An implantable prosthesis system for treating an occlusion in a first vessel, the prosthesis system comprising: a fistula stent (100, 134, 140, 150, 160, 200, 220, 340, 500, 540, 620, 720) implantable in a fistula between a first cavity (30, 116, 300, 700) and a second cavity (32, 118, 302, 702), the fistula stent (100, 134, 140, 150, 160, 200, 220, 340, 500, 540, 620, 720) configured to span interstitial tissue between the first cavity (30, 116, 300, 700) and the second cavity (32, 118, 302, 702), the fistula stent (100, 134, 140, 150, 160, 200, 220, 340, 500, 540, 620, 720) comprising: a proximal end; a distal end; sidewalls between the proximal end and the distal end; a lumen defined by the sidewalls; a first longitudinal section (102, 221, 346, 722) having a first diameter, the first longitudinal section (102, 221, 346, 722) configured to anchor in the first cavity (30, 116, 300, 700); a second longitudinal section (104, 225, 350, 724) having a second diameter different than the first diameter, the second longitudinal section (104, 225, 350, 724) configured to anchor in the second cavity (32, 118, 302, 702); a third longitudinal section (106, 348, 726) tapering between the first longitudinal section (102, 221, 346, 722) and the second longitudinal section (104, 225, 350, 724), wherein at least one of the first longitudinal section (102, 221, 346, 722) and the third longitudinal section (106, 348, 726) comprises a porosity sufficient to direct fluid flow through the lumen substantially without perfusing through the sidewalls; and a venous stent comprising a proximal end segment configured to overlap with the second longitudinal section (104, 225, 350, 724) of the fistula stent (100, 134, 140, 150, 160, 200, 220, 340, 500, 540, 620, 720), wherein the venous stent is configured to line a sidewall of the second cavity (32, 118, 302, 702) to cover collateral vessels of the second cavity (32, 118, 302, 702) and to disrupt a valve located in the second cavity (32, 118, 302, 702). a proximal end; a distal end; sidewalls between the proximal end and the distal end; a lumen defined by the sidewalls; a first longitudinal section (102, 221, 346, 722) having a first diameter, the first longitudinal section (102, 221, 346, 722) configured to anchor in the first cavity (30, 116, 300, 700); a second longitudinal section (104, 225, 350, 724) having a second diameter different than the first diameter, the second longitudinal section (104, 225, 350, 724) configured to anchor in the second cavity (32, 118, 302, 702); a third longitudinal section (106, 348, 726) tapering between the first longitudinal section (102, 221, 346, 722) and the second longitudinal section (104, 225, 350, 724), wherein at least one of the first longitudinal section (102, 221, 346, 722) and the third longitudinal section (106, 348, 726) comprises a porosity sufficient to direct fluid flow through the lumen substantially without perfusing through the sidewalls; and a venous stent comprising a proximal end segment configured to overlap with the second longitudinal section (104, 225, 350, 724) of the fistula stent (100, 134, 140, 150, 160, 200, 220, 340, 500, 540, 620, 720), wherein the venous stent is configured to line a sidewall of the second cavity (32, 118, 302, 702) to cover collateral vessels of the second cavity (32, 118, 302, 702) and to disrupt a valve located in the second cavity (32, 118, 302, 702).