U.S. patent number 3,848,582 [Application Number 05/270,441] was granted by the patent office on 1974-11-19 for portable electrocardiographic signal apparatus.
This patent grant is currently assigned to Medical Research Laboratories, Inc.. Invention is credited to Richard G. Kerwin, Dean L. Milani.
United States Patent |
3,848,582 |
Milani , et al. |
November 19, 1974 |
PORTABLE ELECTROCARDIOGRAPHIC SIGNAL APPARATUS
Abstract
A battery powered cathode ray oscilloscope which is sufficiently
small and lightweight to be hand held is provided on the backside
thereof with electrodes for pressing against a patient's chest
whereby to cause an electrocardiographic signal to be displayed on
the cathode ray screen.
Inventors: |
Milani; Dean L. (Highland Park,
IL), Kerwin; Richard G. (Prospect Hgts., IL) |
Assignee: |
Medical Research Laboratories,
Inc. (Des Plaines, IL)
|
Family
ID: |
23031342 |
Appl.
No.: |
05/270,441 |
Filed: |
July 10, 1972 |
Current U.S.
Class: |
600/372;
600/525 |
Current CPC
Class: |
A61B
5/339 (20210101); A61B 5/332 (20210101) |
Current International
Class: |
A61B
5/044 (20060101); A61B 5/0404 (20060101); A61B
5/0402 (20060101); A61b 005/04 () |
Field of
Search: |
;128/2.5P,2.5R,2.5S,2.6A,2.6E,2.6F,2.6G,2.6R,2.1E,DIG.4
;178/DIG.29,7.8 ;313/87,89,92R ;315/10,30 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Wolters; Robert M.
Claims
The invention is claimed as follows:
1. A portable electrocardiographic signal apparatus comprising a
housing, a display screen on the front of said housing, pickup
electrode means carried by said housing on the back thereof and
positioned externally thereof for placement against a patient's
chest, mounting means for said electrode means extending into said
housing, spring means mounted internally of said housing and
bearing on said mounting means resiliently to bias said electrode
means outwardly of said housing, positive stop means in said
housing acting on said mounting means to limit outward movement of
said electrode means, means in said housing engaging and laterally
stabilizing said mounting means and hence said electrode means,
electronic circuitry means in said housing interconnecting said
electrode means and said display screen, and pistol grip means on
and extending down from the bottom of said housing substantially
centrally thereof for normal gripping of said pistol grip means by
one hand of an operator to support said housing in one hand with
said pickup electrode means against a patient's chest and said
screen disposed toward said operator in ready viewing position for
said operator to display an instantaneous electrocardiographic
signal.
2. A portable apparatus as set forth in claim 1 including means for
adjusting said pistol grip relative to said housing.
3. A portable apparatus as set forth in claim 1 and further
including light sensitive means on the exterior of said housing
interconnected with the electronic circuitry means of said
apparatus to control the brightness of display of said screen.
4. A portable apparatus as set forth in claim 3 wherein said
display screen and said light sensitive means are on the front face
of said housing and the electrodes are on the back of said housing.
Description
The human heart puts out an electrical signal of approximately 1
millivolt upon beating. Electrical signals commonly are picked up
from the chest of a patient by electrodes making good contact with
the skin on the chest by means of an electro-gel. Preferably the
electrodes are arranged in a triangular pattern know an the
Eindhoven triangle. The two outer, upper electrodes comprise pickup
electrodes, while the lower central electrode is a ground
electrode. The two upper electrodes serve as differential input
electrodes to a differential amplifier circuit. The prior
procedures have required relatively long electrode leads which are
prone to picking up external electrical noises, and since the heart
signal is of rather low potential, it is essential that the
electro-gel be used to make good contacts, whereby to apply as high
a signal-to-noise ratio to the inputs of the electrocardiograph
machine as is reasonably possible.
The pattern which a normal human heart makes upon beating is well
known, and has been known for many years. Electrocardiograms
commonly have been made for many years by the use of a moving paper
web and a pen leaving an impression thereon. Many cycles of
heartbeat are recorded in this manner, and can be studied carefully
by a doctor for any possible malfunction of the heart. However,
such examination is time consuming, and hence costly, and requires
cumbersome equipment, whereby electrocardiograms are not commonly
made unless some heart problem is expected, or unless the patient
is having an extensive physical exam.
It is known that a cathode ray oscilloscope can be substituted for
the moving pen type of recording apparatus for making
electrocardiograms, whereby there is an instant display. However,
this again requires the use of expensive and cumbersome machinery
with long lead wires, and with the necessity of electro-gel to make
a good contact between pickup electrodes and the skin of the
patient's chest. Thus, the taking of an electrocardiogram is
discouraged unless it is thought to be essential for some reason.
This is not wise, as it would be ideal to take an electrocardiogram
frequently of any patient whose health is less than the best, in
the same manner that temperature and blood pressure readings are
now taken. Those skilled in the medical art will realize that an
electrocardiogram can be far more significant in revealing
cardiovascular difficulties than can the simple temperature and
blood pressure tests.
Accordingly, in accordance with the present invention, it is
proposed to provide novel apparatus comprising a small cathode ray
oscilloscope, having a tube face for display of about 2 inches by 3
inches. The total depth of the apparatus is on the order of 6 to 8
inches. The apparatus is battery powered and is provided with a
hand grip or handle so that it readily can be supported by a doctor
or technician. Pickup electrodes are provided directly on the back
of the cathode ray oscilloscope unit, whereby leads are
surpassingly short. Furthermore, the leads and the entire
electrical apparatus are shielded by being housed in a metallic
case. Accordingly, it is not necessary to use the electro-gel to
insure proper contact, since a useful signal can be obtained of
lower magnitude than heretofore, and since additional amplification
is of no particular problem since amplifier stages are relatively
cheap and since the signal-to-noise ratio is quite high due to the
substantial total exclusion of noise signals.
The present invention will best be understood with reference to the
accompanying drawings and the following specification, wherein:
FIG. 1 is a perspective view illustrating the application of the
apparatus of the present invention to the chest of a patient;
Fig. 2 is a side view of an apparatus constructed in accordance
with the present invention;
FIG. 3 is a back view thereof as taken from the left end of FIG.
2;
FIG. 4 is a back view similar to FIG. 3 but showing a different
type of electrode arrangement;
FIG. 5 is another back view showing yet another electrode
arrangement;
FIG. 6 is a back view similar to FIG. 5 showing a still further
electrode arrangement;
FIG. 7 is an enlarged fragmentary sectional view taken along the
line 7--7 in FIG. 3 showing a detail of electrode mounting;
FIG. 8 is a view similar to FIG. 7 taken along the line 8--8 in
FIG. 5; FIG. 9 is a fragmentary side view of the apparatus showing
a modified form of handle or hand grip; and
FIG. 10 is a similar view showing a modification for AC or line
current operation.
An electrocardiographic unit constructed in accordance with the
principles of the present invention is shown at 20 in FIGS. 1-3.
The unit or apparatus comprises primarily a cathode ray
oscilloscope including a sheet metal housing 22 of rectangular
frontal construction, and somewhat trapezoidal top and side views.
The total length from front to back is on the order of 6 to 8
inches. The apparatus is provided with a cathode ray tube having a
display surface of face 24 on the order of two inches by three
inches. Control knobs are provided at 26, and a light sensitive
device 28, preferably a cadmium selenide cell is provided on the
front to control the brightness of the cathode screen display in
accordance with ambiant room lighting.
The apparatus is provided on its underside with a pistol grip 30 so
that it can readily be held by the hand 32, as of a doctor, and
pressed against the chest 34 of a patient. A trigger 36 is provided
behind the pistol grip 30 for depression by the index finger to
activate the apparatus to provide the cathode ray screen with the
desired readout of the heartbeat. An envelope of a normal heartbeat
is shown in broken lines at 38, the scale being too small to
reproduce the pulses displayed by a normal heartbeat.
The apparatus is provided on its back with three electrodes 40, 42
and 44. These are respectively the right side and left side
electrodes (also known as negative and positive electrodes) and an
indifferent electrode. These electrodes project only a very short
distance from the rear of the apparatus so as to minimize problems
of noise pickup.
Preferably, as shown in FIG. 7, each electrode, the electrode 40
being exemplary, is provided in the form of a disc 46 having a boss
48 on the rear thereof and having a socket therein cooperating with
a ball 50 on the end of a shaft 52. The shaft projects from the
rear wall 54 of the apparatus, and is resiliently urged outwardly
thereof by a spring 56 encircling the shaft and trapped between an
abutment 58, such as a C washer on the shaft and a depending stop
60 within the housing. A lead wire 62 extends from the inner end of
the shaft 52 to the input of the electronic circuitry, illustrated
as "black boxes" 64 and 66 in broken lines in FIG. 2. The cathode
ray tube 68 having the face or display screen 24 also is shown in
broken line outline in FIG. 2.
Reference heretofore has been made to construction of the case or
housing 22 of metal for shielding purposes. As will be understood,
the same ends can be attained by different means, such as by use of
a molded plastic housing with a foil lining or conductive paint on
the inner surface thereof.
A two lead pickup rather than a three lead pickup is shown in FIG.
4. In this figure the parts remain the same as heretofore
described, similar numerals being used with the addition of the
suffix a. The distinction is, that instead of having the three
electrodes in the Eindhoven triangle, as illustrated in Fig. 3,
there are but two electrodes 44a and 42a, respectively being the
indifferent electrode and the positive electrode. Again, the
electrodes preferably have a ball and socket mounting and are
spring biased to form the firm engagement with the chest of a
patient.
A further modified electrode structure is shown in Fig. 5, the
parts which are similar again being identified by similar numerals,
this time with the addition of the suffix b. In this instance, the
positive electrode 42b is centrally located, and has spaced from it
a negative electrode 40b concentric therewith. Outwardly of the
negative electrode and also in spaced relation therefrom and
concentric therewith is a yet larger ring comprising the
indifferent electrode 44b. In FIG. 8 there will be seen a structure
similar to that in Fig. 7 for supporting the electrodes of FIG. 5,
only the support for the outer ring or indifferent electrode 44b
being shown. There are four arcuately spaced shafts or rods 52b
supporting the ring 44b, each being outwardly biased by a spring
56b compressed between a stop 58b on the shaft and a fixed stop 60b
in the housing. Thus, as in the previous figures, structure is
provided for firmly, yet resiliently, and hence comfortably
postioning the electrodes against the patient's chest. A somewhat
modified electrode display is shown in FIG. 6, this again being a
two lead pickup as distinguished from a three lead pickups of FIGS.
3 and 5. The positive pickup in this instance comprises a ring 42c
having in spaced, insulated relation thereto and concentrically
outwardly therefrom an indifferent electrode 44c. The structure
otherwise remains the same.
The pistol grip 30 shown in FIG. 2 is fixed angular relation
relative to the case or housing. A modification of the structure is
shown in FIG. 9, similar parts being identified by similar numerals
with the addition of the suffic d. A handle 30d is mounted on a
depending flange 65 by means of a threaded stud 67 having a wing
nut 69 thereon. Upon loosening of the wing nut, the handle 30d may
be arranged to any desirable or comfortable position, as
illustrated by the single solid line and two broken line positions
of FIG. 9. Subsequent tightening of the wing nut 69 on the threaded
stud 67 locks the handle in the desired adjusted position.
It is intended that for utmost portability and electrical safety,
the present apparatus should be battery operated. However, it is
contemplated that in some instances it would be desired to use line
cord or AC operation. A modification to this end is shown in FIG.
10, similar numerals again being used with the addition of the
suffix e. The distinguishing feature of FIG. 10 is that the pistol
grip handle 30e is provided with a line cord 70 extending from the
lower end thereof, and leading up through the handle into the
housing for attachment to a power supply unit to operate the
electronic circuits and the cathode ray tube therein.
Due to the small size and light weight of the present apparatus,
and also due to the mounting of the electrodes directly thereon and
the preferred battery operation, it is a simple matter for a doctor
to carry such an apparatus with him, and to take a quick
electrocardiographic signal of a patient as routinely as blood
pressure and temperature and pulse rate are taken. Since the
apparatus can be constructed relatively inexpensively as electronic
medical apparatus goes, and since little additional time is
required for the taking of the instantaneous electrocardiographic
signal, the added cost to the patient for the taking of an
electrocardiographic signal along with the measuring of pulse rate,
blood pressure, and temperature is of inestimable benefit both to
the patient and to the doctor.
The specific examples of the invention as herein shown and
described are for illustrative purposes only. Various changes in
structure will no doubt occur to those skilled in the art, and will
be understood as forming a part of the present invention insofar as
they fall within the spirit and scope of the appended claims.
* * * * *