Willem Einthoven produced the first instrument to detect the electrical activity of the heart and the first reliable electrocardiogram. His discoveries advanced the study of heart disease. Born in Java, Einthoven studied medicine at the University of Utrecht. He became a tought and performed research at the University of Leiden. In 1924, Einthoven was awarded the Nobel Prize in Physiology or Medicine for his discovery of the mechanism of the electrocardiogram. Willem Einthoven died September 28, 1927.