magnetized needles in electromagnetic fields

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. 1668 ? 1729 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. 1745 ? 1769 Edward Bancroft, anThe Coca- Cola Company in the United States since March 27, 1944). 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. 1773 ? 1774 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 acrificed to their recreations; and the unhappy victims of desponding melancholy and deliberate suicide; from the miserable consequences of self-destruction. ” 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 1775

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 Andr? Marie Amp? re. 1820 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. 1825 Leopoldo 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. 1838 ? 1840 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) 1843 ? 1849 H. Bence Jones, Physician at St George’s Hospital, reports on the disappointing results of electrical therapy on his patients.

He concluded that only four of his 23 cases seemed to improve. H. Bence Jones. Remedial Action of Electricity. Lond J Med Feb 1849; s2-1: 125 – 129; doi:10. 1136/bmj. s2-1. 2. 125 1850 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 1856

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 systole. 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. 1858 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. 1867 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. 869-70 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. 1872 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. 1872 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 1872). 1872 ? 1875 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 … hen 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 exploring 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. Br Med J 1875; 2(765):278, Mumenthaler, Mattle Eds. Neurology. 4th Edition. Stuttgart, Thieme: 2004. 876 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 1878 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 1880 French physicist Ars? ne 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 calibrated scale. The d’Arsonval galvanometer is the basis for most modern galvanometers.

Comptes rendus de l’Acad? mie des sciences, 1882, 94: 1347-1350 1884 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 1887 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 1889 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. 1889 Professor John McWilliam, of Aberdeen University, describes ventricular fibrillation as “unexpected, and irretrievable cardiac failure [which] may … present itself in the form of an abrupt onset of fibrillar contraction …

The cardiac pump is thrown out of gear, and the last of its vital energy is dissipated in a violent and prolonged turmoil of fruitless activity in the ventricular walls. ” He also describes the electrical stimulation of the heart in cases of “fatal syncope” in man. “A single induction shock readily causes a beat in an inhibited heart, and a regular series of induction shocks (for example, sixty or seventy per minute) gives a regular series of heartbeats at the same rate. ” McWilliam JA. Cardiac Failure and Sudden Death. Br Med J 1889;1:6-8. McWilliam JA.

Electrical stimulation of the heart in man. Br Med J 1889;1:348? 50. 1890 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 1891 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 1893 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 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 dating from Descartes (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. (For more on Descartes see Henson JR. Descartes and the ECG lettering series. J Hist Med Allied Sci. April 1971;181? 186) 1897 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 1899 ? 1899 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 ventricular fibrillation. Prevost JL, Batelli F. Sur quelques effets des descharges electriques sur le coeur des mammiferes. [On the effects of electric shocks on the hearts of mammals. ] Acad. Sci. Paris, FR. : 1899; 129:1267-1268..

They also report that ventricular fibrillation can be induced by small voltages (40 V). Prevost JL, Batelli F. La Mort Par Les Descharges Electriques. [Death by electrical disharges]. Journ. de Physiol. 1899;1:1085-99. top 1901 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 1902 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, 1902:101-107 1903 Einthoven discusses commercial production of a string galvanometer with Max Edelmann of Munich and Horace Darwin of Cambridge Scientific Instruments Company of London. 1905 Einthoven starts transmitting electrocardiograms from the hospital to his laboratory 1. 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. 1905 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 block. Hay J.

Bradycardia and cardiac arrhythmias produced by depression of certain functions of the heart. Lancet 1906;1:138-143. 1906 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) 1906 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 Aktionstr? me des menslichen Herzens vom Oesophagus und ? ber das Elektrokardiogramm des F? tus. Munch. Med. Wochenschr. 1906;53:811 1907

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. 1908

Edward Schafer of the University of Edinburgh is the first to buy a string galvanometer for clinical use. 1909 Thomas Lewis of University College Hospital, London buys a string galvanometer and so does Alfred Cohn of Mt Sinae Hospital, New York. 1909 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 1910 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 1911 Thomas Lewis publishes a classic textbook. The mechanism of the heart beat. London: Shaw & Sons and dedicates it to Willem Einthoven. 912 Thomas Lewis publishes a paper in the BMJ detailing his careful clinical and electrocardiographic observations of atrial fibrillation. Lewis describes how he and a colleague, Dr Woordruff a vet, identified the condition in horses and, at a later date, witnessed the fibrillating heart of a horse on Bulford Plain. “The chest was opened while the heart was still beating, and I obtained, as did those with me, a clear view of a fibrillating auricle, brought to this state, not by experimental interference, but by disease.