Pacemaker with automatic sensitivity adjustment
First Claim
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1. An implantable cardiac pacemaker for pacing a patient as a function of sensed cardiac signals from said patient'"'"'s heart, comprising:
- stimulus means for delivering stimulus pulses to said patient'"'"'s heart;
sensing means for sensing said patient cardiac signals, said sensing means having measure means for determining a measure of the magnitude of sensed signals, comparing means for comparing each said determined measure to a variable reference and for recognizing a sense when said measure is greater than said reference, and means for adjusting said reference as a function of said comparing; and
control means for controlling said stimulus means as a function of said recognized senses.
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Abstract
There is provided a pacemaker having automatic adjustment of the sensitivity for sensing cardiac signals such as QRS, T and P waves. The pacemaker has software for examining each inputted signal, obtaining a measure of the peak amplitude, e.g. one-half, comparing such measure with a stored software sensitivity level, and adjusting the software sensitivity level each beat so that it effectively tracks beat-to-beat changes in the signal amplitude. The adjusted software sensitivity level is used for determining when an input signal is to be accepted as a true signal, or rejected.
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Citations
20 Claims
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1. An implantable cardiac pacemaker for pacing a patient as a function of sensed cardiac signals from said patient'"'"'s heart, comprising:
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stimulus means for delivering stimulus pulses to said patient'"'"'s heart; sensing means for sensing said patient cardiac signals, said sensing means having measure means for determining a measure of the magnitude of sensed signals, comparing means for comparing each said determined measure to a variable reference and for recognizing a sense when said measure is greater than said reference, and means for adjusting said reference as a function of said comparing; and control means for controlling said stimulus means as a function of said recognized senses. - View Dependent Claims (2, 3, 4)
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5. A system in an implantable pacemaker for sensing patient cardiac signals and automatically adjusting the sensitivity level for accepting a signal as a true cardiac signal, comprising:
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sense means for sensing said cardiac signals having a peak magnitude above a predetermined level;
measure means for obtaining a measure of the peak value of each said sensed signal;sensitivity means for providing a variable sensitivity level, said sensitivity means having a software routine for adjusting said variable sensitivity level as a function of each said sensed software means having means for comparing said peak value measure with said sensitivity level, and adjusting means for adjusting said sensitivity level as a function of said comparison signal. - View Dependent Claims (6, 7, 8, 9)
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10. A method of automatically setting the sense sensitivity level of a pacemaker to a level related to the peak amplitude of periodic input signals being sensed, comprising:
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comparing each said input signal to a predetermined minimum reference level and providing a trigger signal each time said input signal is greater than said reference level; converting said input signal to a digital signal in response to a said trigger signal and determining the peak value of said digital signal; maintaining by software a software sensitivity level; comparing each said peak value with said sensitivity level, and indicating a sensed signal only when said peak value exceeds said sensitivity level; and said maintaining including adjusting said sensitivity level following each said trigger signal so that said sensitivity level is varied as a function of said peak value and the prior maintained sensitivity level. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification