Einthoven

Willem Einthoven (1860–1927) was a Dutch physician and physiologist who pioneered the development of the electrocardiogram (ECG). Born in Semarang, Java, then part of the Dutch East Indies, he studied medicine at Leiden University and later became a professor of physiology there in 1902.

Einthoven built the first practical device to record the heart’s electrical activity, the string galvanometer, around 1903. This instrument enabled the recording of the electrocardiogram, a graphical representation of the heart’s electrical events. He introduced the concept of the Einthoven triangle, formed by three limb leads—I, II, and III—that map the heart’s electrical field and form the basis of standard ECG recording.

A key contribution attributed to him is Einthoven’s law, which states that for standard limb leads, Lead II equals the sum of Leads I and III (Lead II = Lead I + Lead III). His work demonstrated how ECG patterns could reflect heart rate, rhythm, and certain cardiac conditions, laying the foundation for noninvasive cardiac diagnosis.

For his achievements in understanding cardiac physiology and developing the electrocardiograph, Einthoven was awarded the Nobel Prize in Physiology or Medicine in 1924. He remained at Leiden for much of his career and died in 1927 in Leiden. His innovations established the ECG as a essential tool in modern medicine, influencing cardiology for decades and beyond.