Cardiac signal sensing device having sensitivity automatically controlled in response to metabolic demand
First Claim
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1. A patient heartbeat sensing apparatus comprising:
- first means for measuring a physiological parameter of the patient and for providing an output signal which is responsive to the patient'"'"'s metabolic demand as indicated by the measured parameter;
second means for sensing a signal which is responsive to cardiac activity and noise;
third means, having an adjustable sensitivity, for operating on said cardiac activity and noise signal, to determine therefrom the occurrence of a natural heartbeat; and
fourth means for adjusting the sensitivity of said third means in response to said metabolic demand output signal, being responsive to increases in the patient'"'"'s metabolic demand by increasing said sensitivity, and being responsive to decreases in the patient'"'"'s metabolic demand by decreasing said sensitivity.
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Abstract
A pacemaker automatically adjusts sensitivity as a function of metabolic demand. The amplitude of cardiac signals is naturally reduced during exercise. The pacemaker measures a physiological parameter to determine the patient'"'"'s metabolic demand. In response to increases in the patient'"'"'s metabolic demand the sensitivity is increased and in response to decreases in the patient'"'"'s metabolic demand the sensitivity is decreased.
234 Citations
16 Claims
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1. A patient heartbeat sensing apparatus comprising:
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first means for measuring a physiological parameter of the patient and for providing an output signal which is responsive to the patient'"'"'s metabolic demand as indicated by the measured parameter; second means for sensing a signal which is responsive to cardiac activity and noise; third means, having an adjustable sensitivity, for operating on said cardiac activity and noise signal, to determine therefrom the occurrence of a natural heartbeat; and fourth means for adjusting the sensitivity of said third means in response to said metabolic demand output signal, being responsive to increases in the patient'"'"'s metabolic demand by increasing said sensitivity, and being responsive to decreases in the patient'"'"'s metabolic demand by decreasing said sensitivity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of operating a patient heartbeat sensing apparatus, comprising:
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measuring a physiological parametr of the patient which is representative of the metabolic demand of the patient; sensing a signal which is representative of the cardiac electrical activity of the patient; adjusting the sensitivity of the apparatus to said sensed cardiac signal; (i) by increasing said sensitivity in response to a measured increase in said metabolic demand, and (ii) by decreasing said sensitivity in response to a measured decrease in said metabolic demand. - View Dependent Claims (16)
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Specification