The Electrical experimenter

of the most important mech-
OXEanisms of the human body is the
Heart. Its action in health and
disease has been the subject of
attention by numerous prominent
physicians in all parts of the world, par-
Showing How the Extremely Sensitive
Electrical Apparatus Is
Connected up to Patient in Scientifically
Determining Just How
the Heart Beats and Why. The
Apparatus Used for this Measurement
Is Known as the "Electrocardiograph."
(Fig. 2.)
ticularly those interested in fighting heart
disease, the most unrelenting malady with
which one can be stricken. Yet it has
been
dren
said that
in New
15,000 to 20.000 school chil-
York alone are suffering
from it.
In view of its most important function
and delicate • structure, cure, by wa}- of
THE ELECTRICAL EXPERIMENTER May, 1917
The Autograph of Your Heart
By SAMUEL COHEN
tient whose heart is to be examined. These
terminals are three in number and are
made of German silver plates, each of
them being fitted with binding posts connected
to the leads, connecting the plates
with the sensitive galvanometer and
Wheatstone bridge circuit.
Two of the plates are secured
to the arms of the
patient, while the third
terminal is strapt around
the left ankle. Proper
care is taken to see that
the electrical connection
between the body and the
terminal is of low resistance
and for this purpose
a wet cloth which is saturated
with a 20 per cent
salt solution is placed between
the foot and plate
and again the cloth is
wrapt about the plate.
The Wheatstone bridge
circuit is balanced so that
the resistance of the electrical
path between terminals
is constant, and
this is obtained when the
quartz string or filament
of the galvanometer is in
a zero position.
It is evident that a slight addition of
current to tlie galvanometer circuit will
cause a displacement of the filament, which
is recorded on the film. Since the contraction
of the heart creates an electric cur-
rent as found by various scientists, and
arc as characteristic as finger prints or
photographs. Xo two individuals' hearty
beat alike, and the electrocardiograph, by
its extremely delicate registration of the
contraction of the muscle, readily shows
the most minute difference.
A remarkable story of a dying heart is
told b}- the accompanying curves registered
by the electroca diograph. The graphs illustrating
this remarkable story are shown
in the third figure, and these were taken
by Dr. R. H. Halsey, of Xew York City.
The records here reproduced form an
almost complete electrocardiographic record
of the heart b t during the last movements
of the patient's life. Tho death
was expected, yet its actual advent was
much earlier than had been anticipated
the transition from life to death was
abrupt. The w ning of change is to be
found in the lengthened conduction interval
and in the changed ventricular complex
of Fig. 5. That fibrillation of thtventricles
was not the immediate cause of
death is clear from Fig. 6, taken when the
usual signs of life were in abeyance: the
heart was profoundly affected, and the patient
past all possible hope of recovery
before fi rillation ensued.
The record was obtained from a female
patient thirty ye^ s of age, suffering from
broncho-pneumonia of both lower lobes.
The curves were taken one after the other
in quick succession and are described in
this order. In Fig. 1 the frequency of the
heart is 75. The duration of the diastole*
varies from 0.2 sec, to less than 0.1 sec,
as the intensity of this current depends
and is non-rhythmic. The up-stroke of P
is quicker than the downstroke. The con-
operation, is usually impossible.
Therefore, the
only thing left is to carefully
study the heart, locate
the trouble and determine
the reasons for
this trouble. A first aid
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xN the present article we have one of the most interesting and startling
-^revelations of what medical science, plus electricity, is doing to bring
about a clearer understanding of our bodily actions. Herewith is preduction
time is within the
normal limits of 0.2 sec.
T is upward in its direction
and of considerable
excursion. In the second
figure, the frequency of
the heart is 80. There are
in this direction is a biosented a true electrical record of a patient's heart, which shows the fluc- the same vibrations in the
graphical history of the
tuations occurring just before and at the critical moment when life ceased
patient.
The rapid growth of
to exist. In other words, the patient died.
this disease, and the rapid —
"^^^~^^^^~
^^-——-———
advancement ^^^^""^^^ of science _
has led to the development
of a new instrument called the upon the intensity of the heart contrac- the frequency
duration of the diastole.
The electrocardiograph
Figures 3. 4 and 5 show
the different frequencies
of the heart at different
periods. In curve 5,
of contraction of the heart
Elcctroeardiograph. This instrument is
really a modified Einthoven galvanometer,
consisting of a very powerful magnetic
field produced by an electromagtion,
it is therefore obvious that the fine
quartz wire will be displaced a certain
amount by the generation of current by
the heart. With the contraction wave,
appears to have dropt to 45. while
ciation of auricle and ventricle is still
ent. The conduction time is 0.4
double the time in the earlier record.
assopres-
sec:
Durnet
and excited by a constant direct current,
'such as the current given by a storage
battery. A very short air gap is made
between the poles of the magnet and in
this powerful field a fine quartz filament
the .electric potential spreads over the heart
and thus the galvanometer records the
heart beat and also indicates the origin
and path by which the current spreads.
An exact replica of the apparatus used
or fiber is stretched. Delicate adjusting in recordin.g tlie pulsation of the heart is
means are provided for controlling the
tension of this wire. (See Fig. 1.)
A small diafram is placed on the center
of this which closes two small holes that
extend thru in each pole piece. These
holes are the condensing microscopes and
the projecting microscope to focus a fine
beam of light to strike a moving photographic
film. If the wire is slightly displaced
by the passage of an electric current
thru it, it will naturally displace the
small diafram and in turn permit the fine
beam of light to pass thru the openings
and strike the film placed opposite to the
projecting lamp throwing out the fine beam
of light. It will, therefore, be seen that
bv displacing the quartz wire in certain
movements that a record will be made on
the film' accordingly.' This quartz filament
is connected to a Wheatstone bridge of
proper dimensions and also to special
terminals which are connected to the pa-
illustrated in Fig. 2. This shows the apparatus
in actual use and also how the
various electrodes are secured to the patient.
This photograph was taken at the
time a record was actually being made of
the condition of the patient's heart. The
sensitive galvanometer is seen at the left,
while the beam of light is derived from a
powerful arc projector stationed at the extreme
left, but not shown. The instrument
at the extreme right is the photographic
film apparatus. The film is driven at a
definite and uniform speed ly an electric
mntor mounted at the bottom of the machine.
This instrument is placed in exact
line with that of the telescope of the galvanometer
pole-piece. The resistance box
is .shown on the shelf of the galvanometer
table.
The instrument traces its indication of
conditions in the heart by curves on the
photogr-iphic film. These heart pictures
Close View or the Einthoven String Galvanometer
Used in Actually Measuring and
Analyzing the Infinitesimal Electrical Currents
Produced by the Human Heart at
Every Beat. Did You Know that Your
Heart Was a Dynamo? (I;ig. 1.)
ing the very brief interval between the
taking of Figs. 5 and 6. convulsive gasps
and a slow contraction of the skeletal muscles
occurred. In Fig. 6, the change is re-
• Diastole is the period of rest between contractions
of the heart.