Rate responsive cardiac pacemaker and method for providing an optimized pacing rate which varies with a patient's physiologic demand

• US 5,282,839 A
• Filed: 12/14/1992
• Issued: 02/01/1994
• Est. Priority Date: 12/14/1992
• Status: Expired due to Term

• Current Assignee: Dwight N. Holmbo
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Nichols, Lucy M., Bennett, Tommy D., Thompson, David L., Roline, Glenn M.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US07/949,414
• Time in Patent Office: 414 Days
• Field of Search: 128/419 PG
• US Class Current: 607/19
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters

Abstract

A rate responsive cardiac pacemaker for providing an optimized pacing rate of stimulation pulses as a function of at least one selected rate control parameter. Each rate control parameter has a value which varies as a function of changes in a patient'"'"'s physiologic demand and includes a sensor system for sensing the rate control parameter value and for providing a sensor output representative thereof. The cardiac pacemaker also includes a rate response defining means for deriving desired pacing rates as a function of the sensor output, an achievement monitoring means that has a predetermined achievement criterion (primary criterion), for monitoring the relationship between the derived pacing rates and the achievement criterion over an optimization period, and either one of Average Activity level or Average Activity Difference level monitoring means that has a corresponding predetermined minimum and a predetermined maximum Average Activity level or Average Activity Difference level (secondary criterion), for monitoring the relationship between the derived pacing rates and the secondary criterion over an optimization period. Another optimization function is provided by adjusting a sensor weighting value which weights or regulates the relative contribution each sensor'"'"'s derived desired pacing rates will contribute toward the pacemaker-derived optimized pacing rates.

Claims

1. A rate responsive cardiac pacemaker for providing an optimized pacing rate of stimulation pulses as a function of at least one selected rate control parameter, each of said rate control parameters having a value which varies as a function of changes in a patient'"'"'s physiologic demand, comprising:

(A) sensor means for sensing each of said rate control parameter values and for providing a sensor output representative thereof;

(B) control means coupled to each of said sensor means, comprising;

(1) clocking means for setting an optimization period;

(2) rate response defining means for deriving desired pacing rates for each of said sensor means, each said derived desired pacing rate being increased and decreased as a function of said sensor output corresponding thereto, to define a predetermined rate response function for each of said sensor means, such that for a predetermined change in sensor output for each of said sensor means a corresponding change in said desired pacing rate is provided;

(3) achievement monitoring means having a predetermined achievement criterion reflective of expected levels of exercise of said patient, for each of said sensor means, for monitoring the relationship between each of said derived desired pacing rates and said achievement criterion corresponding thereto over a predetermined optimization period, and for providing an achievement output indicative of each of said monitored relationships;

(4) average activity level monitoring means for monitoring an average activity level for said patient, said average activity level corresponding to each of said derived desired pacing rates, and having a predetermined minimum and maximum average activity level reflective of expected levels of exercise of said patient for each of said sensor means, and for monitoring a relationship between each of said derived desired pacing rates and said average activity level corresponding thereto over a predetermined optimization period, and further for providing an average activity level output indicative of each of said monitored relationships;

(5) output means for generating stimulus pulses at optimized pacing rates as a function of each of said derived desired pacing rates; and

(6) rate response control means for adjusting each of said rate response functions as a function of each of said achievement and said average activity level output corresponding thereto, such that each of said adjusted rate response functions provides an increased or decreased change in desired pacing rate corresponding to said predetermined change in sensor output for each of said sensor means.

2. A rate responsive cardiac pacemaker for providing an optimized pacing rate of stimulation pulses as a function of at least two selected rate control parameters, each of said rate control parameters having a value which varies as a function of changes in a patient'"'"'s physiologic demand, comprising:

(A) sensor means for sensing each of said rate control parameter values and for providing a sensor output representative thereof;

(B) control means coupled to each of said sensor means, comprising;

(1) clocking means for setting an optimization period;

(2) rate response defining means for deriving desired pacing rates for each of said sensor means, each said derived desired pacing rate being increased and decreased as a function of said sensor output corresponding thereto, to define a predetermined rate response function for each of said sensor means, such that for a predetermined change in sensor output for each of said sensor means a corresponding change in said desired pacing rate is provided;

(3) achievement monitoring means having a predetermined achievement criterion reflective of expected levels of exercise of said patient, for each of said sensor means, for monitoring the relationship between each of said derived desired pacing rates and said achievement criterion corresponding thereto over a predetermined optimization period, and for providing an achievement output indicative of each of said monitored relationships;

(4) average activity level monitoring means for monitoring an average activity level for said patient, said average activity level corresponding to each of said derived desired pacing rates, and having a predetermined minimum and maximum average activity level reflective of expected levels of exercise of said patient, for each of said sensor means, and for monitoring a relationship between each of said derived desired pacing rates and said average activity level corresponding thereto over a predetermined optimization period, and further for providing an average activity level output indicative of each of said monitored relationship;

(5) sensor weighting control means, for providing an adjusted sensor weighting value, as a function of each of said achievement and said average activity level outputs; and

(6) output means for generating stimulus pulses at optimized pacing rates derived from said adjusted sensor weighting value and each of said desired pacing rates, said sensor weighting value for weighting the relative contribution which each of said desired pacing rates contribute toward said derived optimized pacing rate.

3. A rate responsive cardiac pacemaker according to claim 2, wherein:

(A) said output means for providing optimized pacing rates as a function of each of said derived desired pacing rates;

(B) said control means further comprises;

(1) rate response control means for adjusting each of said rate response functions as a function of each of said achievement and said average activity level output corresponding thereto, such that each of said adjusted rate response functions provides an increased or decreased change in desired pacing rate corresponding to said predetermined change in sensor output for each of said sensor means; and

(C) wherein, said optimized pacing rates are provided as a function of said adjusted rate response functions and said adjusted sensor weighting value.

4. A rate responsive cardiac pacemaker for providing an optimized pacing rate of stimulation pulses as a function of at least one selected rate control parameter, each of said rate control parameters having a value which varies as a function of changes in a patient'"'"'s physiologic demand, comprising:

(A) sensor means for sensing each of said rate control parameter values and for providing a sensor output representative thereof;

(B) control means coupled to each of said sensor means, comprising;

(1) clocking means for setting an optimization period;

(2) rate response defining means for deriving desired pacing rates for each of said sensor means, each said derived desired pacing rate being increased and decreased as a function of said sensor output corresponding thereto, to define a predetermined rate response function for each of said sensor means, such that for a predetermined change in sensor output for each of said sensor means a corresponding change in said desired pacing rate is provided;

(3) achievement monitoring means having a predetermined achievement criterion reflective of expected levels of exercise of said patient, for each of said sensor means, for monitoring the relationship between each of said derived desired pacing rates and said achievement criterion corresponding thereto over a predetermined optimization period, and for providing an achievement output indicative of each of said monitored relationships;

(4) average activity difference level monitoring means for monitoring an average activity difference level for said patient, said average activity difference level comprising a difference of a long term average activity level and a short term average activity level, said average activity difference level corresponding to each of said derived desired pacing rates, and having a predetermined minimum and maximum average activity difference level reflective of expected levels of exercise of said patient for each of said sensor means, and for monitoring a relationship between each of said derived desired pacing rates and said average activity difference level corresponding thereto over a predetermined optimization period, and further for providing an average activity difference level output indicative of each of said monitored relationships;

(5) output means for generating stimulus pulses at optimized pacing rates as a function of each of said derived desired pacing rates; and

(6) rate response control means for adjusting each of said rate response functions as a function of each of said achievement and said average activity difference level outputs corresponding thereto, such that each of said adjusted rate response functions provides an increased or decreased change in desired pacing rate corresponding to said predetermined change in sensor output for each of said sensor means.

5. A rate responsive cardiac pacemaker for providing an optimized pacing rate of stimulation pulses as a function of at least two selected rate control parameters, each of said rate control parameters having a value which varies as a function of changes in a patient'"'"'s physiologic demand, comprising:

(A) sensor means for sensing each of said rate control parameter values and for providing a sensor output representative thereof;

(B) control means coupled to each of said sensor means, comprising;

(1) clocking means for setting an optimization period;

(2) rate response defining means for deriving desired pacing rates for each of said sensor means, each said derived desired pacing rate being increased and decreased as a function of said sensor output corresponding thereto, to define a predetermined rate response function for each of said sensor means, such that for a predetermined change in sensor output for each of said sensor means a corresponding change in said desired pacing rate is provided;

(3) achievement monitoring means having a predetermined achievement criterion reflective of expected levels of exercise of said patient, for each of said sensor means, for monitoring the relationship between each of said derived desired pacing rates and said achievement criterion corresponding thereto over a predetermined optimization period, and for providing an achievement output indicative of each of said monitored relationships;

(4) average activity difference level monitoring means for monitoring an average activity difference level for said patient, said average activity difference level comprising a difference of a long term average activity level and a short term average activity level, said average activity difference level corresponding to each of said derived desired pacing rates, and having a predetermined minimum and maximum average activity difference level for each of said sensor means, and for monitoring a relationship between each of said derived desired pacing rates and said average activity difference level corresponding thereto over a predetermined optimization period, and further for providing an average activity difference level output indicative of each of said monitored relationships;

(5) sensor weighting control means, for providing an adjusted sensor weighting value, as a function of each of said achievement and said average activity difference level outputs; and

(6) output means for generating stimulus pulses at optimized pacing rates derived from said adjusted sensor weighting value and each of said desired pacing rates, said sensor weighting value for weighting the relative contribution which each of said desired pacing rates contribute toward said derived optimized pacing rate.

6. A rate responsive cardiac pacemaker according to claim 5, wherein:

(A) said output means further comprises;

(1) output means for providing optimized pacing rates as a function of each of said derived desired pacing rates;

(B) said control means further comprises;

(1) rate response control means for adjusting each of said rate response functions as a function of each of said achievement and said average activity difference level output corresponding thereto, such that each of said adjusted rate response functions provides an increased or decreased change in desired pacing rate corresponding to said predetermined change in sensor output for each of said sensor means; and

(C) wherein, said optimized pacing rates are provided as a function of said adjusted rate response functions and said adjusted sensor weighting value.

7. A method for providing an optimized pacing rate of stimulation pulses in a rate responsive cardiac pacemaker, as a function of at least one selected rate control parameter, said pacemaker having at least one sensor means comprising at least one sensor for sensing each of said rate control parameters, each said rate control parameter having a value which varies as a function of changes in a patient'"'"'s physiologic demand, the method comprising the steps of:

(A) sensing each of said rate control parameter values and providing a sensor output representative thereof;

(B) deriving desired pacing rates for each of said sensor means, each said derived desired pacing rate being increased and decreased as a function of said sensor output corresponding thereto, to define a predetermined rate response function for each of said sensor means, such that for a predetermined change in sensor output a corresponding change in said desired pacing rate is provided;

(C) monitoring a relationship between each of said derived desired pacing rates and achievement criterion corresponding thereto, said achievement criterion being reflective of expected levels of exercise of said patient over a predetermined optimization period, and providing an achievement output indicative of each of said monitored relationships;

(D) monitoring a relationship between each of said derived pacing rates and an average activity level corresponding thereto over a predetermined optimization period, for providing an average activity level output indicative of each of said monitored relationships, wherein each of said average activity levels is reflective of expected levels of exercise of said patient during said optimization period;

(E) providing stimulus pulses at optimized pacing rates as a function of each of said derived desired pacing rates; and

(F) adjusting each of said rate response functions as a function of each of said achievement criterion and said average activity level outputs corresponding thereto, such that each of said adjusted rate response functions provides an increased or decreased change in desired pacing rate corresponding to said predetermined change in sensor output.

8. A method for providing an optimized pacing rate of stimulation pulses in a rate responsive cardiac pacemaker, as a function of at least one selected rate control parameter, said pacemaker having at least one sensor means comprising at least one sensor for sensing each of said rate control parameters, each said rate control parameter having a value which varies as a function of changes in a patient'"'"'s physiologic demand, the method comprising the steps of:

(A) sensing each of said rate control parameter values and providing a sensor output representative thereof;

(B) deriving desired pacing rates for each of said sensor means, each said derived desired pacing rate being increased and decreased as a function of said sensor output corresponding thereto, to define a predetermined rate response function for each of said sensor means, such that for a predetermined change in sensor output a corresponding change in said desired pacing rate is provided;

(C) monitoring a relationship between each of said derived desired pacing rates and achievement criterion corresponding thereto, said achievement criterion being reflective of expected levels of exercise of said patient over a predetermined optimization period, and providing an achievement output indicative of each of said monitored relationships;

(D) monitoring a relationship between each of said derived pacing rates and an average activity difference level corresponding thereto over a predetermined optimization period, for providing an average activity difference level output indicative of each of said monitored relationships, each said average activity difference level comprising a difference of a long term average activity level and a short term activity level, wherein each of said average activity difference levels is reflective of expected levels of exercise of said patient during said optimization period;

(E) providing stimulus pulses at optimized pacing rates as a function of each of said derived desired pacing rates; and

(F) adjusting each of said rate response functions as a function of each of said achievement criterion and said average activity difference level outputs corresponding thereto, such that each of said adjusted rate response functions provides an increased or decreased change in desired pacing rate corresponding to said predetermined change in sensor output.