library contents |
ECG axis |
ECG history |
ECGs by Example
A (not so) brief history of electrocardiography.
Find out how
electrocuting chickens (1775), getting laboratory assistants to put their hands in buckets of
saline (1887), taking the ECG
of a horse and following it to the slaughterhouse (1909), induction
of indiscriminate angina
attacks (1931), and hypothermic dogs (1953) have helped to
improve our understanding of the
ECG as a clinical tool. And why is the ECG labelled PQRST (1895)?
|17th and 18th Centuries
||The harnessing of electricity, observations of its effects on animal tissues and the discovery of 'animal electricity'.
Gilbert, Physician to Queen Elizabeth I, President of the Royal College
of Physicians, and creator of the 'magnetic philosophy' introduces the
term 'electrica' for objects (insulators) that hold static electricity.
He derived the word from the Greek for amber (electra). It was known
from ancient times that amber when rubbed could lift light materials.
Gilbert added other examples such as sulphur and was describing what
would later be known as 'static electricity' to distinguish it from the
more noble magnetic force which he saw as part of a philosophy to
destroy forever the prevailing Aristotlean view of matter.
Gilbert W. De Magnete, magneticisique corporibus, et de magno magnete tellure. 1600|
- Sir Thomas Browne, Physician, whilst writing to dispel popular
ignorance in many matters, is the first to use the word 'electricity'.
Browne calls the attractive force "Electricity, that is, a power to
attract strawes or light bodies, and convert the needle freely placed".
(He is also the first to use the word 'computer' - referring to people
who compute calendars.)Browne, Sir Thomas. Pseudodoxia Epidemica: Or, enquiries Into Very Many Received Tenents, and Commonly Presumed Truths. 1646: Bk II, Ch. 1. London
- Otto Von Guericke builds the first static electricity generator.
Descarte's reflex ©BIU
work of Rene Descartes, French Philosopher, is published (after his
death) and explains human movement in terms of the complex mechanical
interaction of threads, pores, passages and 'animal spirits'.
He had worked on his ideas in the 1630s but had abandoned publication
because of the persecution of other radical thinkers such as Galileo.
William Harvey had developed similar ideas but they were never
Descartes R. De Homine (Treatise of Man); 1662: Moyardum & leffen, Leiden.|
- Jan Swammerdam, a Dutchman, disproves Descartes' mechanistic
theory of animal motion by removing the heart of a living frog and
showing that it was still able to swim.
On removing the brain all movement stopped (which would be in keeping
with Descarte's theory) but then, when the frog was dissected and a
severed nerve end stimulated with a scalpel the muscles twitched.
This proved that movement of a muscle could occur without any
connection to the brain and therefore the transmission of 'animal
spirits' was not necessary.
Swammerdam's ideas were not widely known and his work was not
published until after his death. However, he wrote many letters and his
friend, Nicolaus Steno, did attack the Cartesian ideas in a lecture in
Paris in 1665. Boerhaave published Swammerdam's 'Book of Nature' in the
1730s which was translated into English in 1758.
electrical stimulation? ©BIU
refines his experiments on muscle contraction and nerve conduction and
demonstrated some to notable figures such as the Grand-Duke Cosimo of
Tuscany who was visiting Swammerdam's father's house on the Oude Schans
One experiment suspended the muscle on a brass hook inside a glass tube
with a water droplet to detect movement and 'irritated' the nerve with
a silver wire.
This produced movement of the muscle and it may have been due to the
induction of a small electrical charge - although Swammerdam would have
been unaware of this.
In the diagram opposite - a) glass tube, b) muscle, c) sliver wire, d) brass wire, e) drop of water, f) investigator's hand.
- Stephen Gray, English scientist, distinguishes between
conductors and insulators of electricity.
He demonstrates the transfer of static electrical charge to a cork ball
across 150 metres of wet hemp thread. Later he found that the transfer
could be achieved over greater distances by using brass wire.
physicist Pieter van Musschenbroek discovers that a partly filled jar
with a nail projecting from a cork in its neck can store an electrical
The jar is named the 'Leyden Jar' after the place of its discovery.
Ewald Georg von Kliest of Pomerania invented the same device
Using a Leyden jar in 1746, Jean-Antoine Nollet, French physicist
and tutor to the Royal family of France sends an electrical current
through 180 Royal Guards during a demonstration to King Louis XV.
- Edward Bancroft, an American Scientist, suggests that
the 'shock' from the Torpedo Fish is electrical rather than mechanical
in nature. He showed that the properties of the shock were similar to
those from a Leyden jar in that it could be conducted or insulated with
appropriate materials. The Torpedo fish and other species were widely
known to deliver shocks and were often used in this way for therapeutic
reasons. However, electrical theory at the time dictated that
electricity would always flow through conductors and diffuse away from
areas of high charge to low charge. Since living tissues were known to
be conductors it was impossible to imagine how an imbalance of charge
could exist within an animal and therefore animals could not use
electricity for nerve conduction - or to deliver shocks. Furthermore,
'water and electricity do not mix' so the idea of an 'electric fish'
was generally not accepted.
Bancroft, E. An essay on the natural history of Guiana, London:T. Becket and P. A. de Hondt, 1769.
|John Walsh, fellow of the Royal Society and Member of Parliament, obtains a visible spark from an electric eel Electrophorus electricus.
The eel was out of water as it was not possible to produce the spark
otherwise. He used thin strips of tin foil and demonstrated his
technique to many colleagues and visitors at his house in London.
Unfortunately he never published his eel experiment though he did win
the Copley medal in 1774 and 1783 for his work. The observations of
Walsh, and Bancroft before him, added to the argument that some form of
animal electricity existed.
Walsh, J. On the electric property of torpedo: in a letter to Ben. Franklin. Phil. Trans. Royal Soc. 1773;63:478-489|
- The Rev. Mr Sowdon and Mr Hawes, apothecary, report on the
surprising effects of electricity in a case report of recovery from
sudden death published in the annual report of the newly founded Humane
Society now the Royal Humane Society.
The Society had developed from 'The Institution for Affording immediate
relief to persons apparently dead from drowning'. It was "instituted in
the year 1774, to protect the industrious from the fatal consequences
of unforseen accidents; the young and inexperienced from being
sacrificed to their recreations; and the unhappy victims of desponding
melancholy and deliberate suicide; from the miserable consequences of
A Mr Squires, of Wardour Street, Soho lived opposite the house from
which a three year old girl, Catherine Sophia Greenhill had fallen from
the first storey window on 16th July 1774.
After the attending apothecary had declared that nothing could be done
for the child Mr Squires, "with the consent of the parents very
humanely tried the effects of electricity.
At least twenty minutes had elapsed before he could apply the
shock, which he gave to various parts of the body without any apparent
success; but at length, upon transmitting a few shocks through the
thorax, he perceived a small pulsation: soon after the child began to
sigh, and to breathe, though with great difficulty.
In about ten minutes she vomited: a kind of stupor, occaisioned by the
depression of the cranium, remained for some days, but proper means
being used, the child was restored to perfect health and spirits in
about a week.
"Mr. Squires gave this astonishing case of recovery to the above
gentlemen, from no other motive than a desire of promoting the good of
mankind; and hopes for the future that no person will be given up for dead, till various means have been used for their recovery."
Since it is clear she sustained a head injury the electricity probably
stimulated the child out of deep coma rather than providing cardiac
defibrillation (see also 1788, Charles Kite).
Annual Report 1774: Humane Society, London. pp 31-32
- Abildgaard shows that hens can be made lifeless with
electrical impulses and he could restore a pulse with electrical shocks
across the chest. "With a shock to the head, the animal was rendered
lifeless, and arose with a second shock to the chest; however, after
the experiment was repeated rather often, the hen was completely
stunned, walked with some difficulty, and did not eat for a day and
night; then later it was very well and even laid an egg."
Abildgaard, Peter Christian. Tentamina electrica in animalibus. Inst Soc Med Havn. 1775; 2:157-61.
Anatomist Luigi Galvani notes that a dissected frog's leg twitches when
touched with a metal scalpel. He had been studying the effects of
electricity on animal tissues that summer.
On 20th September 1786 he wrote "I had dissected and prepared a
frog in the usual way and while I was attending to something else I
laid it on a table on which stood an electrical machine at some
distance from its conductor and separated from it by a considerable
space. Now when one of the persons present touched accidentally and
lightly the inner crural nerves of the frog with the point of a
scalpel, all the muscles of the legs seemed to contract again and again
as if they were affected by powerful cramps."
He later showed that direct contact with the electrical generator or
the ground through an electrical conductor would lead to a muscle
Galvani also used brass hooks that attached to the frog's spinal cord
and were suspended from an iron railing in a part of his garden.
He noticed that the frogs' legs twitched during lightening storms and
also when the weather was fine.
He interperated these results in terms of "animal electricity" or the
preservation in the animal of "nerveo-electrical fluid" similar to that
of an electric eel. He later also showed that electrical stimulation of
a frog's heart leads to cardiac muscular contraction. Galvani. De viribus Electritatis in motu musculari Commentarius. 1791
Galvani's name is given to the 'galvanometer' which is an instrument
for measuring (and recording) electricity - this is essentially what an
ECG is; a sensitive galvanometer.
- Charles Kite wins the Silver Medal of the Humane Society
(awarded at the first Prize Medal ceremony of the Society co-judged
with the Medical Society of London) with an essay on the use of
electricity in the diagnosis and resuscitation of persons apparently
This essay is often cited as the first record of cardiac defibrillation
but the use of electricity suggested by Mr Kite is much different.
For example, on describing a case of drowning from 1785 where
resuscitation had been attempted with artificial respiration, warmth,
tobacco, "volatiles thrown into the stomach, frictions, and various
lesser stimuli" for nearly an hour, he then recalls the use of
"Electricity was then applied, and shocks sent through in every
possible direction; the muscles through which the fluid [electricity]
passed were thrown into strong contractions."
He concluded that electricity was a valuable tool that could determine
whether or not a person, apparently dead, could be successfully
Annual Report 1788: Humane Society, London. pp 225-244.
Kite C. An Essay on the Recovery of the Apparently Dead. 1788: C. Dilly, London.
Volta, Italian Scientist and inventor, attempts to disprove Galvani's
theory of "animal electricity'" by showing that the electrical current
is generated by the combination of two dissimilar metals.
His assertion was that the electrical current came from the metals and
not the animal tissues. (We now know that both Galvani and Volta were
To prove his theory he develops the voltaic pile in 1800 (a column of
alternating metal discs - zinc with copper or silver - separated by
paperboard soaked in saline) which can deliver a substantial and steady
current of electricity.
Enthusiasm in the use of electricity leads to further attempts at
reanimation of the dead with experiments on recently hanged criminals.
Giovani Aldini (the nephew of Galvani) conducts an experiment at the
Royal College of Surgeons in London in 1803. The executed criminal had
lain in a temperature of 30 F for one hour and was transported to the
College. "On applying the conductors to the ear and to the rectum, such
violent muscular contractions were executed, as almost to give the
appearance of the reanimation". Aldini, J. Essai: Théorique et expérimental sur le Galvanisme, Paris (1804), Giovani
Aldini. General Views on the Application of Galvanism to Medical
Purposes Principally in cases of suspended Animation (London: J.
Callow, Princes Street and Burgess and Hill, Great Windmill Street,
1819). Mary Shelly's Frankenstein was published in 1818.
Louis Figuier, Les merveilles de la Science (Paris, 1867), p.653|
|1800 to 1895
||The design of sensitive instruments that could detect the small electrical currents in the heart.
- While demonstrating to students the heating of a platinum wire
with electricity from a voltaic pile at the University of Copenhagen,
Danish physicist Hans Christian Oersted notices
that a nearby magnetized compass needle moves each time the electrical
current is turned on.
He discovers electromagnetism which is given a theoretical basis (with
remarkable speed) by André Marie Ampère.
- Johann (Johan) Schweigger of Nuremberg increases the movement of magnetized needles in electromagnetic fields.
He found that by wrapping the electric wire into a coil of 100 turns the effect on the needle was multiplied.
He proposed that a magnetic field revolved around a wire carrying a current which was later proven by Michael Faraday.
Schweigger had invented the first galvanometer and announced his discovery at the University of Halle on 16th September 1820.
- Leopold Nobili, Professor of Physics at Florence, develops an
'astatic galvanometer'. Using two identical magnetic needles of
opposite polarity, either fixed together with a figure of eight
arrangment of wire loops (in earlier versions), or one moveable needle
with a wire loop and one with a scale (in later versions), the effects
of the earth's magnetic field could be compensated for. In 1827, using
this instrument, he managed to detect the flow of current in the body
of a frog from muscles to spinal cord. He detected the electricity
running along saline moistened cotton thread joining the dissected
frog's legs in one jar to its body in another jar. Nobili was working
to support the theory of animal electricity and this conduction,
transmitted without wires, he felt demonstrated animal electricity.
Matteucci, Professor of Physics at the University of Pisa, and student
of Nobili, shows that an electric current accompanies each heart beat.
He used a preparation known as a 'rheoscopic frog' in which the cut
nerve of a frog's leg was used as the electical sensor and twitching of
the muscle was used as the visual sign of electrical activity. He also
used Nobili's astatic galvanometer for the study of electricity in
muscles typically inserting one galvanometer wire in the open end of
the dissected muscle and the other on the surface of the muscle. He
went on to try and demonstrate conduction in nerve but was unable to do
so (since his galvanometers were not sensitive enough). Matteucci C. Sur un phenomene physiologique produit par les muscles en contraction. Ann Chim Phys 1842;6:339-341|
- Dr Golding Bird, a Physician, accomplished chemist and member
of the London Electrical Society, opens an electrical therapy room at
Guy's Hospital, London treating a large range of diseases. Although the
application of electricity was popular it was not considered a subject
worthy of serious investigation. Because of Bird's reputation as a
researcher electrical therapy achieved popularity amongst London
Physicians including his mentor Dr Thomas Addison. Bird G. Lectures
on Electricity and Galvanism, in their physiological and therapeutical
relations, delivered at the Royal College of Physicians, in March, 1847
(Wilson & Ogilvy, London, 1847)
Emil Du bois-Reymond
physiologist Emil Du bois-Reymond describes an "action potential"
accompanying each muscular contraction.
He detected the small voltage potential present in resting muscle and
noted that this diminished with contraction of the muscle.
To accomplish this he had developed one of the most sensitive
galvanometers of his time.
His device had a wire coil with over 24,000 turns - 5 km of wire. Du
Bios Reymond devised a notation for his galvanometer which he called
the 'disturbance curve'. "o" was the stable equilibrium point of the
astatic galvanometer needle and p, q, r and s (and also k and h) were
other points in its deflection.
Du Bois-Reymond, E. Untersuchungen uber thierische Elektricitat. Reimer, Berlin: 1848.|
- Bizarre unregulated actions of the ventricles (later called
ventricular fibrillation) is described by Hoffa during experiments with
strong electrical currents across the hearts of dogs and cats. He
demonstrated that a single electrical pulse can induce fibrillation.
Hoffa M, Ludwig C. 1850. Einige neue versuche uber herzbewegung. Zeitschrift Rationelle Medizin, 9: 107-144
- Rudolph von Koelliker and Heinrich Muller confirm
that an electrical current accompanies each heart beat by applying a
galvanometer to the base and apex of an exposed ventricle.
They also applied a nerve-muscle preparation, similar to Matteucci's,
to the ventricle and observed that a twitch of the muscle occured just
prior to ventricular systole and also a much smaller twitch after
These twitches would later be recognised as caused by the electrical
currents of the QRS and T waves.
von Koelliker A, Muller H. Nachweis der negativen Schwankung des
Muskelstroms am naturlich sich kontrahierenden Herzen. Verhandlungen
der Physikalisch-Medizinischen Gesellschaft in Wurzberg. 1856;6:528-33.
William thompson (Lord Kelvin), Professor of Natural Philosophy at
Glasgow University, invents the 'mirror galvanometer' for the reception
of transatlantic telegraph transmissions. A small, freely rotating
mirror, with magents stuck to its back is suspended in a fine copper
coil and a reflected spot of light from this mirror 'amplifies' the
small movements when electrical current is present. The whole apparatus
was suspended in an air chamber and the pressure inside could be
adjusted to vary the damping seen on the signals. This galvanometer was
sensitive enough for transatlantic telegraphy.
Thompson improves telegraph transmissions with the 'Siphon Recorder'.
Before d'Arsonval (1880), Thompson uses a fine coil suspended in a
strong magnetic magnetic field. Attached to the coil but isolated from
it by ebonite (an insulator) was a siphon of ink. The siphon was
charged with high voltage so that the ink was sprayed onto the paper
that moved over an earthed metal surface. The siphon recorder could
therefore not only detect currents it could also record them onto paper.
- Alexander Muirhead, an electrical engineer and
pioneer of telegraphy, may have a recorded a human electrocardiogram at
St Bartholomew's Hospital, London but this is disputed. If he had he is
thought to have used a Thompson Siphon Recorder. Elizabeth Muirhead,
his wife, wrote a book of his life and claimed that he refrained from
publishing his own work for fear of misleading others. Elizabeth Muirhead. Alexander Muirhead 1848 - 1920. Oxford, Blackwell: privately printed 1926.
- French physicist Gabriel Lippmann invents a capillary
electrometer. It is a thin glass tube with a column of mercury beneath
sulphuric acid. The mercury meniscus moves with varying electrical
potential and is observed through a microscope.
- Mr Green, a surgeon, publishes a paper on the
resuscitation of a series of patients who had suffered cardiac and / or
respiratory arrest during anaesthesia with chloroform. He uses a
galvanic pile (battery) of 200 cells generating 300 Volts which he
applied to the patient as follows "One pole should be applied to the
neck and the other to the lower rib on the left side." Green T. On death from chloroform: its prevention by galvanism. Br Med J 1872 1: 551-3.
Although this has been reported as an example of cardiorespiratory
resuscitation it is unclear what the exact mechanism seems to be. It is
unlikely to be electric cardioversion or external pacing. It seems to
be another example of electrophrenic stimulation (See also Duchenne
An 'electric' smile.
Benjamin Amand Duchenne de Boulogne, pioneering neurophysiologist,
describes the resuscitation of a drowned girl with electricity in the
third edition of his textbook on the medical uses of electricity. This
episode has sometimes been described as the first 'artificial
pacemaker' but he used an electrical current to induce electrophrenic
rather than myocardial stimulation.
Duchenne GB. De l'electrisation localisee et de son application a
la pathologie et la therapeutique par courants induits at par courants
galvaniques interrompus et continus. [Localised electricity and its
application to pathology and therapy by means of induced and galvanic
currents, interrupted and continuous] 3ed. Paris. JB Bailliere et fils;
- Richard Caton, a Liverpool Physician, presents to the British
Medical Association in July 1875 in Edinburgh. Using a Thompson 'mirror
galvanometer' in animals he shows it was possible to detect 'feeble
currents of varying direction ... when the electrodes are placed on two
points of the external surface, or one electrode on the grey matter and
one on the surface of the skull'. This is the first report of the EEG
(or electroencephalogram). Caton was proving another Physician's
hypothesis, John Hughlings Jackson, who suggested in 1873 that epilepsy
was due to excessive electrical activity in the grey matter of the
brain. Caton R: The electric currents of the brain. BMJ 1875; 2:278, Mumenthaler, Mattle Eds. Neurology. 4th Edition. Stuttgart, Thieme: 2004.
- Marey uses the electrometer to record the electrical activity of an exposed frog's heart. Marey
EJ. Des variations electriques des muscles et du couer en particulier
etudies au moyen de l'electrometre de M Lippman. Compres Rendus
Hebdomadaires des Seances de l'Acadamie des sciences 1876;82:975-977
- British physiologists John Burden Sanderson and
Frederick Page record the heart's electrical current with a capillary
electrometer and shows it consists of two phases (later called QRS and
T). Burdon Sanderson J. Experimental results relating to the
rhythmical and excitatory motions of the ventricle of the frog. Proc R
Soc Lond 1878;27:410-414
- French physicist Arsène d'Arsonval in association with Marcel
Deprez, improves the galvanometer.
Instead of a magnetized needle moving when electrical current flows
through a surrounding wire coil the Deprez-d'Arsonval galvanometer has
a fixed magnet and moveable coil.
If a pointer is attached to the coil it can move over a suitably
The d'Arsonval galvanometer is the basis for most modern galvanometers.
Comptes rendus de l'Académie des sciences, 1882, 94: 1347-1350
- John Burden Sanderson and Frederick Page publish some of their recordings. Burdon
Sanderson J, Page FJM. On the electrical phenomena of the excitatory
process in the heart of the tortoise, as investigated photographically.
J Physiol (London) 1884;4:327-338
- British physiologist Augustus D. Waller of St Mary's Medical School, London publishes the first human electrocardiogram.
It is recorded with a capilliary electrometer from Thomas Goswell, a technician in the laboratory. Waller AD. A demonstration on man of electromotive changes accompanying the heart's beat. J Physiol (London) 1887;8:229-234
- Dutch physiologist Willem Einthoven sees Waller
demonstrate his technique at the First International Congress of Physiologists
in Bale. Waller often demonstrated by using his dog "Jimmy" who would patiently
stand with paws in glass jars of saline.
- GJ Burch of Oxford devises an arithmetical correction for the observed (sluggish) fluctuations of the electrometer.
This allows the true waveform to be seen but only after tedious calculations. Burch
GJ. On a method of determining the value of rapid variations of a
difference potential by means of a capillary electrometer. Proc R Soc
Lond (Biol) 1890;48:89-93
- British physiologists William Bayliss and Edward
Starling of University College London improve the capillary
electrometer. They connect the terminals to the right hand and to the
skin over the apex beat and show a "triphasic variation accompanying
(or rather preceding) each beat of the heart". These deflections are
later called P, QRS and T. Bayliss WM, Starling EH. On the
electrical variations of the heart in man. Proc Phys Soc (14th
November) in J Physiol (London) 1891;13:lviii-lix and also On the electromotive phenomena of the mammalian heart. Proc R Soc Lond 1892;50:211-214
They also demonstrate a delay of about 0.13 seconds between atrial
stimulation and ventricular depolarisation (later called PR interval). On the electromotive phenomena of the mammalian heart. Proc Phys Soc (21st March) in J Physiol (London) 1891;12:xx-xxi
- Willem Einthoven introduces the term
'electrocardiogram' at a meeting of the Dutch Medical Association.
(Later he claims that Waller was first to use the term). Einthoven
W: Nieuwe methoden voor clinisch onderzoek [New methods for clinical
investigation]. Ned T Geneesk 29 II: 263-286, 1893
|1895 to date
||The first accurate recording of the electrocardiogram and its development as a clinical tool.
- Einthoven, using an improved electrometer and a
correction formula developed independently of Burch, distinguishes five
deflections which he names P, Q, R, S and T. Einthoven W. Ueber die Form des menschlichen Electrocardiogramms. Arch f d Ges Physiol 1895;60:101-123
- Why PQRST and not ABCDE? The four deflections
prior to the correction formula were labelled ABCD and the 5 derived
deflections were labelled PQRST. The choice of P is a mathematical
convention (as used also by Du Bois-Reymond in his galvanometer's
'disturbance curve' 50 years previously) by using letters from the
second half of the alphabet. N has other meanings in mathematics and O
is used for the origin of the Cartesian coordinates. In fact Einthoven
used O ..... X to mark the timeline on his diagrams. P is simply the
next letter. A lot of work had been undertaken to reveal the true
electrical waveform of the ECG by eliminating the damping effect of the
moving parts in the amplifiers and using correction formulae. If you
look at the diagram in Einthoven's 1895 paper you will see how close it
is to the string galvanometer recordings and the electrocardiograms we
see today. The image of the PQRST diagram may have been striking enough
to have been adopted by the researchers as a true representation of the
underlying form. It would have then been logical to continue the same
naming convention when the more advanced string galvanometer started
creating electrocardiograms a few years later.
- Clement Ader, a French electrical engineer, reports
his amplification system for detecting Morse code signals transmitted along undersea telegraph lines.
It was never intended to be used as a galvanometer.
Einthoven later quoted Ader's work but seems to have developed his own amplification device independently.
Ader C. Sur un nouvel appareil enregistreur pour cables sous-marins. C R Acad Sci (Paris) 1897;124:1440-1442
|Karel Frederik Wenckebach publishes a paper "On the
analysis of irregular pulses" describing impairment of AV conduction leading
to progressive lengthening and blockage of AV conduction in frogs. This will
later be called Wenckebach block (Mobitz type I) or Wenckebach phenomenon.|
- Jean-Louis Prevost, Professor of Biochemistry, and
Frederic Batelli, Professor of Physiology, both of Geneva discover that
large electrical voltages applied across an animal's heart can stop
Prevost JL, Batelli F: Sur quelques effets des descharges
electriques sur le coeur des mammiferes. Acad. Sci. Paris, FR.: 1899;
- Einthoven invents a new galvanometer for producing
electrocardiograms using a fine quartz string coated in silver based on ideas
by Deprez and d'Arsonval (who used a wire coil). His "string galvanometer" weighs
600 pounds. Einthoven acknowledged the similar system by Ader but later
(1909) calculated that his galvanometer was in fact many thousands of times more sensitive.
Einthoven W. Un nouveau galvanometre. Arch Neerl Sc Ex Nat 1901;6:625-633
- Einthoven publishes the first electrocardiogram recorded on a string galvanometer. Einthoven
W. Galvanometrische registratie van het menschilijk electrocardiogram.
In: Herinneringsbundel Professor S. S. Rosenstein. Leiden: Eduard Ijdo,
- Einthoven discusses commercial production of a
string galvanometer with Max Edelmann of Munich and Horace Darwin of
Cambridge Scientific Instruments Company of London.
- Einthoven starts transmitting electrocardiograms
from the hospital to his laboratory 1.5 km away via telephone cables.
On March 22nd the first 'telecardiogram' is recorded from a healthy and
vigorous man and the tall R waves are attributed to his cycling from
laboratory to hospital for the recording.
- John Hay of Liverpool, publishes pressure
recordings from a 65 year old man showing heart block in which
AV conduction did not seem to be impaired since the a-c intervals on
the jugular venous waves was unchanged in the conducted beats.
This is the first demonstration of what we now call Mobitz type II AV
Hay J. Bradycardia and cardiac arrhythmias produced by depression of certain functions of the heart. Lancet 1906;1:138-143.
- Einthoven publishes the first organised
presentation of normal and abnormal electrocardiograms recorded with a
string galvanometer. Left and right ventricular hypertrophy, left and
right atrial hypertrophy, the U wave (for the first time), notching of
the QRS, ventricular premature beats, ventricular bigeminy, atrial
flutter and complete heart block are all described. Einthoven W. Le telecardiogramme. Arch Int de Physiol 1906;4:132-164 (translated into English. Am Heart J 1957;53:602-615)
- Cremer records the first oesophageal electrocardiogram which
he achieved with the help of a professional sword swallower.
Oesophageal electrocardiography later developed in the 1970s to help
differentiate atrial arrhythmias.
He also records the first fetal electrocardiogram from the abdominal
surface of a pregnant woman.
Cremer. Ueber die direkte Ableitung der Aktionströme des menslichen Herzens vom
Oesophagus und über das Elektrokardiogramm des Fötus. Munch. Med. Wochenschr. 1906;53:811
- Arthur Cushny, professor of pharmacology at University
College London, publishes the first case report of atrial fibrillation.
His patient was 3 days post-op following surgery on an "ovarian
fibroid" when she developed
a "very irregular" pulse at a rate of 120 - 160 bpm. Her pulse was
recorded with a "Jacques sphygmochronograph" which shows the radial
pulse pressure against
time - much like the arterial line blood pressure recordings used in
Intensive Care today.
Cushny AR, Edmunds CW. Paroxysmal irregularity of the heart and auricular fibrillation. Am J Med Sci 1907;133:66-77.
- Edward Schafer of the University of Edinburgh is the first to buy a string galvanometer for clinical use.
- Thomas Lewis of University College Hospital,
London buys a string galvanometer and so does Alfred Cohn of Mt Sinae
Hospital, New York.
Thomas Lewis publishes a paper in the BMJ detailing his careful
clinical and electrocardiographic observations of atrial fibrillation.
At one point Lewis identified a fibrillating horse using the string
galvanometer's electrocardigram recording.
He then followed the horse to the slaughterhouse where he could
visually confirm the fibrillating atrium.
Lewis T. Auricular fibrillation: a common clinical condition. BMJ 1909;42:1528.
- Nicolai and Simmons report on the changes to the electrocardiogram during angina pectoris.
Nicolai DF, Simons A. (1909) Zur klinik des elektrokardiogramms. Med Kiln 5;160
- Walter James, Columbia University and Horatio
Williams, Cornell University Medical College, New York publish the
first American review of electrocardiography. It describes ventricular
hypertrophy, atrial and ventricular ectopics, atrial fibrillation and
ventricular fibrillation. The recordings were sent from the wards to
the electrocardiogram room by a system of cables. There is a great
picture of a patient having an electrocardiogram recorded with the
caption "The electrodes in use".James WB, Williams HB. The electrocardiogram in clinical medicine. Am J Med Sci 1910;140:408-421, 644-669
- Thomas Lewis publishes a classic textbook. The mechanism of the heart beat. London: Shaw & Sons and dedicates it to Willem Einthoven.
- Einthoven addresses the Chelsea Clinical Society in
London and describes an equilateral triangle formed by his standard
leads I, II and III later called 'Einthoven's triangle'. This is the
first reference in an English article I have seen to the abbreviation
'EKG'.Einthoven W. The different forms of the human electrocardiogram and their signification. Lancet 1912(1):853-861
- Bousfield describes the spontaneous changes in the electrocardiogram during angina.
Bousfield G. Angina pectoris: changes in electrocardiogram during paroxysm. Lancet 1918;2:475
- Hubert Mann of the Cardiographic Laboratory,
Mount Sinai Hospital, describes the derivation of a 'monocardiogram'
later to be called 'vectorcardiogram'. Mann H. A method of analyzing the electrocardiogram. Arch Int Med 1920;25:283-294
- Harold Pardee, New York, publishes the first
electrocardiogram of an acute myocardial infarction in a human and
describes the T wave as being tall and "starts from a point well up on
the descent of the R wave".
Pardee HEB. An electrocardiographic sign of coronary artery obstruction. Arch Int Med 1920;26:244-257
- Willem Einthoven wins the Nobel prize for inventing the electrocardiograph.
- Woldemar Mobitz publishes his classification of
heart blocks (Mobitz type I and type II) based on the electrocardiogram
and jugular venous pulse waveform findings in patients with second
degree heart block.
Mobitz W. Uber die unvollstandige Storung der Erregungsuberleitung
zwischen Vorhof und Kammer des menschlichen Herzens. (Concerning
partial block of conduction between the atria and ventricles of the
human heart). Z Ges Exp Med 1924;41:180-237.
- A doctor from the Crown Street Women's Hospital in Sydney,
who wished to remain anonymous, resuscitates a new-born baby with an
electrical device later called a 'pacemaker'. The doctor wanted to
remain anoymous because of the controversy surrounding research that
artificially extended human life.
- Ernstine and Levine report the use of vacuum-tubes to
amplify the electrocardiogram instead of the mechanical amplification
of the string galvanometer. Ernstine AC, Levine SA. A comparison of
records taken with the Einthoven string galvanomter and the
amplifier-type electrocardiograph. Am Heart J 1928;4:725-731
- Frank Sanborn's company (founded 1917 and acquired by Hewlett-Packard
in 1961 and since 1999, Philips Medical Systems) converts their table
model electrocardiogram machine into their first portable version
weighing 50 pounds and powered by a 6-volt automobile battery.
- Sydney doctor Mark Lidwill, physician, and Edgar Booth,
physicist, report the electrical resuscitation of the heart to a
meeting in Sydney. Their portable device uses an electrode on the skin
and a transthoracic catheter. Edgar Booth's design could deliver a
variable voltage and rate and was employed to deliver 16 volts to the
ventricles of a stillborn infant.
- Wolff, Parkinson and White report an electrocardiographic syndrome of short PR interval, wide QRS and paroxysmal tachycardias. Wolff
L, Parkinson J, White PD. Bundle branch block with short P-R interval
in healthy young people prone to paroxysmal tachycardia. Am Heart J
1930;5:685. Later, when other published case reports were examined
for evidence of pre-excitation, examples of 'Wolff Parkinson White'
syndrome were identified which had not been recognised as a clinical
entity at the time. The earliest example was published by Hoffmann in
1909. Von Knorre GH. The earliest published electrocardiogram
showing ventricular preexcitation. Pacing Clin Electrophysiol. 2005
- Sanders first describes infarction of the right ventricle.
Sanders, A.O. Coronary thrombosis with complete heart block and
relative ventricular tachycardia: a case report, American Heart Journal
- Charles Wolferth and Francis Wood describe the
use of exercise to provoke attacks of angina pectoris. They
investigated the ECG changes in normal subjects and those with angina
but dismissed the technique as too dangerous "to induce anginal attacks
Wood FC, Wolferth CC, Livezey MM. Angina pectoris. Archives Internal Medicine 1931;47:339
first patented pacemaker
Albert Hyman patents the first 'artificial cardiac pacemaker' which
stimulates the heart by using a transthoracic needle. His aim was to
produce a device that was small enough to fit in a doctor's bag and
stimulate the right atrial area of the heart with a suitably insulated
needle. His experiments were on animals. His original machine was
powered by a crankshaft (it was later prototyped by a German company
but was never successful). "By March 1, 1932 the artificial pacemaker
had been used about 43 times, with a successful outcome in 14 cases."
It was not until 1942 that a report of its successful short term use in
Stokes-Adams attacks was presented.
Hyman AS. Resuscitation of the stopped heart by intracardial therapy. Arch Intern Med. 1932;50:283|
- Goldhammer and Scherf propose the use of the
electrocardiogram after moderate exercise as an aid to the diagnosis of
Goldhammer S, Scherf D. Elektrokardiographische untersuchungen bei kranken mit angina pectoris. Z Klin Med 1932;122:134
- Charles Wolferth and Francis Wood describe the clinical use of chest leads. Wolferth
CC, Wood FC. The electrocardiographic diagnosis of coronary occlusion
by the use of chest leads. Am J Med Sci 1932;183:30-35
- By joining the wires from the right arm, left arm and left
foot with 5000 Ohm resistors Frank Wilson defines an 'indifferent
electrode' later called the 'Wilson Central Terminal'.
The combined lead acts as an earth and is attached to the negative
terminal of the ECG.
An electrode attached to the positive terminal then becomes 'unipolar'
and can be placed anywhere on the body.
Wilson defines the unipolar limb leads VR, VL and VF where 'V' stands
for voltage (the voltage seen at the site of the unipolar electrode).
Wilson NF, Johnston FE, Macleod AG, Barker PS. Electrocardiograms
that represent the potential variations of a single electrode. Am Heart
- McGinn and White describe the changes to the electrocardiogram during acute pulmonary embolism including the S1 Q3 T3 pattern.
McGinn S, White PD. Acute cor pulmonale resulting from pulmonary embolism: its clinical recognition. JAMA 1935;114:1473.
- American Heart Association and the Cardiac Society of
Great Britain define the standard positions, and wiring, of the chest
leads V1 - V6. The 'V' stands for voltage. Barnes AR, Pardee HEB, White PD. et al. Standardization of precordial leads. Am Heart J 1938;15:235-239
- Tomaszewski notes changes to the electrocardiogram in a man who died of hypothermia.
Tomaszewski W. Changements electrocardiographiques observes chez un homme mort de froid. Arch Mal Coeur 1938;31:525.
- Langendorf reports a case of atrial infarction
discovered at autopsy which, in retrospect, could have been diagnosed
by changes on the ECG.
Langendorf R. Elektrokardiogramm bei Vorhof-Infarkt. Acta Med Scand. 1939;100:136.
- Emanuel Goldberger increases the voltage of
Wilson's unipolar leads by 50% and creates the augmented limb leads
aVR, aVL and aVF.
When added to Einthoven's three limb leads and the six chest leads we
arrive at the 12-lead electrocardiogram that is used today.
- Arthur Master, standardises the two step exercise test (now known as the Master two-step) for cardiac function.
Master AM, Friedman R, Dack S. The electrocardiogram after standard
exercise as a functional test of the heart. Am Heart J. 1942;24:777
- Young and Koenig report deviation of the P-R segment in a series of patients with atrial infarction.
Young EW, Koenig BS. Auricular infarction. Am Heart J. 1944;28:287.
- Gouaux and Ashman describe an observation that helps
differentiate aberrant conduction from ventricular tachycardia.
The 'Ashman phenomenon' occurs when a stimulus falls during the
relative or absolute refractory period of the ventricles and the
aberrancy is more pronounced.
In atrial fibrillation with aberrant conduction this is demonstrated
when the broader complexes are seen terminating a relatively short
cycle that follows a relatively long one.
The QRS terminating the shorter cycle is conducted 'more aberrantly'
because it falls in the refractory period.
The aberrancy is usually of a RBBB pattern.
Gouaux JL, Ashman R. Auricular fibrillation with aberration
simulating ventricular paroxysmal tachycardia. Am Heart J
- Claude Beck, a pioneering cardiovascular surgeon in Cleveland,
successfully defibrillates a human heart during cardiac surgery. The
patient is a 14 year old boy - 6 other patients had failed to respond
to the defibrillator. His prototype defibrillator followed experiments
on defibrillation in animals performed by Carl J. Wiggers, Professor of
Physiology at the Western Reserve University.
Beck CS, Pritchard WH, Feil SA: Ventricular fibrillation of long duration abolished by electric shock. JAMA 1947; 135: 985-989.
Wiggers CJ, Wegria R. Ventricular fibrillation due to single
localized induction in condenser shock supplied during the vulnerable
phase of ventricular systole. Am J Physiol 1939;128:500
- Rune Elmqvist, Swedish engineer who had trained
as a doctor but never practiced, introduces the first ink jet printer
for the transcription of analog physiological signals. He demonstrates
its use in the recording of ECGs at the First International Congress of
Cardiology in Paris in 1950. The machine (the mingograph) was developed
by him at the company that later became Siemens. (Luderitz, 2002)
modern 'Holter' Monitor
physician Norman Jeff Holter develops a 75 pound backpack that can
record the ECG of the wearer and transmit the signal.
His system, the Holter Monitor, is later greatly reduced in size,
combined with tape / digital recording and used to record ambulatory
Holter NJ, Generelli JA. Remote recording of physiologic data by radio. Rocky Mountain Med J. 1949;747-751.|
- Sokolow and Lyon propose diagnostic criteria for
left ventricular hypertrophy i.e. LVH is present if the sum of the size
of the S wave in V1 plus the R wave in V6 exceeds 35 mm.
Sokolow M, Lyon TP. The ventricular complex in left ventricular
hypertrophy as obtained by unipolar precordial and limb leads. Am Heart
- John Hopps, a Canadian electrical engineer and researcher for
the National Research Council, together with two physicians (Wilfred
Bigelow, MD of the University of Toronto and his trainee, John C.
Callaghan, MD) show that a coordinated heart muscle contraction can be
stimulated by an electrical impulse delivered to the sino-atrial node.
The apparatus, the first cardiac pacemaker, measures 30cm, runs on
vacuum tubes and is powered by household 60Hz electrical current.
Bigelow WG, Callaghan JC, Hopps JA. "General hypothermia for experimental intracardiac surgery." Ann Surg 1950; 1132: 531-539.
- Osborn, whilst experimenting with hypothermic dogs, describes
the prominent J (junctional) wave which has often been known as the
He found the dogs were more likely to survive if they had an infusion
of bicarbonate and supposed the J wave was due to an injury current
caused by acidosis.
Osborn JJ. Experimental hypothermia: respiratory and blood pH
changes in relation to cardiac function. Am J Physiol 1953;175:389.
- Richard Langendorf publishes the "rule of bigeminy" whereby ventricular bigeminy tends to perpetuate itself.
Langendorf R, Pick A, Winternitz M. Mechanisms of intermittent
ventricular bigeminy. I. Appearence of ectopic beats dependent upon the
length of the ventricular cycle, the "rule of bigeminy." circulation
- Paul Zoll, a cardiologist, uses a more powerful defibrillator and performs closed-chest defibrillation in a human.
Zoll PM, Linenthal AJ, Gibson P: Termination of Ventricular
Fibrillation in Man by Externally Applied Countershock . NEJM 1956;
long QT syndrome
Jervell and Fred Lange-Nielsen of Oslo describe an autosomal recessive
syndrome of long-QT interval, deafness and sudden death later known as
the Jervell-Lange-Nielsen syndrome.
Jervell A, Lange-Nielsen F. Congenital deaf mutism, functional
heart disease with prolongation of the QT interval and sudden death. Am
Heart J 1957;54:59.|
- Professor Ake Senning, of Sweden, places the first
implantable cardiac pacemaker designed by Rune Elmqvist into a
43-year-old patient with complete heart block and syncope (Arne
- Myron Prinzmetal describes a variant form of angina in which the ST segment is elevated rather than depressed.
Prinzmetal M, Kennamer R, Merliss R, Wada T, Bor N. Angina pectoris. I. A variant form of angina pectoris. Am J Med 1959;27:374.
- Smirk and Palmer highlight the risk of sudden
death from ventricular fibrillation particularly when ventricular
premature beats occur at the same time as the T wave. The 'R on T'
Smirk FH, Palmer DG. A myocardial syndrome, with particular
reference to the occurrence of sudden death and of premature systoles
interrupting antecedent T waves. Am J Cardiol 1960;6:620.
- Italian paediatrician C. Romano and Irish paediatrician O.
Conor Ward (the following year) independently report an autosomal
dominant syndrome of long-QT interval later known as the Romano-Ward
Romano C, Gemme G, Pongiglione R. Aritmie cardiache rare dell'eta pediatrica. Clin Pediatr. 1963;45:656-83.
Ward OC. New familial cardiac syndrome in children. J Irish Med Assoc. 1964;54:103-6
Bruce and colleages describe their multistage treadmill exercise test
later known as the Bruce Protocol.
"You would never buy a used car without taking it out for a drive and
seeing how the engine performed while it was running," Bruce says, "and
the same is true for evaluating the function of the heart."
Bruce RA, Blackman JR, Jones JW, Srait G. Exercise testing in adult normal subjects and cardiac patients. Pediatrics 1963;32:742|
Bruce RA, McDonough JR. Stress testing in screening for cardiovascular disease. Bull. N.Y. Acad Med. 1969;45:1288
- Baule and McFee are the first to detect the magnetocardiogram
which is the electromagnetic field produced by the electrical activity
of the heart.
It is a method that can detect the ECG without the use of skin
Although potentially a useful technique it has never gained clinical
acceptance, partly because of its greater expense.
Baule GM, McFee R. Detection of the magnetic field of the heart. Am Heart J. 1963;66:95-96.
- Mason and Likar modify the 12-lead ECG system for use during
exercise testing. The right arm electrode is placed at a point in the
infraclavicular fossa medial to the border of the deltoid muscle, 2 cm
below the lower border of the clavicle. The left arm electrode is
placed similarly on the left side. The left leg electrode is placed at
the left iliac crest. Although this system reduces the variability in
the ECG recording during exercise it is not exactly equivalent to the
standard lead positions. The Mason-Likar lead system tends to distort
the ECG with a rightward QRS axis shift, a reduction in R wave
amplitude in lead I and aVL, and a significant increase in R wave
amplitude in leads II, III and aVF. Eur Heart J. 1987 Jul;8(7):725-33
Torsade de pointes
|François Dessertenne of Paris publishes the first case of 'Torsade de pointes' Ventricular Tachycardia.
Dessertenne F. La tachycardie ventriculaire a deux foyers opposes variables.
Arch des Mal du Coeur 1966; 59:263|
- Journal of Electrocardiography,
the Official Journal of the International Society for Computerized
Electrocardiology and the International Society of Electrocardiology,
is founded by Zao and Lepeschkin.
- Henry Marriott introduces the Modified Chest Lead 1 (MCL1) for monitoring patients in Coronary Care.
- Rosenbaum reviews the classification of ventricular
premature beats and adds a benign form that arises from the right
ventricle and is not associated with heart disease.
This becomes known as the 'Rosenbaum ventricular extrasystole'.
Rosenbaum MB. Classification of ventricular extrasystoles according to form. J Electrocardiol 1969;2:289.
- Jay Cohn, of University of Minnesota Medical
School, describes the 'syndrome of right ventricular dysfunction in the
setting of acute inferior wall myocardial infarction'.
Cohn JN, Guiha NH, Broder MI. Right ventricular infarction. Am J Cardiol 1974:33:209-214
- Gozensky and Thorne introduce the term 'Rabbit ears' to
Rabbit ears describe the appearence of the QRS complex in lead V1 with
an rSR' pattern (good rabbit) being typical of Right Bundle Branch
Block and an
RSr' (bad rabbit) suggesting a ventricular origin i.e. ventricular
ectopy / tachycardia.
Gozensky C, Thorne D. Rabbit ears: an aid in distinguishing ventricular ectopy from aberration. Heart Lung 1974;3:634.
- Erhardt and colleagues describe the use of a right-sided
precordial lead in the diagnosis of right ventricular infarction which
had previously been thought to be electrocardiographically silent.
Erhardt LR, Sjogrn A, Wahlberg I. Single right-sided precordial
lead in the diagnosis of right ventricular involvement in inferior
myocardial infarction. Am Heart J 1976;91:571-6
- Professor John Pope Boineau of Washington University School of
Medicine publishes a 30-year percpective on the modern history of
electrocardiography. Boineau JP. Electrocardiology: A 30-year
Perspective. Ah Serendipity, My Fulsome Friend. Journal of
Electrocardiology 21. Suppl (1988): S1-9
Brugada and Josep brugada of Barcelona publish a series of 8 cases of
sudden death, Right Bundle Branch Block pattern and ST elevation in V1
- V3 in apparently healthy individuals.
This 'Brugada Syndrome' may account for 4-12% of unexpected sudden
deaths and is the commonest cause of sudden cardiac death in
individuals aged under 50 years in South Asia.
The technology of the electrocardiogam, which is over 100 years old,
can still be used to discover new clinical entities in cardiology.
Brugada P, Brugada J. Right Bundle Branch Block, Persistent ST
Segment Elevation and Sudden Cardiac Death: A Distinct Clinical and
Electrocardiographic Syndrome. J Am Coll Cardiol 1992;20:1391-6|
- Cohen and He describe a new non-invasive approach to
accurately map cardiac electrical activity by using the surface
Laplacian map of the body surface electrical potentials.
He B, Cohen RJ. Body surface Laplacian ECG mapping. IEEE Trans Biomed Eng 1992;39(11):1179-91
Mac 5000, 15-lead ECG
Zalenski, Professor of Emergency Medicine, Wayne State University
and colleagues publish an influential article on the clinical use of
the 15-lead ECG which routinely uses V4R, V8 and V9 in the diagnosis of
acute coronary syndromes. Like the addition of the 6 standardised
unipolar chest leads in 1938 these additional leads increase the
sensitivity of the electrocardiogram in detecting myocardial
Zalenski RJ, Cook D, Rydman R. Assessing the diagnostic value of an
ECG containing leads V4R, V8, and V9: The 15-lead ECG. Ann Emerg Med
- Researchers from Texas show that 12-lead ECGs transmitted via
wireless technology to hand-held computers is feasible and can be
interpreted reliably by cardiologists. Pettis KS, Savona MR,
Leibrandt PN et al. Evaluation of the efficacy of hand-held computer
screens for cardiologists' interpretations of 12-lead
electrocardiograms. Am Heart J. 1999 Oct;138(4 Pt 1):765-70
- Physicians from the Mayo Clinic describe a new hereditary form
of Short QT syndrome associated with syncope and sudden death that they
discovered in 1999. Several genes have since been implicated. Gussak I, Brugada P, Brugada J, et al. Idiopathic short QT interval: a new clinical syndrome? Cardiology. 2000;94(2):99-102
- Danish cardiologists report the successful reduction in the
time between onset of chest pain and primary angioplasty when the ECG
of patients is transmitted wirelessly from ambulance to the
cardiologist's handheld PDA (Personal Digital Assistant). The clinician
can make an immediate decision to redirect patients to the catheter lab
saving time in transfers between hospital departments. Clemmensen
P, Sejersten M, Sillesen M et al. Diversion of ST-elevation myocardial
infarction patients for primary angioplasty based on wireless
prehospital 12-lead electrocardiographic transmission directly to the
cardiologist's handheld computer: a progress report. J Electrocardiol.
2005 Oct;38(4 Suppl):194-8
- Acierno. The History of Cardiology. 1994. New York: Parthenon.
- The Bakken Library and Museum
- Bibliotheque Inter-Universitaire de Medicine, Paris. Source of the
images of 'Descarte's reflex' from De Hominis and Swammerdam's possible
electrical stimulation of a nerve-muscle preparation.
- Burchell HB. A centennial note on Waller and the first human electrocardiogram. Am J Cardiol 1987;59:979-983
- Burnett J. The origins of the electrocardiograph as a clinical
instrument. Medical History Supplement 5: 1985, 53-76. Published as a
monograph. The emergence of modern cardiology. Bynum WF, Lawrence C,
Nutton V, eds. Wellcome Institute for the History of Medicine:1985.
- Cobb, Matthew. Exorcizing the animal spirits: Jan Swammerdam on nerve function. Nature Reviews, Neuroscience 2002;3:395-400
- On Animal electricity: Being an Abstract of the Discoveries of Emil
Du Bios-Reymond (translated). Edited by Dr Bence Jones. 1852.
- Fye WB. A history of the origin, evolution, and impact of electrocardiography. Am J Cardiol 1994;73:937-949
- Geddes LA. Supplement. The Physiologist 1984;27(1):S-1
- Hewlett-Packard - 'History and Mission'
- google.com, altavista.com, excite.com
- Berndt Luderitz. History of the Disorders of Cardiac Rhythm. Third Edition. 2002. Blackwell Publishing.
- Jaakko Malmivuo & Robert Plonsey: Bioelectromagnetism - Principles and Applications of Bioelectric and Biomagnetic Fields, Oxford University Press, New York, 1995
- Nobel Institute. Presentation speech by Professor JE Johansson. The Nobel Prize in Physiology or Medicine 1924.
- North American Society of Pacing and Electrophysiology.
- Pumphrey S. Latitude and the Magnetic Earth. Icon books, Cambridge: 2002. (see also the William Gilbert website)
- Royal Humane Society, Annual Reports. Brettenham House, Lancaster Place, London, WC2 7EP.
- Schamroth L. The 12 Lead Electrocardiogram. Blackwell Scientific Publications, Oxford: 1989.
- Snellen HA. Willem Einthoven (1860-1927) Father of electrocardiography. Kluwer Academic Publishers, Dordrecht: 1995. with thanks to Kees Swenne
- Titomir LI. The remote past and near future of electrocardiography:
Viewpoint of a biomedical engineer. Bratisl Lek Listy
Comments, corrections or additions are very welcome.
This page was first written on 4th December 1996, last updated 3rd January
2006 and the links were working when I last tried them. From here you can go
back to the ECG
library contents or email me, Dean