A variable flow stent is described for use with AV fistulas, TIPS procedures or dialysis grafts. The flow may be varied by adjusting the diameter of the stent. Embodiments include: a covered stent having a secondary chamber that functions as an air or fluid bladder； an expandable chamber within an interior stent covering； a retractable jack device with hooks that engage (snag) opposing walls of the stent； and, a stent with a hollow chamber or pocket in the interior stent covering into which an expandable balloon can be inserted. A self-healing valve is described for inflating or deflating expandable elements within the stent and may be implemented using a self-healing membrane. A radiopaque collar may be used to provide a marker surrounding the self-healing valve. If under-shunting or over-shunting occurs over time, the variable diameter stent may be adjusted using a second procedure.
