Tachycardia hemodynamics detection based on cardiac mechanical sensor signal regularity

• US 20090131996A1
• Filed: 09/10/2008
• Published: 05/21/2009
• Est. Priority Date: 11/21/2007
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Li, Dan
• Granted Patent: US 8,229,556 B2
• Time in Patent Office: Days
• US Class Current: 607/4
• 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 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36564 controlled by blood pressure
• CPC Class Codes: A61N 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone

Abstract

Systems and methods provide for sensing, within a patient and during an event of tachycardia, a signal indicative of a mechanical response of the patient'"'"'s heart to the tachycardia. Regularity of the signal relative to a threshold established for the patient is determined. A state of patient hemodynamics during the tachycardia event is determined based at least in part on the regularity of the signal. One or more anti-tachycardia therapies to treat the tachycardia may be selected based at least in part on the determined state of patient hemodynamics. The selected one or more anti-tachycardia therapies may be delivered to treat the tachycardia.

Claims

1. A method, comprising:

sensing, within a patient and during an event of tachycardia, a signal indicative of a mechanical response of the patient'"'"'s heart to the tachycardia;

determining regularity of the signal relative to a threshold established for the patient;

determining a state of patient hemodynamics during the tachycardia event based at least in part on the regularity of the signal;

selecting one or more anti-tachycardia therapies to treat the tachycardia based at least in part on the determined state of patient hemodynamics; and

delivering the selected one or more anti-tachycardia therapies to treat the tachycardia.

2. The method of claim 1, wherein determining regularity of the signal comprises determining regularity of a morphology of the signal over a period of time.

3. The method of claim 1, wherein determining regularity of the signal comprises comparing the signal to a pre-established template developed for the patient during a previous tachycardia event.

4. The method of claim 1, wherein determining regularity of the signal comprises determining a change in a width of a dominant spectral peak of the signal.

5. The method of claim 1, wherein determining regularity of the signal comprises performing singular value decomposition on the signal.

6. The method of claim 1, wherein determining regularity of the signal comprises computing an entropy estimate of the signal'"'"'s regularity.

7. The method of claim 1, wherein determining the state of patient hemodynamics during the tachycardia event comprises comparing a metric indicative of regularity of the signal to a threshold.

8. The method of claim 7, comprising determining the threshold for a particular patient in relation to the patient'"'"'s normal sinus rhythm.

9. The method of claim 1, wherein:

determining the state of patient hemodynamics during the tachycardia event comprises determining whether the tachycardia event is a stable tachyarrhythmia or an unstable tachyarrhythmia; and

selecting the one or more anti-tachycardia therapies comprises selecting at least one anti-tachycardia pacing therapy in response to determining that the tachycardia event is a stable tachyarrhythmia, and selecting at least one cardioversion or defibrillation therapy in response to determining that the tachycardia event is an unstable tachyarrhythmia.

10. A method, comprising:

sensing, within a patient and during an event of tachycardia, a signal indicative of a mechanical response of the patient'"'"'s heart to the tachycardia;

determining a metric indicative of regularity of the signal relative to one or more thresholds established for the patient; and

quantizing the regularity metric into one of a plurality of discrete levels of hemodynamic stability for assessing a state of patient hemodynamics during the tachycardia event.

11. The method of claim 10, wherein determining regularity of the signal comprises determining regularity of a morphology of the signal over a period of time.

12. The method of claim 10, wherein determining regularity of the signal comprises comparing the signal to a pre-established template developed for the patient during a previous tachycardia event.

13. The method of claim 10, wherein determining regularity of the signal comprises determining a change in a width of a dominant spectral peak of the signal.

14. The method of claim 10, wherein determining regularity of the signal comprises performing singular value decomposition on the signal.

15. The method of claim 10, wherein determining regularity of the signal comprises computing an entropy estimate of the signal'"'"'s regularity.

16. The method of claim 10, wherein the plurality of discrete levels of hemodynamic stability comprises stable and unstable levels, and the regularity metric is quantized into one of stable and unstable levels.

17. The method of claim 10, comprising delivering an anti-tachycardia therapy associated with the level of hemodynamic stability of the patient during the tachycardia event.

18. The method of claim 17, comprising tracking the patient'"'"'s hemodynamics to assess effectiveness of the anti-tachycardia therapy.

19. An implantable system, comprising:

an implantable cardiac mechanical sensor configured to produce a signal indicative of a mechanical response of a patient'"'"'s heart to an event of tachycardia;

a lead comprising one or more electrodes;

detection circuitry coupled to the lead;

energy delivery circuitry coupled to the lead; and

a processor coupled to the sensor, lead, detection circuitry, and energy delivery circuitry, the processor configured to receive the signal during the tachycardia event, determine regularity of the signal relative to a threshold established for the patient, and determine a status of patient hemodynamics during the tachycardia event based at least in part on the regularity of the signal, the processor configured to deliver one or more anti-tachycardia therapies associated with the hemodynamic status of the patient.

20. The system of claim 19, wherein the processor is configured to determine regularity of a morphology of the signal over a period of time.

21. The system of claim 19, wherein the processor is configured to determine regularity of the signal by at least one of comparing the signal to a pre-established template developed for the patient during a previous tachycardia event, determining a change in a width of a dominant spectral peak of the signal, performing singular value decomposition on the signal, and computing an entropy estimate of the signal'"'"'s regularity.

22. The system of claim 19, wherein the processor is configured to determine the state of patient hemodynamics during the tachycardia event by comparing a metric indicative of regularity of,the signal to a threshold developed in relation to a normal sinus rhythm condition of the patient.

23. The system of claim 19, wherein the processor is configured to discriminate between a stable and an unstable state of patient hemodynamics based on regularity of the signal, and to deliver the one or more anti-tachycardia therapies based on stability of patient hemodynamics.

24. The system of claim 19, wherein the sensor comprises at least one of an intracardiac pressure sensor, an intravascular pressure sensor, an accelerometer, a microphone, an impedance sensor configured to sense transthoracic impedance, an impedance sensor configured to sense intracardiac impedance, and an impedance sensor configured to sense intra-myocardial impedance.