Cardiac pacer with battery consumption monitor circuit

• US 4,556,061 A
• Filed: 03/12/1985
• Issued: 12/03/1985
• Est. Priority Date: 08/18/1982
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Cordis Corporation (Cardinal Health, Inc.)
• Inventors: Barreras, Francisco J., Baker, Ira R.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Shein, Mitchell J.
• Application Number:
  US06/710,531
• Time in Patent Office: 266 Days
• Field of Search: 128/419 PT, 128/903-904, 324/426, 324/429, 324/433, 324/436, 320/48, 340/636
• US Class Current: 607/32
• CPC Class Codes: A61N 1/3708 for power depletion

Abstract

A battery powered implantable cardiac pacer includes a battery consumption monitor circuit which develops within an internal counter a cumulative count of battery consumption in milliampere hours. The consumption count may be read out to an external indicator by a multiplex circuit to provide to the user an indication of battery life remaining. An over-current feature within the monitor circuit provides an alarm signal in the event that battery consumption exceeds a predetermined maximum level.

Claims

1. A battery-operated implantable pacer comprising, in combination:

pacer circuit means operable from a unidirectional current source for supplying pacing pulses to a pacer lead;

means including a battery for supplying unidirectional current to said pacer circuit means;

current sensing means coupled between said battery and said pacer circuit means for developing a demand signal indicative of the current being drawn from said battery;

oscillator means responsive to said demand signal for developing a plurality of pulses each indicative of the consumption of a predetermined unit of charge by said pacer circuit means from said battery;

counter means responsive to said pulses for developing a multi-digit output signal continuously indicative of the number of units of charge consumed from said battery, said counter means including a plurality of individual counter elements providing respective digits of said output signal; and

telemetry circuit means responsive to said output signal for providing at a remote location within said range of battery charge states an indication of the total charge consumed from said battery.

2. A battery-operated implantable pacer as defined in claim 1 wherein said current sensing means comprise a resistor connected in series between said battery and said pacer circuit.

3. A battery-operated implantable pacer as defined in claim 2 wherein said oscillator means comprise a voltage controlled oscillator responsive to the voltage developed across said resistor for developing said pulses at a rate proportional to said voltage.

4. A battery-operated pacer as defined in claim 1 wherein said individual counter elements provide only a predetermined most-significant portion of the total count capacity of said counter.

5. A battery-operated implantable pacer as defined in claim 1 including an over-current alarm responsive to said demand signal for providing an alarm to the patient upon the current drawn from said battery exceeding a predetermined maximum level.