Jong Ho Moon, MD, PhD, and colleagues from the Digestive Disease Center and Research Institute, Departments of Internal Medicine, SoonChunHyang, University School of Medicine, in Bucheon and Seoul, South Korea discuss this Original Article, “Effectiveness of a newly designed antireflux valve metal stent to reduce duodenobiliary reflux in patients with unresectable distal malignant biliary obstruction: a randomized, controlled pilot study (with videos).”

Self-expandable metal stents (SEMSs) have been a standard treatment for internal biliary drainage in patients with unresectable distal malignant biliary obstructions (MBOs). However, the duration of stent patency remains inadequate; several factors influence patency. Duodenobiliary reflux caused by placement of a SEMS across the ampulla of Vater is considered to be an important contributor to stent occlusion. Thus, several SEMSs with antireflux functions have been developed to prolong stent patency.

Figure 1. A, The newly developed self-expandable metal stent with an antireflux valve (*).

A newly designed antireflux valve metal stent (ARVMS) was specially designed with an antireflux valve (ARV), which is relatively long (20 mm), being similar in appearance to a windsock. In present study, we evaluated stent patency and duodenobiliary reflux using a barium meal examination caused by a new ARVMS, compared with a conventional SEMS (cSEMS) in patients with MBO. And, the newly developed ARVMS showed superior duration of stent patency and lower incidence of duodenobiliary reflux on barium meal examination compared with the cSEMS.

The addition of an antireflux capacity to a SEMS has been a very attractive solution for duodenobiliary reflux. But, most of the antireflux metal stents couldn’t show the objective results indicating the prevention of duodenobiliary reflux. We studied the antireflux function of an ARVMS via barium meal administration for all patients. As a result, the new ARVMS effectively prevented duodenobiliary reflux. And, complete duodenobiliary reflux was an independent risk factor for stent dysfunction on multivariate analysis. Based on our result, we suggest that prevention of such reflux increases the duration of stent patency.

Figure 5. Duodenobiliary reflux of patients in the ARVMS and cSEMS groups by using a barium meal examination. ARVMS, antireflux valve with metal stent; cSEMS, covered self-expandable metal stent.

Although the new ARVMS shows promise in terms of the duration of patency and prevention of duodenobiliary reflux, stent occlusion cannot be completely prevented using an antireflux function alone. Various unknown factors influence stent patency. Therefore, further effort and studies are required to develop an optimal SEMS for palliative treatment of unresectable MBO. Also, further study is needed for the role of ARVMS in patients with benign biliary stricture or for preoperative biliary drainage.

Read the abstract online here.

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