Posture monitoring using cardiac activation sequences

• US 7,805,185 B2
• Filed: 05/09/2005
• Issued: 09/28/2010
• Est. Priority Date: 05/09/2005
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: In. Cardiac Pacemakers
• Inventors: Sweeney, Robert J., Zhang, Yi
• Primary Examiner(s): Layno; Carl H.
• Assistant Examiner(s): Heller; Tammmie K
• Application Number:
  US11/124,950
• Publication Number:
  US 20060253043A1
• Time in Patent Office: 1,968 Days
• Field of Search: 600/512
• US Class Current: 600/512
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2560/0468 Built-in electrodes
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• 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 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

Cardiac monitoring and/or stimulation methods and systems that provide one or more of monitoring, diagnosing, defibrillation, and pacing. Cardiac signal separation is employed to detect, monitor, track and/or trend a patient'"'"'s posture using cardiac activation sequence information. Devices and methods involve sensing a plurality of composite cardiac signals using a plurality of implantable electrodes. A source separation is performed using the composite cardiac signals, which produces one or more cardiac signal vectors associated with all or a portion of one or more cardiac activation sequences. A change in a patient'"'"'s posture is detected using the cardiac signal vectors. Further embodiments involve sensing the plurality of composite cardiac signals during the patient'"'"'s predominant cardiac rhythm before detecting the change in the patient'"'"'s posture. Other embodiments involve discriminating between one of a postural related change and a cardiac rhythm related change using the cardiac signal vectors.

Claims

1. A method, comprising:

sensing, for a patient, a plurality of composite signals associated with an unknown number of sources using a plurality of implantable electrodes;

performing a source separation using the sensed plurality of composite signals to separate signal components of the sensed plurality of composite signals according to their sources;

producing one or more cardiac signal vectors associated with all or a portion of one or more cardiac activation sequences based on the source separation;

detecting a change in a patient'"'"'s posture between a first postural position and a second postural position different from the first postural position using the one or more cardiac signal vectors;

determining whether the patient is in a predominant cardiac rhythm during the change in the patient'"'"'s posture between the first and second postural positions; and

determining, if the patient is in the predominant cardiac rhythm, that the detected posture change is indicative of the change in the patient'"'"'s posture between the first and second postural positions and not due to a change in the patient'"'"'s cardiac activation sequence.

2. The method of claim 1, comprising:

determining that the patient is not in the predominant cardiac rhythm during the change in the patient'"'"'s posture between the first and second postural positions; and

determining if the detected change in the patient'"'"'s posture is indicative of a physiological change rather than the change in the patient'"'"'s posture.

3. The method of claim 1, comprising:

detecting a change in the one or more cardiac signal vectors; and

discriminating between one of a postural related change and a cardiac rhythm related change using the detected change in the one or more cardiac signal vectors.

4. The method of claim 1, comprising using the patient'"'"'s posture change to interpret the one or more cardiac signal vectors.

5. The method of claim 1, comprising using the patient'"'"'s posture change to interpret a sensor signal selected from the group consisting of heart-rate, heart rhythm, respiration, blood-pressure, temperature, heart sound, cardiac output, cardiac stroke volume, cardiac wall motion, peripheral fluid status, pulmonary fluid status, thoracic impedance, and heart-rate variability.

6. The method of claim 5, further comprising interpreting one or both of a physiologic and pathologic status of the patient using both the selected sensor signal and the patient'"'"'s detected posture change.

7. The method of claim 5, comprising interpreting one or both of a physiologic and pathologic trend of the patient using both the selected sensor signal and the patient'"'"'s detected posture change.

8. The method of claim 1, wherein detecting the change in the patient'"'"'s posture comprises detecting a change in a characteristic of the one or more cardiac signal vectors relative to a baseline of the one or more cardiac signal vectors.

9. The method of claim 8, wherein the baseline of the one or more cardiac signal vectors is updated according to a predetermined criteria.

10. The method of claim 8, wherein the baseline comprises information established by an initial source separation, and the change is detected using a subsequent source separation.

11. The method of claim 1, wherein the one or more cardiac activation sequences are indicative of a plurality of cardiac cycles.

12. The method of claim 1, comprising:

storing templates of one or more characteristics of the one or more cardiac signal vectors associated with sitting, standing, and lying postures of the patient; and

determining, if the patient is in the predominant cardiac rhythm, that the detected posture change is indicative of one of sitting, standing, and lying postures using the stored templates.

13. The method of claim 1, comprising providing a look-up table of cardiac signal vector attributes based on postural changes, wherein detecting the change in the patient'"'"'s posture comprises:

determining attributes of the one or more cardiac signal vectors; and

using the look-up table to associate the determined attributes with the patient'"'"'s posture.

14. The method of claim 1, wherein detecting the change in the patient'"'"'s posture comprises:

categorizing the patient'"'"'s cardiac rhythm; and

matching one or more characteristics of the one or more cardiac signal vectors to pre-established values associated with the category.

15. The method of claim 1, comprising at least two of storing the patient'"'"'s posture information in a memory, communicating the patient'"'"'s posture information to a patient-external device, and displaying the patient'"'"'s posture information on a visual display.

16. The method of claim 1, wherein the source separation comprises a blind source separation.

17. The method of claim 1, comprising:

determining that the patient does not have a predominant cardiac rhythm; and

determining the patient'"'"'s posture using stored cardiac signal vector orientations based on combinations of posture and intrinsic or paced electrophysiology signals of the patient.

18. A system, comprising:

a plurality of implantable electrodes configured for sensing a plurality of composite signals associated with an unknown number of sources;

a housing configured for implantation in a patient;

a controller provided in the housing and coupled to the plurality of electrodes;

a signal processor; and

a memory coupled to the signal processor;

wherein the signal processor is configured to perform a source separation using the sensed plurality of composite signals to separate signal components of the sensed plurality of composite signals according to their sources, the source separation producing one or more cardiac signal vectors associated with all or a portion of one or more cardiac activation sequences, and to store vector information in the memory, the controller configured to;

detect a change in a patient'"'"'s posture between a first postural position and a second postural position different from the first postural position using the one or more cardiac signal vectors;

determine whether the patient is in a predominant cardiac rhythm during the change in the patient'"'"'s posture between the first and second postural positions; and

determine, if the patient is in the predominant cardiac rhythm, that the detected posture change is indicative of the change in the patient'"'"'s posture between the first and second postural positions and not due to a change in the patient'"'"'s cardiac activation sequence.

19. The system of claim 18, wherein the controller determines the patient'"'"'s posture using the vector information.

20. The system of claim 18, further comprising a lead coupled to the controller, wherein at least one of the plurality of electrodes is supported by the lead.

21. The system of claim 18, wherein at least one of the plurality of implantable electrodes is provided on the housing.

22. The system of claim 18, wherein the source separation comprises a blind source separation algorithm.

23. The system of claim 18, wherein the controller is configured to:

determine that the patient is not in the predominant cardiac rhythm during the change in the patient'"'"'s posture between the first and second postural positions; and

determine if the detected change in the patient'"'"'s posture is indicative of a physiological change rather than the change in the patient'"'"'s posture.

24. The system of claim 18, wherein the controller is configured to:

determine that the patient does not have a predominant cardiac rhythm; and

determine the patient'"'"'s posture using stored cardiac signal vector orientations based on combinations of posture and intrinsic or paced electrophysiology signals of the patient.

25. The system of claim 18, wherein:

the memory is configured to store templates of one or more characteristics of the one or more cardiac signal vectors associated with sitting, standing, and lying postures of the patient; and

the controller is configured to determine, if the patient is in the predominant cardiac rhythm, that the detected posture change is indicative of one of sitting, standing, and lying postures using the templates stored in the memory.

26. An implantable cardiac device, comprising:

means for sensing a plurality of composite signals associated with an unknown number of sources using a plurality of implantable electrodes;

means for performing a source separation using the sensed plurality of composite cardiac signals to separate signal components of the sensed plurality of composite signals according to their sources, the source separation producing one or more cardiac signal vectors associated with all or a portion of one or more cardiac activation sequences;

means for detecting a change in a patient'"'"'s posture between a first postural position and a second postural position different from the first postural position using the one or more cardiac signal vectors;

means for determining whether the patient is in a predominant cardiac rhythm during the change in the patient'"'"'s posture between the first and second postural positions; and

means for determining, if the patient is in the predominant cardiac rhythm, that the detected posture change is indicative of the change in the patient'"'"'s posture between the first and second postural positions and not due to a change in the patient'"'"'s cardiac activation sequence.