Cardiac signal display and event detection using multiresolution Z-score transform

• US 8,241,212 B2
• Filed: 07/28/2009
• Issued: 08/14/2012
• Est. Priority Date: 07/24/2006
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Li, Dan, Ni, Quan
• Primary Examiner(s): Patel, Niketa
• Assistant Examiner(s): Voorhees, Catherine
• Application Number:
  US12/510,927
• Publication Number:
  US 20090287068A1
• Time in Patent Office: 1,113 Days
• Field of Search: 607 17- 18, 607/30, 607/20, 600509-510, 600/513, 600/523, 600/525
• US Class Current: 600/301
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/37211 Means for communicating with stimulators

Abstract

A system comprising a medical device including a processor and a Z-score transformation (ZST) module. The system also includes a display in communication with the processor. The processor is adapted to receive sensor data obtained from at least first and second sensors adapted to produce a time-varying physiologic electrical sensor signal. At least one of the first and second sensors is implantable. The ZST module calculates a ZST for the sensor data received from the first sensor and a ZST for the sensor data received from the second sensor. The display is adapted to display the ZSTs in visual correspondence with each other over time.

Claims

1. A method comprising:

sensing at least one time-varying physiologic sensor signal using an implantable sensor;

sampling the sensor signal to obtain sensor data;

calculating a multi-resolution Z-score transformation (ZST) of the sensor data by;

calculating a ZST over a first data segment length of a sensor signal to obtain a first resolution ZST region; and

calculating at least a second ZST over a second data segment length of the sensor signal to obtain at least a second resolution ZST region, wherein at least a portion of the second segment overlaps the first segment, and wherein the second resolution is different than the first resolution; and

displaying the multi-resolution ZST.

2. The method of claim 1, including:

assigning a first display color-code to a first region of the ZST;

assigning a second display color-code to a second region of the ZST, wherein the second, region of the ZST includes a sensor data value that is outside of a predetermined normal value range; and

displaying both the ZST of a sensor signal and one or more color-codes to indicate one or more regions having a value outside the predetermined normal value range.

3. The method of claim 2, wherein the predetermined normal value range is two standard deviations.

4. The method of claim 1, including:

assigning a first display color-code to the first resolution ZST region and a second display color-code to the second resolution ZST region; and

displaying both the ZST of a sensor signal and one or more color-codes to indicate regions of multiple resolution of the ZST.

5. The method of claim 4, including:

sensing a plurality of time-varying physiologic sensor signals;

calculating multi-resolution ZSTs for the plurality of sensor signals;

assigning color-codes to multi-resolution regions of the ZSTs; and

displaying both the ZSTs of the sensor signals and a color map to indicate regions of multiple-resolution of the ZSTs.

6. The method of claim 1, wherein calculating a multi-resolution Z-score transformation (ZST) includes:

calculating a ZST over a first data segment length of a sensor signal to obtain a first resolution ZST; and

calculating at least a second ZST over a second data segment length of the sensor signal to obtain at least a second resolution ZST when prompted through a user interface.

7. The method of claim 1, wherein calculating a multi-resolution ZST includes calculating a multi-resolution ZST when the processor determines that the ZST has a predetermined number of points outside a normal range.

8. The method of claim 1, wherein sampling the sensor signal to obtain sensor data occurs in real time and wherein calculating a ZST includes calculating the multi-resolution ZST while the sensor data is being obtained.

9. The method of claim 8, wherein calculating the ZST includes calculating a ZST Z_x(i) in real time, when a new sensor datum x(i) is obtained, according to

Z_x(i):

=(x(i)−

μ

)/σ

,

where μ

represents a mean and σ

represents a standard deviation.

10. A method comprising:

sensing a first time-varying physiologic sensor signal and sensing at least a second time-varying physiologic sensor signal, wherein at least one of the first and second sensor signals is obtained from an implantable sensor;

sampling the first and second sensor signals to obtain first sensor data and second sensor data;

calculating a Z-score transformation (ZST) for the first sensor data and a ZST for the second sensor data including;

calculating a ZST over a first data segment length of at least one of the first or second sensor data to obtain a first resolution ZST region; and

calculating at least a second ZST over a second data segment length of the same first or second sensor data to obtain at least a second resolution ZST region wherein at least a portion of the second segment overlaps the first segment, and wherein the second resolution is different than the first resolution; and

displaying the ZSTs in visual correspondence with each other over time.

11. The method of claim 10, including:

assigning a first display color-code to a first region of a ZST;

assigning a second display color-code to a second region of the ZST, wherein the second, region of the ZST includes a sensor data value that is outside of a predetermined normal value range; and

displaying both the ZST of a sensor signal and one or more color-codes to indicate one or more regions having a value outside the predetermined normal value range.

12. The method of claim 10, including:

trending the sensor data, of at least one of the first and second sensor signals;

calculating the ZST of trended sensor data; and

displaying at least one ZST of the trended sensor data.

13. The method of claim 10, including sensing a plurality of time-varying physiologic sensor signals, wherein the plurality of sensor signals are related to physiologic cardiovascular events of a subject selected from the group consisting of:

mean arterial pressure;

stroke volume;

heart rate;

respiration rate;

respiration volume;

mechanical vibrations of the subject'"'"'s heart; and

activity of the subject.

14. The method of claim 10, wherein calculating a ZST includes recalculating a ZST when new sampled sensor data is available.

15. The method of claim 10, wherein calculating ZST includes calculating a ZST over a sufficient amount of sensor data to record circadian variance of a sensor signal.

16. The method of claim 10, wherein sensing the first and second sensor signals includes sensing a first sensor signal having a different scale from the second sensor signal with respect to time.

17. The method of claim 10, wherein sensing the first and second sensor signals includes sensing a first sensor signal having a different scale from the second sensor signal with respect to data.

18. The method of claim 10, wherein displaying the ZSTs in visual correspondence with each other over time includes displaying different combinations of the ZSTs according to input received through a graphical user interface.

19. The method of claim 10, wherein displaying the ZSTs in visual correspondence with each other over time includes:

assigning a first display color-code to a ZST region having the first resolution and a second display color-code to a ZST region having the second resolution; and

displaying the ZST of a sensor signal and indicate regions of multiple resolution of the ZST using the color-codes.

20. The method of claim 10, wherein displaying the ZSTs in visual correspondence with each other over time includes displaying both the ZSTs of the sensor signals and a displaying color map to indicate regions of multiple resolution of the ZST.