Estimate of efficiency using acceleration-heart rate ratio

• US 6,459,934 B1
• Filed: 07/21/2000
• Issued: 10/01/2002
• Est. Priority Date: 07/21/2000
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Kadhiresan, Veerichetty
• Primary Examiner(s): Schaetzle, Kennedy
• Assistant Examiner(s): DROESCH, KRISTEN L
• Application Number:
  US09/621,389
• Time in Patent Office: 802 Days
• Field of Search: 600/508-510, 600/513, 600/519-520, 600/483, 600/526, 600/587, 607/3, 607/9, 607/17-19
• US Class Current: 607/9
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371

Abstract

A method for estimating the efficiency of a patient'"'"'s body, and specifically for estimating the efficiency of a patient'"'"'s body while undergoing different cardiac therapies. Acceleration and heart rates of the patient are measured while undergoing various therapies. The acceleration—heart rate ratio for each therapy is calculated. The ratios for each therapy are compared and the therapy that has the highest acceleration—heart rate ratio is determined to be the most efficient. The most efficient therapy allows the patient to have the most acceleration with the lowest corresponding heart rate.

Claims

1. An apparatus for carrying out the method of determining the best cardiac therapy for a patient, comprising a cardiac rhythm management device having:

(a) means for measuring acceleration due to body movement of the patient and producing an electrical signal proportional thereto;

(b) means for measuring heart rate of the patient and producing an electrical signal proportional thereto;

(c) means for storing the acceleration and heart rate measurements;

(d) means for calculating average values of acceleration and heart rate and ratios of acceleration to heart rate;

(e) means for comparing the values and the ratios from different cardiac therapies and determining which therapy is the best for the patient; and

(f) means for displaying the values and the ratios.

2. The apparatus as defined in claim 1 wherein the means for measuring heart rate comprises electrodes on a pacing lead of said cardiac rhythm management device.

3. The apparatus defined in claim 1 wherein the means for measuring acceleration due to body movement is an accelerometer.

4. The apparatus as defined in claim 1 wherein the means for displaying values is a monitor.

5. The apparatus as defined in claim 1 wherein the means for storing, computing and comparing is a microprocessor.

6. The apparatus as defined in claim 5 and further comprising a pulse generator in an implantable cardiac rhythm management device that is signaled by the microprocessor to generate pulses at a determined rate.

17. The method as defined in claim 6 wherein said cardiac rhythm management device includes a closed loop switch that is enabled after the acceleration—

heart rate ratios have been compared and said closed loop switch chooses and automatically programs the therapy with the highest acceleration—

heart ratio.

7. An apparatus for carrying out the method of determining the best cardiac therapy for a patient, comprising:

(a) a pacing lead with at least one electrode for sensing heart rate and that outputs a proportional signal;

(b) a pulse generator that connects to said pacing lead and controls pacing of heart in the patient;

(c) an accelerometer that detects acceleration due to body movement of the patient and outputs a proportional signal;

(d) a microprocessor that connects to and controls said pulse generator, that connects to said accelerometer and receives a signal from said accelerometer, and that computes an efficiency index from heart rate and acceleration values for each therapy performed on the patient, and that is able to choose the best cardiac therapy, which is the one with the highest efficiency index, and that is able to signal said pulse generator to pace the heart of the patient with the best cardiac therapy.

8. The apparatus as defined in claim 7, and further comprising a monitor that is connected to said microprocessor and that displays heart rate and acceleration values and efficiency indexes for therapies that are tested on the patient.

9. A method of estimating efficiency of a patient'"'"'s body, comprising the steps of:

(a) measuring acceleration due to body movement and heartrate of a patient while a first therapy is being administered;

(b) determining a first efficiency index based on a relationship between said heartrate and acceleration values determined in step (a);

(c) measuring acceleration due to body movement and heartrate of the patient while a second therapy is being administered;

(d) determining a second efficiency index based on a relationship between said heartrate and said acceleration values determined in step (c); and

(e) selecting one of the first or second therapies based upon a comparison of said first and second efficiency indices.

10. A method of estimating efficiency of a patient'"'"'s body, comprising the steps of:

(a) defining a measuring period in which acceleration due to body movement and heartrate of a patient are measured;

(b) measuring acceleration due to body movement and heartrate of a patient for a plurality of predetermined time periods less than the defined measuring period within the defined measuring period;

(c) determining an efficiency index based on a relationship between the heartrate and acceleration values for each of the plurality of predetermined time periods; and

(d) computing an average of the efficiency indices determined during each of the plurality of predetermined time periods to determine an average efficiency index for the defined measuring period.

11. The method of estimating efficiency as in either of claim 9 or 10 and further comprising the step of outputting the efficiency index.

12. The method of estimating efficiency as in claim 11, wherein said outputting includes storing the efficiency index in a memory for later readout.

13. The method of estimating efficiency as in claim 11, wherein said outputting includes displaying the efficiency index in graph form.

14. The method as defined in claim 11, wherein said outputting includes displaying the efficiency index in table form.

15. A method for determining the best cardiac therapy for a patient, comprising the steps of:

(a) establishing a monitoring protocol defining;

(i) types of therapies that are to be tested on the patient;

(ii) number of therapies that are to be tested on the patient, and

(iii) a time period during which each therapy is to be tested on the patient;

(b) measuring values of acceleration due to body movement and heart rate of the patient during the defined time period of each of the defined therapies;

(c) calculating an average acceleration—

heart rate ratio for each of the defined therapies;

(d) comparing the average acceleration—

heart rate ratios of the defined therapies; and

(e) determining which of the defined therapies is the best, with the best therapy being the one with the highest average acceleration—

heart rate ratio.

16. A method for determining the best cardiac therapy for a patient, said method comprising the steps of:

(a) providing a cardiac rhythm management device having a programmable microprocessor with a program defining a monitoring protocol including;

(i) types of cardiac pacing therapies that are to be tested on the patient;

(ii) a total time period during which the best cardiac therapy for the patient will be determined;

(iii) a plurality of first time periods within said total time period in which the pacing therapies are to be tested on the patient;

(iv) a plurality of wash-out periods between said first time periods in which no said pacing therapies are tested;

(v) a plurality of second time periods within said first time periods in which values of acceleration due to patient body movement and heart rate will be measured;

(b) measuring and storing average acceleration and heart rate values for each second time period within the first time period of a given pacing therapy;

(c) calculating and storing acceleration—

heart rate ratio and resting heart rate value for each second time period during said given pacing therapy;

(d) repeating steps (b) and (c) for said given pacing therapy until said first time period has elapsed;

(e) calculating and storing average acceleration—

heart rate ratio and average resting heart rate for said given pacing therapy;

(f) running the wash-out period after said given pacing therapy is tested;

(g) repeating steps (b), (c), (d), (e) and (f) for each pacing therapy that is to be tested;

(h) comparing the average acceleration—

heart rate ratios and resting heart rate values from the pacing therapies that were tested; and

(i) determining the best pacing therapy for the patient, which is the one with the highest average acceleration—

heart rate ratio.