The Discovery of the ECG : Fascinating Stories of Electric Fish, Colonialism, Frog Legs and the Telegraph

The History of Humans and Electric Fish :?

It's been known for several millennia that certain types of fish, electric eels, electric rays and electric catfish among many others produce a current powerful enough to stun or even kill its predators or prey (including humans!).?

The electric catfish of the Nile was well known to the ancient Egyptians. The Egyptians reputedly used the electric shock from them when treating arthritic pain. They would use only smaller fish, as a large fish may generate an electric shock from 300 to 400 volts. The Egyptians depicted the fish in their mural paintings and elsewhere; the first known depiction of an electric catfish is on a slate palette of the predynastic Egyptian ruler Narmer about 3100 BC

Electric rays, also known as Torpedo fish, after which the undersea weapon - the Torpedo is named, have been documented since the times of the ancient Greeks. The word comes from the Latin torpere, 'to be stiffened or paralyzed', from the effect on someone who touches the fish. The English word Torpor - a state of physical or mental inactivity, also comes from this Latin root!

The ancient Greeks used electric rays to numb the pain of childbirth and operations. In his dialogue Meno, Plato has the character Meno accuse Socrates of "stunning" people with his puzzling questions, in a manner similar to the way the torpedo fish stuns with electricity. Scribonius Largus, a Roman physician, recorded the use of torpedo fish for treatment of headaches and gout in his Compositiones Medicae of 46 AD.

Colonialism and Electric Fish :?

Millenia later, European explorers (read: colonists) in South America reported the presence of fish that would cause painful shocks, including Bertrand Bajon, a French military surgeon and Ramon Termeyer, a Jesuit missionary in (what is still in 2024) the colony of French Guiana, who conducted early experiments on their numbing electrical discharges. This was described and classified by Carl Linnaeus in 1766.?

An American scientist, colonist and plantation doctor, Edward Bancroft who was living in Dutch Guiana at the time described these South American experiments and his own theories on the shock being caused by an electrical discharge, and not an imperceptibly swift mechanical movement. His theory was based on his own personal experience of experiencing an electric shock from a Leyden Jar (an early capacitor) and the similarity in sensation to the electric eel shock. He was encouraged to write and study these further by Benjamin Franklin, that famous kite flying, electricity enthusiast and founding father of the USA. Later in life, he was employed by Benjamin Franklin as a secretary to the American mission in Paris, where Bancroft was a double agent, spying for both the British and Americans, passing secret messages within messages using invisible ink!?

Benjamin Franklin, one of the pioneers in electricity research, was fascinated by these ‘electric fish’ which were generating a lot of interest in the early days of the study of electricity and after speaking with Bancroft on his South American electric eel observations and theories, encouraged several other scientists including Hugh Williamson (another ‘founding father’ of the USA) and British scientist John Walsh to study these more deeply. In discussions with Benjamin Franklin, John Walsh was intrigued to study the properties of ‘electric fish’ and to verify Bancroft’s observations. In particular, there was an argument as to how a fish could be electric. In those days, electricity was understood as being ‘conducted’ from a place of excess to a place of scarcity. It was difficult to conceive such an imbalance in a living organism at the time, or the means of conduction to specific organs and moreover living in a medium which was known to conduct electric current.

Somehow convinced that he could not find electric rays in England, Walsh crossed the Channel to France to find some to experiment on and brought along a pioneering (and controversial) surgeon John Hunter to dissect them for anatomical studies following the physiological observations. They first interviewed French fishermen and subjected them to electric shocks from a Leyden jar, to confirm that this was a similar sensation to their encounters with the electric ray! They then conducted a series of experiments on electric rays which they described in letters to Benjamin Franklin who had them published. They then proceeded to give public demonstrations of the electric effect of the rays compared to a Leyden jar as was the custom of that era of scientific research. They even had the Austrian emperor Joseph II personally experience both the electric shocks! John Walsh was also quite prescient to observe that Electric Eels have an ‘electric sense’ - an observation noted later by Alessandro Volta, who spoke personally to Walsh and gave an account of how they are able to sense an electric current applied to the water, this theory now called Electroreception was re-discovered over 200 years later.

However, there was a dispute as to whether this was a new form of electricity, because until then electricity, usually generated through friction (above 10,000 V) was characterized by visible sparks as well as attraction and repulsion, which this did not create. However, experiments conducted on the electric eel also by John Hunter and later by Hugh Williamson did generate both sparks as well as attraction/repulsion. John Hunter was also quite prescient to hypothesize that nerves might be ‘subservient to the formation, collection or management of electric fluid’. This was a foundational precept for the eventual evolution of neurophysiology.?

Of course today we know that sparks, as well as attraction/repulsion require a high voltage and low current, whereas a high current and low voltage will still generate a shock but no sparks. Electric Eels, which are freshwater fish, produce a discharge of high voltage up to 600V because freshwater is a poor conductor of electricity whereas Electric Rays, which are saltwater creatures where electricity conducts well, generate anywhere from 8 to 220 V (the Rays used in those experiments generated about 50 V). To do this, the Electric Eels have almost 6000 of their electrocytes (electric cells) arranged in series and 35 of these series stacked in parallel, whereas the Electric Rays have 1000 electrocytes arranged in parallel across many short columns.?

By the 1770s, both Hugh Williamson (In 1775) and John Walsh had described the electrical properties of the Electric Eel and Electric Ray respectively. John Walsh had an interesting life that funded his research. He was private secretary to Robert Clive (yes, that Clive of India notoriety) in the East India company in the 1760s in India and was awarded over ￡56,000 (in today’s money ￡14 million) for participating in the Plassey campaign defeat of Siraj ud-Daula, the nawab of Bengal, and left India with proverbial loot of over ￡147,000 (over ￡36.6 million today). Besides supporting Clive in the British parliament (having bought himself an MP seat), his interests expanded to the electrical properties of Torpedo fish (described above) which won him the Copley medal in 1773.?John Hunter, the surgeon working with Walsh, was himself controversial for numerous things including infecting himself with syphilis and gonorrhea as well as stealing the body of Charles Byrne, an Irish giant (that is a real thing) for examination and dissection, which till today is unburied against the wishes of the man and his wife and in fact was on display until last year (2023) at the Royal College of Surgeons!

Another experiment in 1775 by a Danish veterinarian and physician demonstrated a chicken killed with an electric shock to the chest and then revived with a second shock to the chest. He says ‘However, after the experiment was repeated rather often, the hen was completely stunned, walked with some difficulty and did not eat for a day and night, then later it was very well and even laid an egg’.?

Frog Legs and Electricity :?

In the following decades, 1780s and 90s, these experiments greatly inspired two Italian scientists, Luigi Galvani and Alessandro Volta.?

They inspired Luigi Galvani to experiment in this new field of electrophysiology. An ‘accidental’ electrical discharge caused a dissected frog's leg to jump on its own while the sciatic nerve was being touched by a scalpel. These creepy leg movements inspired people across the world, and the publications of these results were part of a summer reading list of Mary Shelley, which led to the writing of a ghost story that became the novel ‘Frankenstein’.?

In an incredible leap of imagination, well before the cellular theory of life was formulated, Galvani suggested that an electric disequilibrium exists between the interior and exterior of muscle fibers and it does not dissipate because of the insulating property of the delimiting surface between the two compartments. Galvani supposed that a nerve fiber penetrated into a single muscle fiber, thus allowing for electrical flow between the external and internal compartments as needed. This far-sighted theory took another century to reappear and was only completely explained and validated by papers published by Hodgkin, Huxley and Katz in 1952!?

Alessandro Volta was so inspired by the discovery of electric organs by Walsh that he named the electric battery that he invented - ‘organe electrique artificiel’ for its similar shape and for being capable of producing electricity by ‘mere contact of conductive substances’. Volta and Galvani had an ongoing dispute about the nature of electricity, which Galvani proposed was due to a vital ‘life force’ present in living creatures and which Volta contended was due to the contact of conductive substances.?

So now, while humanity knew a little about electricity, we had few means of detecting it. By 1820, a magnetic compass needle was observed to deflect when near an electric current - which was named in honor of Galvani - a galvanometer. In 1825, a new galvanometer was developed which was not affected by the earth's magnetic field and an enterprising 19-year-old Italian scientist Carlo Matteucci used this new device along with Galvani’s frog leg experiment to develop what is now called a frog rheoscope as a sensitive electricity detector. This device was so sensitive that even decades later in 1848, it was considered to be 56,000 times more sensitive than the most sensitive conducting electrometer.?

Matteucci used this frog rheoscope in 1842 to detect an electric current that accompanies each heartbeat in a frog, making him the first person to discover that the heart generates its own electrical current. However, he had no means of recording these over time. So the development of the ECG had to wait another half a century for technology to catch up.

The Telegraph and the ECG :?

That technology came from the mind and hands of William Thomson, Lord Kelvin, after whom the units of absolute temperature are named. Thomson was responsible for some of the biggest advances in electricity measurement and standardization, as part of the Trans-Atlantic Telegraph project, which was successful because of two of his inventions, the mirror galvanometer and later in 1867, the Thomson syphon recorder. The syphon recorder automatically records pulses of current and ‘siphons’ out ink into a tube which marks the recording on a running roll of paper tape.?

This syphon recorder was apparently used by Alexander Muirhead in 1872, who is often credited with recording the first human electrocardiogram by attaching wires to a patient’s wrist. Since this was never published it is generally disputed.

A year later, a more sensitive electrometer was invented by Gabriel Lippmann, who is more famous for being the person who invented color photography. This lippmann capillary electrometer, as it was called, was used by a couple of British physiologists, John Sanderson and Frederick Page to understand the interval between variations in the heart’s electric potential (measured on a frog). In 1878, they characterized two phases of the ECG which would later come to be known as the QRS complex and the T wave.

The first person to demonstrate and publish a recording of the electrocardiogram was a British physiologist, Augustus Waller. He created the first practical ECG machine using the capillary electrometer and first recorded the ECG of his lab technician before touring Europe with his pet bulldog Jimmy, who patiently sat with his paws in glass jars of saline while Waller recorded and demonstrated Jimmy’s ECG. At one of these demonstrations at the First International Congress of Physiology in Switzerland, a Dutch doctor, Willem Einthoven observed this demonstration with a lot of interest. Waller himself however, didn’t think that these ECGs could ever be useful despite recording over 2000 of them over his life. Part of this may have been that the capillary electrometer was not fast enough to record ECGs of any diagnostic value.?

Willem Einthoven, one of the brilliant doctors and biophysicists of the turn of the previous century, born in the Dutch colony of Java, was the son of a physician and went on to follow in his father's footsteps and eventually become professor of physiology at Leiden university in the Netherlands. Let’s not forget the Dutch colonized and massacred Indonesia throughout the colonial era. In fact, ‘Royal Dutch Shell’ has its roots in exploiting the oil resources there, defended by the Dutch colonial government from 1890 until 1941.

Inspired by Waller’s demonstration with his dog, Einthoven made considerable improvements to the recording of cardiac electrical activity with the capillary electrometer and he introduced the term ‘electrocardiogram’ at a meeting of the Dutch Medical Association in 1893. Two years later in 1895 Einthoven managed to distinguish five deflections using an improved electrometer and a correction formula. He named these deflections P, Q, R, S, and T using a mathematical convention dating from Descartes.

Telegraph technology came through once again to save the ECG. In 1897, Clement Adair, a French engineer had developed a galvanometer that used a thin wire string which allowed it to record changes in current with higher sensitivity and at a faster speed, which greatly improved the speed and accuracy of deciphering the submarine telegraph.?

Einthoven’s big breakthrough came with his invention of a sensitive form of this galvanometer in 1901, which he named the ‘string galvanometer’. A year later Einthoven published the first electrocardiogram recorded on his string galvanometer and within a year the production of the world's first commercial ‘ECG machine’ was underway.

Einthoven is also the first to record heart sounds later in his career when bioacoustics became his main interest, which means he’s also the pioneer of what we do at Muse Diagnostics !

Eindhoven knew that ECGs could be used as a diagnostic tool unlike his predecessor Waller and communicated with early cardiologists such as Thomas Lewis who in 1908 along with Arthur MacNalty were the first doctors to use an ECG for diagnostics when they diagnosed Heart Block (fault in the Heart’s pacemaker activity).

And the journey of the ECG now crystallized, mass manufactured as a device, used in medical diagnostics, driven by the sciences of electrophysiology and cardiology.?