Objective:To compare the histological differences between magnetic anastomosis and traditional suture in canine portal vein (PV) .Methods:Eighteen healthy Chinese garden dogs, either gender, 8-12 months and weighing 13.5-18.9 kg, were randomly divided into magnetic compressive anastomats (MCA) group ( n=9) and hand-sewing (HS) group ( n=9) for PV reconstruction. The time of PV anastomosis was compared between the two groups. HE and Masson staining were performed immediately and at 4, 8, 12 and 24 weeks after operation. The ultrastructure of the anastomosis was observed using scanning and transmission electron microscopy. Results:All dogs survived. The PV anastomosis time was significantly shorter in MCA group (3.58±2.75) min than that HS group (12.89±3.12) min, P<0.01. In MCA group, the vascular wall of anastomotic stoma was well aligned immediately after operation, and the shrinkage was obvious in HS group by gross eyes. At 24 weeks, electron microscope scanning showed the re-endothelialization was smooth and endothelial cells arranged regularly at the anastomotic site of the MCA group, whereas different-sized and irregularly aligned endothelial cells and large collagenous fibers arranged in disorder were present at the HS anastomotic stoma. Representative HE and Masson staining confirmed that the magnetic device was associated with decreased infiltration of inflammatory cells and deposition of fibrotic collagen at 24 weeks explanted anastomotic stomas compared with the HS group. Conclusions:Compared with the HS, MCA produced shorter anastomosis time, smooth anastomotic intima, light fibrous tissue hyperplasia, no foreign body residue, mild inflammatory reaction and reliable technique for canines PV anastomosis.

Objective To explore a new method for one-stage repair of the intestinal leakage based on the principle of magnetic compression anastomosis. Methods Twenty-four dogs were randomly divided into experimental group (n = 12) and control group (n = 12) according to random number table. The model of upper and multiple intestinal leakages was established by making transverse incisions of 1 cm in length on the jejunum wall about 50 cm and 100 cm away from the Treitz ligament. Forty-eight hours later, two NdFeB magnetic rings with the magnetic flux of 2500 G were put into the intestine from the leak sites. The leak sites were pressed between the two rings. The ventages in the control group were sutured. The condition of the dogs was observed after the repair of the leakage. The excreting time was recorded, and the leakage pressures of the anastomotic stoma were detected.The positions of the magnetic rings in the experimental group were detected by X ray. Tissues of the anastomotic stoma were processed by hematoxylin eosin and Masson staining. All data were analyzed using the two-sample t test. Results Severe abdominal infection occurred 48 hours after the establishment of the model. All the intestinal leakages in the experimental group were successfully repaired and the dogs survived for a long time. The magnetic rings were excreted six or seven days after the repair. Eight dogs of the control group survived. The leakage pressure of the anastomotic stoma seven days after the repair was (134 ±23)mm Hg (1 mm Hg =0. 133 kPa) in the experimental group and (91 ± 18)mm Hg in the control group, respectively, with a significant difference between the two groups (t = 3.225, P ＜ 0.05). The leakage pressure of the anastomotic stoma 14 days after the repair was (281 ±7)mm Hg in the experimental group and (271 ±21) mm Hg in the control group, respectively, with no significant difference between the two groups (t =0. 988, P ＞ 0.05). Histological observation showed that after the magnetic compression anastomosis, the intestinal muscle and mucosa recovered well, inflammatory reaction was slight and less collagen fiber and scar was formed. Conclusions Application of magnetic ring with the magnetic flux of 2500 G in one-stage repair of the intestinal leakage in the state of severe abdominal infection is safe and reliable.

Objective To explore the feasibility of rapid and sutureless anastomosis of artificial vascular replacement of abdominal aorta in dog models using magnetic compression anastomosis (MCA) technique. Methods Twelve healthy adult crossbred dogs were evenly divided into the MCA and hand suturing (HS) groups according to the anastomosis method between abdominal aorta and artificial blood vessels. The intraoperative duration of abdominal aorta occlusion, intraoperative condition of anastomotic stoma and postoperative imaging examination of anastomotic stoma were compared between two groups. Results The intraoperative duration of abdominal aorta occlusion in the MCA group was significantly shorter than that in the HS group [(5.2±2.3) min vs. (24.4±4.3) min, P < 0.001]. No anastomotic leakage of blood or anastomotic stenosis occurred in the MCA group during the operation. Intraoperative anastomotic leakage of blood occurred in all of the 6 dogs in the HS group. Among them, 1 dog died of excessive blood loss, and 2 dogs experienced mild anastomotic stenosis due to repeated repair. Postoperative color Doppler ultrasound and angiography showed smooth blood flow at the anastomotic stoma without stenosis or thrombosis in the MCA group. In the HS group, 4 dogs presented with anastomotic stenosis on angiography at postoperative 4 weeks. Conclusions MCA technique may achieve rapid and sutureless anastomosis of artificial vascular replacement of abdominal aorta in dog models, which reduces the incidence of anastomotic complications and accelerates postoperative recovery.

A new system of blood flow block for control of bleeding in abdominal operation is composed of an abdominal magnetic blocking unit, an abdominal external electromagnet unit and other non-magnetic operation instrument. The abdominal external electromagnetic unit is placed in advance in the operation bed. The abdominal magnetic blocking unit can be placed directly on the ventral of the large vessels when need to blocking the abdominal large vessels during the operation. According to the non-contact suction characteristics of magnetic materials, the two magnetic units will attract each other and compression the vessels. Using this system for vascular occlusion does not need clear exposure and without separating vessel. There is the advantage of rapid, accurate and reliable for the system.
Abdomen ; blood supply ; Blood Loss, Surgical ; prevention & control ; Electromagnetic Phenomena ; Equipment Design ; Surgical Equipment

The anastomotic reconstruction of liver accessory vessels is the primary surgical procedure in liver transplantation. The overall surgical outcome and long-term patient survival are related to the anastomosis speed and quality. The application of magnetic anastomosis technology based on the concept of magnetic surgery to achieve rapid reconstruction of liver accessory vessels has the unique advantages of safety and high efficiency, which greatly shorten the time of the anhepatic phase and also provide new possibilities for the development of liver transplantation under minimally invasive conditions.

Objective To study the safety and efficacy of magnetic compression anastomosis (MCA) in treatment of biliary anastomotic stricture after orthotopic liver transplantation (LT).Methods Five patients who were treated unsuccessfully by ERCP were admitted to The First Affiliated Hospital of Xi'an Jiaotong University from 2012 January to 2018 May to undergo MCA.The treatment results were analyzed retrospectively.Results In four patients,the treatment was successful while in one patient it failed.For the four successful patients,the biliary stricture length was 2～4 mm.Re-canalization was achieved within 7～12 days and these patients were discharged home without any adverse events.Multiple plastic stents (in 2 patients) or full-covered self-expansion mental stents (in 2 patients) were inserted into the new fistulae after re-canalization.In two patients whose stents were removed,there was no recurrence of biliary strictures after follow-up for 64 months and 59 months,respectively.Conclusion The MCA technique is a revolutionary and effective method of performing interventional choledochocholedochostomy in patients with biliary anastomotic stricture after LT for whom the conventional endoscopic procedures were not successful.

Objective To develop a magnetic anastomosis device for infrahepatic inferior vena cava and verify its feasibility and safety in rat models. Methods According to the anatomical characteristics of rat inferior vena cava, a magnetic device suitable for end-to-end anastomosis of infrahepatic inferior vena cava was designed and manufactured. The device consisted of the inner and outer rings. The inner ring was a coated neodymium-iron-boron magnetic ring, and the outer ring was made of polyetheretherketone by 3D printing. Ten fine holes are evenly distributed on the outer ring, of which 5 fine holes were used to load the fine needles, and the other 5 fine holes were mutually connected with the fine needles of the contralateral anastomosis ring during anastomosis. The outer ring was uniformly loaded with fine needles and then bonded with the inner ring to form a magnetic anastomosis complex. Bilateral ends of vessels passed through the anastomosis ring and were fixed to the fine needles, and then end-to-end vascular anastomosis was performed by mutual attraction of two magnetic anastomosis rings. Twenty SD rats were selected and received end-to-end anastomosis of infrahepatic inferior vena cava with magnetic anastomosis device. The time of vascular occlusion, postoperative survival, postoperative anastomotic patency, gross observation and histological examination of anastomotic stoma were analyzed. Results All rats successfully completed end-to-end magnetic anastomosis of the infrahepatic inferior vena cava, and the time of vascular occlusion was 4~6 min. One rat died at 10 d after operation, and the other rats survived within postoperative 2 months. The patency rates of anastomotic stoma in surviving rats at postoperative 1 d, 3 d, 1 month and 2 months were 100%, 100%, 95% and 95%, respectively. At 2 months after operation, no obvious displacement and angulation of the anastomosis device were seen. No signs of corrosion and cracking of the anastomosis rings were observed. No evident hyperplasia and edema of surrounding tissues were noted. Bilateral ends of vessels were completely healed, and no obvious stenosis or thrombosis was found at the anastomotic stoma. Histological examination showed high continuity of bilateral vascular walls of anastomotic stoma, the inner surface of anastomotic stoma was covered by endothelial cells, and no thrombus or fibrous tissue was attached. Conclusions It is safe and feasible to utilize the self-designed magnetic anastomosis device to perform end-to-end magnetic anastomosis of infrahepatic inferior vena cava in rat models.

It is intractable to Complex biliary stricture therapy after liver transplantation and other biliary operations is intractable.The routine therapies are to place stents with ERCP or do choledochojejunostomy.The former,however,is of little effect for patients with complex biliary stricture or completed obstruction.And the latter is more difficult and is with high rate postoperative complications due to the previous operation history.The application of magnetic compression offers a new direction of minimally invasive therapy of complex biliary structure.This article summarizes the current situation of the therapy of complex biliary structure with magnetic compression and the existing obstacles.

A new system of blood flow block for control of bleeding in abdominal operation is composed of an abdominal magnetic blocking unit, an abdominal external electromagnet unit and other non-magnetic operation instrument. The abdominal external electromagnetic unit is placed in advance in the operation bed. The abdominal magnetic blocking unit can be placed directly on the ventral of the large vessels when need to blocking the abdominal large vessels during the operation. According to the non-contact suction characteristics of magnetic materials, the two magnetic units wil attract each other and compression the vessels. Using this system for vascular occlusion does not need clear exposure and without separating vessel. There is the advantage of rapid, accurate and reliable for the system.

【Objective】 To evaluate the performance of the magnetic artificial blood vessel device for fast non-suture anastomosis of caval reconstruction with artificial blood vessel transplantation after resection in canines. 【Methods】 Sixteen adult mongrel dogs of either gender were randomly divided into two groups for vena cava reconstruction with artificial blood vessel transplantation after inferior vena cava (IVC) resection. Group MCA (n=8): magnetic artificial blood vessel device for IVC reconstruction; Group manual sewing (MS) (n=8): hand suturing for IVC reconstruction. Operation time and stoma errhysis were recorded during operation. Patency and stoma stenosis were confirmed via color Doppler ultrasound scanning and X-ray cholangiography at different time points as late as 4 weeks after surgery. 【Results】 The time required to perform the vascular anastomosis was significantly shorter for the magnetic artificial blood vessel device (6.25±2.25)min than for MS (27.32±5.12)min (P<0.001). There were four cases of stoma errhysis in MS group which had to be repaired (P=0.077). Vascular X-ray angiography and color Doppler ultrasound found normal blood flow and no stoma stenosis in MCA group, but three cases of stoma stenosis in MS groups (P=0.200). Compared with MS group, the magnetic ring device stoma was associated with smooth re-endothelialization and depressed infiltration of inflammatory cells at the anastomotic site. 【Conclusion】 The magnetic artificial blood vessel device offers a simple, fast, reliable, and efficacious technique for vena cava reconstruction with artificial blood vessel transplantation.