MEASUREMENT OF CARDIAC CYCLE LENGTH AND PRESSURE METRICS FROM PULMONARY ARTERIAL PRESSURE

• US 20120277600A1
• Filed: 04/28/2011
• Published: 11/01/2012
• Est. Priority Date: 04/28/2011
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Greenhut, Saul E.
• Granted Patent: US 9,314,205 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/6869 Heart
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: A61N 1/36564 controlled by blood pressure

Abstract

A method and apparatus for monitoring a cardiovascular pressure signal in a medical device that includes determining whether the sensed pressure signal is greater than a first pressure threshold, determining a first metric of the pressure signal in response to the sensed pressure signal being greater than the first pressure threshold, determining whether the sensed pressure signal is greater than a second pressure threshold not equal to the first pressure threshold, determining a second metric of the pressure signal in response to the sensed pressure signal being greater than the first pressure threshold, and determining at least one of a systolic pressure or a diastolic pressure, wherein the at least one of a systolic pressure or a diastolic pressure is determined based on the first metric in response to the pressure signal not being greater than the second threshold, and based on the second metric in response to the pressure signal being greater than the second threshold.

Claims

1. A method of monitoring a cardiovascular pressure signal in a medical device, comprising:

sensing the cardiovascular pressure signal;

determining whether the sensed pressure signal is greater than a first pressure threshold;

determining a first metric of the pressure signal in response to the sensed pressure signal being greater than the first pressure threshold;

determining whether the sensed pressure signal is greater than a second pressure threshold not equal to the first pressure threshold;

determining a second metric of the pressure signal in response to the sensed pressure signal being greater than the first pressure threshold; and

determining at least one of a systolic pressure or a diastolic pressure, wherein the at least one of a systolic pressure or a diastolic pressure is determined based on the first metric in response to the pressure signal not being greater than the second threshold, and based on the second metric in response to the pressure signal being greater than the second threshold.

2. The method of claim 1, further comprising controlling delivery of at least one of electrical stimulation and a therapeutic agent in response to the determined at least one of a systolic pressure or a diastolic pressure.

3. The method of claim 1, wherein the second pressure threshold is equal to the determined first metric of the pressure signal.

4. The method of claim 1, wherein the first metric and the second metric of the pressure signal corresponds to a maximum value of a derivative signal of the pressure signal.

5. The method of claim 1, wherein determining at least one of a systolic pressure or a diastolic pressure comprises:

setting a time window extending from a point prior to one of determining the sensed pressure signal being greater than the first threshold and determining the sensed pressure signal being greater than the second threshold to a corresponding one of the first metric and the second metric;

determining a third metric of a derivative signal of the sensed pressure signal occurring during the time window; and

determining a value of the sensed pressure signal corresponding to the third metric as the diastolic pressure.

6. The method of claim 5, wherein the first metric and the second metric correspond to a maximum of a first derivative signal corresponding to the sensed pressure signal, and the third metric corresponds to a maximum of a second derivative signal corresponding to the sensed pressure signal.

7. The method of claim 1, wherein determining at least one of a systolic pressure or a diastolic pressure comprises:

setting a time window extending from one of determining the sensed pressure signal being greater than the first threshold and determining the sensed pressure signal being greater than the second threshold;

determining a third metric of a derivative signal of the sensed pressure signal; and

determining a value of the sensed pressure signal corresponding to the third metric as the diastolic pressure.

8. The method of claim 7, wherein the first metric, the second metric and the third metric correspond to a maximum of a first derivative signal corresponding to the sensed pressure signal.

9. The method of claim 1, wherein determining at least one of a systolic pressure or a diastolic pressure comprises:

setting a first time window extending from a point prior to one of determining the sensed pressure signal being greater than the first threshold and determining the sensed pressure signal being greater than the second threshold to a corresponding one of the first metric and the second metric;

determining a third metric of a derivative signal of the sensed pressure signal occurring during the first time window;

determining a value of the sensed pressure signal corresponding to the third metric as the diastolic pressure;

setting a second time window extending from one of determining the sensed pressure signal being greater than the first threshold and determining the sensed pressure signal being greater than the second threshold;

determining a fourth metric of a derivative signal of the sensed pressure signal; and

determining a value of the sensed pressure signal corresponding to the fourth metric as the diastolic pressure.

10. The method of claim 9, wherein the second pressure threshold is equal to the determined first metric of the pressure signal.

11. The method of claim 1, further comprising controlling delivery of at least one of electrical stimulation and a therapeutic agent in response to the determined at least one of a systolic pressure or a diastolic pressure.

12. A medical device system for monitoring a cardiovascular pressure signal, comprising:

a sensor sensing a cardiovascular pressure signal; and

a pressure analysis module configured to;

determine whether the sensed pressure signal is greater than a first pressure threshold;

determine a first metric of the pressure signal in response to the sensed pressure signal being greater than the first pressure threshold;

determine whether the sensed pressure signal is greater than a second pressure threshold not equal to the first pressure threshold;

determine a second metric of the pressure signal in response to the sensed pressure signal being greater than the first pressure threshold; and

determine at least one of a systolic pressure or a diastolic pressure, wherein the at least one of a systolic pressure or a diastolic pressure is determined based on the first metric in response to the pressure signal not being greater than the second threshold, and based on the second metric in response to the pressure signal being greater than the second threshold.

13. The system of claim 12, further comprising a controller configured to control delivery of at least one of electrical stimulation and a therapeutic agent in response to the determined at least one of a systolic pressure or a diastolic pressure.

14. The system of claim 12, wherein the second pressure threshold is equal to the determined first metric of the pressure signal.

15. The system of claim 12, wherein the first metric and the second metric of the pressure signal corresponds to a maximum value of a derivative signal of the pressure signal.

16. The system of claim 12, wherein determining at least one of a systolic pressure or a diastolic pressure comprises:

setting a time window extending from a point prior to one of determining the sensed pressure signal being greater than the first threshold and determining the sensed pressure signal being greater than the second threshold to a corresponding one of the first metric and the second metric;

determining a third metric of a derivative signal of the sensed pressure signal occurring during the time window; and

determining a value of the sensed pressure signal corresponding to the third metric as the diastolic pressure.

17. The system of claim 16, wherein the first metric and the second metric correspond to a maximum of a first derivative signal corresponding to the sensed pressure signal, and the third metric corresponds to a maximum of a second derivative signal corresponding to the sensed pressure signal.

18. The system of claim 12, wherein determining at least one of a systolic pressure or a diastolic pressure comprises:

setting a time window extending from one of determining the sensed pressure signal being greater than the first threshold and determining the sensed pressure signal being greater than the second threshold;

determining a third metric of a derivative signal of the sensed pressure signal; and

determining a value of the sensed pressure signal corresponding to the third metric as the diastolic pressure.

19. The system of claim 18, wherein the first metric, the second metric and the third metric correspond to a maximum of a first derivative signal corresponding to the sensed pressure signal.

20. The system of claim 12, wherein determining at least one of a systolic pressure or a diastolic pressure comprises:

setting a first time window extending from a point prior to one of determining the sensed pressure signal being greater than the first threshold and determining the sensed pressure signal being greater than the second threshold to a corresponding one of the first metric and the second metric;

determining a third metric of a derivative signal of the sensed pressure signal occurring during the first time window;

determining a value of the sensed pressure signal corresponding to the third metric as the diastolic pressure;

setting a second time window extending from one of determining the sensed pressure signal being greater than the first threshold and determining the sensed pressure signal being greater than the second threshold;

determining a fourth metric of a derivative signal of the sensed pressure signal; and

determining a value of the sensed pressure signal corresponding to the fourth metric as the diastolic pressure.

21. The system of claim 20, wherein the second pressure threshold is equal to the determined first metric of the pressure signal.

22. The system of claim 12, further comprising a controller configured to control delivery of at least one of electrical stimulation and a therapeutic agent in response to the determined at least one of a systolic pressure or a diastolic pressure.

23. A computer readable medium having computer executable instructions for performing a method in an implantable medical device, the method comprising:

sensing the cardiovascular pressure signal;

determining whether the sensed pressure signal is greater than a first pressure threshold;

determining a first metric of the pressure signal in response to the sensed pressure signal being greater than the first pressure threshold;

determining whether the sensed pressure signal is greater than a second pressure threshold not equal to the first pressure threshold;

determining a second metric of the pressure signal in response to the sensed pressure signal being greater than the first pressure threshold; and

determining at least one of a systolic pressure or a diastolic pressure, wherein the at least one of a systolic pressure or a diastolic pressure is determined based on the first metric in response to the pressure signal not being greater than the second threshold, and based on the second metric in response to the pressure signal being greater than the second threshold.