Universiteit Leiden

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Leiden Classics: Inventor of the electrocardiograph

Many important discoveries have been made in Leiden, and the Leiden Discoveries route guides you through the city to find them. For example, it will take you to the lab of Nobel laureate Willem Einthoven, who was a professor of physiology. His most important invention, the electrocardiograph, is still saving lives today.

Graph of the heart

Nowadays it’s the most natural thing in the world: as soon as a doctor suspects there is something wrong with a patient’s heart, he has a cardiogram made. These graphs, which are also known as ECGs, first saw the light of day in the Kamerlingh Onnes Laboratory, the current home of the Faculty of Law. 

Nobel Prize

In the early 20th century, the laboratory was one of the world’s most important centres for theoretical and technical physics, and it was here that this Leiden professor of physiology built his first electrocardiograph in 1903. In 1924 he was awarded the Nobel Prize in Medicine for this invention.

One of the first commercial electrocardiograph (1911).

Measuring electrical currents

The heart is a sort of electrical device. Electrically charged particles play an important role in the mechanism the body uses to make your heart contract—that is, to make it ‘pump’. It was in the second half of the 19th century that researchers first discovered the effect of these charged particles. That gave Einthoven an idea. His plan? To measure the heart’s electrical currents, graph them and see whether he could detect a difference between the hearts of healthy people and those of people with heart defects.

The heart’s electrical currents are so weak that in Einthoven’s time they were extremely difficult to measure. At that time, the most conductive wires available were so thick that the electrical currents could barely pass through them. The wire gave too much resistance.

Bow and arrow

The only way to address this issue was to somehow produce a much thinner wire that was more conductive. Einthoven tackled this problem in a very unusual way: by using a bow and arrow. He attached a lump of molten quartz to an arrow, which he then shot across the lab with a bow. In this way the arrow stretched the lump of crystal out into a very thin quartz wire. Einthoven then covered this wire with a thin layer of silver, giving him a much thinner wire with excellent conductivity. This was an important step towards constructing the first electrocardiograph. 

Basic scientific research and social innovation

Einthoven died in Leiden in 1927, after enjoying a brilliant academic career. To honour the esteemed scientist and his contributions, Leiden University opened the Willem Einthoven building in 2009 at a ceremony attended by his descendants. The building currently houses Leiden University’s Centre for Science and Technology, among other university offices. Just like Einthoven’s work, this centre builds a bridge between basic scientific research and social innovation. 

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