Systems and methods for detecting and compensating for changes in posture during ischemia detection using an implantable medical device
First Claim
1. A method for use with an implantable medical device for detecting changes in posture in a patient in which the device is implanted, comprising:
- sensing an electrical cardiac signal within the patient using the device;
obtaining atrial paced depolarization integral (PDI) measurements of the cardiac signal affected by one or more of patient posture, patient activity and cardiac ischemia;
determining an atrial PDI baseline level corresponding to a first posture of a patient;
detecting for a significant transient variation period in atrial PDI measurements during which the peak-to-peak values of the PDI measurements fluctuate between two to three times the peak-to-peak values of the atrial PDI measurements defining the first posture atrial PDI baseline level;
detecting for a transient decay period subsequent to a significant transient variation period during which the transient PDI measurements gradually decay to a subsequent baseline atrial PDI corresponding to a second posture of the patient;
detecting, using a microprocessor, a significant change in patient posture when the significant transient variation period is detected, the transient decay period is detected and a difference between the initial atrial PDI baseline and the subsequent atrial PDI baseline exceeds a predetermined threshold indicative of a significant posture change; and
detecting, using the microprocessor, patient activity without a significant change in posture when the significant transient variation period is detected and the difference between the initial atrial PDI baseline and the subsequent atrial PDI baseline does not exceed the predetermined threshold.
1 Assignment
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Accused Products
Abstract
Techniques are described for detecting changes in posture; detecting cardiac ischemia while accounting for changes in posture; and delivering therapy or warning signals in response thereto using the implantable medical device. In one example, the device detects variations in the electrical cardiac signals indicative of a possible episode of cardiac ischemia. Changes in patient posture are detected as well using an accelerometer or similar device. Then, an episode of cardiac ischemia is detected based on the variations in the cardiac signals while distinguishing variations due to changes in posture. In another example, the device instead detects changes in posture based on transient changes in morphological features of electrical cardiac signals.
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Citations
16 Claims
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1. A method for use with an implantable medical device for detecting changes in posture in a patient in which the device is implanted, comprising:
- sensing an electrical cardiac signal within the patient using the device;
obtaining atrial paced depolarization integral (PDI) measurements of the cardiac signal affected by one or more of patient posture, patient activity and cardiac ischemia; determining an atrial PDI baseline level corresponding to a first posture of a patient; detecting for a significant transient variation period in atrial PDI measurements during which the peak-to-peak values of the PDI measurements fluctuate between two to three times the peak-to-peak values of the atrial PDI measurements defining the first posture atrial PDI baseline level; detecting for a transient decay period subsequent to a significant transient variation period during which the transient PDI measurements gradually decay to a subsequent baseline atrial PDI corresponding to a second posture of the patient; detecting, using a microprocessor, a significant change in patient posture when the significant transient variation period is detected, the transient decay period is detected and a difference between the initial atrial PDI baseline and the subsequent atrial PDI baseline exceeds a predetermined threshold indicative of a significant posture change; and detecting, using the microprocessor, patient activity without a significant change in posture when the significant transient variation period is detected and the difference between the initial atrial PDI baseline and the subsequent atrial PDI baseline does not exceed the predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- sensing an electrical cardiac signal within the patient using the device;
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15. A system for use with an implantable medical device for implant within a patient, comprising:
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a cardiac signal detection unit configured to sense an electrical cardiac signal within the patient and to obtain atrial paced depolarization integral (PDI) measurements of the cardiac signal affected by one or more of patient posture, patient activity and cardiac ischemia from the cardiac signal; and a posture change detection unit configured to determine an atrial PDI baseline level corresponding to a first posture of a patient, to detect for a significant transient variation period in the atrial PDI measurements during which the peak-to-peak values of the PDI measurements fluctuate between two to three times the peak-to-peak values of the atrial PDI measurements defining the first-posture atrial PDI baseline level, to detect for a transient decay period subsequent to a significant transient variation period during which the transient PDI measurements gradually decay to a subsequent baseline atrial PDI corresponding to a second posture of the patient, to detect a significant change in patient posture when the significant transient variation period is detected, the transient decay period is detected and a difference between the initial atrial PDI baseline and the subsequent atrial PDI baseline exceeds a predetermined threshold indicative of a significant posture change, and to detect patient activity without a significant change in posture when the significant transient variation period is detected and the difference between the initial atrial PDI baseline and the subsequent atrial PDI baseline does not exceed the predetermined threshold.
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16. A system for use with an implantable medical device for implant within a patient, comprising:
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means for sensing an intracardiac electrogram (IEGM) signal within the patient;
means for obtaining atrial paced depolarization integral (PDI) measurements of the cardiac signal affected by one or more of patient posture, patient activity and cardiac ischemia from the IEGM;means for determining an atrial PDI baseline level corresponding to a first posture of a patient; means for detecting for a significant transient variation in atrial PDI measurements during which the peak-to-peak values of the PDI measurements fluctuate between two to three times the peak-to-peak values of the atrial PDI measurements defining the first-posture atrial PDI baseline level; means for detecting for a transient decay period subsequent to a significant transient variation period during which the transient PDI measurements gradually decay to a subsequent baseline atrial PDI corresponding to a second posture of the patient; means for detecting a significant change in patient posture when the significant transient variation period is detected, the transient decay period is detected and a difference between the initial atrial PDI baseline and the subsequent atrial PDI baseline exceeds a predetermined threshold indicative of a significant posture change; and means for detecting patient activity without a significant change in posture when the significant transient variation period is detected and the difference between the initial atrial PDI baseline and the subsequent atrial PDI baseline does not exceed the predetermined threshold.
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Specification