System and Method for Distinguishing Among Cardiac Ischemia, Hypoglycemia and Hyperglycemia Using an Implantable Medical Device
First Claim
1. A method for use with an implantable medical device for detecting cardiac ischemia in a patient in which the device is implanted, the method comprising:
- tracking paced repolarization peak-based intervals representative of intervals between depolarization events induced by pacing pulses delivered by the implantable medical device, and peaks of corresponding repolarization events within electrical cardiac signals;
tracking sensed repolarization peak-based intervals separate from the paced repolarization peak-based intervals, wherein the sensed repolarization peak-based intervals comprise intervals representative of intervals between intrinsic depolarization events and peaks of corresponding repolarization events within electrical cardiac signals; and
detecting an episode of cardiac ischemia based on a decrease in at least one of the paced repolarization peak-based intervals and the sensed repolarization peak-based intervals.
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Abstract
Techniques are described for detecting ischemia, hypoglycemia or hyperglycemia based on intracardiac electrogram (IEGM) signals. Ischemia is detected based on a shortening of the interval between the QRS complex and the end of a T-wave (QTmax), alone or in combination with a change in ST segment elevation. Alternatively, ischemia is detected based on a change in ST segment elevation combined with minimal change in the interval between the QRS complex and the end of the T-wave (QTend). Hypoglycemia is detected based on a change in ST segment elevation along with a lengthening of either QTmax or QTend. Hyperglycemia is detected based on a change in ST segment elevation along with minimal change in QTmax and in QTend. By exploiting QTmax and QTend in combination with ST segment elevation, changes in ST segment elevation caused by hypo/hyperglycemia can be properly distinguished from changes caused by ischemia.
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Citations
17 Claims
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1. A method for use with an implantable medical device for detecting cardiac ischemia in a patient in which the device is implanted, the method comprising:
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tracking paced repolarization peak-based intervals representative of intervals between depolarization events induced by pacing pulses delivered by the implantable medical device, and peaks of corresponding repolarization events within electrical cardiac signals; tracking sensed repolarization peak-based intervals separate from the paced repolarization peak-based intervals, wherein the sensed repolarization peak-based intervals comprise intervals representative of intervals between intrinsic depolarization events and peaks of corresponding repolarization events within electrical cardiac signals; and detecting an episode of cardiac ischemia based on a decrease in at least one of the paced repolarization peak-based intervals and the sensed repolarization peak-based intervals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A system for use with an implantable medical device for detecting cardiac ischemia in a patient in which the device is implanted comprising:
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a timing unit operative to track paced QTmax values representative of intervals between QRS complexes induced by pacing pulses delivered by the implantable medical device, and peaks of corresponding T-waves within electrical cardiac signals and to separately track sensed QTmax values representative of intervals between intrinsic QRS complexes and peaks of corresponding T-waves within electrical cardiac signals; and a cardiac ischemia detection unit operative to detect an episode of cardiac ischemia based on a decrease in at least one of the paced QTmax intervals and the sense QTmax intervals.
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17. A method for use with an implantable medical device for detecting cardiac ischemia in a patient in which the device is implanted comprising:
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tracking elevations of segments of cardiac signals between depolarization events and corresponding repolarization events within electrical cardiac signals; detecting a possible ischemia based on a change in elevation of the ST segments; tracking repolarization-based intervals representative of intervals between depolarization events and corresponding repolarization events within the electrical cardiac signals; and verifying the detection of ischemia based on an examination of the repolarization-based intervals.
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Specification