MANAGING PRELOAD RESERVE BY TRACKING THE VENTRICULAR OPERATING POINT WITH HEART SOUNDS
First Claim
1. A system comprising:
- an ambulatory device including;
a transducer; and
a control circuit coupled to the transducer, the control circuit configured to;
monitor an S1 heart sound amplitude emitted by a heart of a patient;
monitor a proxy variable indicating preload exhibited by the heart, the proxy variable including at least one of a heart sound amplitude or a blood pressure magnitude;
measure a first inotropic state defined by a state variable pair obtained during a first time period, the state variable pair comprising;
(1) an S1 heart sound amplitude value; and
(2) a proxy variable value;
measure a second inotropic state defined by a state variable pair obtained during a second time period, the state variable pair comprising;
(1) an S1 heart sound amplitude value; and
(2) a proxy variable value; and
determine whether the heart has exhibited an inotropic state change by comparing the state variable pair of the second inotropic state to the state variable pair of the first inotropic state.
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Accused Products
Abstract
A system and method for managing preload reserve and tracking the inotropic state of a patient'"'"'s heart. The S1 heart sound is measured as a proxy for direct measurement of stroke volume. The S3 heart sound may be measured as a proxy for direct measurement of preload level. The S1-S3 pair yield a point on a Frank Starling type of curve, and reveal information regarding the patient'"'"'s ventricular operating point and inotropic state. As an alternative, or in addition to, measurement of the S3 heart sound, the S4 heart sound may be measured or a direct pressure measurement may be made for the sake of determining the patient'"'"'s preload level. The aforementioned measurements may be made by a cardiac rhythm management device, such as a pacemaker or implantable defibrillator.
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Citations
20 Claims
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1. A system comprising:
an ambulatory device including; a transducer; and a control circuit coupled to the transducer, the control circuit configured to; monitor an S1 heart sound amplitude emitted by a heart of a patient; monitor a proxy variable indicating preload exhibited by the heart, the proxy variable including at least one of a heart sound amplitude or a blood pressure magnitude; measure a first inotropic state defined by a state variable pair obtained during a first time period, the state variable pair comprising;
(1) an S1 heart sound amplitude value; and
(2) a proxy variable value;measure a second inotropic state defined by a state variable pair obtained during a second time period, the state variable pair comprising;
(1) an S1 heart sound amplitude value; and
(2) a proxy variable value; anddetermine whether the heart has exhibited an inotropic state change by comparing the state variable pair of the second inotropic state to the state variable pair of the first inotropic state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A system comprising:
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a preload altering device; and an ambulatory device including; a transducer; and a control circuit coupled to the transducer, the control circuit configured to; monitor an S1 heart sound amplitude emitted by a heart of a patient; monitor a proxy variable indicating preload exhibited by the heart, the proxy variable including at least one of a heart sound amplitude or a blood pressure magnitude; measure a first inotropic state defined by a state variable pair obtained during a first time period, the state variable pair comprising;
(1) an S1 heart sound amplitude value; and
(2) a proxy variable value;measure a second inotropic state defined by a state variable pair obtained during a second time period, the state variable pair comprising;
(1) an S1 heart sound amplitude value; and
(2) a proxy variable value; anddetermine whether the heart has exhibited an inotropic state change by comparing the state variable pair of the second inotropic state to the state variable pair of the first inotropic state; and communicate a control signal to the preload altering device using information about the determined inotropic state change; wherein the control circuit monitors a proxy variable indicating preload by monitoring an S3 or S4 heart sound or a blood pressure; and wherein the control circuit monitors a proxy variable indicating preload by;
sensing a plurality of S3 or S4 heart sounds emitted by a heart of a patient, each of which is represented as a time-varying signal with at least one maxima and minima; and
finding a greatest difference between a minima and maxima that are consecutive for each of the time-varying signals representing the plurality of S3 or S4 heart sounds, yielding a set of peak-to-peak differences; and
wherein the control circuit monitors an inotropic state of the heart, using the set of peak-to-peak differences and an indicator of stroke volume.
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20. A system comprising:
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an inotropic state altering device; and an ambulatory device including; a transducer; and a control circuit coupled to the transducer, the control circuit configured to; monitor an S1 heart sound amplitude emitted by a heart of a patient; monitor a proxy variable indicating preload exhibited by the heart, the proxy variable including at least one of a heart sound amplitude or a blood pressure magnitude; measure a first inotropic state defined by a state variable pair obtained during a first time period, the state variable pair comprising;
(1) an S1 heart sound amplitude value; and
(2) a proxy variable value;measure a second inotropic state defined by a state variable pair obtained during a second time period, the state variable pair comprising;
(1) an S1 heart sound amplitude value; and
(2) a proxy variable value; anddetermine whether the heart has exhibited an inotropic state change by comparing the state variable pair of the second inotropic state to the state variable pair of the first inotropic state; and communicate a control signal to the inotropic state altering device using information about the determined inotropic state change; wherein the control circuit monitors a proxy variable indicating preload by monitoring an S3 or S4 heart sound or blood pressure; and wherein the control circuit monitors a proxy variable indicating preload by;
sensing a plurality of S3 or S4 heart sounds emitted by a heart of a patient, each of which is represented as a time-varying signal with at least one maxima and minima; and
finding a greatest difference between a minima and maxima that are consecutive for each of the time-varying signals representing the plurality of S3 or S4 heart sounds, yielding a set of peak-to-peak differences; and
wherein the control circuit monitors an inotropic state of the heart, using the set of peak-to-peak differences and an indicator of stroke volume.
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Specification