Rate-responsive pacemaker
First Claim
1. A pacemaker comprising:
- sensing means for providing a first signal which changes relatively rapidly in response to changes in a patient'"'"'s exercise level but may inaccurately represent the pacing rate appropriate to said exercise level, and a second signal that changes from a normal condition relatively slowly in response to changes in exercise level but which, after having changed from said normal condition, relatively accurately represents a required pacing rate; and
control means for generating a pacing signal to control pacing rate in response to said sensing means, said pacing signal being operative to provide;
(A) a relatively low pacing rate when said first signal has a value less than a threshold;
(B) a predetermined pacing rate higher than said relatively low pacing rate when the first signal exceeds said threshold and the second signal has a value indicative of a pacing rate less than said predetermined pacing rate; and
(C) a pacing rate substantially equal to that indicated by the value of said second signal when the first signal exceeds said threshold and the second signal indicates a rate higher than said predetermined pacing rate, regardless of the amount by which said first signal may exceed said threshold.
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Accused Products
Abstract
A pacemaker has means for producing first and second signals one of which changes rapidly in response to changes in exercise level but may inaccurately represent the appropriate pacing rate. Such signal may be derived from a vibration sensor. The second signal accurately represents the required pacing rate but changes slowly in response to exercise level and may represent any of a number of different physiological variables, such as respiratory rate. The signals may be derived from the same or separate sensors. A control circuit provides a pacing rate appropriate to resting conditions if the first signal has a value less than a threshold regardless of the value of the second signal. The pacing rate is elevated to a predetermined level, such as 95 beats/min, if the first signal exceeds the threshold but the second signal has a value indicative of a pacing rate less than the predetermined level. The pacing rate is further elevated to substantially equal that indicated by the value of the second signal when the first signal exceeds the threshold and the second signal indicates a rate higher than the predetermined rate.
104 Citations
22 Claims
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1. A pacemaker comprising:
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sensing means for providing a first signal which changes relatively rapidly in response to changes in a patient'"'"'s exercise level but may inaccurately represent the pacing rate appropriate to said exercise level, and a second signal that changes from a normal condition relatively slowly in response to changes in exercise level but which, after having changed from said normal condition, relatively accurately represents a required pacing rate; and control means for generating a pacing signal to control pacing rate in response to said sensing means, said pacing signal being operative to provide; (A) a relatively low pacing rate when said first signal has a value less than a threshold; (B) a predetermined pacing rate higher than said relatively low pacing rate when the first signal exceeds said threshold and the second signal has a value indicative of a pacing rate less than said predetermined pacing rate; and (C) a pacing rate substantially equal to that indicated by the value of said second signal when the first signal exceeds said threshold and the second signal indicates a rate higher than said predetermined pacing rate, regardless of the amount by which said first signal may exceed said threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A pacemaker comprising:
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sensing means for providing a first signal which changes relatively rapidly in response to changes in a patient'"'"'s exercise level but may inaccurately represent the pacing rate appropriate to said exercise level, and a second signal that changes from a normal condition relatively slowly in response to changes in exercise level but which, after having changed from said normal condition, relatively accurately represents a required pacing rate; and control means for generating a pacing signal to control pacing rate in response to said sensing means, said pacing signal being operative to provide; (A) a relatively low pacing rate unless said first signal includes frequency components having an amplitude above a predetermined amplitude and a frequency above a threshold frequency of at least 7 Hz; (B) a predetermined pacing rate higher than said relatively low pacing rate when said first signal includes frequency components having an amplitude above said predetermined amplitude and a frequency above said threshold frequency and the second signal has a value indicative of a pacing rate less than said predetermined rate; and (C) a pacing rate substantially equal to that indicated by the value of said second signal when the first signal exceeds said threshold and the second signal indicates a rate higher than said predetermined pacing rate. - View Dependent Claims (16)
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17. A pacemaker comprising:
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sensing means for providing a first signal which changes relatively rapidly in response to changes in a patient'"'"'s exercise level but may inaccurately represent the pacing rate appropriate to said exercise level, and a second signal that changes from a normal condition relatively slowly in response to changes in exercise level but which, after having changed from said normal condition, relatively accurately represents a required pacing rate; and control means for generating a pacing signal to control pacing rate in response to said sensing means, said pacing signal being operative to define, for said first signal, a single substantially constant threshold value, and to provide; (A) a relatively low pacing rate when said first signal has a value less than said threshold value; (B) a predetermined pacing rate higher than said relatively low rate when the first signal exceeds said threshold value and the second signal has a value indicative of a pacing rate less than said predetermined pacing rate; and (C) a pacing rate substantially equal to that indicated by the value of said second signal when the first signal exceeds said threshold and the second signal indicates a rate higher than said predetermined pacing rate.
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18. A pacemaker comprising:
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sensing means for providing a first signal which changes relatively rapidly in response to changes in a patient'"'"'s exercise level but may inaccurately represent the pacing rate appropriate to said exercise level, and a second signal that changes from a normal condition relatively slowly in response to changes in exercise level but which, after having changed from said normal condition, relatively accurately represents a required pacing rate; and control means for generating a pacing signal to control pacing rate in response to said sensing means, said pacing signal being operative to provide; (A) a relatively low pacing rate when said first signal has a value less than a threshold; (B) a predetermined pacing rate higher than said relatively low rate when the first signal exceeds said threshold and the second signal has a value indicative of a pacing rate less than said predetermined pacing rate; (C) a pacing rate substantially equal to that indicated by the value of said second signal when the first signal exceeds said threshold and the second signal indicates a rate higher than said predetermined pacing rate; and said pacing signal being operative to increase said pacing rate above said predetermined pacing rate solely in response to increase in said second signal. - View Dependent Claims (19, 20, 21)
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22. A pacemaker comprising:
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first sensing means for providing a first signal in response to bodily vibrations arising from a patient'"'"'s activity; second sensing means for providing a second signal which changes in response to a physiological parameter which varies in response to a patient'"'"'s activity; and control means for generating a pacing signal to control pacing rate in response to said first and second sensing means, said pacing signal being operative to define for said first signal a threshold for components of said first signal having a frequency of at least 7 Hz, and to provide; (A) a relatively low pacing rate when said first signal is such that said threshold is not exceeded; (B) a predetermined pacing rate which is from 20 to 30 beats/min higher than said relatively low pacing rate when the first signal is such that said threshold is exceeded and the second signal has a value indicative of a pacing rate less than said predetermined pacing rate; and (C) a pacing rate substantially equal to that indicated by the value of said second signal when the first signal is such that said threshold is exceeded and the second signal indicates a rate higher than said predetermined rate; and said pacing signal being operative to increase said pacing rate above said predetermined pacing rate solely in response to increase in said second signal.
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Specification