Coronary artery disease detection signal processing system

Abstract

An auscultatory sound signal acquired by a recording module is coupled through a high-pass filter having a cut-off frequency in the range of 3 to 15 Hz and subsequently filtered with a low-pass filter. The high-pass filter incorporates a pair of high-pass filter input circuits having a corresponding pair input terminals across which the auscultatory sound signal is operatively coupled, wherein each high-pass filter input circuit is associated with a corresponding input of an electronic differential-input amplifier, for each high-pass filter input circuit, the corresponding input terminal is operatively coupled to a first terminal of a corresponding capacitor, the second terminal of the corresponding capacitor coupled to both the corresponding input of the electronic differential-input amplifier and to a first terminal of a corresponding resistor, and the second terminal of the corresponding resistor is operatively coupled to a circuit ground.

What is claimed is: 
     
         1 . (canceled) 
     
     
         2 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject, comprising:
 a. a corresponding auscultatory sound-signal processing channel in correspondence with the at least one electronic auscultatory sound signal of said at least one electronic auscultatory sound signal, wherein said corresponding auscultatory sound-signal processing channel provides for receiving said at least one electronic auscultatory sound signal from the corresponding at least one auscultatory sound-or-vibration sensor of said at least one auscultatory sound-or-vibration sensor, and each said corresponding auscultatory sound-signal processing channel comprises:
 i. a high-pass filter portion comprising either a first electronic differential-input high-pass filter having a 3 dB cut-off frequency in the range of 3 Hz to 15 Hz, or a first differential-input high-pass filter portion of an electronic band-pass filter having a 3 dB cut-off frequency in the range of 3 Hz to 15 Hz, wherein said at least one electronic auscultatory sound signal is operatively coupled to either a differential input of said first electronic differential-input high-pass filter or a differential input of said first differential-input high-pass filter portion of said electronic band-pass filter, said high-pass filter portion comprises a pair of first high-pass filter input circuits in cooperation with a pair of inputs of said electronic differential-input amplifier, said electronic differential-input amplifier comprises either a common first operational amplifier or a corresponding pair of first operational amplifiers, each first high-pass filter input circuit of said pair of first high-pass filter input circuits comprises a first capacitor and a first resistor, a first terminal of said first capacitor is operatively coupled to said at least one electronic auscultatory sound signal, a second terminal of said first capacitor is operatively coupled to a node that is operatively coupled to a corresponding input of said electronic differential-input amplifier, a first terminal of said first resistor is operatively coupled to said node, and a second terminal of said first resistor is operatively coupled to a circuit ground; 
 ii. an amplifier portion comprising an electronic differential-input amplifier associated with either said first electronic differential-input high-pass filter or said first differential-input high-pass filter portion of said electronic band-pass filter; 
 iii. a low-pass filter portion comprising either an electronic low-pass filter, or a low-pass filter portion of said electronic band-pass filter, wherein said electronic low-pass filter or said low-pass filter portion of said electronic band-pass filter is operatively coupled to an output of said electronic differential-input amplifier; and 
 iv. an analog-to-digital converter portion operatively coupled to an output of either said electronic low-pass filter or said electronic band-pass filter, wherein said analog-to-digital converter portion provides for converting said output of either said electronic low-pass filter or said electronic band-pass filter to digital form; and 
   b. a communications interface operatively coupled to an output of said analog-to-digital converter portion, wherein said communications interface provides for transmitting at least one digital signal generated by said analog-to-digital converter portion to a device external of said recording module.   
     
     
         3 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said high-pass filter portion further comprises a second resistor and a second capacitor, said second resistor is in series with said first capacitor, and said second capacitor is in parallel with said first resistor. 
     
     
         4 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said high-pass filter portion further comprises a second high pass filter circuit in cooperation with a second operational amplifier, 
     
     
         5 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 4 , wherein an input of said second operational amplifier is operatively coupled to an output of said electronic differential-input amplifier. and said circuit ground is operatively coupled to the skin of the test subject via a series RC network. 
     
     
         6 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 5 , wherein said circuit ground is operatively coupled to the skin of the test subject via a ground conductor on a surface of said recording module in contact with said skin of said test subject. 
     
     
         7 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said electronic differential-input amplifier is configured with a variable gain, and said variable gain is responsive to an external signal from said device external of said recording module, responsive to said at least one digital signal generated by said recording module. 
     
     
         8 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 7 , further comprising a plurality of resistors and a corresponding plurality of electronically-controllable analog switches, wherein each electronically-controllable analog switch of said plurality of electronically-controllable analog switches provides for controlling an operative coupling a corresponding resistor to a pair of nodes operatively coupled to said electronic differential-input amplifier, wherein when said electronically-controllable analog switch is activated responsive to said external signal, said corresponding resistor is connected electrically in parallel with said pair of nodes, and when said electronically-controllable analog switch is deactivated responsive to said external signal, the resistance across said pair of nodes is unaffected by said corresponding resistor. 
     
     
         9 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said analog-to-digital converter portion incorporates a variable-gain amplifier, and a gain of said variable-gain amplifier is responsive to an external signal from said device external of said recording module, responsive to said at least one digital signal generated by said recording module. 
     
     
         10 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said communications interface comprises a USB interface, wherein said recording module is powered from said USB interface. 
     
     
         11 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said communications interface comprises a wireless interface, further comprising a battery that provides for powering said recording module. 
     
     
         12 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said at least one auscultatory sound-or-vibration sensor is powered by said recording module. 
     
     
         13 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said electronic low-pass filter, or said low-pass filter portion of said electronic band-pass filter, of each said corresponding auscultatory-sound-signal-processing channel has a 3 dB cut-off frequency in the range of 500 Hz to 2.5 KHz so as to provide for detecting coronary artery disease (CAD). 
     
     
         14 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 13 , wherein said electronic low-pass filter, or said low-pass filter portion of said electronic band-pass filter, of each said corresponding auscultatory-sound-signal-processing channel has a 3 dB cut-off frequency in the range of 1 kHz to 2.5 KHz so as to provide for detecting coronary artery disease (CAD). 
     
     
         15 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said recording module further provides for processing an electrographic signal from a corresponding ECG sensor operatively coupled to a corresponding portion of said skin of said test subject, further comprising a corresponding electrographic-signal-processing channel in correspondence with said ECG sensor, wherein said corresponding electrographic-signal-processing channel provides for receiving said electrographic signal from said ECG sensor, and said corresponding electrographic-signal-processing channel comprises:
 a. a high-pass filter portion comprising either a first electronic differential-input high-pass filter having a 3 dB cut-off frequency in the range of  1  Hz to 3 Hz, or a first differential-input high-pass filter portion of an electronic band-pass filter having a 3 dB cut-off frequency in the range of  1  Hz to 3 Hz, wherein said electrographic signal is operatively coupled to either a differential input of said first electronic differential-input high-pass filter or a differential input of said first differential-input high-pass filter portion of said electronic band-pass filter;   b. an amplifier portion comprising an electronic differential-input amplifier associated with either said first electronic differential-input high-pass filter or said first differential-input high-pass filter portion of said electronic band-pass filter;   c. a low-pass filter portion comprising either an electronic low-pass filter, or a low-pass filter portion of said electronic band-pass filter, wherein said electronic band-pass filter or said low-pass filter portion of said electronic band-pass filter is operatively coupled to an output of said electronic differential-input amplifier; and   d. an analog-to-digital converter portion operatively coupled to an output of either said electronic low-pass filter or said electronic band-pass filter, wherein said analog-to-digital converter portion provides for converting said output of either said electronic low-pass filter or said electronic band-pass filter to digital form, wherein said communications interface operatively coupled to an output of said analog-to-digital converter portion.   
     
     
         16 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject, comprising:
 a. a corresponding auscultatory sound-signal processing channel in correspondence with the at least one electronic auscultatory sound signal of said at least one electronic auscultatory sound signal, wherein said corresponding auscultatory sound-signal processing channel provides for receiving said at least one electronic auscultatory sound signal from the corresponding at least one auscultatory sound-or-vibration sensor of said at least one auscultatory sound-or-vibration sensor, and each said corresponding auscultatory sound-signal processing channel comprises:
 i. a high-pass filter portion comprising either a first electronic differential-input high-pass filter having a 3 dB cut-off frequency in the range of 3 Hz to 15 Hz, or a first differential-input high-pass filter portion of an electronic band-pass filter having a 3 dB cut-off frequency in the range of 3 Hz to 15 Hz, wherein said at least one electronic auscultatory sound signal is operatively coupled to either a differential input of said first electronic differential-input high-pass filter or a differential input of said first differential-input high-pass filter portion of said electronic band-pass filter; 
 ii. an amplifier portion comprising an electronic differential-input amplifier associated with either said first electronic differential-input high-pass filter or said first differential-input high-pass filter portion of said electronic band-pass filter; 
 iii. a low-pass filter portion comprising either an electronic low-pass filter, or a low-pass filter portion of said electronic band-pass filter, wherein said electronic low-pass filter or said low-pass filter portion of said electronic band-pass filter is operatively coupled to an output of said electronic differential-input amplifier; and 
 iv. an analog-to-digital converter portion operatively coupled to an output of either said electronic low-pass filter or said electronic band-pass filter, wherein said analog-to-digital converter portion provides for converting said output of either said electronic low-pass filter or said electronic band-pass filter to digital form; and 
   b. a communications interface operatively coupled to an output of said analog-to-digital converter portion, wherein said communications interface provides for transmitting at least one digital signal generated by said analog-to-digital converter portion to a device external of said recording module;   c. wherein said recording module further provides for processing an electrographic signal from a corresponding ECG sensor operatively coupled to a corresponding portion of said skin of said test subject, further comprising a corresponding electrographic-signal-processing channel in correspondence with said ECG sensor, wherein said corresponding electrographic-signal-processing channel provides for receiving said electrographic signal from said ECG sensor, and said corresponding electrographic-signal-processing channel comprises:
 i. a high-pass filter portion comprising either a first electronic differential-input high-pass filter having a 3 dB cut-off frequency in the range of  1  Hz to 3 Hz, or a first differential-input high-pass filter portion of an electronic band-pass filter having a 3 dB cut-off frequency in the range of 1 Hz to 3 Hz, wherein said electrographic signal is operatively coupled to either a differential input of said first electronic differential-input high-pass filter or a differential input of said first differential-input high-pass filter portion of said electronic band-pass filter, said high-pass filter portion comprises a pair of first high-pass filter input circuits in cooperation with a pair of inputs of said electronic differential-input amplifier, said electronic differential-input amplifier comprises either a common first operational amplifier or a corresponding pair of first operational amplifiers, each first high-pass filter input circuit of said pair of first high-pass filter input circuits comprises a first capacitor and a first resistor, a first terminal of said first capacitor is operatively coupled to said electrographic signal, a second terminal of said first capacitor is operatively coupled to a node that is operatively coupled to a corresponding input of said electronic differential-input amplifier, a first terminal of said first resistor is operatively coupled to said node, a second terminal of said first resistor is operatively coupled to a circuit ground, and said circuit ground is operatively coupled to a ground electrode of said ECG sensor applied to the skin of the test subject, via a series RC network, 
 ii. an amplifier portion comprising an electronic differential-input amplifier associated with either said first electronic differential-input high-pass filter or said first differential-input high-pass filter portion of said electronic band-pass filter; 
 iii. a low-pass filter portion comprising either an electronic low-pass filter, or a low-pass filter portion of said electronic band-pass filter, wherein said electronic band-pass filter or said low-pass filter portion of said electronic band-pass filter is operatively coupled to an output of said electronic differential-input amplifier; and 
 iv. an analog-to-digital converter portion operatively coupled to an output of either said electronic low-pass filter or said electronic band-pass filter, wherein said analog-to-digital converter portion provides for converting said output of either said electronic low-pass filter or said electronic band-pass filter to digital form, wherein said communications interface operatively coupled to an output of said analog-to-digital converter portion. 
   
     
     
         17 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 16 , wherein said electronic low-pass filter, or said low-pass filter portion of said electronic band-pass filter, of said corresponding electrographic-signal-processing channel has a 3 dB cut-off frequency in the range of 500 Hz to 2.5 KHz so as to provide for detecting coronary artery disease (CAD). 
     
     
         18 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 17 , wherein said electronic low-pass filter, or said low-pass filter portion of said electronic band-pass filter, of said corresponding electrographic-signal-processing channel has a 3 dB cut-off frequency in the range of 1 kHz to 2.5 KHz so as to provide for detecting coronary artery disease (CAD). 
     
     
         19 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 2 , wherein said recording module further provides for processing a background sound signal from a corresponding microphone, further comprising a corresponding background-sound-signal-signal-processing channel in correspondence with said microphone, wherein said corresponding background-sound-signal-signal-processing channel provides for receiving said background sound signal from said microphone, and said corresponding background-sound-signal-signal-processing channel comprises:
 a. a high-pass filter portion comprising either a first electronic differential-input high-pass filter having a 3 dB cut-off frequency in the range of 65 Hz to 75 Hz, or a first differential-input high-pass filter portion of an electronic band-pass filter having a 3 dB cut-off frequency in the range of 65 Hz to 75 Hz, wherein said background sound signal is operatively coupled to either a differential input of said first electronic differential-input high-pass filter or a differential input of said first differential-input high-pass filter portion of said electronic band-pass filter;   b. an amplifier portion comprising an electronic differential-input amplifier associated with either said first electronic differential-input high-pass filter or said first differential-input high-pass filter portion of said electronic band-pass filter;   c. a low-pass filter portion comprising either an electronic low-pass filter, or a low-pass filter portion of said electronic band-pass filter, wherein said electronic band-pass filter or said low-pass filter portion of said electronic band-pass filter is operatively coupled to an output of said electronic differential-input amplifier; and   d. an analog-to-digital converter portion operatively coupled to an output of either said electronic low-pass filter or said electronic band-pass filter, wherein said analog-to-digital converter portion provides for converting said output of either said electronic low-pass filter or said electronic band-pass filter to digital form, wherein said communications interface operatively coupled to an output of said analog-to-digital converter portion.   
     
     
         20 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 19 , wherein said electronic low-pass filter, or said low-pass filter portion of said electronic band-pass filter, of said corresponding background-sound-signal-signal-processing channel has a 3 dB cut-off frequency in the range of 500 Hz to 2.5 KHz so as to provide for detecting coronary artery disease (CAD). 
     
     
         21 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 20 , wherein said electronic low-pass filter, or said low-pass filter portion of said electronic band-pass filter, of said corresponding background-sound-signal-signal-processing channel has a 3 dB cut-off frequency in the range of 1 kHz to 2.5 KHz so as to provide for detecting coronary artery disease (CAD). 
     
     
         22 - 31 . (canceled) 
     
     
         32 . A recording module for processing at least one electronic auscultatory sound signal from a corresponding at least one auscultatory sound-or-vibration sensor operatively coupled to a portion of the skin of a test subject as recited in  claim 12 , wherein at least one said at least one auscultatory sound-or-vibration sensor comprises an accelerometer that is powered by said recording module.