Dynamic adaptive respiration compensation with automatic gain control

Abstract

A system for determining a location of an electrode of a medical device (e.g., a catheter) in a body of a patient includes a localization block for producing an uncompensated electrode location, a motion compensation block for producing a compensation signal (i.e., for respiration, cardiac, etc.), and a mechanism for subtracting the compensation signal from the uncompensated electrode location. The result is a corrected electrode location substantially free of respiration and cardiac artifacts. The motion compensation block includes a dynamic adaptation feature which accounts for changes in a patient's respiration patterns as well as intentional movements of the medical device to different locations within the patient's body. The system further includes an automatic compensation gain control which suppresses compensation when certain conditions, such as noise or sudden patch impedance changes, are detected.

1 - 7 . (canceled) 
     
     
         8 . A system for determining a motion compensated location of an electrode of a medical device within a body of a patient, comprising:
 a main electronic control unit including:
 a localization block configured to produce an uncompensated electrode location, said localization block being further configured to acquire patch electrode impedance data using associated body surface electrodes and electrode location data using said electrode of said medical device; 
 a compensation block configured to:
 mean-adjust said patch electrode impedance data associated with body surface electrodes and electrode location data associated with said electrode; 
 determine an acquired set of weights such that a linear combination of the product of said weights and said mean-adjusted patch impedance data correspond to said mean-adjusted electrode location data; 
 repeatedly acquire said patch electrode impedance data and said electrode location data, mean-adjust said patch electrode impedance data and said electrode location data, and determine said acquired set of weight for a plurality of different time periods and producing a plurality of acquired sets of weights, and as each successive acquired sets of weights is determined:
 (i) determining a learning parameter based on a distance between successive, acquired sets of weights, 
 (ii) updating a reference set of weights based on said determined learning parameter; 
 
 determine a compensation signal based on said updated reference set of weights and patch electrode impedance data, wherein the compensation signal corresponds to motion artifacts associated with an uncompensated electrode location and wherein the compensation signal is configured to reduce such motion artifacts associated with the uncompensated electrode location; 
 
 a mechanism configured to determine said motion compensated electrode location using said uncompensated electrode location and said compensation signal; and 
 means for generating a visual representation of the medical device on a display based on said motion compensated electrode location. 
   
     
     
         9 . The system of  claim 8  wherein said motion compensated electrode location includes one of a position and orientation (P&O) in a reference coordinate system, said main electronic control unit being further configured to select one or more axes for compensation wherein said compensation block determines a respective set of weights for each selected axis. 
     
     
         10 . The system of  claim 8  wherein said compensation block is configured to determine said set of weights using principal component analysis (PCA). 
     
     
         11 . The system of  claim 8  wherein said mean-adjusted patch and electrode data are in matrix form, said compensation block being further configured (i) to perform singular value decomposition of the mean-adjusted patch data matrix; (ii) to obtain the pseudo-inverse of said mean-adjusted patch data matrix and to apply regularization; and (iii) to determine said set of weights in accordance with the product of said pseudo-inverse mean-adjusted patch data matrix and said electrode location data matrix. 
     
     
         12 . The system of  claim 8  wherein compensation block is further configured to determine a difference between a most-recent acquired set of weights and the current reference set of weights, determine a product of the learning parameter and the difference, and sum the current reference set of weights and the product. 
     
     
         13 . The system of  claim 12  wherein said learning parameter is equal to or greater than zero and equal to or less than one. 
     
     
         14 . The system of  claim 12  wherein said compensation block is further configured to vary said learning parameter in accordance with a distance between successive, acquired sets of weights. 
     
     
         15 . The system of  claim 14  wherein said compensation block is further configured to vary the learning parameter by exponentially reducing said learning parameter as a function of said distance between successive, acquired sets of weights. 
     
     
         16 . The system of  claim 8  wherein said compensation block is further configured to determine said compensation signal by automatically controlling a gain parameter. 
     
     
         17 . The system of  claim 16  wherein said compensation block is configured to set said gain parameter to a default value of 1. 
     
     
         18 . The system of  claim 17  wherein said compensation block is further configured to determine (i) a moving average of said compensation signal; (ii) an average deviation of said compensation signal from said moving average; (iii) a current deviation between a current value of the compensation signal and the moving average; and (iv) reduce said default value of said gain parameter in accordance with a ratio between said average deviation and said current deviation when said current deviation exceeds a deviation threshold. 
     
     
         19 . The system of  claim 18  wherein said motion compensated electrode location includes one of a position and orientation (P&O) in a reference coordinate system, said main electronic control unit being further configured to select one or more axes in the coordinate system for compensation, said gain parameter having respective values for each one of said selected axes. 
     
     
         20 . The system of  claim 8  wherein said electrode is a first electrode and said motion compensated electrode location is a motion compensated first electrode location having associated therewith a coordinate within a reference coordinate system, said localization block being configured to determine an uncompensated second electrode location associated with a second electrode, said compensation block being further configured to apply said compensation signal to said uncompensated second electrode location to produce a motion compensated second electrode location when said uncompensated second electrode location matches said coordinate within a predetermined range.