Einthoven was born in Indonesia in the year 1860. His father who was a doctor, died when Einthoven was still a child. His mother along with her children moved to Netherlands in 1870. He received a medical degree from the University of Utrecht in 1885. After that he went on to become a professor at University of Leiden in 1886.
Before Einthoven's time, it was known that electrical currents were produced by the beating of the heart, but this phenomenon could not be measured accurately without placing electrodes directly over the heart. Einthoven completed a series of prototypes of string galvanometers in 1901. The device used a very thin filament of conductive wire passing between very strong electromagnets (Fig. 1). The electromagnetic field would cause the string to move when current was passed through the filament.
FIG. 1: Photograph of a complete electrocardiography showing the way in which the electrodes are attached to the patient. In this case the hands and one of the feet being immersed in jars of salt solution.
2This string would cast a shadow on a moving role of photographic paper when a light was shone (Fig. 1).
The original machine required cooling water for the powerful electromagnets. It required 5 people to operate it and weighed around 600 lb. This device increased the sensitivity of the standard galvanometer so that the electrical activity of the heart could be measured despite the insulation of flesh and bones.
Much of the terminology used in describing an EKG originated with Einthoven. His assignment of the letters P, Q, R, S and T to the various deflections is still used. The term Einthoven's triangle is named after him.
Einthoven went on to describe the electrocardiographic features of a number of cardiovascular disorders after his development of string galvanometer. Later Einthoven studied the acoustics, particularly heart sounds which he researched with Dr P Battaerd.
He died in Leiden, Netherlands and is buried in the graveyard of the Reformed Church at Haarlemmerstraatweg in Oegstgeest.