Artifact detector

• US 3,905,364 A
• Filed: 04/17/1974
• Issued: 09/16/1975
• Est. Priority Date: 04/17/1974
• Status: Expired due to Term

• Current Assignee: Michael J. Cudahy, Robert D. Sherwood
• Original Assignee: Michael J. Cudahy, Robert D. Sherwood
• Inventors: Cudahy, Michael J., Sherwood, Robert D.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/461,610
• Time in Patent Office: 517 Days
• Field of Search: 128/2.5R,2.5T,2.6A,2.6B,2.6E,2.6F,2.6G,2.6R,2.6V,2.6A,2.1B 340/414,253R,253M,253Y,253Z 328/117,118,139,147,148,149,154 324/13R
• US Class Current: 600/508
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/28 for electrocardiography [ECG]
• CPC Class Codes: Y10S 128/904 Telephone telemetry

Abstract

A detector for ascertaining the presence of artifacts in electrocardiographic data includes a.c. artifact detector circuitry and d.c. artifact detector circuitry coupled in parallel to positive and negative diode banks. The diode banks provide the largest magnitude positive and negative artifact signals to comparison circuitry comprised of a pair of diodes which selects the largest of the positive or negative signals for application to an indicating meter. The detector also includes capacitive means for limiting deflection of the meter during the QRS complex signals of the data and means for rapidly discharging the capacitor at the conclusion of such signals.

Claims

1. An artifact detector for detecting periodic artifacts in an electrocardiographic signal, said artifacts being greater in frequency and smaller in magnitude than the periodically occurring major features of the electrocardiographic signal produced by the functioning of the heart, said artifact detector comprising:

detection circuitry including a saturable amplifier having an input for connection to a source of electrocardiographic signals and an output, the gain of said amplifier being controllable for driving said amplifier into saturation at preselected input signal levels to clip the tops of the major features of the electrocardiographic signal, and a band pass filter coupled to the output of said amplifier, said band pass filter having frequency response characteristic suitable for transmitting signals having frequencies of the artifacts, said detection circuitry having an output providing a periodic signal corresponding to the artifacts;

conversion means coupled to said detection circuitry for converting said periodic signal to a unipolarity signal having a magnitude determined by the magnitude of the periodic signal;

signal responsive indicator means for indicating the presence and magnitude of artifacts in the electrocardiographic signal; and

indicator means driver circuitry coupled to said conversion means and to said indicator means for receiving the unipolarity signal of the conversion means and for providing a driving signal therefrom for said indicator means, said driver circuitry including capacitive means responsive to and chargable by the unipolarity signal for smoothing the unipolarity signal and reducing alterations in the driving signal when said amplifier is driven into saturation by the major features of the electrocardiographic signal, said driver circuitry including means for rapidly discharging said capacitive means at the conclusion of the major features of the electrocardiographic signal.

2. The artifact detector of claim 1 wherein said conversion means includes a pair of diode means connected in parallel between said detection circuitry and said indicator means driver circuitry and includes signal inverting circuitry operatively associated with one of said diode means.

3. The artifact detector of claim 1 wherein said discharging means includes means for delaying the rapid discharge of said capacitive means.

4. The artifact detector of claim 3 wherein said driver circuitry includes a first discharge path for said capacitive means extending between said conversion means and said indicator means and a second, low resistance discharge path for said capacitive means and wherein said discharging means includes means for ascertaining whether said capacitive means is charging or is discharging in said first path and for providing an output signal indicative thereof and timing means operable by said ascertaining means output signal inproviding predetermined time delay and for coupling said dicative of the discharging condition of the capacitive means for providing a predetermined time delay and for coupling said capacitive means to said low resistance discharge path at the end of said time delay for rapidly discharging said capacitive means.

5. The artifact detector of claim 1 suitable for detecting artifacts in a plurality of electrocardiographic signals, said artifact detector including a plurality of detection circuitries as defined in claim 1, each having an amplifier input for connection to a source of electrocardiographic signals, the output signals of said detection circuitries being supplied in parallel to said conversion means, said conversion means including selection means for receiving said output signals, for splitting the periodic signals of said detection circuitries into positive and negative portion signals, and for providing a pair of output signals comprising the largest positive portion signal and the largest negative portion signal, said conversion means further including comparison means for receiving said signals and for providing the largest of the portion signals to said indicator means driver circuitry as the unipolarity signal.

6. The artifact detector of claim 5 wherein said conversion means includes signal smoothing means operatively associated with said comparison means for smoothing said positive and negative portion signals into signals of substantially constant magnitudes determined by the magnitudes of said positive and negative signals.

7. The artifact detector of claim 5 wherein said selection means includes positive and negative diode banks having oppositely poled diodes, each of said banks having a plurality of diodes connected in parallel and coupled to the outputs of said detection circuitries.

8. The artifact detector of claim 5 suitable for detecting artifacts exhibiting d.c. voltage levels in a plurality of electrocardiographic signals, said plurality of detection circuitries having second amplifiers, each of said amplifiers having an input for connection to a source of electrocardiographic signals and having a d.c. response for providing an output signal having a polarity characteristic and corresponding to the d.c. artifacts to an output of said amplifier, the output signals of said detection circuitries being supplied in parallel to said selection means of said conversion means, said selection means providing a pair of output signals to said comparison means, one of said signals comprising the largest of said second amplifier output signals and the portion signals having the same polarity as said second amplifier signals, the second of said signals comprising the largest of the other portion signals, said comparison means providing the largest of the output signals to said indicator means driving circuitry as the unipolarity signal.

9. The artifact detector of claim 1 for detecting artifacts exhibiting d.c. voltage levels in an electrocardiographic signal, said detection circuitry further including a second amplifier having an input for connection to the source of electrocardiographic signals and having a d.c. response for providing an output signal having a polarity characteristic and corresponding to the d.c. artifacts to an output of said amplifier, the output signals of said detection circuitry being supplied in parallel to said conversion means, said conversion means including selection means for receiving said output signals, for splitting the periodic output signal of said detection circuitry into positive and negative portion signals, and for providing a pair of output signals, one of the signals comprising the largest of the second amplifier output signal and the one of the portion signals having the same polarity as the second amplifier output signal, the second of the signals comprising the other of the portion signals, said conversion means further including comparison means for receiving said signals and for providing the largest of the output signals to said indicator means driver circuitry as the unipolarity signal.

10. The artifact detector of claim 9 wherein said selection means includes positive and negative diode banks having oppositelY poled diodes, each of said banks having a plurality of diodes connected in parallel and coupled to the outputs of said detection circuitries.

11. The artifact detector of claim 1 wherein said indicator means comprises an electro-mechanical meter.

12. The artifact detector of claim 11 wherein said meter has a movable indicator displaceable along an associated scale oriented so as to have a right hand end and a left hand end, said meter being so coupled to said indicator means driver circuitry as to cause said meter to deflect from right to left upon energization by said unipolarity signal.

13. An artifact detector for detecting periodic artifacts in a plurality of electrocardiographic data, said artifacts having a frequency greater than the electrocardiographic signal produced by the functioning of the heart, said artifact detector comprising:

a plurality of detection circuitries, each including an amplifier having an input for connection to one of the sources of the electrocardiographic data and an output, and a band pass filter coupled to the output of said amplifier, said band pass filter having frequency response characteristics suitable for transmitting signals having frequencies of the artifacts, each of said detection circuitries having an output providing a periodic signal corresponding to the signal artifacts;

conversion means including selection means to which said outputs of said detection circuitries are coupled in parallel and including comparison means connected between said selection means and an output terminal, said selection means splitting the periodic signals of said detection circuitries into positive and negative portion signals having magnitudes determined by the magnitude of the periodic signals and providing the largest positive portion signal and the largest negative portion signal to said comparison means, said comparison means providing the largest of the portion signals as a unipolarity signal at said output terminal; and

indicating means coupled to the output terminal of said conversion means and responsive to the magnitude of said unipolarity signal for indicating the presence and magnitude artifacts in the electrocardiographic data.

14. The artifact detector of claim 13 wherein said comparison means includes a pair of diode means connected in parallel between said selection means and said output terminal and includes signal inverting circuitry operatively associated with one of the said diode means.

15. The artifact detector of claim 13 wherein said conversion means includes signal smoothing means operatively associated with said comparison means for smoothing said positive and negative portion signals into signals of substantially constant magnitudes determined by the magnitude of said positive and negative signals.

16. The artifact detector of claim 13 wherein said selection means includes positive and negative diodes blanks having oppositely poled diodes, each of said banks having a plurality of diodes connected in parallel and coupled to the plurality of diodes connected in parallel and coupled to the outputs of said detection circuitries.

17. The artifact detector of claim 13 suitable for detecting artifacts exhibiting d.c. voltage levels in a plurality of electrocardiographic data, said plurality of detection circuitries having second amplifiers, each of said amplifiers having an input for connection to a source of electrocardiographic data and having a d.c. response for providing an output signal having a polarity characteristic and corresponding to the d.c. artifact to an output of said amplifiers, said outputs signals of said detection circuitries being supplied in parallel to said selection means of said conversion means, said selection means providing an input signal to said comparison means, one of said signals comprising the largest of said second amplifier output signals and the portion signals having the same polarity as said second amplifier signals, the second of said signals compriSing the largest of the other portion signals, said comparison means providing the largest of the input signals as said unipolarity signal to said indicator means driver circuitry as the unipolarity signal.