Einthoven's Electrocardiograph

The heart's electrical activity had been recorded before Willem Einthoven, but only crudely. Augustus Waller of St Mary's Medical School in London published the first human electrocardiogram in 1887, using a capillary electrometer with electrodes on the chest and back. In 1891 William Bayliss and Edward Starling at University College London showed three phases of electrical activity in each beat with an improved electrometer.

Einthoven, a physiologist at Leiden University who had been born in Java in 1860, refined the capillary electrometer and picked out five deflections in each beat, which he labeled ABCDE. Once the tracing was corrected for the sluggishness of the instrument, he renamed them P, Q, R, S and T. He had introduced the word electrocardiogram at a Dutch medical meeting in 1893.

He then built a new instrument. His string galvanometer, developed in 1901, was highly sensitive, and the complete apparatus weighed about 600 pounds. AlGhatrif and Lindsay date the electrocardiograph's introduction to medicine to 1902; the Nobel Foundation dates Einthoven's construction of the string galvanometer to 1903.

Einthoven also simplified the recording. He cut the number of electrodes to three by dropping the right leg and mouth electrodes, which he judged least useful, and the three leads that remained formed the arrangement still taught as Einthoven's triangle. With the chest X-ray, introduced in 1895, the electrocardiograph gave physicians objective information about the heart's structure and function. Einthoven received the 1924 Nobel Prize in Physiology or Medicine for his discovery of the mechanism of the electrocardiogram.