Electrocardiograms

The first electrocardiograph was invented in 1895. That device looked a lot different from today’s machines, and there are some other contenders for the title of “first.”

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

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• 0:04Holly Frey?

  A rare disease diagnosis can change your life, but it doesn't have to define your future. In season seven of Untold Stories: Life with a Severe Autoimmune Condition, host Martine Hackett continues the conversation with people living with MG, CIDP, and the broader rare disease community, exploring what comes after diagnosis through stories of hope, progress, and connection. Produced by Ruby Studio in partnership with Argentix. Listen on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts.

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• 1:19Tracy V. Wilson?

  down memory lane for season two, sharing lessons on life, love, and loss. These are the kind of insights that only come from experience. So tune in to Silver Linings with The Old Gays on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Workplace chaos. We've all been there. Deadlines are slipping, projects are piling up, and suddenly you realize the missing piece is the right person. That's when you say, this is a job for sponsored jobs. With Indeed Sponsored Jobs, your job post gets a boost so you can connect with quality candidates faster. In fact, sponsored jobs posted directly on Indeed are 95% more likely to report a hire than non-sponsored jobs. Spend less time searching and more time interviewing candidates who check all your boxes. Get

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• 2:14Holly Frey?

  Welcome to Stuff You Missed in History Class, a production of iHeart Radio.

• 2:24Tracy V. Wilson?

  Hello and welcome to the podcast. I'm Tracy V. Wilson.

• 2:28Holly Frey?

  And I'm Holly Frey.

• 2:29Tracy V. Wilson?

  I went to the doctor the other day. I think that's where I picked up the cold that I feel like is still present in my voice a little bit.

• 2:39Holly Frey?

  Probably. That's where sick people often are.

• 2:42Tracy V. Wilson?

  No, I know. I had a mask on the whole time, but you know, stuff happens. While I was there, the doctor wanted to get an EKG, also called an ECG or electrocardiogram. People use those EKG and ECG abbreviations pretty much interchangeably. EKG is just the same word, but in German. While I was waiting for somebody to come back with the machine to do this test, I thought, when was this invented? Probably like the 20s or the 30s. And while waiting, I looked it up on my phone and the answer was 1895. Of course, that 1895 device looked a lot different from today's electrocardiographs, which is what

• 3:26Tracy V. Wilson?

  the machine is called. And there are some other years on either side of 1895 that you could also say was the first. Regardless, though, that was earlier than I was expecting. So, sitting there in the doctor's office, I dropped what I was working on for this show to do an electrocardiogram episode instead. As a confession, I was also working on something that had turned out to be really unwieldy. And while I was in the waiting room, I had been sort of thinking through how in the world I was going to get this unwieldy thing done in time to record it. The unwieldy thing is still coming. It's just coming later. Also, my ECG was normal, in case people are wondering. Like most of our episodes on

• 4:10Tracy V. Wilson?

  medical developments, this does include some animal experimentation. Also, if you're a cardiologist, or otherwise, if you work with a lot of ECGs, I'll just go ahead and apologize. We're not going to talk in a lot of detail.

• 4:25Tracy V. Wilson?

  About what the actual readout means, I don't feel remotely qualified to get into that. And I also don't think our either muddling through it or just reading somebody else's definition, word for word, would actually add to the history of this in a way that would sort of add to it for like typical non-cardiologist, non-physician-type people.

• 4:49Holly Frey?

  So, the heart is a muscle and its beats are controlled by electrical activity generated in the sinus node, also called the sinoatrial node. That's a part of the heart. An electrocardiogram is a non-invasive test that measures this electrical activity using electrodes placed on the skin which are connected to an electrocardiograph, or ECG, machine with lead wires. The machine translates those electrical signals into a graphical representation of a wave, and that is immediately available to be read and interpreted with today's technology. This is typically a fast, painless test, although people who are sensitive to adhesives or to the material the electrodes are made from can experience some irritation.

• 5:34Tracy V. Wilson?

  That happened to me the first time I ever had one.

• 5:37Holly Frey?

  Yeah.

• 5:37Tracy V. Wilson?

  Twenty-something years ago, but not with this one most recently. This technology grew from both the study of electricity and the study of anatomy and physiology. And then all that, of course, started way before the end of the 19th century, when the first ECGs were invented. People have been observing phenomena like static electricity and lightning since before the start of recorded history. And while different societies have had taboos around things like dissections and autopsies, people have also been doing them and examining hearts and other muscles for thousands of years.

• 6:16Holly Frey?

  The word "electricity" was first used in writing by English polymath and Member of Parliament Sir Thomas Brown in 1646, in his Pseudodoxia Epidemica, or "Enquiries into Very Many Received Tenets and Commonly Presumed Truths." This is a book that he wrote to try to correct an assortment of superstitions and commonly-held misinformation. It's actually arranged into seven books, and as an example, the third book is to Devoted to dispelling misinformation about animals, including the idea that elephants don't have joints, that beavers escape hunters by biting off their testicles, although who could blame them? And that the ostrich digesteth iron.

• 6:58Holly Frey?

  Brown's descriptions of electricity are focused on static electricity, including the ability of materials like amber and jet to attract lightweight objects after being rubbed. Similar words like electric and electrical were coined in the 17th century as well.

• 7:16Tracy V. Wilson?

  I was extremely delighted by just the table of contents of this book. In the 1660s, Dutch naturalist Jan Swammerdam carried out experiments on frogs and other animals. This included using his scalpel or another instrument to stimulate nerve tissue during dissections, and that would cause the corresponding muscles to twitch. He believed that these muscular contractions were caused by the flow of animal spirits or nervous fluid. There's some debate about whether these experiments involved electricity. Some of his instruments were made of multiple different metals,

• 7:56Tracy V. Wilson?

  and they had voltage differences that could have produced a small current. If that's the case, though, he definitely was not aware that that was what was happening.

• 8:07Holly Frey?

  About 100 years later, researchers were studying animals like electric rays, also called common torpedoes, as well as electric eels. One was American scientist and spy Edward Bancroft, who described torpedoes and their ability to shock people in his book, "An Essay on the Natural History of Guyana." His description didn't really line up with how people understood electrical charges at this point. It was known that metal could conduct electricity, but that glass and sealing wax couldn't. And the idea of electricity coming from a living thing just seemed bizarre. Earlier descriptions of these animals had concluded that the jolts they produced were physical, not electrical. But Bancroft did some experiments

• 8:52Holly Frey?

  showing that the shock from a torpedo was similar to the electrical charge that could be stored in a Leiden jar.

• 8:59Tracy V. Wilson?

  In 1772, British scientist John Walsh worked off of Bancroft's ideas to experiment with electric rays and found that it was possible to direct the shocks these rays produced through a circuit of four people. He wrote letters about this to Benjamin Franklin, and he was awarded the Royal Society's Copley Medal for his paper on the torpedo in 1773. Then in 1775, Danish physician and veterinarian Peter Christian Abelgard used electrical shocks to, quote, "render lifeless a bird," and then to revive it.

• 9:37Holly Frey?

  Italian researcher Luigi Galvani experimented with frogs, and on September 20th, 1786, he wrote, quote, "I had dissected and prepared a frog in the usual way, and while I was attending to something else, I laid it on a table on which stood an electrical machine at some distance from its conductor and separated from it by a considerable space. Now, when one of the persons present touched accidentally and lightly the inner choral nerves of the frog with the point of a scalpel, all the muscles of the leg seemed to contract again and again as if they were affected by powerful cramps."

• 10:17Holly Frey?

  Other 18th century researchers experimented with using electricity to revive the apparently dead, including English surgeon Charles Kite and Italian scientist Alessandro Volta. It's possible that these experiments were one of the inspirations for Mary Shelley's Frankenstein or the modern Prometheus.

• 10:36Tracy V. Wilson?

  In the early 19th century, Johann Schwager of Nuremberg developed the first galvanometer. That was an instrument to measure electrical current, which was later named in honor of Luigi Galvani. Around the same time, Danish physicist Hans Christian Ehrsted noted that it was possible for changes in electrical current to deflect a compass needle, showing a connection between electricity and magnetism.

• 11:03Holly Frey?

  By the 1830s and 40s, researchers were using galvanometers to study electrical activity in animals, not just ones that could produce an obvious charge like electric rays in eels. This included Italian physicist Leopoldo Nobili in 1834. He developed an instrument called an astatic galvanometer to detect very small electric currents, and he used it to detect a current between a frog's limbs and spinal cord. In 1842, Carlo Matriucci used Nobili's invention to detect electrical currents in the hearts of pigeons.

• 11:40Tracy V. Wilson?

  Within a decade, researchers had started to realize a connection between the electrical activity of the heart and irregular heartbeats, specifically ventricular fibrillation. Mauritz Haffer described this in 1850, following experiments in the lab of his teacher Carl Ludwig. He was able to induce ventricular fibrillation in dogs by exposing their hearts to electrical currents. A few years later, in 1856, Albert von Kulliger and Heinrich Mueller detected electrical activity in frog hearts in a lab in Germany, discovering that the heart generated electricity and that there was a rhythm to it that was associated with each beat.

• 12:25Holly Frey?

  Much of this animal research involved dissections or vivissections, and scientists were detecting electrical signals from exposed skeletal muscles and hearts. But by the late 19th century, people started figuring out ways to record the heart's electrical activity from outside the body. We'll talk more about that after a sponsor break.

• 12:49Speaker 03

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• 12:52Tracy V. Wilson?

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• 13:20Tracy V. Wilson?

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• 13:32Tracy V. Wilson?

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• 14:29Tracy V. Wilson?

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• 14:56Tracy V. Wilson?

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• 16:07Holly Frey?

  We've all done it. Tumble down an internet rabbit hole trying to self diagnose. And sometimes doing our own research can leave us more anxious than informed. Your feed is packed with wellness trends telling you to cold plunge, protein max, detox, track your sleep. But what's actually real? What's exaggerated? What's just wrong? That's exactly what Health vs. Hype from the American Medical Association and iHeartMedia's Ruby Studio is here to find out. Each episode, Emmy nominated science communicator Trace Dominguez, who's racked up billions of views across PBS, Discovery Channel, and YouTube, talks to doctors, influencers, and real people trying these trends.

• 16:49Holly Frey?

  Not to cancel them, not to hype them more, but to actually understand them. Because when it comes to your health, who you listen to matters. Start asking better questions and listen to Health vs. Hype on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

• 17:16Tracy V. Wilson?

  In 1869, Scottish electrical engineer Alexander Muirhead was working at St. Bartholomew's Hospital in London. And he found a way to record the electrical rhythm of a patient's beating heart. He attached an electrode to the patient's wrist and then connected that to a siphon recorder. This recorder was developed by William Thompson as a receiver for the extremely weak electrical signals that had traveled along underwater telegraph cables that used a glass tube with an ink reservoir at one end, which swayed back and forth in response to positive and negative electrical signals. This created a continuous wavering line on a recording paper.

• 18:01Tracy V. Wilson?

  For telegraph cables, that wavering line represented the dots and dashes of Morse code, but in Muirhead's setup, it represented the electrical rhythm of the heart. This was most likely the first ever recording of electrical activity in the heart of a human patient, but Muirhead did not publicize this work.

• 18:25Holly Frey?

  The next major step in the development of the electrocardiogram was the work of British physiologist Augustus Desiree Waller at St. Mary's Hospital, London in 1887. He used a capillary electrometer developed by Gabriel Lipman to record electrical activity from patients' hearts.

• 18:44Tracy V. Wilson?

  This electrometer was made out of a glass tube filled with mercury. One end of the tube was formed into a tiny capillary that could be submerged in diluted sulfuric acid. There was an electrical potential difference between the mercury and the sulfuric acid. So when this setup was connected to the patient's body through electrodes and leads, the curved surface of the mercury in the tube, or the meniscus, would shift in response to the current from the patient's heart. These shifts were tiny, so they were projected onto photosensitive paper using a projecting microscope.

• 19:25Tracy V. Wilson?

  British physiologist John Burden Sanderson and Frederick Page had used a similar device to record a two-phase current and frog heartbeats in 1878.

• 19:36Holly Frey?

  Waller called this a cardiograph, and he did a number of experiments with it, including working with different numbers of leads, sometimes a single lead, sometimes two, and eventually five. Those five electrodes were on all four of the patient's limbs and one in their mouth. He used electrodes strapped to the surface of the patient's body, as well as jars of saline solution that acted as electrodes for the hands and feet. He also did demonstrations of this concept with his dog Jimmy, who would stand with two of his feet in jars of saline.

• 20:11Tracy V. Wilson?

  Jimmy was reportedly a very patient dog.

• 20:16Tracy V. Wilson?

  While Waller was able to record electrical signals from the heart with the capillary electrometer, he didn't really think this was going to be useful in clinical practice. He eventually came to see more value in it, but earlier on, he's quoted as saying, "He didn't imagine that it would see extensive use in hospitals." Quote, "It can be at most of rare and occasional use to afford a record of some rare anomaly of cardiac action."

• 20:45Holly Frey?

  One of the people who saw one of Waller's demonstrations with Jimmy was Dutch physiologist Willem Eintoven. He had been born in Semerang Java in 1860, and he had Jewish ancestry. Ancestors on his father's side had fled to the Netherlands during the Spanish Inquisition. His father and his grandfather were both doctors, and he earned both an MD and a PhD from the University of Utrecht. Eintoven saw Waller's demonstration at the International Congress of Physiology in London in 1887.

• 21:19Tracy V. Wilson?

  After seeing this demonstration, Eintoven started working on his own device, describing it as "an electrocardiogram" at the 1893 Dutch Medical Meeting. Although Eintoven is usually credited with coining this term, he actually gave the credit to Waller. Eintovin started out with a five-lead setup similar to Waller's, but ultimately dropped the two leads that he thought provided the lowest yield for the signal. Those two leads were the one in the mouth and the right leg. That left three leads for both of the patient's hands and their left leg. All the electrodes for the setup were buckets of saline.

• 22:02Holly Frey?

  Eintovin studied the curves produced by this device, noticing that there was a pattern of five deflections for each heartbeat. He labeled these deflections A, B, C, D, and E. He worked with mathematician Heinrich Lorenz to create a formula that would account for inertia and friction within the device. The resulting pattern looked like what we see in an EKG today. Every person's heartbeat is their own, but in a healthy heart that's beating normally, the basic pattern is the same.

• 22:34Tracy V. Wilson?

  Eintovin labeled those five corrected deflections as P, Q, R, S, and T. He probably chose P as the starting point because of a tradition dating back to Rene Descartes of using letters from the second half of the alphabet. The letters N and O were already widely being used for other purposes. Eintovin published a paper detailing all this in 1895 called "Form of the Human Electrocardiogram."

• 23:02Holly Frey?

  Then Eintovin started working on developing a device with a more sensitive galvanometer. He did this with a string galvanometer, made from a thread of quartz coated in silver. This thread was suspended between the poles of an electromagnet, and it shifted within the electromagnetic field in response to the electrical signals from the heart. While this galvanometer was more sensitive, its movements were still teeny tiny, so they had to be magnified and projected onto a running sheet of photographic film. He presented this device for the first time in 1901.

• 23:38Tracy V. Wilson?

  This was pretty similar to a device that had been created by French engineer and aviator Clément Adère for receiving underwater transmissions through wires. It seems like these two men each came up with their devices independently of one another, but Eintovin later did acknowledge Adère's similar work.

• 23:59Holly Frey?

  Although Eintovin's strain galvanometer was more sensitive and precise than the capillary device had been, that did not mean that it was small or easy to use. It weighed more than 660 pounds, or 300 kilograms, and it took up two rooms. It required a large electromagnet, which had to be continually cooled with flowing water to keep it from overheating, and it required five people to operate.

• 24:26Tracy V. Wilson?

  So by 1903, Eintovin was working on making a commercial version of this device, which could actually be usable in clinical medicine. This was not really. That would be a long process, and in the meantime, it just, it wasn't possible to move his device from the laboratory where it took up two rooms to a hospital where it could be used with patients more easily. His colleague Johannes Boshia made a suggestion, and that was to connect the electrocardiogram at the lab to the academic hospital in Leyden, roughly a mile or 1,500 meters away. They did this with a telephone line. Patients in the hospital placed both of their arms and one of their legs in buckets of saline,

• 25:11Tracy V. Wilson?

  with those buckets acting as electrodes, and they were connected to a telephone line that carried their electrical signal to the galvanometer in the lab. Then they could read the electrocardiogram in the lab, almost a mile away. On March 22 of 1905, the first telecardiogram was transmitted from the hospital.

• 25:32Holly Frey?

  Eintovin published a paper called Le Telecardiogram in 1906. This work detailed a number of arrhythmias and other issues that could be detected by examining the results of an electrocardiogram, including mitral insufficiency, left ventricular hypertrophy, premature ventricular contractions, and atrial flutter.

• 25:54Tracy V. Wilson?

  By this point, Cambridge Scientific Instrument Company of London had developed a commercial version of the Eintovin electrocardiograph, and it had sold three of them. All three were for use in laboratory research, though, not for clinical work in human medical patients. The first purchase of one of these machines for clinical work was in 1908.

• 26:17Holly Frey?

  We'll talk about how electrocardiographs and electrocardiograms developed from here after another sponsor break.

• 26:28Tracy V. Wilson?

  For any small business owner, there's a moment when you realize the next hire could be the difference between staying busy and actually growing. The challenge is finding the right person without wasting time sorting through candidates who aren't the right fit. That's where Indeed Sponsored Jobs comes in. When workplace chaos hits and you need someone who can step in and make a difference, this is a job for sponsored jobs. It helps put your job in front of candidates who match the criteria that matter most to you, whether that's skills, experience, certifications, or location. And you're certainly not alone in using Indeed. Join the 3.3 million employers worldwide that use Indeed to connect with quality talent that fits their needs. That's millions of businesses turning to Indeed

• 27:11Tracy V. Wilson?

  to help solve hiring challenges and find people who can help drive results. Spend less time searching and more time actually interviewing candidates who check all your boxes. Less stress, less time, more results. Get your $75 sponsored job credit today at indeed.com/podcast. Terms and conditions apply. Hiring now, then this is a job for Indeed Sponsored Jobs.

• 27:39Holly Frey?

  We've all done it. Tumble down an internet rabbit hole trying to self-diagnose. And sometimes doing our own research can leave us more anxious than informed. Your feed is packed with wellness trends telling you to cold plunge, protein max, detox, track your sleep. But what's actually real? What's exaggerated? What's just wrong? That's exactly what Health vs. Hype from the American Medical Association and iHeartMedia's Ruby Studio is here to find out. Each episode, Emmy-nominated science communicator Trace Dominguez, who's racked up billions of views across PBS, Discovery Channel, and YouTube, talks to doctors, influencers, and real people trying these trends. Not to cancel them, not to hype them

• 28:23Holly Frey?

  more, but to actually understand them. Because when it comes to your health, who you listen to matters. Start asking better questions and listen to Health vs. Hype on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts.

• 28:42Tracy V. Wilson?

  Guess who's back in the house? The old gays return for season two of Silver Linings, their hit podcast from iHeart's Ruby Studio in partnership with ViiV Healthcare. Just wait until you hear what hosts Robert McMillan and Jesay have in store this time around. They strut back down memory lane navigating life, love, loss, and everything that shaped them along the way. And as usual, someone just might break into song. From leather bars to bathhouses, dance floors to drag brunch, nothing stays off limits. These are the kinds of insights that can only come from experience. So, listen to your elders, honey, and discover the silver linings you can take with you. All sass, zero filter, and decades of perspective from four friends proving that queer joy

• 29:27Tracy V. Wilson?

  only gets better with age on the podcast that never gets old. Listen to Silver Linings, available on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts.

• 29:41Speaker 05

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• 30:42Tracy V. Wilson?

  In 1911, Cambridge Instrument Company released a table model of William Einthoven's electrocardiograph. This one was still a lot bigger than most of today's machines that you might see in a doctor's office. It still required patients to sit with both of their hands and one of their feet in buckets of saline. So it was still relatively cumbersome, but it was way more compact than that two-room, 600-pound original version. And doctors had also figured out all kinds of conditions and abnormalities that could be detected and diagnosed through the patterns in an electrocardiogram.

• 31:20Holly Frey?

  Doctors in hospitals were a little slower to adopt this technology than they had been with the first X-ray machines. But by the time this table model was introduced, electrocardiograms were starting to be regarded as critical to cardiac care. We talked about the development of X-rays in our episode on mammography on January 31, 2024, and the modern blood pressure cuff in our episode on hypertension on August 1, 2022. X-ray machines, blood pressure cuffs, and electrocardiograms were all developed and refined around the turn of the 20th century. And together, they were critical to the development of cardiology as a specific medical field.

• 32:01Tracy V. Wilson?

  I've also realized these are three episodes from our catalog, including this one, all inspired by my own medical experiences.

• 32:10Tracy V. Wilson?

  In 1912, Welsh cardiologist Thomas Lewis delivered a lecture at University College Hospital titled "On the evidences of auricular fibrillation treated historically." He described various arrhythmias as clearly visible and recognizable in the waves of an electrocardiogram, including fibrillations. That is, a heart that's fluttering or twitching in an unsynchronized way rather than beating in a regular pattern. He also discussed the examination of a horse that showed evidence of atrial fibrillation due to heart disease, not something that had been induced in the horse through experimentation, which had been the case in some of the other

• 32:52Tracy V. Wilson?

  animal research. He found that the waves from the horse's heart were basically the same as that of a human's, and he confirmed that the heart really was in atrial fibrillation by actually looking at it during a surgical examination.

• 33:09Holly Frey?

  Lewis was a regular correspondent with Eintovin, and he was also building on the work of Scottish cardiologist James Mackenzie, who developed a polygraph machine that traced patients' pulses at the wrist and neck, which could also show evidence of arrhythmias. This was simpler than the polygraph machines that supposedly work as lie detectors today. Those also measure other physiological responses. Like Augustus Waller, who we mentioned earlier, Lewis didn't really think electrocardiograms could be very useful in clinical medicine. But this was largely because they were still pretty cumbersome. ECGs could only capture a few seconds of activity, and since the results were projected onto photosensitive paper,

• 33:52Holly Frey?

  they had to be developed before they could be interpreted. But Mackenzie's polygraph used ink on a running roll of paper. Its pulse tracings were visible immediately. Lewis also noted that, at this point, treatment for suspected cardiac issues was the same, regardless of whether a person had been given an electrocardiogram or not. As the technology improved, though, Lewis updated his opinion, saying, "The time is at hand, if not already come, when an examination of the heart is incomplete if this new method is neglected."

• 34:27Tracy V. Wilson?

  Eintovin was still making new discoveries, and in 1912, he described his system of three leads as an equilateral triangle. That's a concept known as Eintovin's triangle today. His written work on this was probably the first use in writing of the abbreviation EKG.

• 34:47Holly Frey?

  In 1918, physician and professor James Herrick of Chicago demonstrated that it was possible to use an ECG to diagnose a myocardial infarction, commonly called a heart attack. American cardiologist Harold Partey published work on diagnosing coronary artery obstructions through electrocardiograms in 1920.

• 35:10Tracy V. Wilson?

  In 1924, Wilhelm Eintovon was awarded the Nobel Prize in Physiology or Medicine for his discovery of the mechanism of the electrocardiogram. The presentation speech made it clear that this award was not only about Eintovon's development of the electrocardiograph device. It was also about his interpretations of the electrocardiograms, what P, Q, R, S, and T each corresponded to in a beating heart, and how to identify so many different disorders and diseases of the heart through the analysis and interpretation of that one wave. Other researchers had offered other methods of interpretation, but in the words of the

• 35:54Tracy V. Wilson?

  award speech, quote, "Eintovon's concept is the only one which has proved to be tenable."

• 36:01Holly Frey?

  The Nobel Prize came with a monetary award that Eintovon wanted to split with his assistant, who had worked with him during the early years of his work and the development of this device. His name was Vandiverd. Vandiverd had died, though, and Eintovon instead divided the $40,000 prize money with Vandiverd's two sisters, who had been living in poverty. Three years later, on September 29, 1927, Wilhelm Eintovon died of cancer.

• 36:30Tracy V. Wilson?

  Also in 1927, Japanese physician Taro Takemi developed the first portable ECG machine. Two years later, the Sanborn Company of Waltham, Massachusetts, released the Sanborn Visocardiet, which was a portable version that could print the results immediately on a roll of paper. It weighed about 26 pounds or 12 kilograms, and it was powered by a car battery.

• 36:54Holly Frey?

  In 1934, physiologist Frank N. Wilson started working on standardizing the use and placement of electrodes and leads. He realized that the typical three-lead system left some areas of the heart that weren't fully represented in the ECG wave. He added another lead, described as an exploring lead, which could be used along with the three standard leads to read the electrical activity of specific parts of the heart.

• 37:23Tracy V. Wilson?

  I couldn't pinpoint exactly when these machines moved away from having people put their hands and feet in buckets of saline, but these exploratory leads typically went somewhere on the chest, so they would have used surface electrodes. At some point, though, ECGs did start to use only electrodes that were placed on the body. Today, these are usually little adhesive discs.

• 37:46Holly Frey?

  By the 1930s, it had become clear that ECGs could be used to help diagnose whether a patient's chest pain had a cardiac or non-cardiac cause. In 1935, Boston physicians Sylvester McGinn and Paul White published work describing changes in ECG readings that were apparent in patients who were experiencing an acute pulmonary embolism. These changes are now known as the McGinn-White pattern.

• 38:15Tracy V. Wilson?

  In 1938, the American Heart Association and the Cardiac Society of Great Britain tried to standardize the placements of that exploratory lead that had been introduced about four years before. They recommended six specific sites, now known as V1 to V6. These are called the precordial leads or the chest leads today. In 1942, New York cardiologist Emanuel Goldberg also worked with the number and types of leads. And that started moving toward the 12-lead electrocardiogram that is most commonly used today. There are also other numbers of leads that are used for particular purposes, but like

• 38:57Tracy V. Wilson?

  the most common standard in a medical setting today is 12 leads.

• 39:03Holly Frey?

  In 1948, Swedish engineer Runa Elmquist, who had also trained as a physician, developed the first inkjet ECG printer. He would also go on to be a big part of the development of the first implantable pacemaker.

• 39:18Tracy V. Wilson?

  By the 1950s, researchers were working on finding ways to automate ECG readings. The development of automated readings also made other lifesaving developments possible, like automated external defibrillators, which automatically diagnose arrhythmias and then deliver shocks only when they are warranted. Today, a lot of ECGs are automatically analyzed before being reviewed by cardiologists, internists, primary care doctors, or other medical professionals.

• 39:49Holly Frey?

  The automation of ECG readings was possible thanks to the advent of computers and microprocessors, which have continued to have a huge role in making electrocardiograph machines much smaller and easier to use. In 1957, American biophysicist Norman Jeffries Holter developed the Dynamic ECG, often known as the Holter ECG or a Holter monitor, which is a portable device that can continually monitor a patient's heart for 24 hours or more. Today, Holter monitors are wearable devices weighing a couple of pounds at most, but they initially weighed about 83 pounds or 38 kilograms and had to be worn like a huge, heavy backpack.

• 40:32Tracy V. Wilson?

  Magneto-cardiograms were introduced in 1963, which could record heart rhythms without the patient needing to have electrodes on their body. These are very expensive, though, so they never really took off. That same year, American cardiologist Robert A. Bruce developed a protocol to record a person's cardiac signals while they did progressively more intense exercise on a treadmill that today is known as the Bruce Protocol.

• 40:59Holly Frey?

  And of course, ECGs have continued to evolve with changes in technology. By 1999, there were 12-lead ECGs that could send their results directly to handheld computers. Today, there are a range of consumer ECG devices that are tiny, everything from the ECG function on an Apple Watch to a device the size of a credit card that communicates with an app to home devices that can record an ECG and also measure a person's blood pressure. There are pros and cons to all of these, a big one being that while a 12-lead ECG is considered standard in medical settings today, most of these home-use models only use one or two leads.

• 41:42Holly Frey?

  The device or app also typically interprets the ECG automatically and displays the results, and that can lead to various false negatives or false positives.

• 41:52Tracy V. Wilson?

  If you're me and you have an Apple Watch, it could also be that the Apple to watch just incessantly starts over, telling you, like cycling through, all the things that thinks you're doing wrong, rather than ever fully recording the ECG.

• 42:08Tracy V. Wilson?

  I've done a lot of troubleshooting on that that has not been successful. I also have some listener mail that is also somewhat medical related. It is from Edith. Edith says, hi Holly and Tracy. I've been wanting to write forever, but never had anything I thought worthy of writing about until now. This will probably be a combination of things I didn't think worthy, but still want to say and a story. First of all, I'm writing this while in the airport on my way from Boston to Atlanta, which I find kind of funny and coincidental. On my drive to the airport, I was listening to the behind the scenes following the tetanus episode. More on this later. That's the story. First of all, as a 50 year old former theater kid who loves to sew, has far too much clothing and too many pairs of shoes and doesn't like my body to be unexpectedly

• 42:53Tracy V. Wilson?

  exposed to unpleasantness. Slippers for the win, Holly. I see you.

• 43:00Tracy V. Wilson?

  Now I have to thank you for your unintentional PSA. I just turned 50 in April and really had not thought about vaccinations. I mean, I still think and maybe act like I'm 30, but when you all mentioned that we, yes, us, are of an age where we probably only got one measles shot. I was like, huh, I did not know that. So now I know to ask about that at my next physical. Thanks. Okay, okay. Finally, the story in the behind the scenes. You both told stories about extra tetanus shots, so I wanted to tell you about mine. I was in high school in Cambridge, Massachusetts, and I did crew. Of course, we rode on the Charles River. One day when we were putting the boats away, I somehow got caught in a bad spot going around the corner and ended up in the water.

• 43:41Tracy V. Wilson?

  Now I know that the Charles isn't thought of as very clean now, but back then, well, the things you would see floating there were bad, so I fell in and that's how I ended up getting a tetanus booster. I will pause and say that the title of this email is love that dirty water, Boston, you're my home, which is of course a song lyric reference, referencing also the very dirtiness of both the Charles and Boston Harbor at that time. Anyway. Uh, the email continues. Anyway, I don't have any pets, so I'm attaching a variety of collected animal pictures, including a pig video, some horses from our neighbor's farm, an old picture of my daughter, and my brother-in-law's old dog, and a current picture of my daughter on a horse for comparison. Thank you for all you do. As a former Medford

• 44:26Tracy V. Wilson?

  resident for the statement at the beginning of the latest Unearth episode. Love you guys. I tried but failed to keep it short. Edith. Edith, I love this email. Um, regarding vaccinations, we had talked in, I think, a behind-the-scenes of the show about, um, how, uh, I was turning 50 and knew that I meant that meant that I was gonna need to go and get some vaccines that are recommended at the age of 50. I did do that. Those vaccines were shingles and pneumococcal pneumonia. Um, I did both of those at the same time because somehow I thought that the people saying that sometimes the shingles vaccine can make you feel a little unwell, I just thought that might not apply to me. Um, because I am not known to have ever actually had

• 45:09Tracy V. Wilson?

  chickenpox, but it is recommended at the age of 50 anyway. Um, I, I did feel, I felt unwell. Uh, still, much better than getting shingles or pneumonia. So, yeah, that's done. I will need shot two of the shingles shot a little bit later. Also, lots of great animal pictures. Man, I love horse pictures. They're so beautiful.

• 45:33Holly Frey?

  They are beautiful.

• 45:34Tracy V. Wilson?

  These horses are, it's a horse in a foal just running through a field. How great is that? Uh, I don't think I'll watch the pig video while we are sitting here. Um, I love a little pig action.

• 45:45Holly Frey?

  You just reminded me of the funniest thing I've ever seen a pig do. I'm just in my own head now.

• 45:51Tracy V. Wilson?

  Oh.

• 45:52Holly Frey?

  Have you ever seen a pig eat spaghetti?

• 45:54Tracy V. Wilson?

  No.

• 45:55Holly Frey?

  Um, our mutual friend.

• 46:01Holly Frey?

  Who is often prone to wacky hijinks, briefly had a pig. Um, I don't remember how she came in to possession of the pig. She only had it a brief period of time while she was rehoming it and trying to find somebody that actually had like acreage that they could raise a pig on. But in the meantime, she and her amazing mother were just trying to keep the pig fed and happy and her mother started regularly making the pig plates of spaghetti. And it was the cutest thing I ever saw in my life.

• 46:30Tracy V. Wilson?

  I'm imagining what it would look like and it does seem very cute.

• 46:33Holly Frey?

  Well, he was tiny at the time. He was still a piglet. And so he would get the spaghetti all wound around his snout and then try to chase it around the house, trying to get the spaghetti.

• 46:43Tracy V. Wilson?

  Yeah.

• 46:43Holly Frey?

  I wish this were like a required thing that everybody could see in their life because it brings so much joy.

• 46:48Tracy V. Wilson?

  Yeah, um, because I am a fan of Game Changer, I am imagining this pig wearing a tiny hat while eating the spaghetti.

• 46:59Holly Frey?

  He was not.

• 47:02Tracy V. Wilson?

  So, thank you so much, uh, for this email, Edith. The, the Charles River is a lot cleaner than it used to be. As somebody who moved to the Boston area from elsewhere, um, I, I have a fondness for seeing people rowing out on the river. I don't know how local people feel about the rowers. I'm always a little happy when I'm usually on the tee and I go over the bridge and I'm like, ah, people rowing out on the river. So if you would like to send us a note about this or any other podcast, we're [email protected]. Uh, and you can subscribe to our show on the iHeartRadio app and anywhere else you like to get your podcasts.

• 47:44Tracy V. Wilson?

  Stuff You Missed in History Class is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.

• 47:59Holly Frey?

  A rare disease diagnosis can change your life, but it doesn't have to define your future. In season seven of Untold Stories: Life with a Severe Autoimmune Condition, host Martine Hackett continues the conversation with people living with MG, CIDP, and the broader rare disease community, exploring what comes after diagnosis through stories of hope, progress, and connection. Produced by Ruby Studio in partnership with Argenx. Listen on the iHeart Radio app, Apple Podcasts, or wherever you get your podcasts.

• 48:29Tracy V. Wilson?

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• 49:12Tracy V. Wilson?

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• 49:35Speaker 06

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• 50:03Speaker 00

  This is an iHeart Podcast. Guaranteed Human.