Temperature responsive controller for cardiac pacer
First Claim
1. A cardiac pacemaker adapted to vary its pacing rate according to the physiological state of the pacemaker patient, comprising:
- means for detecting the patient'"'"'s central venous blood temperature; and
means responsive to the detected blood temperature for adjusting the pacing rate according to predetermined relationships between blood temperature and desired heart rate including non-exercise related and exercise related terms that depend upon variations in the blood temperature relative to a respective reference temperature, said adjusting means including means for determining a moving dynamic reference temperature that establishes a moving temperature reference value from which to measure the current change in blood temperature indicative of the metabolic need and means to adequately adjust the pacing rate accordingly.
4 Assignments
0 Petitions
Accused Products
Abstract
A controller for variably controlling the pacing rate of a cardiac pacer responsive to temperature which includes a logic and control unit, a parameter communication unit, an analog to digital converter and a temperature sensor. The temperature sensor in the right ventricle or atrium communicates a value related to blood temperature through the analog to digital converter to the logic and control unit. The logic and control unit operates under control of the rate algorithm to calculate a pacing rate value related to variations in the blood temperature. The pacing rate value is calculated as the sum of a reference rate, a natural rate response term, and a dynamic rate response term which contributes rate only in response to physical activity. A step rate response is also added to the calculated pacing rate when predetermined criteria related to the blood temperature and calculated pacing rate indicate the onset of physical activity. Under the control of the rate algorithm, the controller also maintains the level and rate of change of the calculated pacing rate within predetermined limits, and prevents the pacing rate from remaining at the maximum rate limit after physical activity has ceased.
-
Citations
45 Claims
-
1. A cardiac pacemaker adapted to vary its pacing rate according to the physiological state of the pacemaker patient, comprising:
-
means for detecting the patient'"'"'s central venous blood temperature; and means responsive to the detected blood temperature for adjusting the pacing rate according to predetermined relationships between blood temperature and desired heart rate including non-exercise related and exercise related terms that depend upon variations in the blood temperature relative to a respective reference temperature, said adjusting means including means for determining a moving dynamic reference temperature that establishes a moving temperature reference value from which to measure the current change in blood temperature indicative of the metabolic need and means to adequately adjust the pacing rate accordingly. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A cardiac pacemaker having a stimulation rate which is adjusted according to variations of the blood temperature of the patient, comprising:
-
means for measuring the blood temperature; means responsive to measurement of the blood temperature to detect a drop thereof for determining whether said detected temperature drop is indicative of the onset of exercise by the patient, said determining means being adapted to make said determination by applying criteria from the group consisting of (i) the relative difference between the value of the detected blood temperature and the value of a predetermined reference temperature, (ii) whether said relative difference has been less than a preselected value over a predetermined interval, (iii) the magnitude of the detected temperature drop, (iv) the rate of variation of the detected temperature drop, and (v) the present stimulation rate relative to a preselected reference rate; and means responsive to a determination that the detected temperature drop is indicative of the onset of exercise for generating a stepped up stimulation rate. - View Dependent Claims (10, 11, 12)
-
-
13. A stimulus generator for variably controlling the stimulation rate of a cardiac pacer according to variations of the patient'"'"'s blood temperature, comprising:
-
means for sensing the blood temperature; means for determining a moving dynamic variable reference temperature having an instantaneous value related to variations of the sensed blood temperature relative to a preselected rate of variation of the blood temperature; means responsive to the sensed blood temperature and to the relative value of the determined dynamic reference temperature for calculating a dynamic hear rate response related to variations in said sensed blood temperature relative to said dynamic reference temperature attributable to exercise by the patient; and means for combining said dynamic heart rate response with a predetermined bas rate to obtain a desired stimulation rate for said stimulus generator. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
-
-
25. A pulse generator controller for variably controlling the pacing rate of a cardiac pacer, comprising:
-
means for detecting the central venous blood temperature of the pacer patient; means for calculating components of the desired pacing rate related to the detected blood temperature, a moving dynamic reference temperature having a changing value dependent on rate of variation of the detected blood temperature relative to a preselected rate of variation, and a static reference temperature, said components consisting of (i) a predetermined reference rate related to a baseline value of the blood temperature, (ii) a natural rate response related to variations of the blood temperature with the patient'"'"'s circadian rhythm and other non-exercise phenomena relative to the static reference temperature, (iii) a dynamic rate response related to variations of the blood temperature with patient exercise relative to the moving dynamic reference temperature, and (iv) a step rate response related to variations of the blood temperature with onset of patient exercise; and means for combining the calculated components to establish a physiologically appropriate pacing rate, with the contributions of components (ii), (iii) and (iv) being based on the recited variations of the blood temperature.
-
-
26. In a stimulus generator for varying the pacing rate of a cardiac pacer according to the physiological state of the patient, wherein said pacer is of the type responsive to variations in the detected blood temperature with respect to a reference temperature, the improvement comprising means for periodically recalculating said reference temperature as a long term weighted average over a selectable interval.
-
27. A method for variably controlling the pacing rate of a cardiac pacer comprising the steps of:
-
detecting the patient'"'"'s central venous blood temperature; determining a moving dynamic reference temperature that establishes a moving temperature reference value from which to measure that current change in blood temperature indicative of the metabolic need and means to adequately adjust the pacing rate accordingly; calculating a dynamic heart rate response related to variations in said detected blood temperature relative to said dynamic reference temperature, attributable to patient exercise; and combining said dynamic rate response with a predetermined base rate to obtain a desired pacing rate. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35)
-
-
36. A stimulus generator for a rate adaptive cardiac pacemaker, comprising
means for detecting a physiological parameter of a pacemaker patient uniquely indicative of either patient exercise or non-exercise, means responsive to said parameter for processing thereof according to a first algorithm in which heart rate is a function of said parameter under conditions of exercise by a healthy person with a normally functioning heart, means responsive to said parameter for processing thereof according to a second algorithm in which heart rate is a function of said parameter under conditions of non-exercise by a healthy person with a normally functioning heart, means for generating electrical stimuli at a controllably variable rate, and means responsive to said detected parameter for selectively combining said first and second algorithms to control the rate at which stimuli are generated by said generating means, said combining means including means for selectively determining the contribution of each of said first and second algorithms to control the stimulation rate.
-
45. An exercise responsive cardiac pacemaker, comprising
means for detecting the commencement and continuation of patient exercise by monitoring the timely course o a physiological parameter, means for generating electrical stimuli at a controllable rate, means responsive to said detection for controlling the rate at which stimuli are generated by said generating means according to a physiological function representing a combination of an initial temporary increase in heart rate from a non-exercise related heart rate at the moment of detection of commencement of exercise, with selectively variable contributions to rate control attributable to exercise related and non-exercise related components in which heart rate is a function of said physiological parameter in the manner experienced by a healthy person with a normal functioning heart, throughout the detected exercises, and means for selectively varying the contributions of said exercise related and non-exercise related heart rate components to the rate control.
Specification