Pacemaker with optimized rate responsiveness and method of rate control
First Claim
1. A pacing system having rate controllable pulse generator means for generating pacing pulses, first sensor means for developing first signals indicating a first pacing rate, second sensor means for developing second signals indicating a second pacing rate, and rate control means for determining desired pacing rate and controlling the rate of said pulse generator means, said rate means further comprising algorithm means for determining (a) from each of said first and second sensor means signals a respective indicated direction of rate change and amount of rate change, and (b) for determining said desired pacing rate as a function of said directions and amounts.
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Accused Products
Abstract
A pacemaker system is provided for rate responsive pacing, wherein rate is controlled as a function of two or more sensor inputs, each sensor providing a signal representing a respective different control parameter. Preferably a first sensor signal represents a physiologically accurate although slow response signal such as OT interval, and a second sensor represents a relatively fast response such as activity. The two parameter signals are processed so that they are directly comparable and can be compared as indicators of pacing rate throughout the desired pacing range. The algorithm utilizes a parameter control reference curve for each respective parameter, such reference curve representing the desired correlation between pacing rate and the parameter signal. Rate control is accomplished by determining the difference between each processed parameter signal and its corresponding reference point for the current pacing interval, and logically analyzing the two differences to determine which is used to indicate change in pacing rate. Each parameter reference curve is automatically adjustable to correspond to patient conditions. Automatic drift correction of the fast response parameter, such as activity, is used to compensate for conditions where the fast response signal is not likely to be physiologically reflective of the patient condition.
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Citations
49 Claims
- 1. A pacing system having rate controllable pulse generator means for generating pacing pulses, first sensor means for developing first signals indicating a first pacing rate, second sensor means for developing second signals indicating a second pacing rate, and rate control means for determining desired pacing rate and controlling the rate of said pulse generator means, said rate means further comprising algorithm means for determining (a) from each of said first and second sensor means signals a respective indicated direction of rate change and amount of rate change, and (b) for determining said desired pacing rate as a function of said directions and amounts.
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12. A pacemaker system adapted for implantation in the body of a patient, comprising:
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pulse generator means adapted to be rate controlled for generating pacing stimulus pulses; at least first and second sensor means for generating respective first and second pacing rate signals correlative of desired pacing rates; indicator means for deriving from each of said pacing rate signals an indication for direction of desired change of pacing rate and an indication of amount of desired change of pacing rate; rate determining means for determining pacing rate as a predetermined function of said direction and amount indications of each respective sensor means; and rate control means for controlling said pulse generator means in accordance with said determined pacing rate.
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13. A method of pacing utilizing a rate responsive pacing system adapted to provide stimulus pulses to a patient'"'"'s heart at a rate within a predetermined range which is responsive to one or both of a first physiological control parameter and a second fast response control parameter, said system having means for periodically obtaining signals reflective of said control parameters and correlating means for correlating each parameter to a respective indication of desired pacing rate, comprising:
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a) correlating one of said parameter signals so as to adjust its influence relative to the other control parameter signal, whereby pacing rate is primarily determined by said first parameter signal; and b) comparing said respective pacing rate indications and determining pacing rate as a function of said comparison each pacing cycle. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A pacing system having pulse generator means for delivering stimulus pulses and rate adjusting means for adjusting the rate of delivery of said stimulus pulses, slow physiological sensor means for generating a relatively slow response signal representative of desired physiological pacing rate and at least a second fast sensor means for generating a fast response signal having a faster response than said physiological signal to changing patient circumstances such as activity and the like and which is representative of pacing rate, said pacing system being characterized by:
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slow means for deriving a physiological rate indication from said slow signal; fast means for deriving a fast rate indication from said fast signal; means for comparing said physiological and fast rate indications; means for determining a rate factor as a function of said comparing; means for determining desired pacing rate as said physiological rate indication modified by said rate factor; and means for causing said rate factor to move in a direction so as to reduce its modifying effect. - View Dependent Claims (22, 23)
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24. A pacemaker system adapted to continuously vary the rate of generated pacing pulses as a function of sensed patient conditions, and having at least first and second sensors for obtaining signal indications of pacing rate, said sensors having relatively high and low respective rates of response to changing patient conditions, the system having rate determining means characterized by:
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reference means for determining a sensor rate reference for each of said sensors corresponding to each pacing interval at which stimulus pulses are generated; difference means for determining a difference value for each sensor for each pacing interval, each said difference value reflecting the signal of each said sensor compared to the corresponding sensor rate reference for the prior interval; comparing rate means for comparing the difference values of each of said sensors; and rate means for determining rate change as a function of said comparison of difference values. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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31. A pacemaker system adapted to continuously vary the rate of generated pacing pulses as a function of sensed patient conditions, having rate means for controlling pacing rate over a predetermined range of rates in response to a determination of rate change, said means for controlling comprising:
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first means for developing a first indicator of pacing rate based on a first sensed parameter; second means for developing a second indicator of pacing rate based on a second sensed parameter which is a relatively faster-response parameter compared to said first parameter; said second means having conversion means for converting said second indicator so that it has a proportionately lesser influence relative to said first indicator; and algorithm means for comparing said first indicator and said converted second indicator and for determining change in pacing rate as function of said comparing. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A pacemaker having pulse generator means for delivering stimulus pulses and rate adjusting means for adjusting the rate of delivery of said pulses, first sensor means for generating a first response signal representative of desired pacing rate and at least a second sensor means for generating a second response signal representative of the desired pacing rate, said pacemaker being characterized by:
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a) first rate means for deriving a first rate change indication from said first response signal;
second rate means for deriving a second rate change indication from said second response signal; andb) algorithm means operative each pacing cycle for comparing said rate change indications and for selecting one of said rate change indications, and rate means for incrementing or decrementing rate as a predetermined function of said selected rate indication. - View Dependent Claims (42, 43)
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44. A pacing system having pulse generator means for delivering stimulus pulses and rate adjusting means for adjusting the rate of delivery of said stimulus pulses, first sensor means for generating a first signal representative of a first desired pacing rate and at least a second sensor means for generating a second signal representative of a second pacing rate, said pacing system being characterized by:
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first rate indication means for deriving a first rate indication from said first signal; second rate indication means for deriving a second rate indication from said second signal; said rate adjusting means having comparing means for comparing said first rate indication and said second rate indication to provide a rate control signal for control of said rate adjusting; and drift means for changing said second rate indication in a direction to reduce its influence relative to said first rate indication in said comparison. - View Dependent Claims (45, 46, 47, 48)
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49. A pacemaker system having means for providing stimulus pulses to a patient'"'"'s heart at a rate which is responsive to one or both of a first physiological parameter and a second relatively faster-response parameter, said system having sensor means for obtaining signals reflective of said parameters and correlation means for correlating each of said parameters with a respective correlation function to respective first and second indications of pacing rate, said correlation means further comprising influence means for setting the influence of said parameter signals relative to each other so that pacing rate is primarily determined by said physiological signal, and having comparing means for comparing said first and second pacing rate indications and means for determining pacing rate as a function of said comparison.
Specification