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Paper text:
the resectable rates for the hepatic hilar malignant obstruction are variable depending on surgeons , but generally reported to be approximately 10 - 20% ( 1 - 3 ) .
bilateral biliary drainage with stenting for hilar malignant obstructions has been performed for palliative treatment ( 4 , 5 ) .
primary patency rate with the current biliary stents in 12 months has been reported as approximately 12 - 40% ( 1 , 4 , 5 ) .
when the stent is obstructed by the tumor ingrowth or sludge formation , restenting can be reasonable and an ideal option to preserve the functional volume of liver in the course of chemotherapy or to prevent the bile - stasis cholangitis .
however , the necessity of biliary drainage of both liver lobes is still controversial in the hilar malignant obstruction , including the advanced klastkin tumor ( 6 ) .
it is difficult to re - stent bilaterally in order to drain bile , because the wires of the previously inserted stent have a potential risk of preventing the additional stent insertion through the contra - lateral bile duct ( 7 ) . for this reason
, there was a need for a special stent system to improve the patency rate and to allow re - stenting bilaterally when reobstruction happens in patients with a hepatic hilar malignancy .
we introduce a new attempt to improve the patency rate of the biliary stent in patients with inoperable cholnagiocarcinomas by the insertion of a newly designed y - shaped branched covered stent .
it consists of two different stents : a main piece of stent and a contra - lateral limb covered stent ( fig .
a 72-year - old woman was admitted to the hospital complaining of right upper quadrant pain . initial abdominopelvic ct showed hepatic hilar obstruction due to cholangiocarcinoma , extending from hilum of extrahepatic bile duct to distal common bile duct .
elevated total bilirubin level ( 13.0 mg / dl ) and direct bilirubin level ( 10.8 mg / dl ) were found at admission . alkaline phosphatase level ( 1189
iu / l ) and gamma - glutamyl transpeptidase ( 229 mg / dl ) were also elevated .
percutaneous transhepatic biliary drainage ( ptbd ) through the right intrahepatic bile duct ( fig .
we planned on the newly designed y - shaped covered stent insertion on the fourth day after the initial drainage procedure , and performed another ptbd through the left intrahepatic bile duct ( s3 duct ) ( fig .
the drainage catheters were removed and 8 fr sheaths inserted over a 0.035-inch hydrophilic guide wire ( terumo , tokyo , japan ) bilaterally .
first , we inserted and located the main piece of stent into the common bile duct through left ptbd tract ( fig .
the proximal end of the main piece stent ( egis key - mb stent ) ( s&g bio , seoul , korea ) was located in the left intrahepatic bile duct ( ihd ) beyond the boundary of the hilar tumor ( fig .
the short limb covered portion of the main piece stent was directed toward the left side of the common bile duct ( fig .
1c , thin arrows ) . to easily insert and deploy the contra - lateral long limb covered stent ( egis key - cl stent ) ( s&g bio , seoul , korea ) without kinking its struts , the long limb covered stent of the main piece was not to be deployed ( fig .
1d , three thick arrows ) until the contra - lateral long limb covered stent was completely deployed in an adequate position .
after successful negotiation of a guide wire into the short limb covered stent of the main piece , a contra - lateral long limb covered stent was inserted through the right ptbd tract to connect this short limb covered stent of the main piece under the guidance of a 0.035-inch guide wire . after the confirmation that its proximal end was located in the right ihd beyond the boundary of the hilar tumor , we deployed the contra - lateral long limb covered ( fig .
1e ) . finally , the long limb covered stent of the main piece was completely deployed .
a 7 fr drainage catheter was placed through the left ihd with its tip located in the common bile duct . to confirm the correct stent expansion and function
, post - stenting cholangiography was performed through the drainage catheter just after the stent insertion ( fig .
cholangiography showed good bilateral communication via completely expanded stents , and the drainage catheter was removed . on eighth day following the stent placement , total bilirubin and direct bilirubin levels decreased to 2.7 mg / dl and 2.2 mg / dl , respectively .
they have not been elevated in the 12 months following the y - shaped covered stent insertion ( total bilirubin / direct bilirubin = 0.9/0.5 mg / dl ) .
in hilar malignant biliary obstruction , the first requirement for the ideal stent platform is complete coverage of the tumorous bile ducts without interfering with contra - lateral or branched bile duct patency .
( 2 ) reported that percutaneous y - configurated covered biliary stent placement for the malignant hilar obstruction gives the patent biliary flows without interfering the contra - lateral bile flows .
however , even if internal biliary drainage with the other currently available biliary stent is optimally implanted in case of the bilateral hilar malignant obstructed lesion , it may actually impair the contra - lateral bile flow .
this is from the wires of the second stent partially left inside the first stent in the hepatic hilum , when t - configured or y - configured current stent is inserted .
( 8) cited that , in case of the biliary stent - in - stent deployment , even in t or y configuration , there is a risk of its preventing the bile inflow in the area of the stent overlap , leading to sludge formation .
furthermore , there is a possibility that tumor ingrowth will easily occur if the stent mesh is expanded in the area of overlap . on the other hand
, the present newly designed y - shaped covered biliary stent may provide a higher patency rate , as it is a covered stent system .
it does not interfere with the contra - lateral bile flow with its stent - by - stent deployment and its structural configuration ( fig .
if complete coverage of the branched bile ducts with the biliary covered stent is achieved , early reobstruction occurs , and the primary patency rate of the biliary stent will be lower .
this is from the wires of the previously inserted stent having a potential risk of preventing the additional stent insertion through the contra - lateral bile duct , when the reobstruction happens ( 3 , 8) .
this y - shaped covered biliary stent may not prevent the additional stent insertion , even if the biliary obstruction happens again . from the technical perspective , the methods used in this y - configured covered stent implantation are relatively simple , other than at one point of the procedure .
two guide wires are separately inserted into the common bile duct portion through the bilateral tumorous bile ducts .
after the adequate main piece stent system ( egis key - mb stent ) deployment , the contra - lateral limb covered stent ( egis key - cl stent ) is inserted into the short limb covered portion of the main piece stent system .
there is one technical step which is quite different from the usual stenting procedure . during the deployment of the main piece stent system
, the operator should not deploy the long limb covered portion of the main piece system ( fig .
if the operator deploys the long limb covered portion of the main piece system completely , it may interrupt the negotiation of the guide wire or long limb covered stent - introducer passing through the hilar tumorous obstructive lesion into the short limb covered stent of the main piece system .
stent grafts or covered stent are usually more likely to prevent tumor ingrowth than bare stents .
gwon reported that the stent graft may prolong the patency rate in the hilar malignant obstruction ( 2 , 4 ) .
however , there are few limitations in the use of a stent graft or covered stent for treating the advanced hilar bile duct malignancies .
there is a risk of occlusion of branching or contra - lateral bile ducts in a covered stent or stent graft .
hence , the partially covered stents were made with bare ends , which provides better anchoring and stabilization . in this y - covered stent design ,
bare stent extensions on each end of the covered stents ( main trunk , ipsilateral proximal limb , and contra - lateral limbs ) will limit the chances of migration ( fig .
a silicone - covered self - expandable stent system was used , because it provides a larger lumen for bile flow and does not allow as much sludge build - up or occlusion as the polyethylene - covered stent ( 9 ) .
currently there have been only a few stent trials performed for the palliative treatment of the hepatic hilar malignant obstruction ( 1 , 4 , 5 ) , and the image appearances of the hilar lesions have seemed to be satisfactory .
however , long - term or mid - term clinical outcome studies , including the occurrence of reobstruction after the stent insertions , are still sparse .
in fact additional therapies including the radiotherapy , photodynamic therapy , and chemotherapy can lead to longer symptomatic survival , or to longer phases of stent patency after the conservative biliary drainage ( 7 , 10 ) .
it is hoped that this new stent design may give clinicians the opportunity to offer a long - term patent rate , with its covered stent inserted by the y - shaped stent - by - stent deployment . in conclusion ,
the newly designed y - shaped covered stent placement for hilar malignancies provides the following advantages : its ability to drain the bile ducts of both lobes of liver ; and the suppression of the tumor ingrowth effectively , by using silicon covered stents without structural occlusion of contra - lateral bile ducts .
however there is a need for further clinical studies to confirm its long term patency and the ease of the restenting technique .
we report a case in an inoperable patient with the hilar malignant biliary obstruction treated palliatively by the use of a newly designed y - shaped covered stent without interfering contra - lateral bile duct . 
 we percutaneously inserted a newly designed y - shaped covered stent into a biliary tree in an inoperable patient with bismuth type ii cholangiocarcinoma . 
 we checked tubograms , enhanced ct studies , and blood bilirubin levels before , one week after , and at every three month after the stenting , by observing closely the signs of clinical infection as well . 
 the follow - up period was about 12 months . 
 the placement of the y - shaped covered stent was successful and resulted in adequate biliary drainage in the immediate post - procedural tubogram and in the follow - up abdominal ct . 
 the serum bilirubin levels did not show elevation after the insertion of the y - shaped covered stent .