Willem Einthoven, Biological Physicist

In Chapter 7 of the 4th edition of Intermediate Physics for Medicine and Biology, Russ Hobbie and I mention Einthoven’s triangle. This triangle is formed by three electrodes used to measure the electrocardiogram: one on the right arm, one on the left arm, and one on the left leg. Who is this Einthoven of Einthoven’s triangle? He is an excellent example of a scientist well versed in both physics and physiology.

Asimov's Biographical
Encyclopedia.

Asimov’s Biographical Encyclopedia of Science and Technology describes Einthoven in this way:

Einthoven, Willem (eyent’-hoh-ven)
Dutch physiologist
Born: Semarang, Java (now part of Indonesia), May 22, 1860
Died: Leiden, September 29, 1927

Einthoven’s father was a practicing physician serving in the East Indies, which was then a Dutch colony. The father died in 1866, and in 1870 the family returned to the Netherlands and settled in Utrecht. In 1878 Einthoven entered the University of Utrecht and began the study of medicine, although always with considerable interest in physics. He obtained his medical degree in 1885 and was at once appointed to a professorship of physiology at the University of Leiden, serving there the remainder of his life.

The physicist in him provoked his interest in the tiny electric potentials produced in the human body…. In 1903 Einthoven developed the first string galvanometer. This consisted of a delicate conducting thread stretched across a magnetic field. A current flowing through the thread would cause it to deviate at right angles to the direction of the magnetic field lines of force, the extent of the deviation being proportional to the strength of the current. The delicacy of the device was sufficient to make it possible to record the varying electrical potentials of the heart.

Einthoven continually improved his device and worked out the significance of the rises and falls in potential. By 1906 he was correlating the recordings of these peaks and troughs (the result being what he called the electrocardiogram) with various types of heart disorders….For the development of electrocardiography Einthoven was awarded the 1924 Nobel Prize in medicine and physiology.

Willem Einthoven (1860-1927):
Father of Electrocardiology.

I became intrigued by Einthoven’s skill at both mathematics and medicine, so I decided to explore deeper into how he straddled these two fields. The book Willem Einthoven (1860-1927): Father of Electrocardiography, by H. A. Snellen, provided these insights:

[Einthoven’s work] demanded more knowledge of mathematics than Einthoven’s high school and medical training had provided. He supplemented this mainly through self-study; learning differential and integral calculus from Lorentz’ book on the subject in the early 1890’s.

30 Years later he presented a copy of this book to Frank Wilson with the words: “May I send you the excellent book of Lorentz’ Differential- und Integralrechnung? I have learned my mathematics from it after my nomination as a professor in this University and I hope you will have as much pleasure and profit by it as I have had myself.”

In physical matters he was aided by his correspondence and talks with his friend (and later brother-in-law) Julius, who became extra-ordinary professor of physics at Amsterdam and subsequently full professor at Utrecht, where they had studied together.

Einthoven profited also from written and personal contact with the somewhat older and already famous Lorentz, professor of theoretical physics at Leiden….

Einthoven the physiologist with a marked general concern about patients and general medicine was at heart a physicist though not by training and office…

Most of the important topics in the correspondence [between Einthoven and English physiologist A. V. Hill] are reflected in Hill’s obituary of Einthoven in Nature. I quote a few lines, which bear testimony to Hill’s keen observation and his sincere admiration of Einthoven: “Einthoven’s investigations cover a wide range, but they are all notable for the same characteristic—the mastery of physical technique which they show. Einthoven, in spite of his medical training and his office, was essentially a physicist, and the extraordinary value of his contributions to physiology, and therewith indirectly to medicine, emphasizes the way in which an aptitude—in Einthoven’s case a genius—for physical methods can aid in the solution of physiological problems.”

Many scientists have made the leap from physics to biology (see my blog entry of a few weeks ago for examples). Einthoven did the opposite: going from biology to physics. I’ve always suspected this is the more difficult path, and it certainly seems to be the less common one. Yet, he appears to have made the journey successfully. Snellen’s book provides no anecdotes about how Einthoven picked up his mathematics and physics, but I imagine he must of spent many a night slogging through Lorentz’s book, painstakingly teaching himself the subject.

I suspect IPMB can aid physicists moving into biology and medicine. I wonder how useful it is for someone like Einthoven, travelling in the other direction?