Systems and Methods for Myocardial Ischemia Detection

• US 20090234211A1
• Filed: 03/11/2009
• Published: 09/17/2009
• Est. Priority Date: 03/13/2008
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Sachanandani, Haresh G., Zhang, Yi, Li, Dan, Kane, Michael John
• Granted Patent: US 8,864,677 B2
• Time in Patent Office: Days
• US Class Current: 600/345
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• 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 1/36585 controlled by two or more physical parameters

Abstract

Embodiments of the invention are related to devices and methods for myocardial ischemia detection, amongst other things. In an embodiment, the invention includes an implantable medical device including control circuitry, an electrical field sensor in communication with the control circuitry, the electrical field sensor configured to generate a signal corresponding to cardiac electrical fields. The implantable medical device can also include a chemical sensor in communication with the control circuitry, the chemical sensor configured to generate a signal corresponding to the concentration of a physiological analyte that affects cardiac electrical field waveform morphology. The control circuitry can be configured to monitor for the presence of myocardial ischemia by evaluating both the signal generated by the electrical field sensor and the signal generated by the chemical sensor. Other embodiments are also included herein.

Claims

1. An implantable medical device comprising:

control circuitry;

an electrical field sensor in communication with the control circuitry, the electrical field sensor configured to generate a signal corresponding to cardiac electrical fields;

a chemical sensor in communication with the control circuitry, the chemical sensor configured to generate a signal corresponding to the concentration of a physiological analyte that affects cardiac electrical field waveform morphology;

the control circuitry configured to monitor for the presence of myocardial ischemia by evaluating both the signal generated by the electrical field sensor and the signal generated by the chemical sensor.

2. The implantable medical device of claim 1, the physiological analyte that affects cardiac electrical field wave morphology selected from the group consisting of potassium, calcium, and glucose.

3. The implantable medical device of claim 1, the physiological analyte that affects cardiac electrical field wave morphology comprising potassium.

4. The implantable medical device of claim 1, the electrical field sensor comprising a first electrode and a second electrode.

5. The implantable medical device of claim 1, the chemical sensor comprising an optical chemical sensor.

6. The implantable medical device of claim 5, the optical chemical sensor comprising a light source, a light detector, and a chemical sensing element.

7. The implantable medical device of claim 1, the control circuitry configured to identify episodes of myocardial ischemia with the signal generated by the electrical field sensor and confirm the accuracy of such identification with the signal generated by the chemical sensor.

8. The implantable medical device of claim 7, wherein episodes of myocardial ischemia are identified based on ST-segment deviation.

9. The implantable medical device of claim 7, wherein episodes of myocardial ischemia are confirmed based on a concentration of potassium between about 3.8 meq and about 5.0 meq.

10. The implantable medical device of claim 1, the control circuitry further configured to generate an alert when myocardial ischemia is present based on evaluating both the signal generated by the electrical field sensor and the signal generated by the chemical sensor.

11. The implantable medical device of claim 1, wherein the chemical sensor is chronically implanted.

12. The implantable medical device of claim 1, the control circuitry configured to selectively activate the chemical sensor based on the signal generated by the electrical field sensor.

13. A method of detecting myocardial ischemia comprising:

observing a cardiac electrogram signal with an implanted electrical sensor;

monitoring the cardiac electrogram signal for waveform morphologies indicative of acute myocardial ischemia; and

generating an analyte concentration signal with an implanted chemical sensor when the electrogram signal waveform morphology indicates that acute myocardial ischemia is present.

14. The method of claim 13, the analyte concentration signal reflecting the concentration of an analyte selected from the group consisting of potassium, calcium, and glucose.

15. The method of claim 13, the analyte concentration signal reflecting the concentration of potassium.

16. The method of claim 13, the electrical sensor comprising a first electrode and a second electrode.

17. The method of claim 13, generating an analyte concentration signal with an implanted chemical sensor when the electrogram signal waveform morphology indicates demonstrates ST-segment deviation.

18. The method of claim 13, further comprising confirming the acute myocardial ischemia based on the analyte concentration signal.

19. The method of claim 18, wherein acute myocardial ischemia is confirmed based on a concentration of potassium between about 3.8 meq and about 5.0 meq.

20. The method of claim 19, further comprising issuing an alert when myocardial ischemia is confirmed.

21. A method of detecting myocardial ischemia comprising:

observing a cardiac electrogram signal with an implanted electrical sensor;

monitoring the cardiac electrogram signal for waveform morphologies indicative of acute myocardial ischemia; and

comparing the cardiac electrogram signal to morphology templates indicative of abnormal physiological potassium concentrations.

22. The method of claim 21, further comprising generating a morphology template for abnormal physiological potassium concentrations.

23. The method of claim 22, wherein generating a morphology template for abnormal physiological potassium concentrations comprises measuring potassium concentrations and recording concurrent cardiac electrogram signals.

24. The method of claim 22, further comprising updating the morphology template based on additional data regarding potassium concentrations and cardiac electrogram signals.