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Click on the ECG to see an enlargement. | Click on the ECG to see an enlargement. | ||
Where do we look | Where do we look when watching an ECG? | ||
* top left are the patient's information, name, sex and date of birth | * top left are the patient's information, name, sex and date of birth | ||
* at the right of that are below each other the [[heart frequency]], the [[Conduction time intervals (PQ,QRS,QT)|conduction time intervals]] (PQ,QRS,QT/QTc), and the [[cardiac axis]] (P-top axis, QRS axis and T-top axis) | * at the right of that are below each other the [[heart frequency]], the [[Conduction time intervals (PQ,QRS,QT)|conduction time intervals]] (PQ,QRS,QT/QTc), and the [[cardiac axis]] (P-top axis, QRS axis and T-top axis) | ||
* | * further to the right is the interpretation of the ECG written (this often misses in a 'fresh' ECG, but later the interpretation of the cardiologist or computer will be added) | ||
* down left is the 'paper speed' (25mm/s on the horizontal ax), the sensitivity (10mm/mV) and the filter's frequency (40Hz, filters noise from eg. lights) | * down left is the 'paper speed' (25mm/s on the horizontal ax), the sensitivity (10mm/mV) and the filter's frequency (40Hz, filters noise from eg. lights) | ||
* finally there is a calibration on the ECG, on the beginning of every lead is a vertical block that shows how high 1mV is. So the height and depth of these signals are a measurement for the voltage. If this is not the set 10mm, there is something wrong with the machine. | * finally there is a calibration on the ECG, on the beginning of every lead is a vertical block that shows how high 1mV is. So the height and depth of these signals are a measurement for the voltage. If this is not the set 10mm, there is something wrong with the machine. | ||
* further we have the ECG leads themselves of course, | * further we have the ECG leads themselves of course, these will be discussed below. | ||
Note the lay-out | Note that the lay-out is different for every machine, but all of the information above can be found. | ||
{{clr}} | {{clr}} | ||
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!<flash>file=Single_cardiomyocyte.swf|width=382|height=315|quality=best|align=right||</flash> | !<flash>file=Single_cardiomyocyte.swf|width=382|height=315|quality=best|align=right||</flash> | ||
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| | | This movie shows the contraction of a single (rabbit)heartcell. The glass electrode measures the electrical current in the heartcell(according to the[[w:Patch_clamp|patch-clamp method]]). The electrical signal is written in blue and shows the actionpotential. ''Courtesy of Arie Verkerk and Antoni van Ginneken''. | ||
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In '''1843''' Emil Du Bois-Reymond, a german physiologist, was the to describe "action potentials" of muscular contraction. He used a highly sensitive galvanometer, which contained more than 5 km of wire. Du Bios Reymond named the different waves: "o" was the stable equilibrium and he was the first to use the p, q, r and s to describe the different waves. ''Du Bois-Reymond, E. Untersuchungen uber thierische Elektricitat. Reimer, Berlin: 1848.'' | In '''1843''' Emil Du Bois-Reymond, a german physiologist, was the to describe "action potentials" of muscular contraction. He used a highly sensitive galvanometer, which contained more than 5 km of wire. Du Bios Reymond named the different waves: "o" was the stable equilibrium and he was the first to use the p, q, r and s to describe the different waves. ''Du Bois-Reymond, E. Untersuchungen uber thierische Elektricitat. Reimer, Berlin: 1848.'' | ||
In '''1850''' M. Hoffa described how | In '''1850''' M. Hoffa described how he could induce irregular contractions of the ventricles of doghearts by administering electrical shock. ''Hoffa M, Ludwig C. 1850. Einige neue versuche uber herzbewegung. Zeitschrift Rationelle Medizin, 9: 107-144'' | ||
In '''1887''' | In '''1887''' the English physiologist Augustus D. Waller from Londen published the first human electrocardiogram. He used a capillar-electrometer. ''Waller AD. A demonstration on man of electromotive changes accompanying the heart's beat. J Physiol (London) 1887;8:229-234'' | ||
[[wikipedia:Einthoven|Willem Einthoven]] (1860-1927) | [[wikipedia:Einthoven|The dutchman Willem Einthoven]] (1860-1927) introduced in 1893 the term 'electrocardiogram'. He described in '''1895''' how he used a galvanometer to visualize the electrical activity of the heart. In 1924 he received the Nobelprize for his work on the ECG. He connected electrodes to a patienta showed the electrical difference between two electrodes on the galvanometer. We still now use the term: Einthovens'leads. The string galvanometer (see Image) was the first clinical instrument on the recording of an ECG. | ||
In 1905 | In 1905 Einthoven recorded the first 'telecardiogram' from the hospital to his laboratoy 1.5 km away. | ||
In 1906 publiceert Einthoven het eerste artikel waarin een serie (afwijkende) ECG bevindingen worden beschreven: linker en rechter ventrikelhypertrofie, linker en rechter atriumdilatatie, de U golf, notching van het QRS comples, ventriculaire extrasystolen, bigemini, boezemflutter en totaal AV blok. ''Einthoven W. Le telecardiogramme. Arch Int de Physiol 1906;4:132-164'' | In 1906 publiceert Einthoven het eerste artikel waarin een serie (afwijkende) ECG bevindingen worden beschreven: linker en rechter ventrikelhypertrofie, linker en rechter atriumdilatatie, de U golf, notching van het QRS comples, ventriculaire extrasystolen, bigemini, boezemflutter en totaal AV blok. ''Einthoven W. Le telecardiogramme. Arch Int de Physiol 1906;4:132-164'' | ||