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The History of the Electrocardiogram (EKG/ECG)

  • Writer: FibonacciMD
    FibonacciMD
  • 4 days ago
  • 5 min read

Updated: 2 days ago


Patient getting one of the first electrocardiograms.
Patient getting one of the first electrocardiograms.

By Stuart M. Caplen, MD 


The electrocardiogram (EKG or ECG) is a medical advance that created a tracing of the heart’s electrical activity and led to the diagnosis of myocardial infarctions, arrhythmias, pathological conditions in the heart, and even certain electrolyte disorders.  The term EKG comes from the German word Elektrokardiogramm, which remains in use today.  This is the story of how the EKG/ECG machine was developed.


Luigi Galvani

In 1780, Dr. Luigi Galvani, an Italian physician, first noted that muscle contractions could be induced in frogs’ legs.  There are a number of different accounts of how this was discovered, but according to an 1804 book, Galvani was in his laboratory and preparing to have frog soup for dinner.  The frogs were placed on a table near an electrical device, and one of his lab partners accidentally touched one of the frog’s nerves with a scalpel. The leg contracted and a spark was produced.  His wife witnessed this and informed Galvani.  He began experimenting and discovered that contractions could be induced when two different metals touched a nerve.  In the lab, they attached brass hooks to spinal nerves and hung the frog’s legs on an iron railing, which would cause the leg to kick.  He concluded that nerves and muscles required electricity to function.

  

Carlo Matteucci

Dr. Carlo Matteucci, an Italian physicist expanded on Galvani’s work, and in the mid-1800s demonstrated that each heartbeat in a frog is accompanied by an electrical current, providing some of the earliest evidence of the heart’s electrical properties.


Augustus Desiré Waller

In 1887, British physiologist Augustus Desiré Waller, after experiments on animals, recorded the first human electrocardiogram using a capillary electrometer.  This device detects changes in electrical potential and voltage by observing small movements in a mercury column within a narrow glass tube when connected to an electrolyte solution.  Waller required subjects to place their hands and forearms or, in demonstrations involving his dog Jimmy (AKA Jimmie), its paws in a jar of saline solution.  He mounted a photographic plate on a slowly moving toy train to capture the tracings.  Although the resulting recordings were crude, they were the first EKG/ECG tracings ever documented.


Waller’s dog Jimmy in a demonstration of the electrometer.
Waller’s dog Jimmy in a demonstration of the electrometer.
Electrocardiogram tracing seen on photographic plate moved by toy train.
Electrocardiogram tracing seen on photographic plate moved by toy train.

Willem Einthoven

Einthoven and his string galvanometer
Einthoven and his string galvanometer

In 1902, inspired by Waller’s work, Dutch physiologist Willem Einthoven invented the string galvanometer, a far more sensitive instrument capable of recording cardiac electrical activity, which still required putting limbs into salt water.


In 1903, Einthoven invented what is recognized as the first clinical EKG/ECG machine, which weighed about 600 pounds and required several people to operate.  He introduced terminology that is still in use today: the P wave for atrial depolarization, the QRS complex for ventricular depolarization, and the T wave for ventricular repolarization. 


(Depolarization is the change in electrical charge across a cell membrane that allows positively charged sodium ions to enter the cell, initiating the electrical signal that leads to contraction of the myocardium (heart muscle).  Repolarization occurs during the resting phase, allowing positively charged potassium ions to exit the cell so that the myocardium is ready for the next contraction.) 


He also named the electrical views of the heart as leads I, II, and III (known collectively as Einthoven’s triangle), based on the limb leads, which are used to record the cardiac electrical activity.  This nomenclature is still in use today.

Einthoven’s triangle

In 1924, Einthoven was awarded the Nobel Prize in Physiology or Medicine "for his discovery of the mechanism of the electrocardiogram".


Early string galvanometer
Early string galvanometer
Early string galvanometer
Early string galvanometer

Frank Sanborn

In 1928, Frank Sanborn developed a more practical version of the EKG/ECG machine.  It weighed 50 pounds and was typically powered by an automobile battery.  It represented a major step toward routine clinical use. 


Sanborn EKG
Sanborn EKG


Later version of Sanborn EKG Machine
Later version of Sanborn EKG Machine

Norman “Jeff” Holter

In 1947, Norman “Jeff” Holter, a biophysicist, created a prototype of the first mobile electrocardiographic recorder, which produced radioelectrocardiograms and transmitted the EKG/ECG tracings by radio waves.  The device weighed approximately 80-85 pounds.  Although not practical for routine use, Holter’s concept eventually led to the development of the modern Holter monitor, a lightweight device that records continuous EKG/ECG tracings while patients go about their daily activities.


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Robert Bruce

In 1963, cardiologist Robert Bruce introduced the EKG/ECG treadmill stress test.  The Bruce protocol he created is still used today in a modified fashion, evaluating the heart’s response to increasing levels of exertion.  He famously noted, "You would never buy a used car without taking it out for a drive and seeing how the engine performed while it was running, and the same is true for evaluating the function of the heart.”


Robert Bruce monitoring a Stress Test
Robert Bruce monitoring a Stress Test

The journey from Galvani's accidental discovery of muscle contraction to the modern EKG/ECG machine was a pivotal technological achievement.  The EKG/ECG transformed cardiology, and provided the first non-invasive window into the heart's electrical function, enabling a more specific diagnosis of conditions such as arrhythmias and myocardial infarctions.  Further innovations by Frank Sanborn and Norman Holter led to portable devices and continuous monitoring, while Robert Bruce's cardiac stress test expanded the technology’s clinical utility.  Today, the EKG/ECG remains a rapid and indispensable diagnostic tool, a testament to the cumulative efforts of the scientists involved in its invention. 


If you liked this article, you may also enjoy reading The History of Insulin and Type 1 Diabetes. 

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FibonacciMedicine EKG/ECG product links

As an Amazon Associate FibonacciMedicine earns from qualifying purchases.


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References

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