St. Jude Medical Ab

Pacesetter Ab

Jan Lindberg

Martin Obel

Niklas Sk&ouml;ldengen

Tryggve Hemmingsson

Kjell Helen

Hans Abrahamsson

In a method and apparatus for determining the depleted capacity of a CFtype battery used in an implantable medical device, average values of battery voltage and battery current drawn from the battery are measured during a measurement time, the length of which exceeds a battery voltage recovery time after a load change, and wherein the actual depleted capacity of the battery is determined by predetermined relations between combinations of the average values of voltage and current and depleted battery capacity.

Method and apparatus for determining depleted capacity of a battery

In a method and an apparatus for detecting the status of a battery in an implantable heart stimulator, the battery impedances measured and an increased value of the measured impedance is detected, from which an impedance based value of the remaining battery capacity is determined. The increase in impedance is analyzed to determine whether the impedance increase is a reliable indicator of the remaining battery capacity. If it is determined that the impedance increase is not reliable for determining the battery capacity, the total charge depletion of the battery is measured and a charge depletion-based value of the remaining battery capacity is determined.

Method and circuit for determining the battery status in a medical implant

A medical implant such as a heart stimulator has a detector which detects an extracorporeally generated interrogation signal for at least one predetermined working parameter of the medical implant. The interrogation signal is generated by an interrogation signal device capable of only unidirectional communication to the medical implant. The implant includes a response signal generator which generates an extracorporeal detectable response signal, detectable, for example, by a stethoscope, which indicates only if the interrogated working parameter has a satisfactory value or a non-satisfactory value.

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Sollentuna, Sweden

Jan Lindberg