Posture monitoring using cardiac activation sequences

• US 20060253043A1
• Filed: 05/09/2005
• Published: 11/09/2006
• Est. Priority Date: 05/09/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Sweeney, Robert J., Zhang, Yi
• Granted Patent: US 7,805,185 B2
• Time in Patent Office: Days
• 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 in accordance with the present invention 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 a plurality of composite cardiac signals using a plurality of implantable electrodes;

performing a source separation using the sensed plurality of composite cardiac signals;

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; and

detecting a change in a patient'"'"'s posture using the one or more cardiac signal vectors.

2. The method of claim 1, comprising sensing the plurality of composite cardiac signals during the patient'"'"'s predominant cardiac rhythm before detecting 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 the patient'"'"'s physiologic and pathologic status 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 the patient'"'"'s physiologic and pathologic trend 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.

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 one or more 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. A cardiac system, comprising:

a plurality of electrodes configured for sensing a composite cardiac signal, thereby providing a plurality of composite cardiac signals;

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, 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 vector information used for characterizing the patient'"'"'s posture.

17. The system of claim 16, wherein the controller determines the patient'"'"'s posture using the vector information.

18. The system of claim 16, further comprising a lead coupled to the controller, wherein at least one of the plurality of electrodes is supported by the lead.

19. The system of claim 16, wherein at least one of the plurality of implantable electrodes is provided on the housing.

20. The system of claim 16, wherein the source separation comprises a blind source separation algorithm.

21. An implantable cardiac device, comprising:

means for sensing a plurality of composite cardiac signals using a plurality of implantable electrodes;

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

means for characterizing a patient'"'"'s posture using the one or more cardiac signal vectors.