Accelerometer-based monitoring of the frequency dynamics of the isovolumic contraction phase and pathologic cardiac vibrations

Abstract

Methods and systems are disclosed that characterize cardiac function using an acceleration sensor to acquire and analyze the frequency dynamics associated with the isovolumic contraction phase (“ICP”). This information can be used to characterize heart function; optimize therapy for cardiomyopathy, including CRT therapy (including pacing intervals and required pharmacologic therapy); and to optimize CCM therapy. In addition, this information can be used to identify target pacing regions for CRT lead placement. Further, analyzing the frequency dynamics can be used to characterize pathologic heart vibrational motion, such as mitral regurgitation and the third or fourth heart sound, and the response of this motion to therapy for cardiomyopathy.

1 . A system for monitoring cardiac function, comprising:
 a catheter component, the catheter component including:
 a portion for insertion within or on a patient's heart, the insertion portion including an acceleration sensor; 
 an external portion including a connector to carry signals from the acceleration sensor; 
 a signal receiving and analysis component, the signal receiving and analysis component including:
 a frequency analyzer to analyze the frequency dynamics of at least the S1 heart sound as measured by the acceleration sensor. 
 
   
     
     
         2 . The device of  claim 1 , wherein the sensor measures acceleration in three perpendicular components. 
     
     
         3 . The device of  claim 1 , wherein the frequency analyzer analyzes the frequency dynamics of the S1 heart sound as well as the frequency dynamics of at least one other heart sound. 
     
     
         4 . The device of  claim 1 , wherein the sensor is synchronized with a cardiac electrical signal indicative of the onset of myocardial contraction. 
     
     
         5 . The device of  claim 1 , wherein the cardiac function monitored is heart failure. 
     
     
         6 . The device of  claim 1 , wherein the frequencies analyzed are greater than about 20 Hz. 
     
     
         7 . The device of  claim 4 , further comprising an ECG component to measure an ECG of the patient, and wherein the sensor is synchronized with the R-wave measured by the ECG. 
     
     
         8 . The device of  claim 7 , wherein the signal receiving and analysis component further comprises a circuit implemented in hardware, software, firmware, or a combination of the above, to analyze the frequency change of the signal measured by the sensor. 
     
     
         9 . A method for monitoring cardiac function, comprising:
 inserting a catheter into a patient, a distal tip of the catheter including a section that resides within or on a patient's heart, the section including an acceleration sensor;   receiving signals from the acceleration sensor at a signal receiving and analysis component;   analyzing the frequency dynamics of at least the S1 heart sound as measured by the acceleration sensor.   
     
     
         10 . The method of  claim 9 , further comprising analyzing the frequency dynamics of at least one other heart sound besides the S1. 
     
     
         11 . The method of  claim 9 , wherein the cardiac function monitored is heart failure. 
     
     
         12 . A system for optimizing CRT lead placement and/or CRT device timing intervals, comprising:
 a test pacing component to perform test pacing of a patient's heart;   a catheter component, the catheter component including:
 a portion for insertion within or on a patient's heart, the insertion portion including an acceleration sensor to monitor heart sounds responding to the test pacing; 
 an external portion including a connector to carry signals from the acceleration sensor; 
 a signal receiving and analysis component, the signal receiving and analysis component including:
 a frequency analyzer to analyze the frequency dynamics of at least the S1 heart sound as measured by the acceleration sensor in response to the test pacing. 
 
   
     
     
         13 . The system of  claim 12 , wherein the sensor measures acceleration in three perpendicular components. 
     
     
         14 . The system of  claim 12 , wherein the frequency analyzer analyzes the frequency dynamics of the S1 heart sound as well as the frequency dynamics of at least one other heart sound. 
     
     
         15 . The system of  claim 12 , wherein the sensor is synchronized with a pacing spike from the test pacing component. 
     
     
         16 . The system of  claim 14 , wherein the frequencies analyzed include those at frequencies greater than about 20 Hz. 
     
     
         17 . The system of  claim 12 , wherein the test pacing component is a pacing guidewire. 
     
     
         18 . A method for optimizing CRT lead placement and/or CRT device timing intervals, comprising:
 inserting a catheter into a patient, a distal tip of the catheter including a section that resides within or on a patient's heart, the section including an acceleration sensor;   inserting a test pacing component within or on a patient's heart;   test pacing the patient's heart;   receiving signals from the acceleration sensor at a signal receiving and analysis component in response to the test pacing;   analyzing the frequency dynamics of at least the S1 heart sound as measured by the acceleration sensor in response to the test pacing.   
     
     
         19 . The method of  claim 18 , further comprising analyzing the frequency dynamics of at least one other heart sound besides the S1. 
     
     
         20 . A system for monitoring cardiac function, comprising:
 an implantable component, the implantable component including an acceleration sensor and a transmitter;   a signal receiving and analysis component, the signal receiving and analysis component including:
 a receiver to receive signals from the transmitter; and 
 a frequency analyzer to analyze the frequency dynamics of at least the S1 heart sound as measured by the acceleration sensor. 
   
     
     
         21 . The system of  claim 20 , wherein the sensor measures acceleration in three perpendicular components. 
     
     
         22 . The system of  claim 20 , wherein the receiver is a wand-type receiver. 
     
     
         23 . The system of  claim 20 , wherein the implantable component further comprises a rechargeable battery and wherein the signal receiving and analysis component further comprises a wireless battery charger for recharging the battery. 
     
     
         24 . The system of  claim 20 , wherein the frequency analyzer analyzes the frequency dynamics of the S1 heart sound as well as the frequency dynamics of at least one other heart sound. 
     
     
         25 . A method for monitoring cardiac function, comprising:
 subcutaneously inserting an implantable component into a patient, the implantable component including an acceleration sensor and a transmitter;   receiving signals from the acceleration sensor at a signal receiving and analysis component;   receiving signals from a surface electrode disposed on the implantable component;   synchronizing the acceleration sensor with a signal received from the surface electrode corresponding to the onset of myocardial contraction;   analyzing the frequency dynamics of at least the S1 heart sound as measured by the acceleration sensor.   
     
     
         26 . The method of  claim 25 , further comprising analyzing the frequency dynamics of at least one other heart sound besides the S1. 
     
     
         27 . The method of  claim 25 , wherein the frequencies analyzed are greater than about 20 Hz. 
     
     
         28 . A system for long-term monitoring of heart failure, comprising:
 a. a housing, including:
 a) an accelerometer; 
 b) A transceiver chip coupled to the accelerometer; 
 c) A battery coupled to the accelerometer; 
   b. wherein said housing is structured and configured to be implanted sub-cutaneously to monitor vibrational motion of the heart.   
     
     
         29 . The system of  claim 28 , further comprising at least one surface electrode structured within or on the housing for sensing a surface ECG. 
     
     
         30 . The system of  claim 28 , wherein the housing is integrated into a CRT device. 
     
     
         31 . The system of  claim 28 , wherein the housing is integrated into an implantable defibrillator. 
     
     
         32 . The system of  claim 31 , wherein the housing is integrated into a leadless implantable defibrillator. 
     
     
         33 . The system of  claim 29 , wherein the accelerometer senses vibrational motion in a time window of 100 milliseconds or less following a QRS of the surface ECG. 
     
     
         34 . A method for monitoring cardiac function, comprising:
 c. installing an acceleration sensor within or on a patient's heart;   d. installing a surface ECG electrode and measuring a patient's surface ECG; and   e. sensing vibrational motion in a time window following the R-wave measured by the surface ECG.   
     
     
         35 . The method of  claim 34 , wherein the sensing further comprises sensing acceleration in three perpendicular components. 
     
     
         36 . The method of  claim 34 , wherein the sensing is at a frequency greater than about 20 Hz. 
     
     
         37 . The method of  claim 34 , wherein the sensing further comprises sensing vibrational motion in a time window of 100 milliseconds or less following a QRS of the surface ECG. 
     
     
         38 . The method of  claim 34 , wherein the acceleration sensor and the surface ECG electrode are disposed within a single housing. 
     
     
         39 . A method for optimizing CRT device timing intervals, comprising:
 test pacing a patient's heart;   monitoring heart sounds responding to the test pacing using an acceleration sensor;   receiving signals corresponding to the monitored heart sounds;   analyzing the frequency dynamics of the received signals;   varying an AV or VV timing interval of the test pacing while analyzing the changes of the varying on the frequency dynamics.   
     
     
         40 . The method of  claim 39 , wherein the test pacing includes test pacing with a pacing guidewire. 
     
     
         41 . The method of  claim 39 , wherein the acceleration sensor is mounted on a catheter. 
     
     
         42 . The method of  claim 39 , wherein the receiving signals includes receiving signals including at least the S1 heart sound.