Measurement of cardiac cycle length and pressure metrics from pulmonary arterial pressure

• US 10,362,946 B2
• Filed: 04/18/2016
• Issued: 07/30/2019
• 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.
• Primary Examiner(s): Messersmith, Eric J
• Application Number:
  US15/131,770
• Publication Number:
  US 20160302673A1
• Time in Patent Office: 1,198 Days
• 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, the method comprising:

sensing, by a medical device, the cardiovascular pressure signal;

comparing, by the medical device, the sensed cardiovascular pressure signal to a first threshold;

identifying, by the medical device, a first sense in response to the sensed cardiovascular pressure signal exceeding the first threshold;

in response to and as a result of identifying the first sense, comparing, by the medical device, the sensed cardiovascular pressure signal to a second threshold not equal to the first threshold;

identifying, by the medical device, a second sense subsequent to the first sense if the sensed cardiovascular pressure signal exceeds the second threshold;

identifying, by the medical device, a third sense subsequent to the first sense and in response to the sensed cardiovascular pressure signal exceeding the first threshold; and

determining, by the medical device, a cardiac cycle length based on one of the first sense and the third sense or the second sense and the third sense.

2. The method of claim 1, further comprising controlling, based on the determined cardiac cycle length, delivery of at least one of electrical stimulation or a therapeutic agent.

3. The method of claim 2, further comprising delivering the at least one of the electrical stimulation or the therapeutic agent based on the determined cardiac cycle length.

4. The method of claim 1, wherein the second threshold is equal to a value of the sensed cardiovascular pressure signal occurring subsequent to the first sense.

5. The method of claim 4, wherein the value corresponds to a maximum value of a derivative signal of the sensed cardiovascular pressure signal.

6. The method of claim 1, wherein determining the cardiac cycle length comprises determining the cardiac cycle length based on the second sense and the third sense, and wherein the method further comprises:

determining a first value of the sensed cardiovascular pressure signal in response to identifying the second sense;

determining a second value of the sensed cardiovascular pressure signal in response to identifying the third sense;

determining a length of time between the first value of the sensed cardiovascular pressure signal and the second value of the sensed cardiovascular pressure signal; and

determining the cardiac cycle length based on the determined length of time.

7. The method of claim 6, wherein the second threshold is equal to the first value of the sensed cardiovascular pressure signal determined in response to identifying the second sense.

8. The method of claim 6, wherein the first value of the sensed cardiovascular pressure signal corresponds to a maximum value of a derivative signal of the sensed cardiovascular pressure signal.

9. The method of claim 1, further comprising:

determining a first value of the sensed cardiovascular pressure signal in response to identifying the first sense;

determining a second value of the sensed cardiovascular pressure signal in response to identifying the third sense;

determining, in response to the sensed cardiovascular pressure signal not being greater than the second threshold, a length of time between the first value of the sensed cardiovascular pressure signal and the second value of the sensed cardiovascular pressure signal; and

determining the cycle length based on the determined length of time.

10. The method of claim 1, wherein the medical device is an implantable medical device.

11. The method of claim 10, wherein sensing the cardiovascular pressure signal comprises, sensing, by the implantable medical device implanted within a pulmonary artery, a pulmonary artery pressure signal as the cardiovascular pressure signal.

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

a sensor configured to sense the cardiovascular pressure signal; and

processing circuitry configured to;

compare the sensed cardiovascular pressure signal to a first threshold;

identify a first sense in response to the sensed cardiovascular pressure signal exceeding the first threshold;

in response to and as a result of identifying the first sense, compare the sensed cardiovascular pressure signal to a second threshold not equal to the first threshold;

identify a second sense subsequent to the first sense if the sensed cardiovascular pressure signal exceeds the second threshold;

identify a third sense subsequent to the first sense and in response to the sensed cardiovascular pressure signal exceeding the first threshold; and

determine a cardiac cycle length based on one of the first sense and the third sense or the second sense and the third sense.

13. The system of claim 12, wherein the processing circuitry is configured to control, based on the determined cycle length, delivery of at least one of electrical stimulation or a therapeutic agent.

14. The system of claim 12, wherein the second threshold is equal to a value of the sensed cardiovascular pressure signal occurring subsequent to the first sense.

15. The system of claim 14, wherein the value corresponds to a maximum value of a derivative signal of the sensed cardiovascular pressure signal.

16. The system of claim 12, wherein the processing circuitry is configured to:

determine the cardiac cycle length based on the second sense and the third sense;

determine a first value of the sensed cardiovascular pressure signal in response to identifying the second sense;

determine a second value of the sensed cardiovascular pressure signal in response to identifying the third sense;

determine a length of time between the first value of the sensed cardiovascular pressure signal and the second value of the sensed cardiovascular pressure signal; and

determine the cardiac cycle length based on the determined length of time.

17. The system of claim 16, wherein:

the second threshold is equal to the first value of the sensed cardiovascular pressure signal determined in response to identifying the second sense; and

the first value of the sensed cardiovascular pressure signal corresponds to a maximum value of a derivative signal of the sensed cardiovascular pressure signal.

18. The system of claim 12, wherein the processing circuitry is configured to:

determine a first value of the sensed cardiovascular pressure signal in response to identifying the first sense;

determine a second value of the sensed cardiovascular pressure signal in response to identifying the third sense;

determine, in response to the sensed cardiovascular pressure signal not being greater than the second threshold, a length of time between the first value of the sensed cardiovascular pressure signal and the second value of the sensed cardiovascular pressure signal; and

determine the cardiac cycle length based on the determined length of time.

19. The system of claim 12, wherein the medical device system comprises an implantable medical device comprising the sensor and the processing circuitry.

20. The system of claim 12, wherein the sensor is configured to be implanted within a pulmonary artery and sense a pulmonary artery pressure signal as the cardiovascular pressure signal.

21. A computer readable medium comprising computer executable instructions that, when executed, cause a processor of an implantable medical device to:

control sensing of the cardiovascular pressure signal;

compare the sensed cardiovascular pressure signal to a first threshold;

identify a first sense in response to the sensed cardiovascular pressure signal exceeding the first threshold;

in response to and as a result of identifying the first sense, compare the sensed cardiovascular pressure signal to a second threshold not equal to the first threshold;

identify a second sense subsequent to the first sense if the sensed cardiovascular pressure signal exceeds the second threshold;

identify a third sense subsequent to the first sense and in response to the sensed cardiovascular pressure signal exceeding the first threshold; and

determine a cardiac cycle length based on one of the first sense and the third sense or the second sense and the third sense.