Artifact cancellation to suppress far-field activation during electrophysiology mapping

Abstract

A method for mapping a cardiac chamber includes sensing activation signals of intrinsic physiological activity with a plurality of electrodes disposed in or near the cardiac chamber, the activation signals including a near-field activation signal component and a far-field activation signal component, isolating R-wave events in the activation signals, generating a far-field activation template representative of the far-field activation signal component based on the R-wave events, and filtering the far-field activation template from the activation signals to identify the near-field activation signal components in the activation signals.

We claim: 
     
         1 . A method for mapping a cardiac chamber, the method comprising:
 sensing activation signals of intrinsic physiological activity with a plurality of electrodes disposed in or near the cardiac chamber, the activation signals including a near-field activation signal component and a far-field activation signal component;   determining consecutive far-field activation signal components, of the far-field activation signal components, having consistent amplitudes;   generating a far-field activation template representative of the far-field activation signal components using the determined consecutive far-field activation signal components having consistent amplitudes; and   filtering the far-field activation template from the activation signals to identify the near-field activation signal components in the activation signals.   
     
     
         2 . The method according to  claim 1 , wherein the step of generating a far-field activation template comprises:
 obtaining a reference timing for far-field events; and   segmenting the activation signals sensed by each electrode around far-field events according to the obtained reference timing.   
     
     
         3 . The method according to  claim 2 , wherein the far-field event corresponds to a ventricular activation signal and the reference timing corresponds to at least one of a Q-wave and an R-wave event in an electrogram. 
     
     
         4 . The method according to  claim 1 , wherein the step of generating a far-field activation template comprises:
 averaging the far-field events in the segmented activation signals from each electrode.   
     
     
         5 . The method according to  claim 1 , wherein the step of filtering the far-field activation template from the activation signals comprises:
 subtracting the far-field activation template from the activation signals at or near the isolated far-field events.   
     
     
         6 . The method according to  claim 5 , wherein, prior to subtracting the far-field activation template, the step of filtering the far-field activation template from the activation signals further comprises:
 fitting an amplitude of the far-field template to correspond to an amplitude of each isolated far-field event.   
     
     
         7 . The method according to  claim 1 , wherein the step of filtering the far-field activation template from the activation signals comprises:
 identifying a time period during which the far-field activation signal component is present; and   filtering the far-field activation template only during the time period.   
     
     
         8 . The method according to  claim 1 , further comprising:
 averaging the far-field activation template with far-field activation signal components during a predetermined number of subsequent far-field events to update the far-field activation template.   
     
     
         9 . The method according to  claim 1 , wherein the filtering step comprises:
 blanking electrodes in the array based on a comparison of an amplitude of the generated far-field template and an amplitude of the sensed far-field signals.   
     
     
         10 . A method for reconstructing electrical activity propagation along an electrode array within a cardiac chamber, the method comprising:
 sensing activation signals of intrinsic physiological activity with a plurality of electrodes disposed in or near the cardiac chamber, the activation signals including a near-field activation signal component and a far-field activation signal component;   obtaining a reference timing for far-field events in the activation signals;   segmenting the activation signals sensed by each electrode around the far-field events according to the obtained reference timing in the activation signals;   averaging the segmented activation signals to generate a far-field activation template; and   filtering the far-field activation template from the activation signals to identify the near-field activation signal components in the activation signals.   
     
     
         11 . The method according to  claim 10 , wherein the far-field event corresponds to a ventricular activation signal and the reference timing to at least one of a Q-wave and an R-wave event in an electrogram. 
     
     
         12 . The method according to  claim 10 , wherein the step of filtering the far-field activation template from the activation signals comprises:
 subtracting the far-field activation template from the activation signals at or near the isolated far-field events.   
     
     
         13 . The method according to  claim 12 , wherein, prior to subtracting the far-field activation template, the step of filtering the far-field activation template from the activation signals further comprises:
 fitting an amplitude of the far-field template to correspond to an amplitude of each isolated far-field event.   
     
     
         14 . The method according to  claim 10 , wherein the step of filtering the far-field activation template from the activation signals comprises:
 identifying a time period during which the far-field activation signal component is present; and   filtering the far-field activation template only during the time period.   
     
     
         15 . The method according to  claim 10 , and further comprising:
 averaging the far-field activation template with far-field activation signal components during a predetermined number of subsequent R-wave events to update the far-field activation template.   
     
     
         16 . The method according to  claim 10 , wherein the filtering step comprises:
 blanking electrodes in the array based on a comparison of an amplitude of the generated far-field template and an amplitude of the sensed far-field signals.   
     
     
         17 . A catheter system comprising:
 a plurality of mapping electrodes configured to sense activation signals of intrinsic physiological activity disposed in or near the cardiac chamber, the activation signals including a near-field activation signal component and a far-field activation signal component; and   a processing system associated with the plurality of mapping electrodes, the signal processing system configured to:
 isolate far-field events in the activations; 
 generate a far-field activation template representative of the far-field activation signal components based on the isolated far-field events; 
 adjusting the far-field activation template by fitting an amplitude of the far-field activation template to correspond to an amplitude of each isolated far-field event; and 
 filter the adjusted far-field activation template from the activation signals to identify the near-field activation signal components in the activation signals and to map the identified near-field activation signal component. 
   
     
     
         18 . The catheter system according to  claim 17 , the processing system configured to determine consecutive far-field activation signal components, of the far-field activation signal components, having consistent amplitudes; and wherein to generate a far-field activation template, the processing system is configured to generate the far-field activation template representative of the far-field activation signal components using the determined consecutive far-field activation signal components having consistent amplitudes. 
     
     
         19 . The catheter system according to  claim 17 , wherein to generate a far-field activation template, the processing system is configured to: obtain a reference timing for far-field events; segment the activation signals sensed by each electrode around far-field events according to the obtained reference timing to isolate the R-wave event in the activation signal; and average the isolated far-field events in the segmented activation signals from each electrode to generate the far-field activation template. 
     
     
         20 . The catheter system according to  claim 17 , wherein to filter the far-field activation template, the processing system is configured to subtract the far-field activation template from the activation signals at or near the isolated far-field events.