'''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 develops from 'The Institution for Affording Immediate Relief to Persons Apparently Dead from Drowning'. It is "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 self-destruction."
A Mr Squires, of Wardour Street, Soho, lives opposite the house from which a three year old girl, Catherine Sophia Greenhill falls from a
first story window on 16th July 1774. After the attending apothecary declares 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, occasioned 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."
'''1869-70''' Alexander Muirhead, an electrical engineer and pioneer of telegraphy, possibly records a human electrocardiogram at St Bartholomew's Hospital, London but this is disputed. He is thought to have used a Thompson Siphon Recorder. Elizabeth Muirhead, his wife, writes a book of his life, claiming 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 suffered cardiac and/or respiratory arrest during
anaesthesia with chloroform. He uses a galvanic pile (battery) of 200 cells generating 300 Volts, which he applies 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).
[[image:Duchenne_de_belogne.jpg|thumb|150px|left|Guillaume Benjamin Amand Duchenne de Boulogne]]'''1872''' Guillaume 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; 1872
'''1935''' McGinn and White describe the changes to the electrocardiogram during acute pulmonary embolism, including the S1 Q3 T3 pattern. <cite>McGinn</cite>
'''1938''' The 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
'''1938''' 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.
'''1939''' Langendorf reports a case of atrial infarction discovered at autopsy
which, in retrospect, could have been diagnosed by changes on the ECG. <cite>Langendorf</cite>
'''1942''' 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.
'''1942''' Arthur Master standardizes 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
'''1944''' 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.
'''1947''' Gouaux and Ashman describe an observation that helps differentiate aberrant conduction from ventricular tachycardia. The 'Ashman phenomenon' occurs when a stimulus takes place 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. <cite>Gouaux</cite>
'''1947''' 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. <cite>Beck</cite>
'''1948''' 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)
'''1950''' 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. <cite>Bigelow</cite>
whilst experimenting with hypothermic dogs, describes the prominent J (junctional) wave which has often been known as the "Osborn wave". 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.
'''1955''' 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 1955;11:442.
'''1959''' Myron Prinzmetal describes a variant form of angina in which the ST segment is elevated rather than depressed. <cite>Prinzmetal</cite>
'''1960''' 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' phenomenon. 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.
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 syndrome. <cite>Romano</cite><cite>Ward</cite>
[[image:Bruce_portrait.jpg|thumb|150px|left|Robert Bruce]]'''1963''' Robert 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." <cite>Bruce1</cite><cite>Bruce2</cite>
'''1963''' 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 electrodes. Although potentially a useful technique it has never gained clinical acceptance, partly because of its greater expense. <cite>Baule</cite>
'''1966''' 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. <cite>Papouchado</cite>
'''1966''' François Dessertenne of Paris publishes the first case of '[[Torsade de pointes]]' Ventricular Tachycardia. <cite>Dessertenne</cite>
'''1968''' Henry Marriott introduces the Modified Chest Lead 1 (MCL1) for monitoring patients in Coronary Care.
'''1969''' 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'. <cite>Rosenbaum</cite>
'''1974''' Jay Cohn, of University of Minnesota Medical School, describes the 'syndrome of right ventricular dysfunction in the setting of acute inferior wall myocardial infarction'. <cite>Cohn</cite>
'''1974''' Gozensky and Thorne introduce the term 'Rabbit ears' to electrocardiography. 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. <cite>Gozensky</cite>
'''1976''' 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. <cite>Erhardt</cite>
'''1988''' Professor John Pope Boineau of Washington University School of Medicine publishes a 30-year
percpective on the modern history of electrocardiography. <cite>Boineau</cite>
[[image:Brugada.jpg|thumb|150px|left|Pedro Brugada]]'''1992''' Pedro 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. <cite>Brugada</cite>
'''1992''' 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. <cite>He</cite>
[[Image:modern_ecg.jpg|thumb|150px|The last generation of ECG equipment. Image courtesy of [http://www.gehealthcare.com/euen/cardiology/ General Electric]]]
'''1993''' Robert Zalenski, Professor of Emergency Medicine, Wayne State University Detroit, 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 infarction. <cite>Zalenski</cite>
'''1999''' 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. <cite>Pettis</cite>
'''2000''' 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. <cite>Gussak</cite>
'''2005''' 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. <cite>Clemmensen</cite>
'''2008''' Dr. Haïssaguerre et al.
have studied ECGs from patients with idiopathic ventricular fibrillation and find that patients with early repolarization on their ECG (elevation of the QRS-ST junction of at least 0.1 mV from baseline, which is usually considered a benign finding) is associated with a doubled risk of ICD shock during follow up. <cite>Haiss</cite>