Patent ID: 6148235
Filing Date: 2000-11-14
Classification: A61N

Abstract:
An implantable device for generating and delivering stimulus pulses to a location in a patient's body, having a battery which provides energy to said device, said battery having an internal impedance which changes with cumulative expenditure of energy, a controllable pulse generator for generating said stimulus pulses, said device further having impedance means for measuring said battery impedance, said impedance means comprising:voltage means for measuring the voltage output of said battery;timing means operative following a delivered stimulus pulse for timing a sequence of measuring times which occur before a next delivered stimulus pulse;a predetermined test load, and connecting means for connecting said test load across said battery at one of said measuring times of said sequence;triggering means for triggering said voltage means to measure said battery voltage output at each of said measuring times; andcalculating means for calculating the battery impedance as a function of the battery voltages measured at each of said measuring times.