Electrocardiograms

Summary

Stuff You Missed in History Class: Electrocardiograms

Released: June 16, 2025 | Hosts: Holly Fry & Tracy V. Wilson | Production: iHeartPodcasts

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Introduction

In this episode of Stuff You Missed in History Class, hosts Holly Fry and Tracy V. Wilson delve into the fascinating history and evolution of electrocardiograms (EKGs or ECGs). From the early experiments with electricity and animal anatomy to the sophisticated, portable devices we use today, the episode provides a comprehensive overview of how ECG technology has become indispensable in modern medicine.

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The Birth of Electrical Understanding in Biology (00:02 - 09:08)

Tracy begins the discussion with a personal anecdote about getting an ECG at the doctor's office, which sparked her curiosity about its origins. She reveals, “I dropped what I was working on for this show to do an electrocardiogram episode instead” (00:39).

The hosts explore the early intersections of electricity and biology, highlighting how humanity's long-standing fascination with electricity, dating back to observations of static and lightning, laid the groundwork for understanding the heart's electrical activity. They reference Sir Thomas Browne’s 1646 work where he first used the term "electricity," emphasizing the gradual shift from mystical interpretations to scientific inquiry.

Key figures discussed include Jan Swammerdam, who in the 1660s conducted experiments that may have inadvertently discovered electrical currents, and Edward Bancroft, whose 1772 studies on electric rays challenged existing notions by demonstrating that the shocks from these animals were electrical in nature (09:08).

Notable Quote: Tracy reflects on Swammerdam’s work, stating, “If that's the case, though, he definitely was not aware that that was what was happening” (08:17), underscoring the serendipitous nature of early scientific discoveries.

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Advancements in Understanding the Heart's Electrical Activity (09:09 - 20:01)

The conversation advances to the late 18th and 19th centuries, focusing on pivotal experiments by Luigi Galvani and others who began to link electrical activity with muscular contractions. Tracy mentions, “Galvani experimented with frogs” (09:08), highlighting his accidental discovery of electricity’s role in muscle movement.

The hosts then detail the progression to Johann Schwager's development of the galvanometer in 1811, an instrument essential for measuring electrical currents. This section underscores how the galvanometer became a crucial tool in detecting the heart's electrical signals.

In the mid-19th century, Moritz Hoffa and Albert von Colliger made significant strides in associating electrical activity with heart rhythms and irregularities. Their work paved the way for recognizing conditions like ventricular fibrillation and atrial flutter through electrical measurements (12:34).

Notable Quote: Holly explains, “An electrocardiogram is a non-invasive test that measures this electrical activity” (05:44), simplifying the concept for the audience while setting the stage for the historical narrative.

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From Animal Research to Human Applications (20:02 - 34:53)

The hosts transition to the late 19th and early 20th centuries, spotlighting Willem Einthoven's groundbreaking contributions. After witnessing Augustus Waller's 1887 demonstrations with a dog named Jimmy, Einthoven developed his own electrocardiogram, refining the technology to better capture the heart's electrical patterns (21:10).

Einthoven's innovation of the string galvanometer in 1901 marked a significant leap, allowing for more precise and continuous recordings of heart activity. Despite its size and complexity, Einthoven's device laid the foundation for clinical electrocardiography.

Tracy recounts, “On March 22nd of 1905, the first telecardiogram was transmitted from the hospital” (25:22), illustrating the early adoption of ECG technology in medical settings.

Notable Quote: Holly describes Einthoven’s dedication: “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” (22:24), highlighting the thoughtful methodologies behind scientific advancements.

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Technological Refinements and Clinical Integration (34:54 - 48:21)

As the technology matured, the episode covers the 20th-century enhancements that made ECGs more accessible and clinically valuable. James Herrick’s 1918 demonstration of ECGs in diagnosing heart attacks and Harold Pardee’s 1920 work on coronary artery obstructions underscore the growing medical importance of electrocardiography.

Tracy notes, “In 1924, Willem Einthoven was awarded the Nobel Prize for his discovery of the mechanism of the electrocardiogram” (34:53), celebrating the recognition of ECG’s significance in medical science.

The discussion moves to the development of portable ECG machines in the 1920s and 1930s, such as the Sanborn Visocardiet, which allowed for immediate printouts and greater mobility in medical diagnostics (36:13).

Notable Quote: Tracy emphasizes the impact of standardization efforts: “In 1938, the American Heart Association and the Cardiac Society of Great Britain tried to standardize the placements of that exploratory lead” (37:58), illustrating the collaborative efforts to make ECG interpretation more uniform across medical practices.

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Modern Innovations and Future Directions (48:22 - End)

Holly and Tracy explore the late 20th and early 21st centuries, focusing on the miniaturization and automation of ECG technology. The introduction of the Holter monitor in 1957 by Norman Jeffries Holter revolutionized continuous heart monitoring, making it feasible for patients to undergo extended ECG recordings outside clinical settings (39:32).

The hosts discuss the advent of consumer-grade ECG devices, such as those integrated into smartwatches and portable accessories, highlighting both their accessibility and the challenges they pose, like the prevalence of false positives and negatives due to limited leads (40:42).

Tracy shares a personal anecdote about using an Apple Watch for ECG monitoring, humorously lamenting its frequent interruptions: “If you're me and you have an Apple watch, it could also be that the Apple watch just incessantly starts over telling you like cycling through all the things you're doing wrong” (41:36).

Notable Quote: Holly summarizes the technological journey: “ECGs have continued to evolve with changes in technology, making electrocardiograph machines much smaller and easier to use” (39:32), encapsulating the ongoing advancements in the field.

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Listener Engagement and Personal Stories

Interspersed with historical analysis, Holly and Tracy engage with listener contributions, sharing Edith’s email about her experiences with vaccinations and personal stories dating back to high school incidents that involved tetanus boosters. These segments add a relatable and human element to the episode, bridging past technological developments with present-day medical practices.

Notable Quote: Tracy responds warmly to Edith’s story: “These horses are. It's a horse and a foal just running through a field. How great is that?” (46:16), showcasing the hosts' ability to connect with their audience on a personal level.

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Conclusion

The episode concludes by tying the historical advancements of electrocardiograms to their critical role in today's healthcare. Holly and Tracy reflect on how ECG technology has transformed cardiology, enabling early detection and treatment of heart conditions that were once poorly understood.

Final Thought: Tracy muses, “As the technology improved, it became clear that ECGs are critical to cardiac care,” (31:03) underscoring the indispensable nature of ECGs in modern medicine.

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Key Takeaways

• Early Discoveries: The foundational experiments linking electricity with biological functions were crucial for the development of ECGs.
• Pioneering Figures: Scientists like Willem Einthoven played a pivotal role in refining ECG technology, earning significant accolades such as the Nobel Prize.
• Technological Evolution: From large, cumbersome machines to portable and consumer-friendly devices, ECG technology has continually adapted to meet medical and personal health needs.
• Clinical Impact: ECGs have become essential tools in diagnosing and managing heart diseases, significantly improving patient outcomes.
• Future Prospects: Ongoing innovations promise even greater accessibility and integration of ECG monitoring in everyday life, though challenges remain in ensuring accuracy and reliability.

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For more engaging historical insights, subscribe to Stuff You Missed in History Class on the iHeartRadio app or your preferred podcast platform.

Transcript

[Tracy V. Wilson]

This is an I heart podcast.

[Holly Fry]

Listen to your elders, honey. You might know them from their viral videos, but now the old gays are pulling back the curtain with their new podcast, Silver Linings with the Old Gays, brought to you in partnership with iHeart's Ruby Studio and Veeve Healthcare. Hosts Robert, Mick, Bill and Jesse serve their lifetime of wisdom when it comes to love, sex, community and whatever else they've got on the gay agenda. So check out Silver Linings with the old gays on the iHeartRadio app or wherever you get your podcasts.

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Taking over the helm of NBC Nightly News, a 75 year old broadcast, it's a great responsibility.

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You have to go out there to bring people at home. Closer to the store. Wildfires continue to be a threat. With that massive hurricane comes the massive response. The best reporters in our business know how to listen. And when you listen, you get the truth. For NBC News, NBC News, I'm Tom Galamas.

[Tracy V. Wilson]

That's what we do every night.

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NBC Nightly News with Tom, Tom Yamas, evenings on NBC. Are there any pictures of you online? Then you could already be in a massive police database without even knowing it.

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[Holly Fry]

Welcome to Stuff youf Missed in History. Class a production of iHeartRadio.

[Tracy V. Wilson]

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

[Holly Fry]

And I'm Holly Fry.

[Tracy 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.

[Holly Fry]

Probably that's where sick people often are.

[Tracy 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 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 at 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 gonna 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 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 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.

[Holly Fry]

So the heart is a muscle and its beats are controlled by electrical activity generated in the sinus node, also called the sinoatrial nod. 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.

[Tracy V. Wilson]

That happened to me the first time I ever had one. Yes, 20 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.

[Holly Fry]

The word electricity was first used in writing by English polymath and Member of Parliament Sir Thomas Browne in 1646 in his Pseudodoxia Epidemica, or Inquiries 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 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. 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.

[Tracy 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 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, 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.

[Holly Fry]

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

[Tracy 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.

[Holly Fry]

Italian researcher Luigi Galvani experimented with frogs, and on September 20, 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 crural nerves of the frog with the point of a scalpel, all the muscles of the legs seem to contract again and again as if they were affected by powerful cramps. 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.

[Tracy 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 Oersted noted that it was possible for changes in electrical current to deflect a compass needle, showing a connection between electricity and magnetism.

[Holly Fry]

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 and 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 Matiucci used Nobili's invention to detect electrical currents in the hearts of pigeons.

[Tracy 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. Moritz Hoffa described this in 1850, following experiments in the lab of his teacher, Car 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 Colliger 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 heart beat.

[Holly Fry]

Much of this animal research involved dissections or vivisections, 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.

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[Andrea Gunning]

I'm Andrea Gunning, host of the podcast Betrayal. Police Lieutenant Joel Kern used his badge to fool everyone, most of all his wife, Caroline.

[Tracy V. Wilson]

He texted, I've ruined our lives. You're going to want to divorce me.

[Andrea Gunning]

Caroline's husband was living another life behind the scenes. He betrayed his oath to his family and to his community.

[Dexter Thomas]

She said you left bruises, pulled her hair, that type of thing.

[Tracy V. Wilson]

No?

[Andrea Gunning]

How far would Joel go to cover up what he'd done?

[Holly Fry]

You're unable to keep track of all your lies and quite frankly, I question how many other women may bring forward allegations in the future.

[Andrea Gunning]

This season of Betrayal investigates one officer's decades of deception. Lies that left those closest to him questioning everything they thought they knew. Listen to betrayal on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

[Dexter Thomas]

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[Tracy V. Wilson]

In 1869, Scottish electrical engineer Alexand 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. 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.

[Holly Fry]

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 Lippman to record electrical activity from patients hearts.

[Tracy 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. British physiologists John Burdon Sanderson and Frederick Page had used a similar device to record a two phase current in frog heartbeats in 1878.

[Holly Fry]

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.

[Tracy V. Wilson]

Jimmy was reportedly a very patient dog. 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.

[Holly Fry]

One of the people who saw one of Waller's demonstrations with Jimmy was Dutch physiologist Willem Eintoven. He had been born in semarang, 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. Eindhoven saw Waller's demonstration at the International Congress of Physiology in London in 1887.

[Tracy V. Wilson]

After seeing this demonstration, Eindhoven started working on his own device, describing it as an electrocardiogram at the 1893 Dutch Medical Meeting. Although Eindhoven is usually credited with coining this term, he actually gave the credit to Waller. Eindhoven 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 this setup were buckets of saline.

[Holly Fry]

Einthoven 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 Eindric Lorentz 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.

[Tracy V. Wilson]

Eindhoven 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. Eindhoven published a paper detailing all this in 1895 called form of the Human Electrocardiogram.

[Holly Fry]

Then Eindhoven 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.

[Tracy V. Wilson]

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

[Holly Fry]

Although Eindhoven's string 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.

[Tracy V. Wilson]

So by 1903, Eindhoven 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 Bascha made a suggestion, and that was to connect the electrocardiogram at the lab to the Academic hospital in Leiden, roughly a mile or 1500 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, 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 22nd of 1905, the first telecardiogram was transmitted from the hospital.

[Holly Fry]

Eindhoven 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.

[Tracy V. Wilson]

By this point, Cambridge Scientific Instrument Company of London had developed a commercial version of the Eintoven 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.

[Holly Fry]

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

[Tom Yamas]

Hi Zoe Saldana. Welcome to T Mobile. Here's your new iPhone 16 Pro on us.

[Andrea Gunning]

Thanks. And here's my old phone to trade in.

[Tom Yamas]

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[Andrea Gunning]

There's always a trade in.

[Tom Yamas]

Not right now. At T Mobile.

[Andrea Gunning]

I feel like I have to give you something in return for karma.

[Tom Yamas]

That's okay.

[Andrea Gunning]

I don't really have much in my purse. Oh, let's see. Hand sanitizer. It's lavender.

[Tom Yamas]

I'm good. Seriously.

[Andrea Gunning]

Let me check this pocket. Oh, mints.

[Tom Yamas]

Really, I'm fine.

[Andrea Gunning]

Oh, I have raisins. I'm a mom. Wait, wait one sec.

[Tracy V. Wilson]

I've got cupcakes. The car.

[Tom Yamas]

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[Unknown]

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[Andrea Gunning]

I'm Andrea Gunning, host of the podcast Betrayal. Police Lieutenant Joel Kern used his badge to fool everyone, most of all his wife, Caroline.

[Tracy V. Wilson]

He texted, I've ruined our lives. You're going to want to divorce me.

[Andrea Gunning]

Caroline's husband was living another life behind the scenes. He betrayed his oath to his family and to his community.

[Dexter Thomas]

She said you left bruises, pulled her hair, that type of thing.

[Tracy V. Wilson]

No.

[Andrea Gunning]

How far would Joel go to cover up what he'd done?

[Holly Fry]

You're unable to keep track of all your lies. And quite frankly, I question how many other women may bring forward allegations in the future.

[Andrea Gunning]

This season of Betrayal and Fox investigates one officer's decades of deception. Lies that left those closest to him questioning everything they thought they knew. Listen to betrayal on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

[Dexter Thomas]

Are there any pictures of you online? I'm not just talking about Google. I'm talking anywhere.

[Jake Hanrahan]

Clear View scrapes together images From Facebook, from LinkedIn, from Venmo account.

[Dexter Thomas]

That database is now being used by police departments all across the country to match criminal suspect photos. And sometimes it makes mistakes.

[Jake Hanrahan]

So in this one case, two of their search results that I think were in the top 10 of the search results were Michael Jordan, a picture of Michael Jordan.

[Dexter Thomas]

But cops are still using it to make arrests.

[Jake Hanrahan]

Police, they are trusting this software to lead them to the right suspect. But you're not even being told that it was used, let alone given any of the details, details about how it works.

[Dexter Thomas]

This is not Minority Report. This is happening right now. People are getting arrested and doing actual time in jail after being picked out by a computer. I'm Dexter Thomas, host of Kill Switch, where every Wednesday we explain the right now of living in the future. You can turn off the computer, but do not let the computer turn you off. Listen to Kill switch in the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

[Tracy V. Wilson]

In 1911, Cambridge Instrument Company released a table model of William Eindhoven'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.

[Holly Fry]

Doctors and 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 BL 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.

[Tracy V. Wilson]

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

[Holly Fry]

Lewis was a regular correspondent with Einthoven, 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, 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, quote, the time is at hand, if not already come, when an examination of the heart is incomplete if this new method is neglected.

[Tracy V. Wilson]

Eindhoven 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 Eindhoven's triangle today. His written work on this was probably the first use in writing of the abbreviation EKG.

[Holly Fry]

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 Pardee published work on diagnosing coronary artery obstruction through electrocardiograms in 1920.

[Tracy V. Wilson]

In 1924, Willem Eindhoven 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 Eindhoven's development of the electrocardiograph device. It was also about his interpretations of the electrocardiogram, what PQRs 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 award speech quote, eindhoven's concept is the only one which has proved to be tenable.

[Holly Fry]

The Nobel Prize came with a monetary award that Eindhoven 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 Vandiverde. Vandivert had died, though, and Einthoven instead divided the $40,000 prize money with Vande Verde's two sisters, who had been living in poverty. Three years later, on September 29, 1927, Willem Einthoven died of cancer.

[Tracy 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.

[Holly Fry]

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.

[Tracy 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.

[Holly Fry]

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.

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

[Holly Fry]

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.

[Tracy V. Wilson]

By the 1950s, researchers were working on finding ways to automate ECG readings. The development of automated readings also made other life saving 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.

[Holly Fry]

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.

[Tracy V. Wilson]

Magnetocardiograms 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.

[Holly Fry]

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. 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.

[Tracy 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 things you're doing wrong rather than ever fully recording the ecg. 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. So 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 exposed to unpleasantness. Slippers for the win. Holly, I see you 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 measle 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. 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, 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 resident for the statement at the beginning of the latest Unearthed episode. Love you guys. I tried but failed to keep it short. Edith Edith, I love this email regarding vaccinations. We had talked in, I think behind the scenes on the show about how I was turning 50 and knew that I meant that meant that I was going to 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. 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, because I am not known to have ever actually had chickenpox, but it is recommended at the age of 50. Anyway, I did feel. I felt unwell. Still much better than getting shingles or pneumonia. You. 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.

[Holly Fry]

They are.

[Tracy V. Wilson]

These horses are. It's a horse and a foal just running through a field. How great is that? I don't think I'll watch the pig video while we are sitting here.

[Holly Fry]

I love a little pig action. You just reminded me of the funniest thing I've ever seen a pig do. I'm just in my own head now. Oh, have you ever seen a pig eat spaghetti?

[Tracy V. Wilson]

No.

[Holly Fry]

Our mutual friend, who is often prone to wacky hijinks, briefly had a pig. I don't remember how she came into 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.

[Tracy V. Wilson]

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

[Holly Fry]

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.

[Tracy V. Wilson]

Yeah.

[Holly Fry]

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

[Tracy V. Wilson]

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

[Holly Fry]

He was not.

[Tracy V. Wilson]

So thank you so much for this email, Edith. The Charles river is a lot cleaner than it used to be. As somebody who moved to the Boston area from elsewhere, 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, aw, people rowing out on the river. So if you would like to send us a note about this or any other podcast, we're a history [e-mail], and you can subscribe to our show on the iHeartradio app and anywhere else you like. To get your podcasts, Stuff youf 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.

[Dexter Thomas]

Are there any pictures of you online? Then you could already be in a massive police database without even knowing it.

[Jake Hanrahan]

Clearview scrapes together images From Facebook, from LinkedIn, from Venmo accounts accounts.

[Dexter Thomas]

I'm Dexter Thomas, host of Kill Switch, a podcast about how living in the future is affecting us right now.

[Jake Hanrahan]

Police, they are trusting this software with this magical ability to lead them to the right suspect.

[Dexter Thomas]

In this episode, we dive into how cops are using AI and facial recognition and sometimes getting it wrong and putting innocent people behind bars.

[Jake Hanrahan]

So if your accuser is this algorithm, but you're not even being told that it was used, let alone given any of the details about how it works.

[Dexter Thomas]

Listen to Kill Switch on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

[Tom Galamas]

OpenAI is a financial abomination, a thing that should not be an aberration, a symbol of rot at the heart of Silicon Valley. And I'm gonna tell you why on my show, Better Offline, the rudest show in the tech industry where we're breaking down why OpenAI, along with other AI companies, are dead set on lying to your boss that they can take your job. I'm also going to be talking with the greatest minds in the industry about all the other ways the rich and powerful are ruining the computer. Listen to Better offline on the iHeartRadio app, Apple Podcasts, wherever you happen to get your podcasts. I'm Jake Hanrahan, journalist and documentary filmmaker. Away Days is my new project reporting on countercultures on the fringes of society all across the world. Live from the underground, you'll discover no rules fighting, Japanese street racing, Brazilian favela life, and much more. All real, completely uncensored. Listen to the Away Days podcast, reporting from the underbelly on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

[Holly Fry]

A body, a suspect, and a hundred years of silence. Buried Bones is a podcast about the forgotten crimes history tried to leave behind.

[Tom Yamas]

A common misperception about serial predators is that every single time they commit a crime, they commit it the same way.

[Holly Fry]

The past is a way of talking, if you know what to listen for.

[Tom Yamas]

New episodes every Wednesday on the exactly right network.

[Holly Fry]

Listen to Buried phones on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

[Tracy V. Wilson]

This is an iHeart podcast.