Respiration-synchronized heart sound trending

Abstract

Respiration-synchronized heart sound trends can be detected using an implantable medical device, including a respiration sensor, a respiration phase detector, a heart sound sensor, a heart sound detector, and a processor. The implantable medical device can also include a cardiac sensor. The respiration-synchronized heart sound trends can include heart sounds occurring during specific phases of a respiration signal, such as inspiration or expiration. The heart sound signal can be gated or the heart sound sensor can be enabled or disabled using the cardiac sensor or the respiration sensor. Further, the heart sound trends can be displayed using an external display, and can provide information about a cardiovascular status using an analysis module, or the analysis module and a blood volume sensor.

1 . A system comprising:
 an implantable medical device, including:
 a respiration sensor, configured to sense a respiration signal; and 
 a heart sound sensor, configured to sense a heart sound signal; 
   an implantable or external respiration phase detector, coupled to the respiration sensor, configured to detect at least one phase of the respiration signal;   an implantable or external heart sound detector, coupled to the heart sound sensor, configured to detect at least one heart sound of the heart sound signal; and   an implantable or external processor, coupled to the respiration phase detector and the heart sound detector, wherein the processor is configured to automatically produce at least one heart sound trend over at least a portion of at least one respiration cycle using the at least one heart sound, the at least one heart sound trend occurring during a specified at least a portion of at least one phase of the respiration signal.   
   
   
       2 . The system of  claim 1 , wherein the at least one heart sound trend includes at least one measurement, feature, characteristic, computation, or interval of at least one heart sound. 
   
   
       3 . The system of  claim 2 , wherein the at least one measurement, feature, characteristic, computation, or interval of at least one heart sound includes at least one of an amplitude of a heart sound, a time interval between a first heart sound and a second heart sound, an energy of a heart sound, and a normalized measurement, feature, characteristic, computation, or interval of the heart sound signal by another measurement, feature, characteristic, computation, or interval of the heart sound signal. 
   
   
       4 . The system of  claim 1 , wherein the implantable medical device includes:
 a cardiac sensor, coupled to the heart sound detector, configured to sense a cardiac signal; and   wherein the heart sound detector is configured to detect at least one heart sound of the heart sound signal using information from the cardiac signal.   
   
   
       5 . The system of  claim 4 , wherein the at least one heart sound includes at least one measurement, feature, characteristic, computation, or interval between at least one cardiac signal feature and at least one heart sound feature. 
   
   
       6 . The system of  claim 4 , including an implantable or external gating circuit, coupled to the cardiac sensor and the heart sound detector, wherein the gating circuit is configured to obtain a gated heart sound signal by gating the heart sound signal using information from the cardiac signal, and wherein the heart sound detector is configured to detect at least one heart sound of the gated heart sound signal. 
   
   
       7 . The system of  claim 4 , wherein the heart sound sensor is coupled to the cardiac sensor, wherein the heart sound sensor is enabled or disabled using information from the cardiac signal. 
   
   
       8 . The system of  claim 1 , wherein the heart sound sensor is coupled to the respiration sensor, wherein the heart sound sensor is enabled or disabled using information from the respiration signal. 
   
   
       9 . The system of  claim 1 , wherein the heart sound sensor is coupled to the respiration phase detector, wherein the heart sound sensor is enabled during the specified at least a portion of at least one phase of the respiration signal. 
   
   
       10 . The system of  claim 1 , including an implantable or external gating circuit, coupled to the respiration phase detector and the heart sound detector, wherein the gating circuit is configured to obtain a gated heart sound signal by gating the heart sound signal using information from the respiration phase detector, and wherein the heart sound detector is configured to detect at least one heart sound of the gated heart sound signal. 
   
   
       11 . The system of  claim 1 , including an external display, coupled to the processor, wherein the display is configured to display information from the processor. 
   
   
       12 . The system of  claim 1 , including an implantable or external analysis module, coupled to the processor, wherein the analysis module is configured to provide information about at least one cardiovascular status using information from the at least one heart sound trend. 
   
   
       13 . The system of  claim 12 , wherein the analysis module is configured to provide information about the at least one cardiovascular status using information from the at least one heart sound trend occurring during at least a portion of the at least one specified phase of the respiration signal. 
   
   
       14 . The system of  claim 12 , wherein the implantable medical device includes an implantable blood volume sensor, coupled to the processor, wherein the blood volume sensor is configured to detect information about a blood volume. 
   
   
       15 . The system of  claim 14 , wherein the analysis module is configured to provide information about the at least one cardiovascular status using information from the at least one heart sound trend and the blood volume sensor. 
   
   
       16 . The system of  claim 15 , wherein the analysis module is configured to provide information about the at least one cardiovascular status using information from the at least one heart sound trend occurring during at least a portion of at least one specified phase of the respiration signal and using information from the blood volume sensor. 
   
   
       17 . A system comprising:
 means for sensing a respiration signal within a body;   means for detecting at least one phase of the respiration signal;   means for sensing a heart sound signal within the body;   means for detecting at least one heart sound of the heart sound signal; and   means for automatically producing at least one heart sound trend, over at least a portion of at least one respiration cycle, wherein the at least one heart sound trend is indicative of at least one heart sound occurring during a specified at least a portion of at least one phase of the respiration signal.   
   
   
       18 . A method comprising:
 sensing a respiration signal using an implanted respiration sensor;   detecting at least one phase of the respiration signal;   sensing a heart sound signal using an implanted heart sound sensor;   detecting at least one heart sound of the heart sound signal; and   automatically producing at least one heart sound trend, over at least a portion of at least one respiration cycle, wherein the at least one heart sound trend is indicative of at least one heart sound occurring during a specified at least a portion of at least one phase of the respiration signal.   
   
   
       19 . The method of  claim 18 , wherein automatically producing the at least one heart sound trend includes automatically producing at least one measurement, feature, characteristic, computation, or interval of at least one heart sound. 
   
   
       20 . The method of  claim 19 , wherein automatically producing at least one measurement, feature, characteristic, computation, or interval of at least one heart sound includes at least one of an automatically producing an amplitude of a heart sound, automatically producing a time interval between a first heart sound and a second heart sound, automatically producing an energy of a heart sound, and automatically producing a normalized measurement, feature, characteristic, computation, or interval of the heart sound signal by another measurement, feature, characteristic, computation, or interval of the heart sound signal. 
   
   
       21 . The method of  claim 18 , including:
 sensing a cardiac signal using an implanted cardiac sensor; and   wherein the detecting at least one heart sound includes using information from the cardiac signal.   
   
   
       22 . The method of  claim 21 , wherein the automatically producing at least one heart sound trend includes automatically producing at least one measurement, feature, characteristic, computation, or interval between at least one cardiac signal feature and at least one heart sound feature. 
   
   
       23 . The method of  claim 21 , including gating the heart sound signal using a gating circuit to detect at least one heart sound, wherein the gating the heart sound signal includes using information from the cardiac signal. 
   
   
       24 . The method of  claim 21 , including enabling or disabling the heart sound sensor using information from the cardiac signal. 
   
   
       25 . The method of  claim 18 , including enabling or disabling the heart sound sensor using information from the respiration signal. 
   
   
       26 . The method of  claim 18 , including enabling the heart sound sensor during at least one of the specified at least a portion of at least one phase of the respiration signal. 
   
   
       27 . The method of  claim 18 , including gating the heart sound signal to detect at least one heart sound, wherein the gating the heart sound signal includes gating the heart sound signal using information from the respiration signal. 
   
   
       28 . The method of  claim 18 , including displaying the at least one heart sound trend. 
   
   
       29 . The method of  claim 18 , including providing information about at least one cardiovascular status using information from the at least one heart sound trend. 
   
   
       30 . The method of  claim 29 , wherein providing information about at least one cardiovascular status includes using information from the at least one heart sound trend occurring during specified different first and second phases of the respiration signal. 
   
   
       31 . The method of  claim 29 , including detecting information about a blood volume using an implanted blood volume sensor. 
   
   
       32 . The method of  claim 31 , wherein providing information about the at least one cardiovascular status includes using information from the at least one heart sound trend and using information about the blood volume. 
   
   
       33 . The method of  claim 32 , wherein providing information about the at least one cardiovascular status includes using information from the at least one heart sound trend occurring during specified different first and second phases of the respiration signal and using information about the blood volume.