SYSTEM AND METHOD FOR ISCHEMIA CLASSIFICATION WITH IMPLANTABLE MEDICAL DEVICE

• US 20080183086A1
• Filed: 01/31/2007
• Published: 07/31/2008
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Lu, Steven N., Warman, Eduardo N., Song, Zhendong, Musley, Shailesh K.V.
• Granted Patent: US 7,894,884 B2
• Time in Patent Office: Days
• US Class Current: 600/508
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: Y10S 128/92 Computer assisted medical diagnostics
• CPC Class Codes: Y10S 128/923 by comparison of patient data to other data

Abstract

An implantable medical device monitors ST segment data collected from EGM. ST trends are established and monitored over time. The IMD is able to discern whether the data indicate supply ischemia, demand ischemia, or other physiological causes. The IMD is then able to provide appropriate information and alerts.

Claims

1. A method comprising:

obtaining an electrogram representing cardiac data from an implantable medical device for a plurality of cardiac cycles; and

evaluating the ST segment data points; and

determining whether the evaluated ST segment data points indicate supply ischemia.

2. The method of claim 1, further comprising:

determining whether the evaluated ST segment data points indicate demand ischemia.

3. The method of claim 1, wherein determining an ST segment data point further comprises:

identifying a peak of an R wave;

adding a predetermined time interval to the identified peak; and

identifying a recorded value at a time identified by the predetermined time interval after the as the ST segment data point.

4. The method of claim 3, further comprising:

determining a PR isoelectric baseline value;

subtracting the PR isoelectric baseline value from the recorded value to identify the ST segment data point.

5. The method of claim 1, wherein evaluating the ST segment data points further comprises:

monitoring the ST segment data point values; and

initiating an a timer interval if a given ST segment data point value exceeds a threshold value, wherein determining whether the evaluated ST segment data points indicate supply ischemia occurs based upon data collected during the timer.

6. The method of claim 5, further comprising:

determining a maximum ST segment data point value during the timer;

determining a first time interval from initiation of the timer until the maximum ST segment data point value occurs; and

determining that the evaluated ST segment data points do not indicate supply ischemia if the first time interval is less than a first short value or greater than a first long value.

7. The method of claim 6, further comprising:

determining that the evaluated ST segment data points do not indicate supply ischemia if less than a predetermined percentage of the ST segment data point occurring during the timer interval exceed the threshold value.

8. The method of claim 6, further comprising:

determining that the evaluated ST segment data points do not indicate supply ischemia if an ST segment data point occurring at a termination of the timer interval is less than a predetermined percentage of the maximum ST segment data value.

9. The method of claim 6, further comprising:

calculating a slope of the ST segment data points prior to the maximum ST segment data point; and

determining that the evaluated ST segment data points do not indicate supply ischemia if the slope is less than a first slope value.

10. The method of claim 1, wherein evaluating the ST segment data points further comprises:

monitoring the ST segment data point values; and

processing the values using a predetermined filter bank.

11. The method of claim 1, wherein evaluating the ST segment data points further comprises:

monitoring the ST segment data point values; and

processing the values by comparing to a template.

12. An apparatus comprising:

means for obtaining an electrogram representing cardiac data from an implantable medical device for a plurality of cardiac cycles;

means for determining an ST segment data point for each of the cardiac cycles;

means for evaluating the ST segment data points; and

means for determining whether the evaluated ST segment data points indicate supply ischemia.

13. The apparatus of claim 12, further comprising:

means for determining whether the evaluated ST segment data points indicate demand ischemia.

14. The apparatus of claim 12, wherein the means for determining an ST segment data point further comprise:

means for identifying a peak of an R wave;

means for adding a predetermined time interval to the identified peak; and

means for identifying a recorded value at a time identified by the predetermined time interval after the R wave as the ST segment data point.

15. The apparatus of claim 14, further comprising:

means for determining a PR isoelectric baseline value;

means for subtracting the PR isoelectric baseline value from the recorded value to identify the ST segment data point.

16. The apparatus of claim 12, wherein the means for evaluating the ST segment data points further comprise:

means for monitoring the ST segment data point values; and

means for initiating an a timer interval if a given ST segment data point value exceeds a threshold value, wherein determining whether the evaluated ST segment data points indicate supply ischemia occurs based upon data collected during the timer.

17. The apparatus of claim 16, further comprising:

means for determining a maximum ST segment data point value during the timer;

means for determining a first time interval from initiation of the timer until the maximum ST segment data point value occurs; and

means for determining that the evaluated ST segment data points do not indicate supply ischemia if the first time interval is less than a first short value or greater than a first long value.

18. The apparatus of claim 16, further comprising:

means for determining that the evaluated ST segment data points do not indicate supply ischemia if less than a predetermined percentage of the ST segment data point occurring during the timer interval exceed the threshold value.

19. The apparatus of claim 16, further comprising:

means for determining that the evaluated ST segment data points do not indicate supply ischemia if an ST segment data point occurring at a termination of the timer interval is less than a predetermined percentage of the maximum ST segment data value. 20. The apparatus of claim 16, further comprising;

means for calculating a slope of the ST segment data points prior to the maximum ST segment data point; and

means for determining that the evaluated ST segment data points do not indicate supply ischemia if the slope is less than a first slope value.