Willem Einthoven was a Dutch physiologist who, in 1924, was awarded the Nobel Prize in Physiology or Medicine for his invention of a string galvanometer that he used to produce the electrocardiogram (EKG), a physical recording of the electrical activity of the heart. He originated many of the ideas that govern both the technical aspects and clinical interpretation of EKG. This instrument has been vital in assessing certain types of heart disease because it records the electrical action of the heart in a noninvasive fashion. He also developed "Einthoven's Triangle," which is a central theoretical aspect in the administration and interpretation of EKG records.
Einthoven was born on May 21, 1860, in Semarang, Java, Dutch East Indies. His father, although born in the Netherlands, served as an army medical officer in the Indies. Later, he set up a medical practice in Semarang, but passed away when Einthoven was 10. His mother decided to return the family back to Holland. He entered the University of Utrecht in 1878 as a medical student, intending to follow in his father's footsteps. Einthoven graduated with a degree in medicine and was appointed professor of physiology at the University of Leiden. He served at this post from 1886 until his death in 1927. Although he was trained in medicine, Einthoven discovered that he excelled in physics and worked to measure electrical signals in humans.
He showed interest in recording the heartbeat as early as 1891. At that time, a device called the capillary electrometer was used to register the changes of electrical potential caused by contractions of the heart muscle. The apparatus was not accurate or practical for scientific and diagnostic applications. Einthoven was interested in developing an instrument that would directly record the electrical changes in the heart. In 1903, he designed the string galvanometer, which measured the changes in the electrical activity of the heart caused by muscular contractions and recorded them graphically. It consisted of a very thin wire of quartz held in a magnetic field. When the wire was magnified and its movements recorded on film, Einthoven could make precise measurements of the heart's electrical activity. This device revolutionized the field of medicine. It was originally referred to in German as "Elektrokardiogramm" or EKG. In most Western countries it is now called ECG (electrocardiogram).
The instrument became an important tool in the diagnosis of heart disease, with Einthoven spearheading the investigation into the applications of the technology. Einthoven recognized differences in the tracings obtained from various types of heart disease. In 1906, he published the first organized presentation of normal and abnormal electrocardiograms recorded with a string galvanometer. In his treatise, Einthoven identified pathologies such as hypertrophy, ventricular premature beats, and complete heart block. This continued a previous pattern of Einthoven's, for as early as 1895, he had distinguished the five deflections normally seen in an EKG recording which he designated P, Q, R, S, and T. Subsequently, Einthoven refined models of the string galvanometer, including the development of an electrophonocardiogram to measure heart sounds in 1915. He also applied this technology to other devices used to measure electrical currents in muscles, nerves, and the eye. Modern EKG machines are still based on Einthoven's original invention and allow physicians to monitor heart function and to detect damage from heart attacks and other causes.
In 1886, Einthoven married Frédérique Jeanne Louise de Vogel. Together, they had four children, some of whom had distinguished scientific careers themselves. Einthoven died on September 28, 1927, leaving a remarkable legacy in the field of electrocardiography.
JAMES J. HOFFMANN