Electrocardiogram

Dutch physiologist, professor, and inventor Willem Einthoven performed research and invented concepts for recording electrical heart impulses that greatly evolved the field of cardiology and led to the development of one of the most important diagnostic tools in all of medicine: the electrocardiogram, or EKG. His adaptation of the string galvanometer made it possible to accurately measure variations in electrical potential caused by heart muscle contractions and to record them graphically.

Einthoven was born on May 21, 1860 in Semarang, on the island of Java, then the Dutch East Indies and now part of Indonesia. There his father served as an army medical officer for the Netherlands. Einthoven lived there until he was ten years old when his mother, widowed four years before, decided to return to the Netherlands with her six children. The family settled in Utrecht in 1878.

Einthoven was an avid athlete and astute student, participating in sports such as gymnastics, fencing, and rowing. Following in his father’s footsteps, he became interested in medicine, studying the subject at the University of Utrecht. His interest veered toward physiology, and he completed his doctoral degree in this field in 1885, producing several remarkable research papers, including a study of the human elbow joint, studies on the human eye, and a doctoral thesis on “Stereoscopy by means of color variation.”

In 1886, Einthoven, after having been certified to serve as a general practitioner, was offered a position as professor of physiology at the University of Leiden. He accepted and would serve in this post for the rest of his life and career. This position gave him a place to delve into groundbreaking research endeavors in areas of particular interest to him. At first, this included study of the movement of the human eye. He published several papers on the topic. Later, he became keenly interested in the area of respiratory function. His focus turned to electrical phenomena in physiology, mostly as related to the human heart.

At that time, close to the turn of the century, little was known about this subject. Medical study of the heart was very undeveloped, though the concept of electrocardiography had been introduced as early as the 17th century. British physiologist Augustus D. Waller had recorded the first electrocardiogram with a tool called a “capillary electrometer” in 1887. Einthoven conducted an analysis of Waller’s work and published a classic paper on the subject.  He began registering heart sounds himself using this tool, but he quickly realized that the instrument’s inertia produced errors.  He sought a better method.

A string galvanometer had been used earlier for purposes such as amplifying electrical signals over undersea cable. Einthoven thought this technology might also work to measure the tiny electrical variations generated by the heart.  In 1901, he completed a model of a string galvanometer using a silver-coated, thin, lightweight quartz string, combining ideas from earlier research done by others in the field. Each current that passes through the quartz string was sent by electrodes attached to a patient's body.  The electrodes would deflect the string when a small electrical charge on the body arose from the heart muscle. The silver coating would make the string opaque when placed in a beam of light and would throw a shadow onto a plate. The point of the shadow would shine through to a photographic film and form in a continuous line or curve showing the movement of the string.

The medical community was impressed with Einthoven’s highly sensitive prototype. After his publishing results of the first electrocardiogram using the device in 1902, commercial interest came quickly. The string galvanometer went into production in 1903.

Further improvements and developments followed, pushing the device into mainstream use. In 1905, the first “telecardiogram” was recorded and sent by telephone wire from laboratory to hospital. The following year, Einthoven published a complete presentation of normal and abnormal electrocardiograms recorded with a string galvanometer. He spent several more years studying patterns of records of normal heart activity in order to create a standard for accurately interpreting results.

In 1911, Thomas Lewis published a textbook on the mechanism of the human heartbeat, which was dedicated to Einthoven. The abbreviation “EKG” first appeared in an article in English in 1912. Later developments by scientists, including Emanuel Goldberger, evolved the standard electrocardiogram that is used today. Einthoven continued to conduct research in this area and other fields until the end of his life.

Einthoven was recognized with a number of honors for his achievements during the course of his career, including membership in the Dutch Royal Academy of Sciences. He was awarded the Nobel Prize for Physiology or Medicine in 1924 for his work in the area of electrical heart properties and the electrocardiograph. He died on Sept. 29, 1927 in Leiden, the Netherlands at the age of 71.