Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ELECTRODELESS EKG SENSOR SHEET
Field of the Invention
This invention relates to low cost disposable devices for
electrocardiographic monitoring and telemetry, and more
particularly devices for interfacing between a patient and
electrocardiography apparatus. More particularly, the invention
concerns an electrocardiographic device which can be used without
electrodes.
Backctround of the Invention
Electrocardiographic monitoring and telemetry have been in use
in the United States for some time for screening and diagnosis of
cardiopathy. Electrocardiography provides a graphic registration,
commonly known as an EKG, of movements of the heart using
electrical signal sensing. In general, electrical leads used to
transmit signals from the patient's cardiovascular system are fixed
to the skin of the patient individually, at suitable locations,
using suction cups and conductive adhesives to provide the
necessary electrical connection for reading the heart movements
through a patient's skin.
For screening and evaluation, the patient should be ambulatory
so that readings can be taken during different degrees of physical
exertion to demonstrate the reaction of the heart to differing
stresses. A standard type of testing includes electrocardiographic
monitoring of a patient during a set of standardized treadmill
exercises. It is well recognized that this type of screening and
evaluation are important for diagnosis of new ischemic cardiac
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episodes in the chronically symptomatic cardiac patient as well as
the identification of "silent ischemic" periods of myocardial
oxygen insufficiency not associated with classic chest pain. These
ischemic electrocardiographic changes can be accurately recognized
only if a full screen electrocardiogram is performed. The standard
full screen electrocardiogram includes readings taken by
electrically conductive leads at standard chest positions combined
to provide readings.
Periodic electrocardiograms can provide a physician with a
cardiographic profile of an individual patient for early detection
and diagnosis of cardiovascular diseases. For purposes of
providing an accurate profile, it is important that each
electrocardiogram be taken with leads affixed about the same
location on the patient. The accuracy of each electrocardiogram
requires that the leads be accurately placed and that they remain
fixed while the patient is ambulatory. In addition, to provide
accurate information for an individual patient, a series of
electrocardiograms are taken and compared to one another to detect
changes in the reaction of the individual patient's heart to the
same stresses. Therefore, it is important that placement of the
leads be consistent from one electrocardiogram session to another.
As can be appreciated, accurately placing and securing a large
number of leads can be difficult and time consuming. In addition,
electrocardiograms are taken periodically and the results compared
to one another to provide a continuing profile of an individual
patient's heart movements for early diagnosis and treatment of
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heart disease and to identify "silent ischemic" periods of
myocardial oxygen insufficiency in chronically symptomatic cardiac
patients. It would therefore be advantageous to have a device for
accurate placement of leads for accurately reproducing test
conditions for comparison between testing episodes.
Although a full- screen, twelve point electrocardiogram
provides the most accurate picture for recognizing ischemic
electrocardiographic changes, because of the time required to place
and secure individual leads, electrocardiograms taken during an
acute symptomatic episode of a cardiac patient are generally
limited to two- to four-lead readings. It would therefore be
advantageous to have a device which enables more leads to be
accurately placed and secured quickly during an acute symptomatic
episode.
U.S. Patent No. 4,608,987 to H.E. Mills relates to a vest-like
garment having a plurality of aperatures adapted for receiving
electrodes. However, there is no provision to ensure that the
electrodes are placed each time of reuse of the vest about the same
location.
U.S. Patent No. 4,583,549 to S. Manoli relates to an ECG
electrode pad with a plurality of ECG electrodes which are
repositioned with regard to each other and not with reference to
their previous position.
U.S. Patent No. 4,365,634 to Bare et al discloses a multi-
terminal electrode construction having a pair of separate support
members adapted for the transcutaneous application of an electrode
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to a patient. A multiterminal design is provided by a conductive
pattern printed on a semiflexible sheet. The pattern is printed
with conductive ink in a binder composition. However, there is no
means provided which can ensure the reapplication of the terminals
to the same location so as to obtain a better comparison of test
results.
U.S. Patent No. 4,593,698 to R.J. Athans discloses an
electrocardiograph sensor positioning device for repeatedly
positioning electrocardiograph sensors. The device establishes a
longitudinal reference between two anatomical landmarks on an
individual. A second reference path is then found and recorded.
The recorded locations are necessary to ensure a similar location.
One of the problems with the use of the device requires that the
second examining physician have the information from the first
physician in order to obtain readings at the same locations. The
device of the invention provides uniform examination without
requiring information from others on placement of the electrodes.
U.S Patent No. 4,763,660 discloses a multilayer disposable
electrode belt device which contains a plurality of flexible non-
conductive layers. There is also provided anatomatical placement
reference means.
Telephonic units for transmitting ECG signals to ECG receiving
equipment at a cardiologist's office are described generally in
U.S. Patent No. 3,910,260. Usually such transmission takes place
in emergency vehicles where prior medical history may not be
readily available. In order to obtain meaningful and reliable
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information repeatable ECG signals are necessary for the
cardiologist. None of the prior art devices have provided a low
cost solution to obtaining repeatable ECG signals in the field by
untrained or non-professionals parties.
The present invention provides an easily manufactured
accurate, repeatable placement of leads for electrocardiograms
which is repeatable without knowledge of the previous locations.
The device of this invention lowers the time involved in placement
and affixation by providing a sensor sheet incorporating multiple
leads which are preferably pre-wired to a terminus that can connect
to a standard electrocardiographic cable or to a telemetric unit,
as more fully discussed below.
Summary of the Invention
In general, the present invention includes a low cost flexible
single layered vest or bib for electrically connecting a patient
with an electrocardiographic monitoring device. The bib has
incorporated therein electrical conducting strips or wires for
transmitting electrical impulses from a patient to be monitored to
the electrocardiograph device. The bib incorporates at least six,
preferably 8-12, of the strips in a predetermined pattern
corresponding to a standard, full screen electrocardiogram. The
strips are used both as electrodes and as transmitters for the
electrical impulses. The conventional sensory electrodes are
optional since the apparatus can function effectively without them.
Each of the strips includes a first end mounted at
predetermined positions on a patient's chest and a second end for
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connection with an electrocardiographic device.
More particularly, the present invention includes a single
sheet non-conductive substrate, for example, a sheet of non-
conductive natural or plastic material polyvinyl chloride,
polyethylene polyphenylene, terephthalate, cotton, rayon, and the
like, having incorporated therein a plurality of electrically
conductive strips or wires. Each strip includes a first end
portion or receptor end adapted for electrical connection with the
skin of the patient for receiving electrical impulses. A second
end of each strip terminates in a common electrical connector or
cable junction on the sheet which is adapted for connection with a
standard type of cable juncture for connection with the
electrocardiograph device.
It is a feature of the invention to provide electrically
conductive adhesive means pre-applied to the strips for assuring
electrical contact with skin. One or more positioning members are
included to facilitate positioning the bib in the proper location
on the patient's chest to assure that each of the pre-positioned
conductors or electrodes is located in appropriate overlying
relationship for obtaining readings at selected locations on the
patient's chest. The positioning members are advantageously
located to overlie the easily recognizable bony chest landmarks of
the patient, i.e. the clavicles and sternum. The positioning
members are slots, notches, openings in the bib for locating by
touch the sternum notch and the clavicle notch.
A standard pattern may be printed in any suitable manner on
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the bib to further facilitate positioning of the bib on the
patient. The pattern includes an outline of the clavicles and
sternum landmarks, or any other recognizable outline of the chest
landmarks.
The conductive strips are printed on a single layered film or
sheet by any conventional printing or silk screening type of
process. The portion of the strip which need not be exposed can be
coated with a non-conductive coating or adhesive material which can
be cured.
It is therefore an object of the present invention to provide
a method and apparatus which may repeatedly position a plurality of
body electrodes about the same position on the body without
knowledge of the prior positioning.
It is a further object of the invention to provide a garment
for supporting a plurality of electrocardiograph sensing strips
which are set in a predetermined pattern that can be repeatedly
placed on a patient's body about the same position for connection
to electrocardiograph equipment.
It is still further object of the invention to provide a
garment having a plurality of electrocardiograph' sensing strips
without electrodes which can be placed on a patient by untrained
parties or the patient grovides reliable and repeatable ~ECG
signals.
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According to an aspect of the present invention there
is provided an apparatus for wearing by a patient about the
chest area for transmitting electrical impulses from the
patient to an electrocardiograph, the apparatus comprising
a single flexible non-conductive sheet having an upper end
and a lower end, first means on the flexible sheet for
positioning the apparatus at its upper end at the
clavicular notch and a second positioning means on the
sheet for positioning the apparatus at the sternum notch, a
plurality of electrically conductive strips or wires
mounted on the sheet, each strip or wire having a first end
adapted for electrical connection with the skin of the
patient, and a second end adapted for connection with a
terminal for transmitting electrical impulses to an
electrocardiograph device, whereby positioning the
apparatus at the clavicular notch and at the sternum notch
causes positioning of the conductive strips on or about the
same position repeatedly.
Brief Description of the Drawings
Fig. 1 is a front view of a preferred embodiment of
the invention.
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Fig. 2 is a view similar to Fig. 1, showing the preferred
embodiment in phantom to illustrate placement of the sheet on a
patient.
Fig. 3 is a similar to Fig. 2 and illustrates the sternum and
clavicle positioning means.
Detailed Description of the Preferred Embodiment
An illustrated in Fig. 1, a preferred embodiment of the
electrode-less EKG sensor sheet of the instant invention includes
a single layered flexible sheet or bib 10 having a contact surface
11 for placement on the chest region of a patient.
A plurality of electrically conductive strips are mounted on
the bib 10 to transmit electrical impulses from the patient' s chest
to an electrocardiographic recording device. In the preferred
embodiment illustrated in the drawing, with reference to Fig. 1,
the strips are configured in the pattern normally used in the chest
configuration for standard treadmill exercise testing. More
particularly, the strips include the normal limb leads or strips
for extremities such as a right arm strip 20, left arm strip 21,
right leg strip 22, left leg strip 23 as well as the normal chest
strips 24, 25, 26, 27, 28 and 29. The four limb strips alone can
provide a standard two- or four-lead or strip electrocardiogram.
The four limb strips when combined with the chest strips 24 and 25
in addition to the individual strips provide the standard type 12
lead electrocardiogram.
tnlith reference to Fig. 2, the right arm strip 20 and the left
arm strip 21 are located below the clavicles bilaterally. The
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right leg strip 22 and left leg strip 23 are located below the
sternum. The chest strip 26 is located approximately at the mid-
axillary line. Each of strips 20-29 is electrically connected at
one end to a suitable connector such as cable junction 30
illustrated in Figures 1 and 2.
Each. of the strips 20-29 includes an exposed receptor end,
such as end 35 on the left arm strip 21. A conductive adhesive or
gel 38 is preferably applied to the end 35 to assure good
electrical contact with the patient's skin.
Although the individual receptors, such as the receptor 35
having the conductive adhesive 38 may provide sufficient adhesion
for maintaining the bib 10 in position, it is an additional feature
of the present invention to provide two or more positioning members
for more accurate placement of the bib on a patient's chest. In a
preferred embodiment as illustrated in Fig. 2, the positioning
members are located for placement over bony portions of the anatomy
which are easily recognized. More particularly, in the illustrated
embodiment the positioning members are located for placement over
the clavicles and sternum, the bony chest landmarks, and include
clavicle patches 42 and 43, an upper sternum patch~44, and a lower
sternum patch 45. The positioning members or patches 42-45 may
include any suitable adhesive applied to the contact surface 11 of
the bib 10.
As can now be appreciated, by mounting the strips 20-19
securely to the bib 10 and thus pre-positioning the receptors ends
such as end 35, accurate placement for accurate and reproducible
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test results is greatly facilitated. The positioning patches 42-45
further assure that the bib l0~wi11 remain in place throughout the
testing session.
For additional ease in placement, the bib 10 may color-encoded
on the visible or non-contacting bib surface for ready recognition
of the bony, chest landmarks, and may include, for example a
colored portion on the non-contacting surface of the bib 10 as
illustrated by hatching shown on the patches 42-45 in Fig. 2. An
outline and/or colored markings for each of the clavicles and
sternum and/or lead receptors such as outline 50 may also be
printed on the non-contacting bib surface for ease in bib
placement.
As shown in Fig. 3, a bib 10 may be provided with a slot or
notch 60 which positions the upper portion of the bib 10 at the
clavicular notch. The slot 52 is then utilized to align the bib 10
with the sternum notch. With the alignment along the clavicular
notch and sternum notch the receptor ends then automatically can be
repeatedly placed about the chest when the bib 10 is wrapped around
the body since the electrodes maintain the same pattern and
location. The bib 10 may be tied with belts 54, 54' or a VELCRO
fastener 53, 53'.
The bib 10 can be provided in a range of sizes, for example
large, medium and small, to accommodate patients of differing
stature. The bib can also be anatomically constructed to provide
for women patients. The bib may be formed from any non-conductive
flexible natural or synthetic sheet material which is capable of
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accepting a print, for example, cotton, Mylar, polyolefin
(polypropylene, polyethylene), polyvinyl chloride, nylon, and the
like or mixtures thereof.
The strips or wires can be of any electrically conductive
graphite, polymer or metal, graphite, and the like, for example, N-
vinyl pyrrolidone, copper, silver, aluminum, and the like or alloys
thereof. The strips can be made of metal foil or made from a
conductive paste of the metal in particle form in a suitable binder
which is printed or silk screened onto the bib. Alternatively, a
single wire or a multiplicity of fine wires may be adhered onto the
bib by a non-conductive adhesive in the desired pattern. The
conductive polymer may be heat pressed or otherwise adhered to the
bib.
If desired, the exposed conductive strips or wires way be
partially coated with a coating solution of a non-conductive
polymeric material so that only the selective end portions are
exposed. Suitable coatings include polyesters, ethylene-vinyl
acetate copolymer, polyvinyl chloride and copolymers thereof, ABS,
acrylic rubbers, and the like.
The apparatus of the invention has the advantage of being
easily manufactured and not requiring the use of conventional
electrodes. However, if greater sensitivity is desired, electrodes
can be added onto the end strip by any conventional fastening.
Although the invention has been discussed and illustrated as
using metallic strips, the invention is not limited to electrically
conducting strips, and any technique for incorporating conductive
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materials in a predetermined pattern into a flexible sheet material
can be used. Other modifications can be made without departing
from the spirit of the invention, the scope of which is set forth
in the following claim.
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