Method and apparatus for detecting atrial filling pressure

Abstract

A cardiac rhythm management system provides for ambulatory monitoring of hemodynamic performance based on quantitative measurements of heart sound related parameters for diagnostic and therapeutic purposes. Monitoring of such heart sound related parameters allows the cardiac rhythm management system to determine a need for delivering a therapy and/or therapy parameter adjustments based on conditions of a heart. This monitoring also allows a physician to observe or assess the hemodynamic performance for diagnosing and making therapeutic decisions. Because the conditions of the heart may fluctuate and may deteriorate significantly between physician visits, the ambulatory monitoring, performed on a continuous or periodic basis, ensures a prompt response by the cardiac rhythm management system that may save a life, prevent hospitalization, or prevent further deterioration of the heart.

1 . (canceled) 
     
     
         2 . A system comprising:
 a heart sound sensor configured to sense a heart sound signal of a patient's heart;   a heart sound detector, coupled to the heart sound sensor, the heart sound detector configured to detect at least one parameter using the heart sound signal, the at least one parameter including information about an S3 heart sound, and wherein the heart sound detector is configured to identify an S2 heart sound and to identify the S3 heart sound relative to the identified S2 heart sound; and   a processor circuit, coupled to the heart sound detector, the processor circuit configured to use the parameter including information about the S3 heart sound to provide a diagnostic indicator about the patient.   
     
     
         3 . The system of  claim 2 , wherein the heart sound detector is configured to detect, as the at least one parameter, a duration of the S3 heart sound; and
 wherein the processor circuit is configured to use the duration of the S3 heart sound to identify, as the diagnostic indicator, a change in a ventricular diastolic filling pattern.   
     
     
         4 . The system of  claim 2 , wherein the heart sound detector is configured to identify a time of onset of the S2 heart sound and to identify a time of onset of the S3 heart sound relative to the time of onset of the S2 heart sound, and wherein the heart sound detector is configured to detect the at least one parameter using S3 information gathered at or after the identified time of onset of the S3 heart sound. 
     
     
         5 . The system of  claim 2 , wherein the heart sound detector is configured to detect a fundamental frequency of the S3 heart sound as the at least one parameter. 
     
     
         6 . The system of  claim 5 , wherein the processor circuit is configured to provide, as the diagnostic indicator, an indication of the heart's left ventricular wall stiffness using the fundamental frequency. 
     
     
         7 . The system of  claim 6 , comprising a therapy circuit configured to provide a therapy to the patient;
 wherein the therapy provided to the patient is adjustable based on the indication of the heart's left ventricular wall stiffness.   
     
     
         8 . The system of  claim 2 , wherein the heart sound detector is configured to detect an amplitude of the S3 heart sound as the at least one parameter. 
     
     
         9 . The system of  claim 8 , wherein the processor circuit is configured to provide, as the diagnostic indicator, an indication of a left ventricle filling rate using the amplitude of the S3 heart sound. 
     
     
         10 . The system of  claim 8 , wherein the processor circuit is configured to provide, as the diagnostic indicator, an indication of a left atrial filling pressure using the amplitude of the S3 heart sound. 
     
     
         11 . The system of  claim 8 , wherein the processor circuit is configured to distinguish between at least two atrial filling pressures using the amplitude of the S3 heart sound. 
     
     
         12 . The system of  claim 2 , wherein the heart sound detector is configured to detect the at least one parameter, including information about the S3 heart sound, using a central tendency of a portion of the heart sound signal that corresponds to the S3 heart sound. 
     
     
         13 . The system of  claim 2 , wherein the heart sound detector is configured to detect a pitch of the S3 heart sound as the at least one parameter. 
     
     
         14 . A method comprising:
 sensing a heart sound signal of a patient's heart using a heart sound sensor;   detecting parameters using the heart sound signal, the parameters including information about an S2 heart sound and information about an S3 heart sound, wherein the S3 heart sound is identified using the information about the S2 heart sound; and   providing a diagnostic indicator about the patient based on the information about the S3 heart sound.   
     
     
         15 . The method of  claim 14 , wherein the detecting the parameters includes detecting information about an S3 heart sound pitch, and wherein the providing the diagnostic indicator includes providing a left ventricular wall stiffness indication based on the S3 heart sound pitch. 
     
     
         16 . The method of  claim 14 , wherein the detecting the parameters includes detecting information about a fundamental frequency of an S3 heart sound, and wherein the providing the diagnostic indicator includes providing a left ventricular wall stiffness indication based on the fundamental frequency of the S3 heart sound. 
     
     
         17 . The method of  claim 14 , wherein the detecting the parameters includes detecting a time of onset of the S3 heart sound relative to a timing of the S2 heart sound. 
     
     
         18 . The method of  claim 14 , wherein the detecting the parameters includes detecting a duration of the S3 heart sound, and wherein the providing the diagnostic indicator about the patient includes providing information about a change in a ventricular diastolic filling pattern using the detected duration. 
     
     
         19 . The method of  claim 18 , wherein the providing the diagnostic indicator about the patient includes providing information about a change in a ventricular diastolic filling pattern using the detected duration. 
     
     
         20 . A system comprising:
 a heart sound sensor, configured to sense a heart sound signal of a heart;   a heart sound detector, coupled to the heart sound sensor, the heart sound detector configured to detect at least one parameter using the heart sound signal, the at least one parameter including information about an S3 heart sound; and   a processor, coupled to the heart sound detector, the processor configured to distinguish between at least two atrial filling pressure magnitudes using the at least one parameter, wherein the at least one parameter is different from each of the at least two atrial filling pressure magnitudes being distinguished;   wherein the information about the S3 heart sound includes a peak amplitude of the S3 heart sound and a timing of the S3 heart sound.   
     
     
         21 . The system of  claim 20 , wherein the information including the timing of the S3 heart sound includes information about an onset of S3 relative to an onset of S2.