Method and apparatus for displaying electrocardiographic signals

• US 4,528,988 A
• Filed: 05/01/1984
• Issued: 07/16/1985
• Est. Priority Date: 03/10/1982
• Status: Expired due to Fees

• Current Assignee: Del Mar Avionics
• Original Assignee: Del Mar Avionics
• Inventors: Wong, Alan S.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US06/605,905
• Time in Patent Office: 441 Days
• Field of Search: 128/710, 128/712
• US Class Current: 600/525
• CPC Class Codes: G01R 13/22 Circuits therefor

Abstract

An improved system for displaying annotated physiological signals processes the signals for two dimensional display on an oscilloscope, for annotation with time-of-day and patient information, and for marking relative to a plurality of detected, abnormal physiological events. The physiological signal is traced during a first time interval after which the time-of-day and patient information is annotated appropriately on the display during a second time interval. During a third time interval, the display is marked to identify those physiological events which have been detected by the system as being abnormal. The display is created with maximum fidelity and without loss of signal information by this three pass process. Two independent channels of physiological signals are displayed on alternate horizontal lines in the display, again without loss of signal fidelity, by tracing the first channel during a first sweep and simultaneously storing the second channel within a memory for display during a second sweep. Display is made in any one of a plurality of display formats in one of a plurality of operational modes through the use of program counters which step through various memories devoted to storage of the physiological signals, of the annotations and of the abnormality markers to generate a coordinated display in the three pass process. X-sweep and y-sweep signals are generated for the oscilloscope with ease by generating a binary word encoded to correspond to the selected display format, which binary word is coupled to the input of a digital-to-analog convertor. The output of the digital-to-analog convertor is a current which is proportional to the magnitude of the binary word, which output is used as the input to a sawtooth generator and which in turn generates the appropriate x-sweep or y-sweep signal.

Claims

1. In a single beam CRT having x and y deflections for generating an annotated, two dimensional, ECG plot, an improvement for printing on a recording media within said CRT character annotations and an ECG plot, said improvement comprising:

an x-axis circuit for selectively coupling one of at least two x-sweep signals to said CRT for control of x-deflection of said CRT;

a character ramp generator coupled to said x-axis circuit for providing a component of said x-sweep signal corresponding to said character annotations;

an ECG ramp generator coupled to said x-axis circuit for providing a component of said x-sweep signal corresponding to said ECG plot;

a y-axis circuit for selectively coupling one of at least two y-sweep signal to said CRT for control of y-deflection of said CRT;

a source of ECG signals coupled to said y-axis circuit for providing a component of said y-sweep signal corresponding to said ECG plot;

a character line generator coupled to said y-axis circuit for providing a component of said y-sweep signal corresponding to said character annotation;

a beam intensification circuit for varying the intensity of said single beam of said CRT, said beam intensification circuit being coupled to said CRT;

character and data selector circuit for generating beam intensification signals corresponding to selected character annotations, said character and data selector means being coupled to said beam intensification circuit;

a control logic circuit coupled to said character ramp generator, ECG ramp generator, character line generator, beam intensification circuit, character and data selector circuit, x-axis circuit, and y-axis circuit to provide timing, coordination and activation among each of them, said control logic circuit also coupled to said CRT in order to synchronize operation of said character ramp generator, ECG ramp generator, character line generator, beam intensification circuit, character and data selector circuit, x-axis circuit, and y-axis circuit to operation of said CRT through said control logic circuit,

whereby the x-sweep and y-sweep rates and beam intensity of said CRT may be selectively controlled and varied when displaying said character annotations and said ECG plot to display said character annotations at a substantially greater speed than said ECG plot without loss of displayed character annotation intensity and with minimum loss of ECG plot fidelity.