Third heart sound activity index for heart failure monitoring
First Claim
1. An implantable cardiac rhythm management system, comprising:
- a cardiac sensing circuit configured to sense at least one electrogram;
a cardiac event detector coupled to the cardiac sensing circuit and configured to produce a cardiac signal indicative of heart beats using the at least one electrogram;
an acoustic sensor configured to sense an acoustic signal indicative of third heart sounds (S3);
a sensor processing circuit coupled to the acoustic sensor and configured to precondition the sensed acoustic signal;
a heart sound processor coupled to the cardiac event detector and the sensor processing circuit, the heart sound processor including;
a beat counter configured to count the heart beats using the cardiac signal;
a heart sound detector configured to detect S3 using the preconditioned acoustic signal;
a heart sound counter configured to count S3 beats each being a heart beat during which one of S3 is detected; and
a heart sound analyzer including a ratio calculator to calculate an S3 index being a ratio of a number of the S3 beats counted during a predetermined time period to the number of the heart beats counted during the predetermined time period; and
a hermetically sealed can housing at least the cardiac sensing circuit, the cardiac event detector, the sensor processing circuit, and the heart sound processor.
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Abstract
A cardiac rhythm management system provides for the trending of a third heart sound (S3) index. The S3 index is a ratio, or an estimate of the ratio, of the number of S3 beats to the number of all heart heats, where the S3 beats are each a heart beat during which an occurrence of S3 is detected. An implantable sensor such as an accelerometer or a microphone senses an acoustic signal indicative heart sounds including S3. An S3 detector detects occurrences of S3 from the acoustic signal. A heart sound processing system trends the S3 index on a periodic basis to allow continuous monitoring of the S3 activity level, which is indicative of conditions related to heart failure.
118 Citations
20 Claims
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1. An implantable cardiac rhythm management system, comprising:
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a cardiac sensing circuit configured to sense at least one electrogram; a cardiac event detector coupled to the cardiac sensing circuit and configured to produce a cardiac signal indicative of heart beats using the at least one electrogram; an acoustic sensor configured to sense an acoustic signal indicative of third heart sounds (S3); a sensor processing circuit coupled to the acoustic sensor and configured to precondition the sensed acoustic signal; a heart sound processor coupled to the cardiac event detector and the sensor processing circuit, the heart sound processor including; a beat counter configured to count the heart beats using the cardiac signal; a heart sound detector configured to detect S3 using the preconditioned acoustic signal; a heart sound counter configured to count S3 beats each being a heart beat during which one of S3 is detected; and a heart sound analyzer including a ratio calculator to calculate an S3 index being a ratio of a number of the S3 beats counted during a predetermined time period to the number of the heart beats counted during the predetermined time period; and a hermetically sealed can housing at least the cardiac sensing circuit, the cardiac event detector, the sensor processing circuit, and the heart sound processor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for analyzing heart sounds, comprising:
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sensing at least one electrogram; producing a cardiac signal indicative of heart beats using the at least one electrogram; sensing an acoustic signal indicative of third heart sounds (S3) using an implantable acoustic sensor; preconditioning the sensed acoustic signal; processing the cardiac signal and the acoustic signal using an implantable medical device, the processing including; counting the heart beats using the cardiac signal; detecting S3 using the preconditioned acoustic signal; counting S3 beats each being a heart beat during which one of S3 is detected; and calculating an S3 index being a ratio of a number of the S3 beats counted during a predetermined time period to the number of the heart beats counted during the predetermined time period. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification