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Tiered therapy cardiac detection system having a global counter

  • US 5,913,878 A
  • Filed: 02/10/1998
  • Issued: 06/22/1999
  • Est. Priority Date: 02/10/1998
  • Status: Expired due to Fees
First Claim
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1. A medical device having tiered therapy cardiac detection system, the medical device comprising:

  • the detection system comprising;

    a sensing system that senses cardiac signals representative of beat-to-beat intervals;

    a therapy delivery system that delivers at least one therapy in response to a detected cardiac dysrhythmia corresponding to one of a plurality of programmed zones of heart rates; and

    a tiered therapy cardiac detection system, includinga global counter that counts at least all beat-to-beat intervals indicating a rate greater than a programmed threshold value which is representative of a minimum heart rate for delivering any therapy once a predetermined initial threshold condition has been met;

    a plurality of window memories, each window memory corresponding to a given one of the plurality of zones and storing at least an indication of whether each of a last N cardiac signals are within that programmed zone of heart rates;

    a plurality of parameter memories, each parameter memory corresponding to a given one of the plurality of zones and storing a programmed trigger value of the global counter required in order for a therapy in that zone to be delivered; and

    processing circuitry that determines whether the predetermined initial threshold condition has been met and, in response, evaluates the global counter, the window memories and the parameter memories on a beat-by-beat basis and indicates that a cardiac dysrhythmia has been detected for a given zone if the global counter exceeds the programmed trigger value for that zone and the indications stored by the window memory for that zone satisfy predetermined criteria.

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