Methods and apparatus for filtering EGM signals detected by an implantable medical device
First Claim
1. A method for use by an Implantable Medical Device (IMD) of filtering a physiological signal having a predetermined frequency bandwidth, the method comprising:
- obtaining an analog physiological signal from a sensor coupled to the IMD;
filtering the analog physiologic signal with a high pass filter (HPF), the cut-off frequency of the HPF being within the predetermined frequency bandwidth, wherein a low-band portion of the predetermined frequency bandwidth is attenuated in the filtered physiologic signal;
sampling and digitizing the filtered physiologic signal as a digital data set in a real time order;
compressing the data set by lossy data compression; and
reverse time order filtering the compressed digital data set in reverse time order employing a digital IIR filter having characteristics substantially matching the cut-off frequency and filter characteristics of the HPF to substantially remove distortions of the filtered analog physiologic signal introduced by the HPF.
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Accused Products
Abstract
An analog physiologic signal, e.g., the cardiac EGM, sensed by an IMD is filtered with a high pass filter (HPF), the cut-off frequency of the HPF being within a predetermined frequency bandwidth, wherein a low-band portion of the predetermined frequency bandwidth is attenuated in the filtered physiologic signal. The filtered physiologic signal is digitized in real time order, and the digital data set is filtered in reverse time order employing a digital IIR filter having characteristics substantially matching the cut-off frequency and filter characteristics of the HPF. When the system is implemented within an IMD, the filtered digital data set is compressed by lossy compression algorithm, and the compressed data set is filtered in reverse time order. In certain embodiments, the filtered digital data set is uplink telemetry transmitted to an external medical device, and the uplink telemetered data set is filtered in reverse time order employing a digital backward IIR filter resident in the external medical device.
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Citations
28 Claims
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1. A method for use by an Implantable Medical Device (IMD) of filtering a physiological signal having a predetermined frequency bandwidth, the method comprising:
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obtaining an analog physiological signal from a sensor coupled to the IMD;
filtering the analog physiologic signal with a high pass filter (HPF), the cut-off frequency of the HPF being within the predetermined frequency bandwidth, wherein a low-band portion of the predetermined frequency bandwidth is attenuated in the filtered physiologic signal;
sampling and digitizing the filtered physiologic signal as a digital data set in a real time order;
compressing the data set by lossy data compression; and
reverse time order filtering the compressed digital data set in reverse time order employing a digital IIR filter having characteristics substantially matching the cut-off frequency and filter characteristics of the HPF to substantially remove distortions of the filtered analog physiologic signal introduced by the HPF. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for use by an Implantable Medical Device (IMD) of filtering a physiological signal having a predetermined frequency bandwidth, the method comprising:
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obtaining an analog physiological signal from a sensor coupled to the IMD;
filtering the analog physiologic signal with a high pass filter (HPF), the cut-off frequency of the HPF being within the predetermined frequency bandwidth, wherein a low-band portion of the predetermined frequency bandwidth is attenuated in the filtered physiologic signal;
sampling and digitizing the filtered physiologic signal as a digital data set in a time order; and
filtering the compressed data set in reverse time order employing a digital IIR filter having characteristics substantially matching the cut-off frequency and filter characteristics of the HPF to substantially remove distortions of the filtered analog physiologic signal introduced by the HPF. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. Apparatus for use by an Implantable Medical Device (IMD) for filtering a physiological signal having a predetermined frequency bandwidth, the method comprising:
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a sensor coupled to the IMD for sensing an analog physiological signal;
a high pass filter (HPF) for filtering the analog physiologic signal, the HPF having a the cut-off frequency within the predetermined frequency bandwidth, wherein a low-band portion of the predetermined frequency bandwidth is attenuated in the filtered analog physiologic signal;
means for sampling and digitizing the filtered physiologic signal as a digital data set in a real time order;
means for compressing the data set by lossy data compression; and
a digital IIR filter having characteristics substantially matching the cut-off frequency and filter characteristics of the HPF for reverse time order filtering the compressed digital data set to substantially remove distortions of the filtered analog physiologic signal introduced by the HPF. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. Apparatus for use by an Implantable Medical Device (IMD) for filtering a physiological signal having a predetermined frequency bandwidth, the method comprising:
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a sensor coupled to the IMD for sensing an analog physiological signal;
a high pass filter (HPF) for filtering the analog physiologic signal, the HPF having a the cut-off frequency within the predetermined frequency bandwidth, wherein a low-band portion of the predetermined frequency bandwidth is attenuated in the filtered analog physiologic signal;
means for sampling and digitizing the filtered physiologic signal as a digital data set in a real time order; and
a digital IIR filter having characteristics substantially matching the cutoff frequency and filter characteristics of the HPF for reverse time order filtering the digital data set to substantially remove distortions of the filtered analog physiologic signal introduced by the HPF. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification