In spite the progress in telemedicine, wide use
of digital technologies and other achievements of data transfer
systems, transtelephonic ECG up till now cannot compete with standard
one as to its quality. Therefore it is supposed that an ECG transmitted
via phone cannot be a valid document describing the electric activity
of the patient's heart. This widely spread opinion was undoubtedly
correct and based on serious errors of transtelephonic electrocardiography
that lover its diagnostic value.
Among the most significant drawbacks one can name
- Analog data transmission is the most serious defect, which
leads to the dependence of the quality of transmitted ECG from
the quality of telephone line. Most frequently the degradation
of signal-to-noise ratio occurs due to added line noise.*
- Acoustic coupling of the carrier emitter and handset microphone.
This solution itself is acceptable, but combined with analog data
transmission makes so indigestible hybrid that high quality electrocardiograms
become an exception, but not a rule. The rule in this case will
be highly noisy ECG, which forces the doctor to guess what happened
- No indication of communication interruption. In this case,
instead of the signal, you can receive anything you like, and
only the operator's intuition can help to distinguish technical
problems form cardiological ones.
- Non-synchronous transmission of the channels, which lowers
the diagnostic value of the ECG and makes to remember the times
when electrocardiographs were one-channel ones.
- Absence of indication of a poor electrode contact in the transmitter,
which requires extremely high qualification of the receiving station
operator. Indeed, one has only the artifact shape to guess a poor
contact of the electrode and must inform at the end of transmission
the sender on this. And, of cause, the investigation must be repeated.
- Improper application of electrodes (they are displaced in respect
to required application points). This situation can lead both
hyperdiagnosis and omission of pathognomonic phenomena, and to
* Systems of this type usually use transmission of frequency-modulated
pilot signal. With relatively small deviation caused by the bandwidth
limitations of a telephone line and, especially, by the signal passing
through systems with frequency multiplexing (still used in some
regions), one can rarely obtain 'pure', i.e. noiseless ECG even
with perfectly applied electrodes.
If we imagine simultaneous action of these factors, we can only
admire the enthusiasm of the people working with the transtelephonic
electrocardiography and agree that this investigation has low diagnostic
value, far beyond comparison with the standard 12-channel ECG recorded
in a clinic.
Nevertheless the telemedicine progresses and demand in the remote
ECG grows. And to make this investigation full-value one must eliminate
the above mentioned factors and obtain electrocardiograms ABSOLUTELY
IDENTICAL to those obtained in clinics.
Now we will try to list the requirements to a transtelephonic electrocardiograph.
We exclude from consideration the requirements to ECG amplifiers
(you must try hard to make a bad amplifier using modern components).
Thus, a transtelephonic apparatus must be a standard 12-channel
device with synchronous transmission of all channels, it must have
a digital link with a central station, automatically indicate bad
application of electrodes, and the central station must inform on
communication interruptions and/or automatically correct malfunctions.
Also, do not forget that the entire system must be adapted to Russian
and Ukrainian communication lines and faultlessly operate under
Besides, solving the problems of urgent diagnosis, the system must
be survivable, that is, it must not reject the transmission, as
e-mail does, but fight till the end trying to transmit at least
some portion of electrocardiogram even under conditions of rural
switchboard, because infarction is not a slight cold.
Let us suppose that all these requirements are satisfied and the
obtained ECG does not differ from a standard one (Fig. 1). The record
is made by means of a peripheral device of the system of transtelephonic
electrocardiography "Тelecard GSM" with chlorine-silver
disposable electrodes manufactured by Nessler Medizintechnik, located
in standard pick-up points. Transmission was carried out by means
of a cell phone Ericsson 1018, standard GSM-900. It is obvious that
this record can be interpreted as a usual electrocardiogram and
it is possible to compare records of such quality with those, which
will be made later, after the patient will be admitted to a clinic.
One cal also expect that such a system will trace slight changes
in ECG during loading, medication, etc.
Record shown in Fig 2 is made when the patient drove a car in heavy
city traffic. Clearly visible are not only the increase of heart
rate frequency, but also changes of the shape of electrocardiogram
complexes. There can be no doubt that pathological changes in ECG
will be recorded similar to a standard 12-channel electrocardiograph.
Nevertheless, irreproachable digital quality of transmission does
not guarantee correct diagnosis when the electrodes are applied
improperly or when simplified, i.e. ersatz electrodes are used.
This apparently trivial notion far from always is taken into account
in practical work. The reasons must be looked for in the field of
psychology rather than technology.
Let us take into account that transtelephonic ECG always was an
investigation of not a first grade and it is quite clear that there
is no use to waist good electrodes on ECG which will in any case
become 'dirty' and of small diagnostic value. Besides, mass production
of toy electrocardiographs with built-in metal electrodes (apply
it to the chest and see ECG on the screen) has substantially reduced
the exactingness to the quality of recording. And if we consider
the number of half-operable 'Malysh' (Midget) (model of electrocardiograph)
with ink recording which are used, it is not surprising that a doctor
makes statement without any hesitation from an ECG with noise, trend,
interference and 50 Hz hum. He can be understood - anyway, there
will be no better recording.
Now we try to simulate a typical situation with ersatz electrodes.
The record shown in Fig.3 was made with stainless steel electrodes
20 mm in diameter.
Standard gel was used, the places of electrode application were
usual. The result can be called expected, as it is hard to imagine
that respectful companies manufacturing disposable electrodes and
respectful clinics all over the world, which use them, did not hit
upon pieces of stainless steel in stead of electrodes. That is,
there is no need to prove that a good ECG requires good electrodes,
just see the result. But fact that electrodes must be applied to
proper places must be proved, and best of all experimentally but
Let us carry out such an experiment: record a standard ECG (Fig.
4), reapply disposable electrodes to the position usual for cycle
ergometry (Fig. 5) and then make one more recording, placing the
electrodes in a single belt, as it is done in some system of transtelephonic
ECG (Fig. 6). Records 3 through 6 are made with a standard 12-channel
Of course, in the latter case (Fig 6) the differences are so large
that the ECG BECOMES NONSTANDARD, and correct diagnosis is possible
only by a specially trained investigator deprived from the possibility
to use the generally accepted ECG semantics. It would be better
to free the reader from contemplation of the record made with the
combination of ersatz electrodes with the belt locating them in
non-standard places. For the reason of humaneness.
Commercial companies, which consult on the basis of wide implementation
of transtelephonic electrocardiographs, have made their business
rather lucrative. The greatest achievements are in Israel, where
locally manufactured equipment is widely used. In Russia systems
of remote ECG diagnosis are already working in Moscow, Saint-Petersburg
and some other large cities. There is no doubt that soon the companies
offering their clients similar services will appear in the Ukraine
as well. This is really extremely necessary aid to the patients
from the risk group of corresponding groups of diseases. The transtelephonic
electrocardiography has an excellent future in the market of advanced
medical technologies and their applications in the interest of the
However, thoughtless transfer of foreign designs to local conditions
is fraught with rather serious complications. In particular, completely
different diagnoses can be established from one and the same ECG
by two specialists, one of which is guided by the generally accepted
international ECG standards, and the second uses the standards specially
adapted to non-standard application of electrodes. In the case of
diagnostic error, which has lead to substantial aggravation of the
patient's health or his or her death, this contradiction immediately
jumps from the narrowly medical field to the legal or even criminal
It would be better to avoid such collisions already at the stage
of studying the experience of others. For this it will be sufficient
either to use the systems of transtelephonic ECG working with the
standard leads, or carry out additional standardization oriented
to the electrode application technique distorted in respect to the
generally accepted one. Besides, it is necessary also to additionally
retrain the cardiologists who begin to work with non-standard transtelephonic
diagnostic equipment. Nevertheless, the patient's electrocardiograms
obtained with such "non-standard" service will have a
diagnostic value only within this service itself and cannot be used
by other cardiologists not completed the course of retraining without
the risk of making an error.
Which version is more expedient - it is up to the reader to judge,
as well as up to those state officials, who is responsible for certifying
and legalizing foreign medical diagnostic equipment in Ukraine and
Russia. However, we are sure that the digital 12-channel transtelephonic
ECG, which does not differ from the standard one, will substitute
the ersatz cardiographs, which the telemedical market offers today.