Method and apparatus for optimization and assessment of response to extra-systolic stimulation (ESS) therapy

• US 7,970,466 B2
• Filed: 10/07/2003
• Issued: 06/28/2011
• Est. Priority Date: 10/07/2003
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Sheth, Nirav V., Mulligan, Lawrence J., Burnes, John E., Deno, D. Curtis
• Primary Examiner(s): Patel; Niketa
• Assistant Examiner(s): Lavert; Nicole F
• Application Number:
  US10/680,494
• Publication Number:
  US 20050075675A1
• Time in Patent Office: 2,821 Days
• Field of Search: 607/9, 607/23, 607 18- 19, 128/419, 600/510
• 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 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: A61N 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone

Abstract

A method and apparatus for optimizing and assessing the response to extra-systolic stimulation (ESS) are provided. An optimization/monitoring parameter is calculated as a function of potentiation ratio, PR, and recirculation fraction, RF, derived from measurements of myocardial contractile function during and after ESS. PR may be computed as the ratio of the contractile function on post-extra-systolic beats during ESS to baseline contractile function. RF may be computed as the slope of a linear regression performed on a plot of the contractile function for a post-extra-systolic beat versus the contractile function for the previous post-extra-systolic beat after ESS is ceased. The ESI resulting in a maximum optimization/monitoring parameter, preferably computed as the product of PR and RF, is determined as the optimal ESI. The operating ESI may be automatically adjusted, and/or PR and RF data may be stored for monitoring purposes.

Claims

1. A method of optimizing delivery of an extra-systolic stimulation (ESS) therapy for a plurality of extra-systolic intervals (ESIs), comprising:

setting a test ESI for delivery of an ESS therapy;

applying the ESS therapy at the test ESI;

determining a potentiation ratio (PR) and a recirculation fraction (RF);

storing the previously determined PR and RF with the test ESI;

incrementing or decrementing the test ESI to a new value test ESI within a predetermined range of values and repeating the first four steps, wherein the new value test ESI is substituted for the test ESI;

calculating a product of RF and PR for each test ESI;

determining an optimal ESI that corresponds to a maximal product of RF and PR; and

setting an operating ESI to the optimal ESI.

2. A method according to claim 1, further comprising performing the ESS therapy delivery in an implantable pulse generator.

3. Previously presented) A method according to claim 1, wherein determining PR and RF comprises deriving a contractile function from an output signal from a mechanical sensor.

4. A method according to claim 3, wherein the mechanical sensor comprises an accelerometer.

5. A method according to claim 4, further comprising disposing an accelerometer in mechanical communication with a ventricle.

6. A method according to claim 1, wherein determining PR and RF comprises deriving a contractile function from an output signal from a mechanical sensor disposed in fluid communication with a ventricle.

7. A method according to claim 6, wherein the mechanical sensor comprises a fluidic pressure sensor.

8. A method according to claim 7, further comprising disposing a fluidic pressure sensor in fluid communication with a right ventricle.

9. A method of optimizing delivery of an extra-systolic stimulation (ESS) therapy for a given extra-systolic interval (ESI), comprising:

determining a baseline contractile function parameter when an ESS therapy is withheld or not delivered for a sufficient time or number of cardiac cycles for any related hemodynamic enhancement to substantially cease;

delivering the ESS therapy for an interval of time or for a number of cardiac cycles;

calculating an ESS therapy contractile function parameter during the delivery of the ESS therapy;

calculating a potentiation ratio (PR) based on the baseline contractile function parameter and the ESS therapy contractile function parameter;

ceasing delivery of the ESS therapy;

determining a recirculation fraction (RF) for several cardiac cycles following the ceasing delivery of the ESS therapy; and

calculating a product of PR and RF.

10. A method according to claim 9, further comprising performing the ESS therapy delivery in an implantable pulse generator.

11. A method according to claim 9, wherein determining PR and RF comprises deriving a contractile function from an output signal from a mechanical sensor.

12. A method according to claim 11, wherein the mechanical sensor comprises an accelerometer.

13. A method according to claim 12, further comprising disposing an accelerometer in mechanical communication with a ventricle.

14. A method according to claim 9, wherein determining PR and RF comprises deriving a contractile function from an output signal from a mechanical sensor disposed in fluid communication with a ventricle.

15. A method according to claim 14, wherein the mechanical sensor comprises a fluidic pressure sensor.

16. A method according to claim 15, further comprising disposing a fluidic pressure sensor in fluid communication with a right ventricle.

17. A method according to claim 9, wherein determining the PR and RF further comprises deriving a contractile function from an output signal from a physiologic sensor, said physiologic sensor comprising a one of:

a saturated oxygen sensor, a lactate sensor, a glucose sensor.

18. A computer readable non-transitory storage medium for storing instructions for optimizing delivery of an extra-systolic stimulation (ESS) therapy for a plurality of extra-systolic intervals (ESIs) comprising:

instructions for setting a test ESI;

instructions for determining a potentiation ratio (PR) and a recirculation fraction (RF);

instructions for storing the previously determined PR and RF with the test ESI;

instructions for incrementing or decrementing the test ESI to a new value within a predetermined range of values and repeating the first three steps;

instructions for calculating a product of RF and PR for east test ESI;

instructions for determining an optimal ESI that corresponds to a maximal product of RF and PR; and

instructions for setting an operating ESI to the optimal ESI.

19. An apparatus for optimizing delivery of an extra-systolic stimulation (ESS) therapy for a plurality of extra-systolic intervals (ESIs), comprising:

means for setting a test ESI;

means for determining a potentiation ratio (PR) and a recirculation fraction (RF);

means for storing the previously determined PR and RF with the test ESI;

means for incrementing or decrementing the test ESI to a new value within a predetermined range of values and repeating the first three steps;

means for calculating a dot product of RF and PR for each test ESI;

means for determining an optimal ESI that corresponds to a maximal product of RF and PR; and

means for setting an operating ESI to the optimal ESI.

20. A method of monitoring the delivery of an extra-systolic stimulation (ESS) therapy during continuous delivery of the ESS therapy, comprising:

setting an extra systolic interval (ESI) to a test setting;

delivering the ESS therapy at the test setting for a number of cardiac cycles;

calculating an ESS therapy contractile function parameter during the delivery of the ESS therapy at the test setting;

adjusting the ESI to a next test setting;

delivering the ESS therapy at the next test setting for a number of cardiac cycles;

calculating the ESS therapy contractile function parameter for the next test setting during the delivery of the ESS therapy at the next test setting;

calculating a potentiation ratio parameter for the next test setting based on the first test setting contractile function parameter and the next test setting contractile function parameter;

adjusting the next test setting by a predetermined increment beat-by-beat for a number of cardiac cycles up to a maximum ESI,

calculating the ESS therapy contractile function parameter for each beat immediately subsequent to the adjusted next test setting; and

determining a recirculation fraction parameter in response to the ESS therapy contractile function parameters calculated for each beat corresponding to each of the adjusted next test settings;

setting the ESI to a second next test setting and calculating a potentiation ratio parameter and a recirculation fraction parameter for the second next test setting; and

determining an optimal ESI in response to a maximal product of the potentiation ratio parameter and the recirculation fraction parameter calculated for the next test setting and the second next test setting.