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Recognizing ventricular tachycardia condition using dual chamber sense information

  • US 5,978,700 A
  • Filed: 05/06/1998
  • Issued: 11/02/1999
  • Est. Priority Date: 05/07/1997
  • Status: Expired due to Term
First Claim
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1. An apparatus for detecting ventricular tachycardia, comprisingan atrium sensor for sensing electrical activity in an atrium and a ventricle sensor for sensing electrical activity in a ventricle of a heart;

  • a timer for detecting an instant of occurrence of the respective electrical activity;

    a first and second calculation unit, each having an input side connected to the ventricle sensor and the atrium sensor, respectively, and to the timer, for calculating R--R or P--P intervals between successive electrical activities in the ventricle and in the atrium, respectively, and for selectively forming mean R--R and mean P--P interval values over a predetermined period of time or a predetermined number of calculated R--R and P--P intervals, respectively;

    a threshold memory for storing at least one threshold value for the R--R intervals or mean R--R interval values;

    a first comparator unit, connected to the outputs of the first calculation unit and of the threshold value memory, for comparing the R--R intervals or mean R--R interval values with the at least one threshold value and for outputting a first classification signal characterizing the outcome of the comparison;

    first and second interval memory units, connected to the output of the first and second calculation units, respectively, for storing a predetermined number of respective calculated R--R or P--P intervals, or mean R--R or mean P--P interval values in memory;

    second comparator unit, connected to the output of one of (a) the first and second calculation units and (b) the first and second interval memory units, for comparing the P--P intervals with the R--R intervals and for outputting a second classification signal characterizing the outcome of the comparison;

    a third and fourth calculation unit, connected to the output of at least one of (a) the first and second calculation units and (b) the first and second interval memory units, respectively, for calculating a change over time between successive R--R and P--P intervals or the mean R--R and mean P--P interval values,first and second criterion memories for storing, respectively, a predetermined stability criterion for the change over time between successive R--R and P--P intervals or mean R--R and mean P--P interval values; and

    a third and fourth comparator unit, each having an input side connected to the output of the third and fourth calculation units, respectively, and to the first and second criterion memories, respectively, for comparing the calculated change over time in the R--R or P--P intervals with an associated stability criterion stored in the respective criterion memory and for outputting a third and fourth classification signal characterizing the outcome of the comparison.

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