Patent ID: 8221354

Claim:
An implantable medical device for the infusion of a therapeutic substance into an anatomy, the medical device comprising: a bulkhead comprising an electrical power source, a pump operably connected to the electrical power source, and an asymmetric reservoir surface; an elastic bladder attached to the bulkhead over the reservoir surface, wherein the elastic bladder and the reservoir surface define an interior volume of a reservoir, wherein the elastic bladder is exposed to ambient pressure outside of the medical device, wherein the elastic bladder elastically deforms when loaded with therapeutic substance such that the therapeutic substance is pressurized above ambient pressure, and wherein the elastic bladder conforms to the reservoir surface of the bulkhead when the internal volume of the reservoir is at ambient pressure; a pump port operably connecting an inlet of the pump to the interior volume of the reservoir; and an outlet port through which the therapeutic substance is pumped out of the medical device using the pump.