The present invention provides an apparatus and method for optimizing flow in an A-V dialysis graft having a selectable constricted section. Electronic pressure and flow sensors in the arterial and venous ends of the graft are electronically coupled to a monitor to detect the arterial and venous environments and change the degree of stenosis to optimize flow. The stenosis or narrowing within the graft creates resistance for the purpose of decreasing the flow rate and pressure at the outflow end. The selectable restricted section may be provided by a balloon or a thin “slit” type valve with flexible leaves to provide the required resistance. The “slit” valve allows access to wires or catheters for the purpose of any type of graft maintenance.
