Apparatus And Method Of Monitoring The Electrical Activity Of The Heart Of A Human With Armpit Located Electrodes

Abstract

Apparatus and method for quickly, easily and reliably monitoring the electrical activity of the heart of a human. In the exemplary embodiment there is provided an electrode construction for use with well-known cardiac monitoring means comprising a carbon impregnated plastic body having a conductive grid embedded therein with a lead electrically connected thereto and extending from the body. These electrodes are adapted for placement and retention in the user's armpits to pick up the heartbeat signal and transmit it to the cardiac monitor.

Description

SUMMARY OF THE INVENTION

The tremendous amount of research and development work being done in the heart monitoring field has led to many interesting and valuable developments both with regard to the circuitry for the cardiac monitor itself and the electrodes which are adapted to be placed on the patient to pick up the heartbeat signal. It is to the electrode aspect and method of picking up the heartbeat signal that this invention is directed.

In the past, the electrodes have taken the form of variously shaped metal elements which are brought into direct contact with the skin. In order to increase conductivity a conductive paste is often interposed between the electrode and the skin. The problems with such an arrangement are many and varied, for example, due to the direct contact between the electrode and the body and the chemical nature of each problem relating to polarization, chemical reaction, skin irritation, possible noise, and contact or movement artifact are experienced. The chemical reaction may extend to the point where a battery effect is produced, or a chemical reaction produced which is detrimental to the skin may be developed.

Although all of the concepts with regard to contact and movement artifact may not be completely known it is apparent that factors which contribute to such are change in resistance caused by change in applied pressure, change in distribution of the conducting ions caused by shearing and possible distortion of the electrode during movement. Additionally, the movement of muscles and bones in the area of and between the electrodes can cause appreciable noise increase with attendant poor signal discrimination.

It must also be understood that patients invariably dislike metal electrodes, conducting paste and complicated means for retaining the electrodes in position on the body.

In order to obviate many of the aforementioned problems, electrodes have been made of plastic with a conducting medium therein to pick up the heartbeat signal which is obviously quite weak. Here again conductive pastes and the like are employed to make certain that proper and necessary signal strength is picked up by the electrode.

In addition to the above, it must be remembered that the skin itself has an appreciable resistance factor. Further, the distance the heartbeat signal must travel before reaching the pick up electrodes is an important consideration. In fact an electrode which could be applied to the body without any preliminaries would be most desirable.

In view of the foregoing, it is an object of this invention to provide a system of detecting heartbeat wherein the electrodes of a cardiac monitoring device are positioned in the armpits of the patient and held there by the pressure of the arm pressing against the body in the area of the armpit.

It is another object of this invention to provide for use with a conventional cardiac monitor a pair of electrodes which are free from chemical reaction when placed on the user.

It is yet another object of this invention to provide an electrode as above wherein the electrode has a body of plastic with carbon distributed thereon and an electrically conducting grid is embedded therein.

It is another object of this invention to provide an electrode as above which does not require the use of a conductive paste between the electrode and the user's body.

IN THE DRAWINGS

FIG. 1 is a pictorial view illustrating the manner in which the electrodes are applied to the user's body to pick up the heartbeat signal,

FIG. 2 is a schematic view illustrating the basic components of typical heartbeat detection and monitoring apparatus,

FIG. 3 is a perspective view of the electrode of this invention,

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 3 showing the disposition of the conductive grid in the electrode body, and

FIG. 5 is a horizontal sectional view taken along line 5--5 of FIG. 4 illustrating the grid and attached lead embedded in the body.

DETAILED DESCRIPTION OF THE INVENTION

The electrodes of this invention are adapted to be used with a battery operated cardiac monitor such as that described in U.S. Pat. No. 3,613,670 to H. J. Edenhofer. This device takes the signal picked up by the two-spaced electrodes on the body and converts them to pulsing light or to an audible beeping signal indicative of heartbeat by, among other means, amplifying the signal and sufficiently suppressing noise and/or artifact components of the signal to prevent spurious triggering of the output indications.

As best illustrated in FIG. 1, the patient 10 is holding the cardiac monitor 12 in his left hand and has placed electrodes 14 and 16 in his armpits with the upper portion of each arm pressing against the electrode to provide firm contact with the body.

Referring to FIG. 2, the electrodes 14 and 16 are attached via respectively associated electrical leads to a cardiac monitor 12 provided with a lamp 18 for producing the visual signal and a speaker 20 for the audible beeping. The monitor 12 is also provided with an "on" and "off" switch 22. Other and additional features may be embodied in the cardiac monitor 12 but the flashing lamp 18 and beeping speaker 20 are the most important elements for this type of heart monitoring.

The construction of the electrodes 14 and 16, both being alike, is shown in FIGS. 3-5. The electrode comprises a body 30 made of carbon filled plastic preferably a vinyl type, however, other types of plastics may be used. The body 30 has a rectangular base portion 32 topped with a triangular upper portion 34. As indicated in the cross sectional view of FIG. 4, the body is pentagonal in cross section with a horizontal bottom 36, parallel vertical and equal sides 38 and 40 and inwardly slanted top sides 42 and 44 of equal length.

Referring to FIGS. 4 and 5, a conducting screen or grid 50 is embedded in the body 30 so as to be horizontally disposed with respect to bottom 36. The bare ends 52 of lead-in wire 54 are soldered to the screen 50 and likewise embedded in the body 30.

In actual use, the electrode is approximately 2 1/2 inches long, and 1 1/8 inches wide. The thickness at the middle section which is the greatest is roughly 1/4 inch. It is preferred that stranded wire be used for the lead-in wire 54 to provide desirable flexibility and ease of handling.

Although the use and method involved should be amply clear, a brief summary follows. When an individual wishes to check his heartbeat he places electrodes 14 and 16 in his armpits and makes certain that the electrodes are firmly in place. While holding the cardiac monitor 12 in his hand, the switch 22 is turned to the "on" position and the heartbeat signal is immediately produced by either the flashing light 18 or the audible beeper 20. If there is some question as to the heartbeat the user may immediately call his doctor and have him listen to the heartbeat and at least prescribe temporary care.

As previously set forth, the advantages of the electrode of this invention are numerous and important. First of all, with this electrode construction no conductive paste is needed. Thus all of the mess and bother attendant such is eliminated. Additionally, the plastic from which the body is made is generally inert. By this it is meant that there will be no chemical reaction between it and the skin of the user. Further, there will be no reaction from any moisture or oiliness that may be found on the user's skin. Still further, the electrode will not corrode and is readily cleaned so as to have a long use life. Also there will be no allergy problems. The use of a conductive grid over the wide area of the rectangular base of the electrode provides maximum signal pick up, thus increasing reliability even under adverse circumstances.

The shape of the electrode 14 is not necessarily limited to that disclosed, although that configuration does have some advantages particularly when used in the armpit. The length is such that it may be easily handled and readily placed in the armpit. The bottom flat side 36 and the triangular top 34 make it possible for the portion of the armpit defined by the upper torso to receive the flat bottom 36 and the upper arm to engage the triangular portion 34. This provides good gripping and contact such that the arm in its normal relaxed position will hold the electrode in place in the armpit and provide sufficient contact for the heartbeat signal to be picked up.

The placing of the electrodes 14 and 16 in the armpits of the user presents many advantages. Specifically, the armpit area is warm and generally somewhat damp thus providing a very good area for transfer of weak electric signals. Additionally, there may be some type of salt or the equivalent present which would constitute an electrolyte and further enhance pick up of the signal. Further, the location of the electrodes in the armpits means that the electrodes will be in close proximity to the heart, thus a stronger signal should be received. It should also be noted that the stratum corneum on the armpit area is relatively thin thereby decreasing skin resistance. The type of flesh that the heartbeat signal passes through to reach the electrodes in the armpits presents less signal transmission difficulties than would be experienced in measuring heartbeat by signal take off on the lower arms or legs.

It would appear that the concept of placing non-corrosive type electrodes in the armpit to pick up heartbeat signals is a substantial advance in cardiac monitoring.

Although only one exemplary embodiment has been specifically described and explained herein, those skilled in the art, in view of the above discussion, will appreciate that many specific features of this particular exemplary embodiment may be adapted, modified and changed without materially departing from the teachings of this invention as defined in the following claims.

Claims

We claim:

1. A method of monitoring the electrical activity of the heart of a human under one of a variety of conditions including self monitoring under emergency conditions by the use of a portable battery operated monitoring apparatus which includes a pair of electrode bodies having exterior surface means for enabling the bodies to be easily positioned in the armpits of the human to be monitored and to be conveniently and comfortably self-retained in such position solely by the human by engagement between the adjacent arm portions and torso in the armpit areas, said method comprising the steps of

positioning said electrode bodies within the armpits of the human to be monitored and self-retaining the same therein solely by the human by engagement of the bodies between the adjacent arm portions and torso in the armpit areas,

establishing a conductive circuit from a position spaced from said bodies which extends through said bodies to the exterior surface means thereof and between the latter through the torso of the human through which the electrical impulses within the torso of the human which trigger the heartbeats of the human are reliably conducted,

amplifying the electrical impulses conducted in said circuit and substantially suppressing other electrical signals, such as artifact and the like, which may be conducted in said circuit, and

reliably producing output indications representative of the electrical impulses of the heart of the human.

2. A method of monitoring the electrical activity of the heart of a human under one of a variety of conditions including self monitoring under emergency conditions by the use of a portable battery operated monitoring apparatus which includes a pair of electrode bodies having dry exterior surface means for enabling the bodies to be easily positioned in the armpits of the human to be monitored and to be conveniently and comfortably self-retained in such position solely by the human by engagement between the adjacent arm portions and torso in the armpit areas, said method comprising the steps of

positioning said electrode bodies within the armpits of the human to be monitored in a dry condition and self-retaining the same therein solely by the human by engagement of the bodies between the adjacent arm portions and torso in the armpit areas,

establishing a conductive circuit from a position spaced from said bodies which extends through said bodies to the dry exterior surface means thereof and between the latter through the torso of the human, without the provision of conductive paste or the like between said dry exterior surface means and the skin engaged thereby, through which circuit the electrical impulses within the torso of the human which trigger the heartbeats of the human are reliably conducted,

amplifying the electrical impulses conducted in said circuit and substantially suppressing other electrical signals, such as artifact and the like, which may be conducted in said circuit, and

reliably producing output indications representative of the electrical impulses of the heart of the human.

3. Apparatus for monitoring the electrical activity of the heart of a human under one of a variety of conditions including self-monitoring under emergency conditions, said apparatus comprising:

housing means for enabling the same to be easily and conveniently carried by a human operator,

a pair of separate electrode bodies,

said electrode bodies having exterior surface means for enabling said bodies to be easily positioned in the armpits of a human to be monitored and to be conveniently and comfortably self-retained in such position solely by the human by engagement between the adjacent arm portions and torso in the armpit areas,

an elongated flexible lead element extending between each electrode body and said housing means,

electrical conductor means operable when said electrode bodies are positioned and retained in the armpits of a human as aforesaid, for establishing an electrical circuit within said housing means which extends therefrom through said lead elements and through said electrode bodies to the exterior surface means thereof and between the latter through the torso of the human through which the electric impulses within the torso of the human which trigger the heartbeats of the human are reliably conducted from the torso to said housing means, and

battery operated electric circuit means carried by said housing means operable in response to the conducting of said electrical impulses through the aforesaid electrical circuit by said electrical conductor means to said housing means to amplify said electrical impulses and substantially suppress other electrical signals, such as artifact and the like, which may be conducted in said circuit, and to reliably produce output indications representative of the electrical impulses of the heart of the human.

4. Apparatus as in claim 3 wherein each of said electrode bodies is formed of electrically conductive material in a three dimensional configuration defining substantially the entire exterior surface means thereof for making electrical connection to the substantially enclosed skin surface areas of the human armpit when the upper arm is in its normal relaxed position substantially adjacent to the human body thus maximizing the area of electrical contact with the human armpit tissues.

5. Apparatus for monitoring the electrical activity of the heart of a human under one of a variety of conditions including self-monitoring under emergency conditions, said apparatus comprising:

housing means for enabling the same to be easily and conveniently carried by a human operator,

a pair of separate electrode bodies,

said electrode bodies having dry exterior surface means for enabling said bodies to be easily positioned in the armpits of a human to be monitored in a dry condition and to be conveniently and comfortably self-retained in such position solely by the human by engagement between the adjacent arm portions and torso in the armpit areas,

an elongated flexible lead element extending between each electrode body and said housing means,

electrical conductor means operable when said electrode bodies are positioned and retained in the armpits of a human as aforesaid, for establishing an electrical circuit within said housing means which extends therefrom through said lead elements and through said electrode bodies to the dry exterior surface means thereof and between the latter through the torso of the human, without the provision of conductive paste or the like between said dry exterior surface means and the skin engaged thereby, through which circuit the electric impulses within the torso of the human which trigger the heartbeats of the human are reliably conducted from the torso to said housing means, and

battery operated electric circuit means carried by said housing means operable in response to the conducting of said electrical impulses through the aforesaid electrical circuit by said electrical conductor means to said housing means to amplify said electrical impulses and substantially suppress other electrical signals, such as artifact and the like, which may be conducted in said circuit, and to reliably produce output indications representative of the electrical impulses of the heart of the human.

6. Apparatus as in claim 5 wherein each of said electrode bodies is formed from a carbon loaded plastic material, which material defines substantially the entire dry exterior surface means thereof.

7. Apparatus as in claim 6 wherein each of said lead elements is embedded within the associated electrode body.

8. Apparatus as in claim 7 wherein each of said electrode bodies has an elongated configuration in one direction and the lead element associated therewith extends therefrom generally in said one direction.