Extension of electrocardiography (ecg) acquisition capabilities of catheter-based cardiac system

Abstract

A method includes receiving analog body-surface signal from body-surface electrode, and multiple analog unipolar signals from multiple unipolar electrodes of an invasive probe. A first unipolar electrode is assigned to serve as a common electrical ground and a common timing reference for the analog unipolar signals and the analog body-surface signal. The analog unipolar signals are digitized to produce digital unipolar signals sampled relative to a digital ground. Defined are an analog bipolar signal between the first unipolar electrode and a second unipolar electrode of the probe, and digital bipolar signal formed from the first unipolar electrode and the second unipolar electrode. Ground and timing offsets between the analog bipolar signal and the digital bipolar signal are estimated, while the first unipolar electrode is connected to the digital ground. The ground offset and the timing offset are applied in measuring a third unipolar signal, sensed by a third unipolar electrode.

1 .- 8 . (canceled) 
     
     
         9 . A method, comprising:
 receiving, at a circuit:   (i) at least one analog body-surface signal created from one or more body-surface electrodes attached externally to a patient, and   (ii) a plurality of analog unipolar signals created from a plurality of unipolar electrodes inserted in the patient, at least one of the plurality of unipolar electrodes being configured as a common electrical ground and a common timing reference for the plurality of analog unipolar signals and the analog body-surface signal;   defining, using a processor:   (i) an analog bipolar signal, and   (ii) a digital bipolar signal based on the analog unipolar signals and the common electrical ground and timing reference; and   correcting, using the processor, an identified offset between the analog bipolar signal and the digital bipolar signal.   
     
     
         10 . The method according to  claim 9 , wherein the identified offset is an offset selected from the group consisting of a timing offset and a ground offset. 
     
     
         11 . The method according to  claim 9 , further comprising digitizing the plurality of analog unipolar signals to produce a plurality of respective digital unipolar signals by sampling the plurality of analog unipolar signals relative to the common electrical ground, wherein the defining the analog bipolar signal and the digital bipolar signal are further based on the plurality of respective digital unipolar signals. 
     
     
         12 . The method according to  claim 11 , wherein the plurality of analog unipolar signals and the plurality of respective digital unipolar signals comprise electrocardiograms. 
     
     
         13 . The method according to  claim 11 , wherein the circuit comprises an analog to digital converter (ADC) module, and wherein the plurality of analog unipolar signals are digitized by the ADC. 
     
     
         14 . The method according to  claim 9 , wherein the circuit comprises a Wilson Central Terminal (WCT) signal, and wherein the analog body-surface signal being received by the WCT. 
     
     
         15 . The method according to  claim 9 , wherein the circuit comprises an analog to digital converter (ADC) module, and wherein the plurality of analog unipolar signals are received by the ADC. 
     
     
         16 . The method according to  claim 9 , further comprising passing, using the processor, the analog bipolar signal and the digital bipolar signal through a high-pass filter. 
     
     
         17 . The method according to  claim 9 , further comprising passing, using the processor, the analog bipolar signal and the digital bipolar signal through a cross-correlator circuit. 
     
     
         18 . An apparatus, comprising:
 circuitry, which is configured to receive (i) at least one analog body-surface signal created from one or more body-surface electrodes attached externally to a patient, and (ii) a plurality of analog unipolar signals created from a plurality of unipolar electrodes inserted in the patient;   at least one of the plurality of unipolar electrodes being configured as a common electrical ground and a common timing reference for the plurality of analog unipolar signals and the analog body-surface signal; and   a processor, which is configured to:
 define (i) an analog bipolar signal and (ii) a digital bipolar signal based on the analog unipolar signals and the common electrical ground and timing reference, and 
 correct an identified offset between the analog bipolar signal and the digital bipolar signal. 
   
     
     
         19 . The apparatus according to  claim 18 , wherein the identified offset is an offset selected from the group consisting of a timing offset and a ground offset. 
     
     
         20 . The apparatus according to  claim 18 , wherein the processor is further configured to digitize the plurality of analog unipolar signals to produce a plurality of respective digital unipolar signals by sampling the plurality of analog unipolar signals relative to the common electrical ground, wherein defining the analog bipolar signal and the digital bipolar signal are further based on the plurality of respective digital unipolar signals. 
     
     
         21 . The apparatus according to  claim 20 , wherein the circuitry further comprises an analog to digital converter (ADC) module, and wherein the plurality of analog unipolar signals are digitized by the ADC. 
     
     
         22 . The apparatus according to  claim 18 , the processor and a portion of the circuitry being included in a legacy system. 
     
     
         23 . The apparatus according to  claim 18 , the circuitry comprising a Wilson Central Terminal (WCT), and wherein the analog body-surface signal being received by the WCT. 
     
     
         24 . The apparatus according to  claim 18 , wherein the circuitry comprises an analog to digital converter (ADC) module, and wherein the plurality of analog unipolar signals are received by the ADC. 
     
     
         25 . The apparatus according to  claim 18 , wherein the processor is further configured to pass the analog bipolar signal and the digital bipolar signal through a high-pass filter. 
     
     
         26 . The apparatus according to  claim 18 , wherein the processor is further configured to pass the analog bipolar signal and the digital bipolar signal through a cross-correlator circuit. 
     
     
         27 . A system, comprising:
 a circuit configured to:
 receive (i) at least one analog body-surface signal from electrodes attached externally to a patient, and (ii) a plurality of analog unipolar signals from a plurality of electrodes inserted in the patient, and 
 produce, based on the plurality of analog unipolar signals, a plurality of respective digital unipolar signals; and 
   a processor configured to:
 define an analog bipolar signal based on the analog unipolar signals; 
 define a digital bipolar signal formed from the plurality of respective digital unipolar signals, 
 estimate a ground offset and a timing offset between the analog bipolar signal and the digital bipolar signal, and 
 apply the ground offset and the timing offset in measuring a new signal sensed by one of the plurality of electrodes inserted in the patient, relative to the at least one analog body-surface signal. 
   
     
     
         28 . The system according to  claim 27 , wherein the processor is further configured to pass the analog bipolar signal through at least one of a high-pass filter or a cross-correlator circuit.