Devices and methods for accelerometer-based characterization of cardiac function and identification of LV target pacing zones

Abstract

Systems according to the invention employ an acceleration sensor to characterize displacement and vibrational LV motion, and uses this motion data to characterize the different phases of the LV cycle for analyzing LV function. Systems may identify a target pacing region or regions in the LV or RV using the acceleration sensor by localizing regions of late onset of motion relative to the QRS, or isovolumic contraction, or mitral valve closure, or by pacing of target regions and measuring LV function in response to pacing. Systems further provide an implantable or non-implantable acceleration sensor device for measuring LV motion and characterizing LV function. An implantable myocardial acceleration sensing system (“IAD”) includes at least one acceleration sensor, a data acquisition and processing device, and an electromagnetic, e.g., RF, communication device. The IAD may be integrated into the pacing lead of a CRT device and can operate independently of the CRT IPG.

1 . A device for monitoring cardiac function, comprising: 
 a. At least one acceleration sensor for disposition within or on a patient's heart;    b. Wherein the acceleration sensor includes means for sensing both vibrational and displacement motion frequencies.    
     
     
         2 . The device of  claim 1 , wherein the acceleration sensor is designed to detect vibrational frequencies between about 20 Hz and 150 Hz and displacement motion frequencies less than about 20 Hz.  
     
     
         3 . The device of  claim 1 , wherein the acceleration sensor is designed to detect vibrational frequencies related to mitral regurgitation greater than about 150 Hz.  
     
     
         4 . The device of  claim 1 , further comprising a circuit implemented in hardware or software, or both, for mathematically integrating the displacement motion acceleration signals.  
     
     
         5 . The device of  claim 1 , wherein the sensor is implemented within or on a catheter, and wherein the catheter is structured and sized such that the same may be disposed in the veins of the left ventricle of the patient's heart.  
     
     
         6 . The device of  claim 1 , wherein the sensor is a MEMs capacitive acceleration sensor.  
     
     
         7 . The device of  claim 6 , wherein the sensor further comprises an integrated inductive coil.  
     
     
         8 . The device of  claim 1 , further comprising at least two acceleration sensors disposed within or on a patient's heart, wherein each sensor includes means for sensing both vibrational and displacement motion frequencies.  
     
     
         9 . The device of  claim 8 , wherein the at least two acceleration sensors include two or three dual-axis sensors, having four or six axes for motion sensing, and wherein the sensor axes are disposed in a perpendicular fashion to one another.  
     
     
         10 . The device of  claim 9 , wherein for four axes for sensing, three are for motion sensing of the heart in three orientations, and the fourth is for high frequency sensing; and wherein for six axes for sensing, three are for motion sensing of the heart in three orientations, and three are for high frequency sensing.  
     
     
         11 . The device of  claim 10 , wherein the high frequency sensing is to monitor changes in mitral regurgitation.  
     
     
         12 . The device of  claim 1 , wherein the sensor is disposed on an endovascular catheter.  
     
     
         13 . The device of  claim 12 , wherein the endovascular catheter is a guide catheter or a coronary sinus catheter.  
     
     
         14 . The device of  claim 13 , wherein the endovascular catheter is a coronary sinus catheter, and further comprising an occlusion balloon coupled to the catheter.  
     
     
         15 . The device of  claim 13 , wherein the endovascular catheter is a coronary sinus catheter, and further comprising a pacing electrode coupled to the catheter.  
     
     
         16 . The device of  claim 1 , wherein the sensor is disposed on a guidewire.  
     
     
         17 . The device of  claim 1 , wherein the sensor is disposed on an LV lead.  
     
     
         18 . The device of  claim 12 , further comprising a coronary stenting device removably mounted to the endovascular catheter.  
     
     
         19 . The device of  claim 7 , further comprising a coronary stenting device removably mounted to an endovascular catheter on which is also mounted the sensor, wherein the inductive coil is integral to the stenting device.  
     
     
         20 . A method for identifying CRT pacing regions, comprising: 
 a. Placing an acceleration sensing device in a patient's heart;    b. Sensing acceleration signals at one or more frequencies;    c. Comparing the sensed acceleration signals to a reference point indicative of the start of systole or diastole.    
     
     
         21 . A method for monitoring cardiac function, comprising: 
 a. Placing at least two acceleration sensing devices in a patient's heart;    b. Sensing acceleration signals at two or more frequencies.    
     
     
         22 . The method of  claim 21 , wherein the cardiac function monitored corresponds to post-systolic shortening.  
     
     
         23 . A method for monitoring cardiac function, comprising: 
 a. Placing at least two acceleration sensing devices in a patient's heart;    b. Sensing acceleration signals at one or more frequencies;    c. Wherein one of the devices measures vibrational motion and another measures displacement motion.    
     
     
         24 . The method of  claim 23 , wherein at least one sensing device detects myocardial vibrations indicative of isovolumic contraction or relaxation or valve closure and wherein another detects myocardial displacement.  
     
     
         25 . A method for identifying CRT pacing regions, comprising: 
 a. Placing a sensing device in a patient's heart;    b. Pacing target pacing regions with a pacing device;    c. Measuring signals corresponding to heart function;    d. Placing a CRT lead is a region where the pacing causes a favorable change in the heart function signal.    
     
     
         26 . The method of  claim 25 , wherein the heart function signal is the myocardial performance index.  
     
     
         27 . A method for identifying CRT pacing regions, comprising: 
 a. Placing an acceleration sensing device in a patient's heart;    b. Pacing target pacing regions with a pacing device;    c. In response to the pacing, measuring acceleration signals indicative of LV function.    
     
     
         28 . The method of  claim 16 , wherein the signals indicative of LV function include the time intervals of the LV cycle phases, the peak amplitude of the LV cycle phases, signals related to mitral regurgitation, the time from QRS onset to aortic or pulmonic valve closure, the length of isovolumic contraction, the diastolic filling time, the peak acceleration, velocity, or shortening during isovolumic contraction, the myocardial performance index, and combinations of the above.  
     
     
         29 . The method of  claim 16 , wherein the device is placed in one of the left ventricular veins.  
     
     
         30 . A method for identifying CRT pacing regions, comprising: 
 a. Placing an acceleration sensing device in a patient's heart;    b. Sensing acceleration signals at one or more frequencies;    c. Identifying regions of late onset of motion from the sensed acceleration signals;    d. Wherein said regions of late onset of motion are the CRT pacing regions.    
     
     
         31 . The method of  claim 30 , further comprising disposing electrodes from a pacemaker device near or on the regions of late onset motion.  
     
     
         32 . A method for identifying cardiac features, comprising: 
 a. Placing an acceleration sensing device in a patient's heart, the device including a catheter with an acceleration sensor disposed at or near the distal tip of the catheter;    b. Moving said device in proximity to a cardiac feature;    c. Sensing signals corresponding to vibration or deflection due to blood flow from the cardiac feature.    
     
     
         33 . The method of  claim 32 , wherein the cardiac feature is the coronary ostium or a vein branch.  
     
     
         34 . The method of  claim 32 , wherein the sensing is performed using Doppler ultrasound, a MEMs pressure sensor, or an anemometry device.  
     
     
         35 . A device for monitoring acceleration of tissue in a human body, comprising: 
 a. At least one acceleration sensor chip for disposition within or on a tissue in a patient;    b. A flexible circuit mounted to said sensor chip for carrying signals from said sensor chip to a signal analysis unit;    c. At least one capacitor disposed on the flexible circuit adjacent said sensor chip for decoupling or attenuating noise voltages such that the signal to noise ratio of signals from said sensor chip to reach the signal analysis unit is higher than in the absence of said at least one capacitor.