MONITORING CARDIOVASCULAR CONDITIONS USING SIGNAL TRANSIT TIMES

• US 20100331708A1
• Filed: 06/23/2010
• Published: 12/30/2010
• Est. Priority Date: 06/29/2009
• Status: Abandoned Application

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Hatib, Feras
• Application Number:
  US12/822,122
• Publication Number:
  US 20100331708A1
• Time in Patent Office: Days
• US Class Current: 600/481
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 8/02 Measuring pulse or heart rate
• CPC Class Codes: A61B 8/065 to determine blood output from the heart in general A61B5/029

Abstract

Methods for monitoring cardiovascular conditions, i.e., hyperdynamic circulation, vasodilation, vasoconstriction, or central-to-peripheral arterial pressure decoupling conditions are described. These methods involve measuring a central signal proportional to or a function of the subject'"'"'s heart activity and a peripheral signal proportional to or a function of a signal related to the central signal. Then calculating a time difference between features in the central and peripheral signals representing the same heart event. The cardiovascular condition is indicated if the time difference is greater or lower than a threshold value, if the time difference is greater or lower than a threshold value over a specified period of time, or if there is a significant statistical change in the times over the specified time period. These methods can alert a user that a subject is experiencing the cardiovascular condition, which can enable a clinician to appropriately provide treatment to the subject.

Claims

1. A method for monitoring a cardiovascular condition in a subject comprising:

measuring a central signal proportional to or a function of the subject'"'"'s heart activity;

measuring a peripheral signal proportional to or a function of a signal related to the central signal; and

calculating a time difference between signal features representing the same heart events for the central signal and the peripheral signal,

wherein the cardiovascular condition is indicated if the time difference is greater than a threshold value.

3. The method of claim 1 or 2, wherein the cardiovascular condition is vasodilation.

4. The method of claim 1 or 2, wherein the cardiovascular condition is vasoconstriction.

5. The method of claim 1 or 2, wherein the cardiovascular condition indicates the occurrence of hyperdynamic circulation.

6. The method of claim 1 or 2, wherein the cardiovascular condition is central-to-peripheral pressure or flow decoupling.

7. The method of any of claim 3, 5, or 6, wherein the threshold value is 150 milliseconds or greater.

8. The method of claim 4, wherein the threshold value is 100 milliseconds or less.

11. The method of claim 1, wherein the threshold value is 5 minutes or greater.

13. The method of claim 1, wherein the cardiovascular condition is indicated is the time difference is greater than the threshold value for a specified time period.

14. The method of claim 13, wherein the specified time period is 5 minutes or greater.

15. The method of claim 1 or 2, wherein the central signal proportional to or a function of the subject'"'"'s heart activity is one or more of electrocardiogram, aortic pressure, aortic flow, ultrasound, Doppler, transthoracic bioimpedance, or heart sounds.

16. The method of claim 1 or 2, wherein the peripheral signal proportional to or a function of a peripheral equivalent to the first signal is peripheral pressure, peripheral flow, ultrasound, Doppler, tonometry, or pulse oximetry.

17. The method of claim 1 or 2, wherein the central signal is aortic pressure and the peripheral signal is peripheral pressure.

18. The method of claim 1 or 2, wherein the central signal is aortic flow and the peripheral signal is peripheral flow.

19. The method of claim 1 or 2, wherein the central signal is an electrocardiogram signal and the peripheral signal is peripheral arterial pressure.

20. The method of claim 1, wherein the time difference between the central signal and the peripheral signal is continually monitored.

21. The method of claim 1, wherein the time difference between the central signal and the peripheral signal is displayed on a graphical user interface.

22. The method of claim 21, wherein the time difference between the central signal and the peripheral signal is displayed as a bar graph or a trend graph.

26. The method of claim 1, further comprising alerting a user when the cardiovascular condition is indicated.

28. The method of claim 26 or 27, wherein the user is alerted by publishing a notice on a graphical user interface.

29. The method of claim 26 or 27, wherein the user is alerted by emitting a sound.

2. A method for monitoring a cardiovascular condition in a subject comprising:

measuring a central signal proportional to or a function of the subject'"'"'s heart activity;

measuring a peripheral signal proportional to or a function of a signal related to the central signal; and

calculating a time difference between signal features representing the same heart event for the central signal and the peripheral signal,

wherein the cardiovascular condition is indicated if there is a significant statistical change in the time difference over a specified time period.

9. The method of claim 2, wherein the statistically significant change is 50 milliseconds or greater.

10. The method of claim 2, wherein the statistically significant change is 0.4 standard deviations or greater.

12. The method of claim 2, wherein the specified time period is 5 minutes or greater.

23. The method of claim 2, wherein the time difference between the central signal and the peripheral signal or a statistical change over time is continually monitored.

24. The method of claim 2, wherein the time difference between the central signal and the peripheral signal or a statistical change over time is displayed on a graphical user interface.

25. The method of claim 24, wherein the time difference between the central signal and the peripheral signal or a statistical change over time is displayed as a bar graph or a trend graph.

27. The method of claim 2, further comprising alerting a user when the cardiovascular condition is indicated.