After thoracoscopic lobectomy was first proposed by Lewis in 19925, the field of thoracoscopic surgery has shown rapid advances and has gradually replaced thoracotomy. Traditional thoracoscopic surgery requires the creation of three poking holes to target the lesion tissue to form a quadrilateral surgical area. Subsequently, thoracic surgeons pursued more minimally-invasive methods, and proposed single-port and double-port surgery. In 2004, Rocco G completed the first single-port thoracoscopic wedge resection6. Subsequently, efforts were made to further develop thoracoscopic surgery with reduced poke holes. Several studies have shown that reducing the number of poke holes reduces intraoperative bleeding, postoperative pain, drainage time, and hospital stay3,7,8. However, irrespective of the method, more operating instruments will inevitably need to pass in and out of the thoracic cavity through the same poking hole, which is likely to cause instrument collision and interference with surgical operations9,10. In addition, it also increases the difficulty of learning for the surgeon11. In this study, we developed a magnetic anchor technique for thoracoscopy to effectively alleviate the problem of mutual interference between endoscopic instruments.
The magnetic anchor technique-assisted laparoscopic surgery was first reported by the Cadeddu team. They developed a magnetic anchoring and guidance system (MAGS) and proposed the replacement of some traditional laparoscopic instruments with this system12. They used this system to successfully perform transvaginal cholecystectomy13 and laparoscopic nephrectomy14 in several pigs. Clinical trials of this system were subsequently carried out15. The results demonstrated the safety and feasibility of magnetic anchor technique-assisted poke-reducing laparoscopic surgery, which can reduce instrument collisions and improve the operating space.
Kume et al. developed a magnet-retracting forceps16 and used it to pull out the gallbladder during laparoscopic cholecystectomy in a pig model. The device afforded good exposure of the surgical field. Subsequently, Dominguez et al. developed the TD-magnet system and used the device to perform cholecystectomy in 40 patients17. They solved the shortcomings of the device designed by Kume et al, separated the magnet and the gallbladder, and demonstrated a better range of motion. At the same time, Dominguez wrapped the magnets to allow simultaneous use of multiple magnets in the body.
Under the leadership of Professor Lv Yi, our team has summarized the application of magnetic force and further explored and conducted research in recent years. We proposed a magnetic surgical system, which incorporates a variety of technical theories. It mainly includes magnetic anchor technique (MAT), magnetic compression technique (MCT), magnetic navigation technique (MNT), magnetic levitation technique (MLT), magnetic tracer technique (MTT), and magnetic drive technique (MDT) [1]. Using the theory of magnetic anchor technology, we designed a magnetic anchoring internal grasper, which has been successfully applied to laparoscopic cholecystectomy18, laparoscopic hysterectomy19, and laparoscopic appendectomy.
At present, the use of magnetic anchor technology in thoracic surgery mainly includes the 3MP system for treatment of pectus excavatum20 and to assist thoracoscopic surgery. To the best of our knowledge, there are few reports on the use of magnetic anchor technology for thoracoscopic surgery. Martinez-Ferro et al. completed laparoscopic lung wedge resection in a patient applying the magnetic anchoring device to single port laparoscopic surgery in 201121; however, they did not conduct further studies. We have accumulated experience in the application of magnetic anchored internal grasping forceps to assist laparoscopic puncture-reduction surgery in the early stage. In this study, the magnetically anchored built-in grasping forceps were extended to assist thoracoscopic poke-reduction surgery, and we assessed the feasibility and safety of its use in beagle dogs. In assisted thoracoscopic puncture-reduction surgery, the magnetic anchored built-in grasping forceps provided good exposure of the surgical field. It allowed for good exposure and dissection of the blood vessels and bronchus. Moreover, the grasping forceps provided enough traction force to assist in cutting the lung tissue.
Compared with the TD-magnet system, the grasping forceps designed by us has a good range of motion and reduces the use of wires to control its activities. We use a silk thread to connect the internal grasper and the target magnet, so that the target magnet and the tissue grasper do not have to form a fixed angle, which increases the range of movement of the target magnet. The position of the anchoring magnet is adjusted to control the internal grasping forceps to expose the surgical field. At the same time, the distance between the anchoring magnet and the chest wall is adjusted to adjust the traction force. On the side of the target magnet, we adopt the coating shielding technology to effectively prevent the attraction between the target magnet and the cavity mirror device. At the same time, only the tail end of the target magnet is exposed, which is helpful in withdrawal of the target magnet. Although we have documented the variation in the magnetic force of the two magnets with change in the distance, it still requires the surgeon to learn by practice and gain experience in controlling the traction force during the operation; however, this does not entail a steep learning curve. The disadvantage is that it may necessitate an assistant to control the anchoring magnet, but if an effective external holding device is used, the need for assistance can be avoided.
In this study, we only used a single target magnet to assist surgery. The MAGS developed by the Cadeddu team can replace multiple laparoscopic devices and accommodate multiple magnetic anchoring devices in the abdominal cavity. However, further studies are required to assess the feasibility of replacing the endoscopic grasping forceps with more magnetic anchoring devices in the thoracic cavity. We believe that magnetic anchoring devices should not be used too much. On the one hand, the capacity of the thoracic cavity is fixed, and its ability to accommodate multiple magnetic anchoring devices, like the abdominal cavity, needs to be further discussed. On the other hand, a magnetic anchor internal grasper is sufficient for thoracoscopic wedge resection, and the built-in target magnet may be interfered by multiple external anchoring magnets, thereby affecting the operation.
Although we have achieved experimental success, this research still has shortcomings. First of all, in our study, we mainly performed the resection of the right lung tissue, and did not make repeated attempts on multiple lung lobes. Further studies are required to assess the suitability of this device for other more complex disease models. Secondly, we did not make a statistical comparison of the effect of using or not using a magnetic anchoring device on the operation, but just made a judgment based on the surgeon’s experience. In addition, because there are still differences in the structure of beagles and humans, whether the device has the same effect in the human body needs further research. However, we believe that magnetic anchor technology can play a useful role in lung resection, lobectomy, and other operations. We can thoroughly extend this technology to single-port thoracoscopic surgery to achieve a more minimally invasive effect.