Trending S1 heart sounds amplitudes in ambulatory patients for worsening HF detection
First Claim
1. An apparatus comprising:
- a cardiac signal sensing circuit configured to sense a plurality of cardiac signals representative of electrical cardiac activity of a subject;
a heart sound sensing circuit configured to sense a plurality of heart sound signals representative of intrinsic mechanical cardiac activity of the subject; and
a signal processing circuit configured to;
detect a signal fiducial in a sensed cardiac signal and initiate a measurement window in a time relationship to the detected fiducial;
determine amplitudes of S1 heart sounds during the measurement window using the plurality of sensed heart sound signals;
calculate a short-term central tendency of the S1 heart sound amplitudes over a time duration of N days, where N is a positive integer less than or equal to five;
calculate a long-term central tendency of the S1 heart sound amplitudes for a time duration longer than N days, during different days than the short-term central tendency, and at least partially prior to the short-term central tendency;
trend a long-term to short-term difference between the calculated long-term central tendency of the S1 heart sound amplitudes and the calculated short-term central tendency of the S1 heart sound amplitudes; and
generate an alert using the calculated short-term central tendency and the calculated long-term central tendency.
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Accused Products
Abstract
An apparatus comprises a cardiac signal sensing circuit, a heart sound sensing circuit, and a signal processing circuit. The cardiac signal sensing circuit is configured to sense a plurality of cardiac signals representative of electrical cardiac activity of a subject. The heart sound sensing circuit is configured to sense a plurality of unfiltered heart sound signals representative of intrinsic mechanical cardiac activity of the subject. The signal processing circuit is configured to: detect an R-wave in a sensed cardiac signal and initiate a measurement window in a time relationship to the detected R-wave; determine amplitude of an S1 heart sound using a heart sound signal sensed during the measurement window; trend S1 heart sound amplitudes determined for the plurality of the unfiltered heart sound signals; and generate an alert when the trended S1 heart sound amplitude decreases below a threshold amplitude value.
18 Citations
17 Claims
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1. An apparatus comprising:
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a cardiac signal sensing circuit configured to sense a plurality of cardiac signals representative of electrical cardiac activity of a subject; a heart sound sensing circuit configured to sense a plurality of heart sound signals representative of intrinsic mechanical cardiac activity of the subject; and a signal processing circuit configured to; detect a signal fiducial in a sensed cardiac signal and initiate a measurement window in a time relationship to the detected fiducial; determine amplitudes of S1 heart sounds during the measurement window using the plurality of sensed heart sound signals; calculate a short-term central tendency of the S1 heart sound amplitudes over a time duration of N days, where N is a positive integer less than or equal to five; calculate a long-term central tendency of the S1 heart sound amplitudes for a time duration longer than N days, during different days than the short-term central tendency, and at least partially prior to the short-term central tendency; trend a long-term to short-term difference between the calculated long-term central tendency of the S1 heart sound amplitudes and the calculated short-term central tendency of the S1 heart sound amplitudes; and generate an alert using the calculated short-term central tendency and the calculated long-term central tendency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of controlling operation of a medical device system, the method comprising:
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sensing a plurality of cardiac signals representative of electrical cardiac activity of a subject; sensing a plurality of heart sound signals representative of intrinsic mechanical cardiac activity of the subject; determining amplitude of an S1 heart sound using a heart sound signal during a measurement window initiated in a specified time relationship to a signal fiducial detected in a cardiac signal; calculating a short-term central tendency of the S1 heart sound amplitudes over a time duration of N days, where N is a positive integer less than or equal to five; calculating a long-term central tendency of the S1 heart sound amplitudes for a time duration longer than N days, during different days than the short-term central tendency, and at least partially prior to the short-term central tendency; trending a long-term to short-term difference between the calculated long-term central tendency of the S1 heart sound amplitudes and the calculated short-term central tendency of the S1 heart sound amplitudes; and generating an alert using the calculated short-term central tendency and long-term central tendency. - View Dependent Claims (13, 14)
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15. A system comprising a first medical device and a second medical device, wherein the first medical device includes:
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a cardiac signal sensing circuit configured to sense a cardiac signal representative of electrical cardiac activity of a subject; an R-wave detection circuit configured to detect an R-wave in a sensed cardiac signal; a heart sound sensing circuit configured to sense an heart sound signal representative of intrinsic mechanical cardiac activity of the subject; a sampling circuit configured to produce sampled values of the heart sound signal during a measurement window initiated in a time relation to the R-wave detected in the cardiac signal; a first communication circuit configured to communicate the sampled values to the second medical device, wherein the second medical device includes; a second communication circuit configured to communicate information with the first medical device including to receive the sampled values; and a signal processing circuit configured to; calculate a root mean square (RMS) value of amplitude of an S1 heart sound during the measurement window; calculate a short-term central tendency of the RMS values of S1 heart sound amplitude for a time duration of N days, where N is a positive integer less than or equal to five; calculate a long-term central tendency of the RMS values of S1 heart sound amplitude for a time duration longer than N days, wherein the long-term central tendency is calculated during different days than the short-term central tendency and at least partially prior to the short-term central tendency; trend a long-term to short-term difference between the calculated long-term central tendency and the calculated short-term central tendency; and generate an alert using the calculated short-term central tendency and long-term central tendency. - View Dependent Claims (16, 17)
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Specification