemotherapy or long-term infusion therapy. To improve the success rate of one-time insertion of the Huber needle, we developed a novel Y-Z magnetic TIVAP (Y-Z MTIVAP), which we produced using three-dimensional printing technology.

Materials and methods

The Y-Z MTIVAP includes a magnetic port body and a magnetic positioning device. For testing, we established four venous port implantation models using the two types of TIVAPs and two implantation depth ranges (≤5 mm and >5 mm). Twenty nurses performed Huber needle puncture with the four models, and we recorded the number of attempts required for successful needle insertion, the operation time, and the operator's satisfaction.

Results

The success rate for one-time needle insertion with the Y-Z MTIVAP was significantly higher than that with the traditional TIVAP at either depth range (100% vs. 75% at ≤5 mm, p = 0.047; 95% vs. 35% at >5 mm, p < 0.001). With increasing implantation depth, the success rate for one-time insertion was significantly reduced with the traditional TIVAP (75% at ≤5 mm vs. 35% vs. >5 mm, p = 0.025), but the success rate with the Y-Z MTIVAP was not significantly affected (100% vs. 95%, p = 1.000). The operation time with the Y-Z MTIVAP was significantly shorter than that with the traditional TIVAP at either depth range (both p < 0.001), and 90% of operators reported that the Y-Z MTIVAP was superior to the traditional TIVAP.

Conclusions

The theoretical design of Y-Z MTIVAP is feasible, and the preliminary in vitro simulation experiment shows that it can significantly improve puncture success rate and shortened operation time.

Magnetic anchor technique assisted laparoscopic cholecystectomy in swine

Magnetic anchor device based on the principle of magnet heteropolar attraction can assist laparoscopic surgery and reduce abdominal wall trauma. This study explored the feasibility of use of our self-designed magnetic anchor device for reduced-port laparoscopic cholecystectomy (LC) through animal experiments. Twelve experimental pigs (15-20 kg) were randomly divided into study group (magnetic anchor technique assisted 2-port LC, n = 6) and control group (conventional 3-port LC, n = 6). Operative time, intraoperative blood loss, and postoperative complications were compared between the two groups. LC was successfully performed in all 12 pigs. There was no significant between-group difference with respect to operative time (study group: 35.83 ± 5.12 min; control group: 34.50 ± 5.13 min, P = 0.662) or intraoperative blood loss (< 50 mL per animal in both groups). In the experimental group, there was no malfunction of the magnetic anchoring device, the use process was smooth, and the tissue traction and surgical field exposure were satisfactory. There were no perioperative complications such as bile duct injury, bile leakage, or bleeding in both groups. We demonstrated the feasibility of use of the self-designed magnetic anchor device in reduced-port LC. The device has important clinical application value.

An experimental study of magnetic compression technique for ureterovesical anastomosis in rabbits

This study aimed to explore the feasibility of the magnetic compression technique (MCT) for ureterovesical anastomosis in a rabbit model with ureteral obstruction. The distal ureteral obstruction model using female New Zealand rabbits was induced by ligating the distal end of the right ureter with silk thread for four weeks. A pair of cylindrical NdFeB magnets (daughter magnet and parent magnet) with a hole in the center was used for the ureterovesical anastomosis. The daughter magnet and the parent magnet were respectively placed close to the obstruction site through the dilated proximal ureter and urethra, and then the daughter-parent magnets pair was attracted together automatically. Postoperative X-rays were taken to confirm the position of the magnets. The anastomotic stoma specimens were obtained two weeks postoperatively, and the anastomotic stoma formation was observed by the naked eye and histological staining. The operation time and the anastomotic burst pressure were measured. The ureter was significantly dilated in the fourth week after ligation, which satisfied the placement of the daughter magnet. The ureterovesical magnet placements were successfully performed in ten experimental rabbits, with an operation time of 36.5 ± 6.09 min. The parent and daughter magnets attracted each other well and were subsequently removed through the urethra two weeks postoperatively, resulting in the establishment of ureterovesical anastomosis. The anastomotic burst pressure was 147.5 ± 14.59 mmHg. Gross specimens and histological examination of the anastomotic stoma showed that the anastomotic stoma healed well. MCT is feasible and simple for ureterovesical anastomosis.