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Dual chamber cardiac pacing from a single electrode

  • US 5,265,601 A
  • Filed: 05/01/1992
  • Issued: 11/30/1993
  • Est. Priority Date: 05/01/1992
  • Status: Expired due to Term
First Claim
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1. A pacemaker, comprising:

  • a pulse generator, for producing cardiac stimulating pulses;

    a lead, coupled to said pulse generator via a first coupling capacitor, having an electrode on its distal end, said electrode being disposed in a venous channel of a patient'"'"'s heart;

    signal processing circuitry means, coupled to said lead via a second coupling capacitor, for receiving from said lead electrical cardiac signals received by said electrode in said venous channel and said signal processing circuitry filtering and amplifying said cardiac signals to produce a processed cardiac output signal;

    a first sense amplifier, coupled to said signal processing circuitry and receiving said processed cardiac output signal, said first sense amplifier having a first sensitivity threshold voltage such that electrical signals having a voltage level below said first sensitivity threshold are not amplified by said first sense amplifier;

    a second sense amplifier, coupled to said signal processing circuitry and receiving said processed cardiac output signal, said second sense amplifier having a second sensitivity threshold voltage, higher than said first sensitivity threshold voltage, such that electrical signals having a voltage level below said second sensitivity threshold are not amplified by said second sense amplifier;

    logic circuitry, having first and second inputs for receiving first and second input signals, and having first and second outputs for producing first and second output signals, said first and second inputs coupled to said first and second sense amplifiers, respectively;

    such that a processed cardiac output signal which has a voltage which exceeds said first sensitivity threshold voltage but does not exceed said second sensitivity threshold voltage causes said first output signal, and not said second output signal, to be asserted, and such that a processed electrical cardiac signal which has a voltage which exceeds both said first and second sensitivity threshold voltages causes said second output signal and not said first output signal to be asserted;

    said pacemaker further comprising controlling circuitry means, receiving said first and second output signal, for controlling delivery of cardiac pacing pulses, and for causing a cardiac pacing pulse to be delivered from said electrode at a first stimulating energy level if said first output signal is not asserted within a first predetermined time interval following assertion of said second output signal;

    said controlling circuitry means further causing a cardiac pacing pulse to be delivered at a second stimulating energy level, higher than said first stimulating energy level, if said second output signal is not asserted within a second predetermined time interval following assertion of said first output signal.

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