Interesting to know

Brief history of electrocardiography
Before Einthoven.
1. In 1842, the German physiologist Dubois-Raymond discovered that when a frog's heart contracts, an electric current arises: action potential.
2. In 1872, Lippman invented the mercury capillary electrometer, which made it possible to observe changes in the action potential under a microscope, and Oust Waller was the first to record these action potentials in humans.
The Age Of Einthoven
1. In 1887, the Dutch physiologist William Einthoven (Einthoven) demonstrated at the 1st International Congress of Physiologists in London a curve of the potentials of the action of the heart, the clarity of which impressed everyone. This curve was recorded using the invented string galvanometer. After 2 years, Einthoven assigns the name "electrocardiogram" to an action potential curve.
3. In 1895, Einthoven gives the name to all the teeth of an electrocardiogram: P, Q, R, S, T; later they also singled out the U wave.
4. In 1901, Einthoven designed the world's first electrocardiograph, which used a string galvanometer. This miracle of the technology of its time weighed more than 100 kg.
5. 1905 Einthoven transmits an ECG telegraph at a distance of 1.5 km: from the clinic to his laboratory.
6. 1906. Einthoven publishes the world's first guide to electrocardiography.
6. Einthoven sends a letter to the London Society of Clinicians, where he describes the technique of vector analysis of the electrocardiogram in an isosceles triangle.
7. 1924 William Einthoven is awarded the Nobel Prize.
     Here are some photos of the Einthoven era.
From left to right, top to bottom: "First studies", "First industrial electrocardiograph, weight - more than 100 kg", "First ECG recorded in humans", "Einthoven records an ECG for himself", "Einthoven's string galvanometer.
Photo from the first textbook on electrocardiography, 1906
It looked like an electrocardiograph in 1917.
Portrait in the year of the Nobel Prize (1924).
 After Einthoven.
 1. In 1932-1948, the American physiologist Wilson (Wilson) developed a method of unipolar chest leads, publishes their vector analysis. A vector analysis of probable intrathoracic leads leads him to believe that in myocardial infarction, the ventricular ECG complex should be represented by a single negative QS wave.
2. 1942 Goldberger developed strengthened single-pole leads, substantiated the position on the position of the heart.
3. 1952. WHO experts adopt a standard (protocol) for recording and decoding electrocardiograms.