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 repolarization peak-based intervals representative of intervals between depolarization events and peaks of corresponding repolarization events within electrical cardiac signals;
tracking repolarization end-based intervals representative of intervals between depolarization events and ends of corresponding repolarization events within electrical cardiac signals; and
detecting an episode of cardiac ischemia based on the combination of a decrease in the repolarization peak-based intervals and a lack of significant change in durations of the repolarization end-based intervals.
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Accused Products
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.
147 Citations
16 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 repolarization peak-based intervals representative of intervals between depolarization events and peaks of corresponding repolarization events within electrical cardiac signals; tracking repolarization end-based intervals representative of intervals between depolarization events and ends of corresponding repolarization events within electrical cardiac signals; and detecting an episode of cardiac ischemia based on the combination of a decrease in the repolarization peak-based intervals and a lack of significant change in durations of the repolarization end-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 repolarization peak-based intervals representative of intervals between depolarization events and peaks of corresponding repolarization events within electrical cardiac signals and to track repolarization end-based intervals representative of intervals between depolarization events and ends of corresponding repolarization events within electrical cardiac signals; and a cardiac ischemia detection unit operative to detect an episode of cardiac ischemia based on the combination of a decrease in the repolarization peak-based intervals and a lack of significant change in durations of the repolarization end-based intervals.
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Specification