Endoscopy 2016; 48(07): 607-608
DOI: 10.1055/s-0042-108438
Editorial
© Georg Thieme Verlag KG Stuttgart · New York

A small magnet with a large potential to replace surgery in repairing a disconnected bile duct after living-donor liver transplantation

Takao Itoi
1   Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan
,
Kazuhiko Kasuya
2   Third Department of Surgery, Tokyo Medical University, Tokyo, Japan
› Author Affiliations
Further Information

Publication History

Publication Date:
28 June 2016 (online)

Living-donor liver transplantation (LDLT) has become common worldwide in patients with end-stage liver disease. Following LDLT, duct-to-duct anastomoses have been popularized as a method for bile duct reconstruction. However, bile duct reconstruction was thought of as an “Achilles’ heel” because of bile duct complications as long as four decades ago [1] [2]. In fact, these complications occur in 20 % – 35 % of patients undergoing LDLT, even when it is carried out by skilled surgeons [3] [4]. Of these complications, biliary strictures including anastomotic and non-anastomotic strictures are the most common after liver transplantation. In particular, anastomotic strictures are often observed after LDLT.

Interventional endoscopy and interventional radiology using balloon dilation and stent placement are some of the options for the treatment of bile duct strictures as minimally invasive therapy before performing surgical intervention. Recently, endotherapies such as the placement of removable self-expanding metal stents [5] and multiple plastic stents [6] have been reported as effective treatments of refractory anastomotic strictures [7]. However, a disconnected bile duct has had to be treated by surgical intervention alone.

To overcome this issue, magnetic compression anastomosis (MCA) was developed by Yamanouchi et al. in 1998 for entero-enterostomy without surgical intervention [8]. We reported the first case of MCA for choledocho-choledochostomy in 2003 [9]. Since then, several further reports on MCA for choledocho-choledochostomy have been published [10] [11] [12] [13].

In the procedure described by all of these previous reports, two cylindrical samarium – cobalt (Sm – Co) rare-earth magnets of 3 – 4 mm in diameter, depending on the diameter of the bile duct in each patient, were prepared and attached to a nylon wire or nylon/silk thread. One magnet was advanced through a 14-Fr sheath catheter via the percutaneous transhepatic biliary drainage (PTBD) route. The other magnet was advanced into the bile duct via the transpapillary route by endoscopic retrograde cholangiopancreatography (ERCP) after endoscopic sphincterotomy and/or endoscopic papillary balloon dilation.

Aside from inserting the magnet via the PTBD route, advancement of a magnet to the biliary obstruction site using ERCP is always challenging because of two big obstacles: (1) carrying an unstable magnet with a nylon loop or silk thread from the mouth to the duodenum using a conventional duodenoscope; and (2) selective insertion of the magnet into the bile duct proximal to the disconnected site via the papilla of Vater. These procedures may be difficult to perform smoothly even for skilled ERCP endoscopists unless they have previous experience of several cases [14].

In this issue of Endoscopy, Ersoz et al. [15] describe the first feasibility study on the evaluation of a newly designed magnet for MCA in patients with a disconnected bile duct after LDLT. This new magnet has two major advantages over previous magnets: (1) it is a small but powerful magnet, and (2) it is an over-the-wire magnet. The magnet is a nickel-coated, cylindrical neodymium – iron – boron earth magnet with a diameter of 2.4 mm and a length of 5 mm, whereas our magnet has a diameter of 3 – 4 mm. Hence, their small magnet can be carried through the duodenoscope after reaching the papilla of Vater.

Theoretically, a small magnet cannot provide as much power. Surprisingly, the small magnet developed by Ersoz et al. (diameter 2.4 mm) has a magnetic field of 6661 gauss, whereas our magnet (diameter 3 – 4 mm) has a magnetic field of 3000 – 4000 gauss. In our personal experience, a magnet with 3000 – 4000 gauss enables the creation of an anastomosis across up to 2 cm of disconnected length. As it is well known that the disconnected length in post-LDLT patients is mostly within 2 cm, this small magnet has sufficient compression power for the treatment of a disconnected bile duct after LDLT. In fact, in this study by Ersoz et al., MCA was successfully conducted in all cases.

An over-the-wire magnet is a novel concept. With the previous MCA technique, carrying the magnet from the mouth to the disconnected site took a long time and was occasionally difficult or impossible, so there has been an urgent need to standardize the MCA technique. However, as a through-the-scope magnet with a guidewire lumen meant a small magnet with small power, we were unable to develop such a magnet. Therefore, this novel magnet developed by Ersoz et al. appears to be a breakthrough innovation for spreading the MCA technique for the repair of a disconnected bile duct before shifting to surgical intervention.

A small magnet also does not require a large introducer for the PTBD route. In the previous procedure, a 14-Fr introducer was needed, whereas in the procedure described by Ersoz et al., a 7-Fr introducer was used. A thinner introducer reduces the pain experienced by the patient that is caused by tract dilation.

The most important point in the study of Ersoz et al. was that their ideal magnet for the MCA technique is not a prototype but is commercially available in Turkey. As there are many patients across different countries with a disconnected bile duct after LDLT, it is our hope that this magnet will soon be available for use outside of Turkey.

Regarding limitations, the study by Ersoz et al. was a single-center study involving a small number of cases and the maximum disconnected length over which the magnet was able to create the anastomosis was not clarified.

Taken together, MCA using this novel magnet of 2.4-mm in diameter as developed by Ersoz et al. appears to be feasible and useful in patients with a disconnected bile duct after LDLT. A multicenter study involving a large number of cases is warranted to fully establish the effectiveness and reliability of this newly developed magnet.