Methods and apparatus for classifying cardiac events with an implantable cardiac device
First Claim
1. An implantable cardiac device for monitoring a cardiac signal from a patient'"'"'s heart via leads connected to said heart, processing a segment of said cardiac signal that corresponds to a cardiac event, and classifying said cardiac event as being one of a plurality of possible types of cardiac events, each such possible type of cardiac event being characterized by a separate set of reference values, the implantable cardiac device comprising:
- sensing circuitry connected to said leads for measuring said cardiac signals;
buffer means for storing said cardiac signals;
means for generating a set of feature values for said cardiac signal segment; and
means for classifying said cardiac event by comparing said set of feature values to said sets of reference values to determine the closest match to said set of feature values from among said sets of reference values.
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Accused Products
Abstract
Methods and apparatus are provided for classifying cardiac events with an implantable cardiac device. Cardiac signals are stored in a buffer. When a significant cardiac event is confirmed, a corresponding segment of the stored cardiac signals is processed to generate a set of feature values. The set of feature values is compared to various sets of reference values. Each set of reference values preferably corresponds to a separate type of cardiac event, so that the cardiac device may classify the significant cardiac event by matching its set of feature values to a set of reference values. Feature values include the maximum positive and negative slew rates exhibited by the cardiac signal during the segment, the maximum positive and negative signal amplitudes, the times to reach the maximum positive and negative signal amplitudes, the area under the cardiac signal curve, the area under the cardiac signal curve above zero as compared to the area below zero, and the number of zero crossings made by the cardiac signal. Additional feature values are generated by simultaneously processing the cardiac signals measured along two different vector directions in the heart.
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Citations
64 Claims
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1. An implantable cardiac device for monitoring a cardiac signal from a patient'"'"'s heart via leads connected to said heart, processing a segment of said cardiac signal that corresponds to a cardiac event, and classifying said cardiac event as being one of a plurality of possible types of cardiac events, each such possible type of cardiac event being characterized by a separate set of reference values, the implantable cardiac device comprising:
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sensing circuitry connected to said leads for measuring said cardiac signals; buffer means for storing said cardiac signals; means for generating a set of feature values for said cardiac signal segment; and means for classifying said cardiac event by comparing said set of feature values to said sets of reference values to determine the closest match to said set of feature values from among said sets of reference values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A method for monitoring cardiac signals from a patient'"'"'s heart with an implantable cardiac device having sensing circuitry connected to said heart via leads for receiving said cardiac signals and having a buffer in which a cardiac signal segment that corresponds to a cardiac event is stored, the method including the classification of said cardiac event as being one of a plurality of possible types of cardiac events, each such possible type of cardiac event being characterized by a separate set of reference values, the method comprising the steps of:
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measuring said cardiac signals with said sensing circuitry; storing said cardiac signals in said buffer; generating a set of feature values for said cardiac signal segment; and classifying said cardiac event by comparing said set of feature values to each of said sets of reference values to determine the closest match to said set of feature values from among said sets of reference values. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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59. An implantable cardiac device for monitoring a cardiac signal from a patient'"'"'s heart via leads connected to said heart, processing a segment of said cardiac signal that corresponds to a cardiac event, and classifying said cardiac event as being one of a plurality of possible types of cardiac events, each such possible type of cardiac event being characterized by a separate set of reference values, the implantable cardiac device comprising:
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sensing circuitry, connected to said leads, for simultaneously measuring cardiac signals with a first pair of electrodes along a first vector in said heart and a second pair of electrodes along a second vector in said heart; buffer means for storing said cardiac signals; means for generating a set of feature values for said cardiac signal segment, said means for generating comprising means for comparing said cardiac signals measured along said first vector with said cardiac signals measured along said second vector; and means for classifying said cardiac event by comparing said set of feature values to said sets of reference values to determine the closest match to said set of feature values from among said sets of reference values.
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60. A method for monitoring cardiac signals from a patient'"'"'s heart with an implantable cardiac device having sensing circuitry connected to said heart via leads for receiving said cardiac signals and having a buffer in which a cardiac signal segment that corresponds to a cardiac event is stored, the method including the classification of said cardiac event as being one of a plurality of possible types of cardiac events, each such possible type of cardiac event being characterized by a separate set of reference values, the method comprising the steps of:
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using said sensing circuitry to simultaneously measure cardiac signals with a first pair of electrodes along a first vector in said heart and with a second pair of electrodes along a second vector in said heart; storing said cardiac signals in said buffer; generating a set of feature values for said cardiac signal segment by comparing said cardiac signals measured along said first vector with said cardiac signals measured along said second vector; and classifying said cardiac event by comparing said set of feature values to each of said sets of reference values to determine the closest match to said set of feature values from among said sets of reference values.
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61. An implantable cardiac device for monitoring a cardiac signal from a patient'"'"'s heart via leads connected to said heart, processing a segment of said cardiac signal that corresponds to a cardiac event, and classifying said cardiac event as being one of a plurality of possible types of cardiac events, each such possible type of cardiac event being characterized by a separate set of reference values, the implantable cardiac device comprising:
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sensing circuitry connected to said leads for measuring said cardiac signals; buffer means for storing said cardiac signals; means for generating a set of feature values for said cardiac signal segment, wherein the feature values are selected from the group consisting of; a maximum positive slew rate, a maximum negative slew rate, a maximum positive signal amplitude, a maximum negative signal amplitude, a time to reach a maximum positive signal amplitude, a time to reach a maximum negative signal amplitude, an area under said cardiac signal segment, an area under said cardiac signal segment above zero as compared to an area under said cardiac signal segment below zero, and a number of zero crossings made by said cardiac signal segment; and means for classifying said cardiac event by comparing said set of feature values to said sets of reference values to determine the closest match to said set of feature values from among said sets of reference values. - View Dependent Claims (62, 63)
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64. A method for monitoring cardiac signals from a patient'"'"'s heart with an implantable cardiac device having sensing circuitry connected to said heart via leads for receiving said cardiac signals and having a buffer in which a cardiac signal segment that corresponds to a cardiac event is stored, the method including the classification of said cardiac event as being one of a plurality of possible types of cardiac events, each such possible type of cardiac event being characterized by a separate set of reference values, the method comprising the steps of:
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measuring said cardiac signals with said sensing circuitry; storing said cardiac signals in said buffer; generating a set of feature values for said cardiac signal segment selected from the group of feature values consisting of; a maximum positive slew rate, a maximum negative slew rate, a maximum positive signal amplitude, a maximum negative signal amplitude, a time to reach a maximum positive signal amplitude, a time to reach a maximum negative signal amplitude, an area under said cardiac signal segment, an area under said cardiac signal segment above zero as compared to an area under said cardiac signal segment below zero, and a number of zero crossings made by said cardiac signal segment; and classifying said cardiac event by comparing said set of feature values to each of said sets of reference values to determine the closest match to said set of feature values from among said sets of reference values.
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Specification