RATE METER, PARTICULARLY A BEAT-BY-BEAT CARDIOTACHOMETER

• US 3,602,222 A
• Filed: 09/16/1968
• Issued: 08/31/1971
• Est. Priority Date: 09/16/1968
• Status: Expired due to Term

• Current Assignee: Richard A. Herndon
• Original Assignee: Richard A. Herndon
• Inventors: Herndon, Richard A.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US04/759,961
• Time in Patent Office: 1,079 Days
• Field of Search: 128/2.5P,2.5T,2.06 324/78E 307/279
• US Class Current: 600/515
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval

Abstract

A ratemeter, particularly a cardiotachometer is provided having means for detecting, amplifying and transmitting only the R-waves of a patient'"'"''"'"'s ECG. A pulse generator including a level detector is responsive to the R-waves to generate beat pulses. Signal generator means are responsive to the beat pulses to produce control signals to alternately operate first and second integrators. The integrators generate output pulses proportional to the beat-by-beat heart beat rates which pulses are then displayed on first indicator means. Second indicator means are included to detect and indicate cardiac arrhythmia.

Claims

1. In apparatus for processing electrocardiographic signals including recurring R-waves which are representative of the heart beats of a patient, the combination of:

terminal means for receiving said electrocardiographic signals;

amplifier means connected to said terminal means for amplifying said electrocardiographic signals;

filter means connected to said amplifier means for transmitting said R-waves while attenuating the remainder of said electrocardiographic signals whereby to transmit only said Rwaves;

level-detecting means connected to said filter means, said level detecting means including means responsive to said R-waves for establishing a time varying threshold level proportional to the magnitude of said R-waves, said level-detecting means being so designed that said threshold level is exceeded only by said Rwaves, whereby only said R-waves are transmitted therethrough;

multivibrator means connected to said level-detecting means for producing a pair of coincident beat pulses in response to each of said R-waves;

signal-generating means responsive to each pair of said beat pulses for producing a set of control signals in response thereto;

first and second integrating means, each being selectively operable for generating output signals representative of its time interval of operation, said first and second integrating means being responsive to said sets of control signals to be alternately operated during the time intervals between successive ones of said R-waves whereby said first integrating means produces a first series of output signals proportional to the beat-by-beat rate of the even occurring ones of said Rwaves, and said second integrating means produces a second series of output signals proportional to the beat-by-beat rate of the odd occurring ones of said R-waves; and

means connected to said first and second integrating means for displaying said first and second series of said output pulses.

2. The invention recited in claim 1 wherein said level detecting means is for transmitting only those electrical signals of positive and negative polarities having magnitudes exceeding said threshold level, and wherein said threshold is a time-decaying threshold level proportional to the magnitudes of said R-waves.

3. In integrator means having an input terminal and an output terminal, the combination of:

amplifier means having an input terminal and an output terminal, said amplifier output terminal being connected to said integrator output terminal;

charge storing means being connected between said amplifier input and output terminals;

a field-effect transistor having a source, drain and gate electrodes;

said source electrode being connected to said amplifier input terminal;

said gate electrode being connected to said amplifier output terminal; and

said drain electrode being connected to said integrator input terminal whereby an output signal inversely proportional to the time of integration is generated on said integrator output terminal whenever a constant voltage signal is applied to said integrator input terminal to drive said integrator means.

4. The invention recited in claim 3 including means for selectively discharging said charge storing means.

5. The invention recited in claim 4 wherein said means for selectively discharging said charge storing means comprises:

a field-effect transistor having a drain-to-source current path connected in shunt with said charge storing means; and

means connected to said gate electrode for selectively switching the impedance of said drain-to-source current path between a first and second state, said drain-to-source impedance being substantially infinite in said first state whereby said charge storing means holds its charge, and said drain-to-source impedance being finite in said second state whEreby said charge storing means discharges through said drain-to-source current path.

6. In apparatus for processing event signals wherein each event signal is representative of a recurring event, the combination of:

terminal means for receiving said event signals;

means connected to said terminal means for producing a set of control signals in response to each of said event signals;

first and second integrating means each being selectively operable for generating output signals representative of its time interval of operation, said first and second integrating means being responsive to said sets of control signals to be alternately operated during the time intervals between successive ones of said event signals, whereby said first integrating means produces a first series of output signals proportional to the beat-by-beat rate of the even occurring ones of said event signals, and said second integrating means produces a second series of output signals proportional to the beat-by-beat rate of the odd occurring ones of said event signals; and

means connected to said first and second integrating means for displaying said first and second series of output signals, each of said first and second integrating means further including;

amplifier means having an input terminal and an output terminal;

charge storing means being connected between said amplifier input and output terminals;

a field effect transistor having a source electrode, a drain electrode, and a gate electrode, said source electrode being connected to said amplifier input terminal, and said gate electrode being connected to said amplifier output terminal;

voltage-generating means connected to said drain electrode for selectively generating a constant voltage to drive said integrating means;

discharging means being responsive to said sets of control signals for selectively discharging said charge storing means in time phase with alternate ones of said event signals, said voltage generating means being responsive to said sets of control signals for driving said integrating means during the alternate time intervals between successive ones of said event signals which immediately follow the discharge of said charge storing means whereby said integrating means produces a series of output signals on said amplifier output terminal linearly proportional to the beat-by-beat rate of alternate occurring ones of said event signals.

7. The invention recited in claim 6 in which said event signals processed are electrocardiographic signals including recurring R-waves which are representative of the heart beats of a patient, including:

amplifier means connected to said terminal means for amplifying said electrocardiographic signals; and

filter means connected between said amplifier means and said means for producing said sets of control signals for transmitting said R-waves while attenuating the remainder of said electrocardiographic signals whereby to transmit only said R-waves to said means for producing said sets of control signals.