Systems and methods for distinguishing cardiac ischemia from systemic influences on IEGM morphology using an implantable medical device
First Claim
1. A method, for use with an implantable medical device, for distinguishing cardiac ischemia from other conditions affecting a morphology of electrical cardiac signals sensed within a patient in which the device is implanted, the method comprising:
- monitoring electrical cardiac signals from a plurality of spatially-distinct locations within a heart of the patient;
detecting changes in morphological features of the electrical cardiac signals indicative of possible cardiac ischemia within the patient;
determining whether the changes in the morphological features are the result of spatially localized changes within a portion of the heart by;
determining that the changes in the detected morphological features are global if the changes are detected in signals detected at each of the plurality of spatially-distinct locations; and
determining that the changes in the detected morphological features are local if the changes are detected in signals detected at one or more, but not all, of the plurality of spatially-distinct locations;
determining that the changes in morphological features of the electrical cardiac signals indicate cardiac ischemia if the changes are determined to be local; and
determining that the changes in morphological features of the electrical cardiac signals indicate systemic influences if the changes are determined to be global.
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Abstract
Techniques are provided for use in a pacemaker or implantable cardioverter/defibrillator (ICD) for distinguishing cardiac ischemia from other conditions affecting the morphology of electrical cardiac signals sensed within a patient, such as hypoglycemia, hyperglycemia or other systemic conditions. In one example, the device detects changes in morphological features of cardiac signals indicative of possible cardiac ischemia within the patient, such as changes in ST segment elevation within an intracardiac electrogram (IEGM). The device determines whether the changes in the morphological features are the result of spatially localized changes within a portion of the heart and then distinguishes cardiac ischemia from other conditions affecting the morphology of electrical cardiac signals based on that determination. In another example, the device exploits the interval between the peak of a T-wave (Tmax) and the end of the T-wave (Tend). A significant increase in the Tend−Tmax interval is indicative of ischemia rather than a systemic condition.
50 Citations
15 Claims
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1. A method, for use with an implantable medical device, for distinguishing cardiac ischemia from other conditions affecting a morphology of electrical cardiac signals sensed within a patient in which the device is implanted, the method comprising:
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monitoring electrical cardiac signals from a plurality of spatially-distinct locations within a heart of the patient; detecting changes in morphological features of the electrical cardiac signals indicative of possible cardiac ischemia within the patient; determining whether the changes in the morphological features are the result of spatially localized changes within a portion of the heart by; determining that the changes in the detected morphological features are global if the changes are detected in signals detected at each of the plurality of spatially-distinct locations; and determining that the changes in the detected morphological features are local if the changes are detected in signals detected at one or more, but not all, of the plurality of spatially-distinct locations; determining that the changes in morphological features of the electrical cardiac signals indicate cardiac ischemia if the changes are determined to be local; and determining that the changes in morphological features of the electrical cardiac signals indicate systemic influences if the changes are determined to be global. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system, for use with an implantable medical device, for distinguishing cardiac ischemia from other conditions affecting a morphology of electrical cardiac signals sensed within a patient in which the device is implanted, the system comprising:
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a plurality of electrodes configured to monitor electrical cardiac signals from a plurality of spatially-distinct locations within a heart of the patient; a morphological feature detecting unit operative to detect changes in morphological features of the electrical cardiac signals indicative of possible cardiac ischemia within the patient; and a cardiac ischemia discrimination unit configured to; determine that the changes in the detected morphological features are global if the changes are detected in signals detected at each of the plurality of spatially-distinct locations; determine that the changes in the detected morphological features are local if the changes are detected in signals detected at one or more, but not all, of the plurality of spatially-distinct locations; wherein; when the changes in the detected morphological features are determined to be global, the cardiac ischemia discrimination unit is configured to determine that the changes in morphological features of the electrical cardiac signals indicate systemic influences; and when the changes in the detected morphological features are determined to be local, the cardiac ischemia discrimination unit is configured to determine that the changes in the morphological features of the electrical cardiac signals indicate cardiac ischemia.
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15. A system, for use with an implantable medical device, for distinguishing cardiac ischemia from other conditions affecting a morphology of electrical cardiac signals sensed within a patient in which the device is implanted, the system comprising:
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a plurality of electrodes configured to monitor electrical cardiac signals from a plurality of spatially-distinct locations within a heart of the patient; a morphological feature detecting unit operative to detect changes in morphological features of the electrical cardiac signals indicative of possible cardiac ischemia within the patient; a timing unit operative to track repolarization-based intervals of intervals between the peaks of T-waves and the ends of T-waves within the electrical cardiac signals; and a cardiac ischemia discrimination unit configured to; determine if the T-wave based intervals indicate a cardiac ischemia or systemic influences; determine that the changes in the detected morphological features are global if the changes are detected in signals detected at each of the plurality of spatially-distinct locations; determine that the changes in the detected morphological features are local if the changes are detected in signals detected at one or more, but not all, of the plurality of spatially-distinct locations; wherein; when the changes in the detected morphological features are determined to be global and the T-wave based intervals indicate systemic influences, the cardiac ischemia discrimination unit is configured to determine that the changes in morphological features of the electrical cardiac signals indicate systemic influences; and when the changes in the detected morphological features are determined to be local and the T-wave based intervals indicate cardiac ischemia, the cardiac ischemia discrimination unit is configured to determine that the changes in the morphological features of the electrical cardiac signals indicate cardiac ischemia.
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Specification