Objective:To design magnets to locate colorectal neoplasms based on magnetic tracer technology, and to test its feasibility and safety by animal experiments.Methods:The magnets used for endoscopic localization of colorectal tumors consist of a tracer magnet and a pursuit magnet, both of which are ring-shaped Nd-Fe-B magnets. Eight healthy Beagle dogs were used as animal models. Tumor locations were assumed in the different parts of the colon and rectum under colonoscopy. The tracer magnet was sent to the hypothetical tumors by endoscopic soft tissue clamp and fixed near the tumors. After 24 hours, laparoscopic surgery was performed under general anesthesia. The pursuit magnet was inserted near the resected colon or rectum through the main operating hole. The tracer magnet was absorbed to the pursuit magnet to identify the location of tumors.Results:The tracer magnet and pursuit magnet were successfully designed and processed. The suction force between the tracer magnet and the pursuit magnet at zero distance was 16 N. All the 8 Beagle dogs successfully received indwelling of magnets under colonoscopy, and no magnets fell off after 24 hours. After the placement of pursuit magnet under laparoscopy, the two magnets attracted each other rapidly and accurately, and successfully completed localization of tumor site without any damage during the operation.Conclusion:Colonoscopy combined with laparoscopy for colorectal neoplasms localization based on magnetic tracer technique is simple, accurate, safe and feasible.

Objective:To study the feasibility of establishing gastrointestinal anastomosis by magnetic compression technique in rabbits.Methods:Ten healthy New Zealand rabbits were selected as models for gastrointestinal anastomosis by magnetic compression technique. Daughter and parent magnets suitable for gastrointestinal anastomosis in rabbits were designed and manufactured. A daughter magnet was inserted into the stomach through the purse fistula in the lack of blood vessel area of gastric body, and was pushed into the duodenum along the intestinal tract. And then a parent magnet was inserted through the stomach fistula. The daughter and parent magnets were automatically attracted and pressed the gastric and intestinal walls after they were adjusted in the proper position. The stomach fistula was closed with purse string suture. After ischemia, necrosis, detachment of the tissues between magnets, gastrointestinal anastomosis was established, and the magnets and necrotic tissues were expelled together from the body through the digestive tract. Survival of experimental animals was observed. Anastomotic specimens were obtained one month after operation. The blasting pressure of anastomotic stoma was measured, and the healing of anastomotic stoma was observed with naked eyes.Results:According to the pre-designed operative route, 10 New Zealand rabbits all successfully completed the operation and survived one month after surgery. No complications occurred during perioperative period. The operation time was 35.80±4.71 min (range 28.00-43.00 min), and the magnet discharge time was 11.40±1.56 days (range 9.00-14.00 days). Anastomotic specimens were obtained one month after the operation. Gross observation showed that the anastomotic stoma of gastrointestinal bypass anastomosis healed well, and the surrounding tissues adhered slightly. The anastomotic bursting pressure was 103.00±7.95 mmHg (range 94.00-113.00 mmHg) (1 mmHg=0.133 kPa).Conclusion:The establishment of gastrointestinal anastomosis by magnetic compression technique in rabbits is simple and effective.

Objective To verify the feasibility and safety of stomach tumor marker localization based on magnetic tracer technique in dogs.Methods Six male Beagle dogs were examined by gastroscopy.Then tracer magnets were sent to the "tumor" locations assumed in advance and fixed near the "tumors" by endoscopic soft tissue clamp.Laparoscopic gastric tumor localization was performed under general anesthesia 24 hours later.The tracer magnet was placed near the tumor on the surface of the stomach through the operating hole after the conventional establishment of laparoscope puncture parallel mirror to explore the tracer magnet.After the two magnets were attracted,the location of the tracer magnet seen under the laparoscope was the location of the gastric tumor,so as to complete the labeling and positioning of the lesion.Results All the 6 Beagle dogs were successfully implanted with tracer magnets under gastroscopy.Twenty-four hours after the gastroscopy,the pursuit magnet was successfully implanted during laparoscopic surgery.The two magnets automatically attracted each other and formed a sandwich structure of "tracer magnet-gastric wall-pursuit magnet ",which completed the location and identification of gastric tumor under the laparoscopy.Conclusion Gastroscopy combined with laparoscopy based on magnetic tracer technique is simple,accurate,safe and feasible.

Based on the principle of magnetic anastomosis technique, the design of magnetic anastomosis system for endoscopic tissue clamping is proposed. The system includes a semi-ring magnet, a special structure transparent cap and a detachable push rod. With the help of the existing digestive endoscopy and endoscopic tissue gripper, the endoscopic close clamping and anastomosis of the bleeding or perforated tissue can be completed. After the anastomosis, the magnet falls off and is discharged through the digestive tract. Animal experiments showed that the system was easy to use, the fistula was clamped firmly, the magnet was discharged for 7~21 days, and there was no magnet retention and digestive tract obstruction. Further safety verification, optimization of endoscopic operation, the system can be used in clinical trial.
Anastomosis, Surgical ; Animals ; Constriction ; Endoscopy, Gastrointestinal ; Magnetics ; Magnets

Objective    To investigate the feasibility of magnamosis rings designed based on magnetic compression technique in esophageal anastomosis reconstruction. Methods    According to the anatomical characteristics of esophagus in SD rats, the esophageal magnamosis rings were designed. SD rats were used as animal models (n=10, 5 males and 5 females) to complete the magnetic anastomosis reconstruction of the cervical esophagus using magnamosis rings, and the operation time, animal survival, postoperative complications, magnetic rings excretion time were recorded. Two weeks after operation, the rats were killed, and the esophageal anastomotic specimens were obtained. The blasting pressure of the anastomotic site was measured and the formation of the anastomotic site was observed with naked eyes. Results    Esophageal magnamosis was successfully performed in 10 SD rats, and the median operation time was 11 (8-13) min. All rats survived without anastomotic leakage, anastomotic stenosis, or magnetic rings incarceration. The magnetic rings were discharged after 8 (5-10) days and the burst pressure was higher than 300 mm Hg. Visual observation showed that the anastomotic muscle healed well and the mucosa was smooth. Conclusion    The magnetic compression technique  can be used for anastomosis reconstruction of esophagus, which has the advantages of simple operation and reliable anastomosis effect, and has clinical application prospect.