Managing preload reserve by tracking the ventricular operating point with heart sounds
First Claim
1. A system comprising:
- a preload altering device;
an implantable device includinga transducer;
a control circuit coupled to the transducer, the control circuit configured to cooperate with the transducer to monitor an S1 heart sound emitted by a heart of a patient, monitor a proxy variable indicating preload exhibited by the heart, and communicate a control signal to the preload altering device to deliver a level of a diureticwherein the control circuit is configured to measure a first state of the patient based on a first monitored S1 heart sound and a first monitored proxy variable and to measure a second state of a patient based on a second monitored S1 heart sound and a second monitored proxy variable; and
wherein the control circuit is configured to determine that the heart has reached a critical preload by a comparison of the first state to the second state; and
wherein the control circuit is configured to determine that the heart has reached a critical preload by a determination of a slope between the first state and the second state and comparing the slope to a threshold value, the threshold value being a value that approximately corresponds with the critical preload level on a Frank Starling curve.
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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.
96 Citations
17 Claims
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1. A system comprising:
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a preload altering device; an implantable device including a transducer; a control circuit coupled to the transducer, the control circuit configured to cooperate with the transducer to monitor an S1 heart sound emitted by a heart of a patient, monitor a proxy variable indicating preload exhibited by the heart, and communicate a control signal to the preload altering device to deliver a level of a diuretic wherein the control circuit is configured to measure a first state of the patient based on a first monitored S1 heart sound and a first monitored proxy variable and to measure a second state of a patient based on a second monitored S1 heart sound and a second monitored proxy variable; and wherein the control circuit is configured to determine that the heart has reached a critical preload by a comparison of the first state to the second state; and wherein the control circuit is configured to determine that the heart has reached a critical preload by a determination of a slope between the first state and the second state and comparing the slope to a threshold value, the threshold value being a value that approximately corresponds with the critical preload level on a Frank Starling curve. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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monitoring an S1 heart sound amplitude emitted by a heart of a patient; monitoring 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; measuring a first preload 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;measuring a second preload 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; anddetermining whether the heart has exhibited a preload state exceeding the critical preload by comparing the state variable pair of the second preload state to the state variable pair of the first preload state; communicating the preload state to a preload altering device if the determined preload state exceeds the critical preload. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification