METHOD AND SYSTEM FOR DISPLAY OF ELECTROCARDIOGRAPHIC (ECG) SIGNALS

• US 3,853,119 A
• Filed: 10/19/1973
• Issued: 12/10/1974
• Est. Priority Date: 10/19/1973
• Status: Expired due to Term

• Current Assignee: Israel Mayer Stein, Ronald Thomas Peterson
• Original Assignee: Israel Mayer Stein, Ronald Thomas Peterson
• Inventors: Peterson, Ronald Thomas, Stein, Israel Mayer
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/407,825
• Time in Patent Office: 417 Days
• Field of Search: 128/2.6A,2.6G,2.6R,2.1B,2.1R,2.5R
• US Class Current: 600/521
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/339 Displays specially adapted therefor
• CPC Class Codes: A61B 5/346 Analysis of electrocardiograms

Abstract

The method and system is described for displaying electrocardiograhic (ECG) signals on a cathode ray oscilloscope. The R wave components of the recurring ECG signals are detected and used to control a sweep generator which provides time base signals which are applied to the horizontal deflection input terminals of the oscilloscope. The analog ECG signal is digitized, stored in a memory for a predetermined period of time and then reconverted back into analog ECG signals for application to the vertical deflection inputs of the oscilloscope. The delay of the signal using the digital electronic circuitry provides requisite flexibility so that it may be utilized to display either real time ECG signals and also high speed ECG signals which have been collected and magnetically recorded at real time and then played back at many times real time as in long term electrocardiography.

Claims

1. A method of displaying analog ECG signals with the aid of an oscilloscope which has a time base input and an amplitude input, said method comprising the steps of a. digitizing said signals to provide a first digital output upon each corresponding recurring portion thereof and a plurality of second digitally coded signals each corresponding to a successive amplitude increment thereof, b. storing said second signals each for predetermined periods of time, c. reconverting said second signals into their analog ECG signal form, d. applying said reconverted second signal to the amplitude input of said oscilloscope, e. generating a time base signal synchronous with said first digital output, and f. applying said time base signal to the time base input of said oscilloscope.

2. The invention as set forth in claim 1 wherein said digitizing step includes the steps of a. detecting the occurrence of said corresponding recurring portions, b. producing a pulse upon each detection to provide said first digital outputs, c. sampling said ECG signals at a rate very much greater than the expected rate for normal ECG signals of said first outputs, d. producing very many more of said second signals than said first signals.

3. The invention as set forth in claim 1 wherein said predetermined periods of time are less than the expected period for normal ECG signals of said first outputs.

4. The invention as set forth in claim 2 wherein said predetermined periods of time for storing second signals during said storing step are each for a period of time of less duration than the expected period between said first signals for normal ECG signals.

5. The invention as set forth in claim 4 wherein said generating step includes the steps of a. generating a time base signal which increases in amplitude from a certain amplitude, b. resetting said signal to said certain amplitude in accordance with the occurrence of said first output.

6. A system for displaying ECG signals on an oscilloscope having amplitude and time base inputs, said system comprising a. means for digitizing ECG signals to provide first digital outputs upon occurrence of a recurring portion of each said ECG signals and second digital outputs each consisting of a multi-bit digital signal upon successive incremental portions of said ECG signals which corresponds to the amplitude thereof, b. memory means for storing said second digital signals for predetermined periods of time, c. digital to analog converter means responsive to said second signals after storage thereof in said memory means for providing signals corresponding to said first signals, d. means for aPplying said signals from said converting means to said amplitude inputs of said oscilloscope, e. means for generating time base signals synchronous with said first digital signals, and f. means for applying said time base signals to said time base input of said oscilloscope.

7. The invention as set forth in claim 6 wherein said memory means has a plurality of storage locations for each of said second digital signals, and means for retaining said digital signals in said memory for a predetermined period of time.

8. The invention as set forth in claim 7 wherein said memory means comprises a random access memory, address counter means for controlling the locations into which said second digital signals are loaded and from which said second digital signals are read out, said retaining means including means for applying timing signals to said counter at a rate much greater than the rate of repetition of said corresponding recurring portions of said ECG signals in normal ECG signals for selecting said loading and readout locations and the time when each thereof is addressed by said counter.

9. The invention as set forth in claim 7 wherein said memory is a shift register, into the first stage of which said second digital signals are read in and from the last stage of which said signals are read out into said digital to analog conversion means, and said retaining means including means for applying shift pulses to said register at a rate very much greater then the rate of occurrence of said first digital signals.

10. The invention as set forth in claim 8 wherein said memory means further comprises a plurality of latches each for a different bit of said second digital signal, and said retaining means includes means for applying second timing signals for loading said second digital signals when read out of said random access memory into said latches, said second timing signals being at the same rate as said first named timing signals and displaced in time ahead of said first timing signals.

11. The invention as set forth in claim 10 wherein said digitizing means includes a R-wave detector for providing as said first digital signal, said generating means includes means coupled to said R-wave detector for providing a pulse synchronous with said first digital signal, a saw-tooth wave generator, and means for reinitiating said wave synchronously with said pulse, said wave from said saw-tooth wave generator providing said time base input to said oscilloscope.