August 1, 2022 • 41 mins
Ancient cultures all over the world used the pulse as a diagnostic tool. And eventually, we figured out how to measure blood pressure, and hypertension came to be viewed as a disease.
Research:
- Booth, Jeremy. “A Short History of Blood Pressure Measurement.” Proceedings of the Royal Society of Medicine. Vol. 70. Nov. 1977. https://journals.sagepub.com/doi/pdf/10.1177/003591577707001112
- Elias, Merrill F. and Amanda L. Goodell. “Setting the record straight for two heroes in hypertension: John J. Hay and Paul Dudley White.” Journal of Clinical Hypertension. 9/21/2019. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8030549/#jch13650-bib-0004
- Greene, Jeremy A. “Releasing the Flood Waters: Diruil and the Reshaping of Hypertension.” Bulletin of the History of Medicine, Vol. 79, No. 4, Winter 2005. https://doi.org/10.1353/bhm.2005.0153
- Harold, John Gordon. “Harold on History | Historical Perspectives on Hypertension.” American College of Cardiology. 11/20/2017. https://www.acc.org/latest-in-cardiology/articles/2017/11/14/14/42/harold-on-history-historical-perspectives-on-hypertension
- Hay, John. “The Significance of a Raised Blood Pressure.” British Medical Journal. 7/11/1931.
- Johnson, Richard J. et al. “The discovery of hypertension: evolving views on the role of the kidneys, and current hot topics.” Renal Physiology. 1/2/2015. https://doi.org/10.1152/ajprenal.00503.2014
- Kotchen, Theodore A. “Historical Trends and Milestones in Hypertension Research: A Model of the Process of Translational Research.” Hypertension. Vol. 58, 2011. https://doi.org/10.1161/HYPERTENSIONAHA.111.177766
- Labos, Christopher. “The Current Hypertension Controversy: There is None..” McGill. 2/8/2018. https://www.mcgill.ca/oss/article/general-science/current-hypertension-controversy-there-none
- Lüscher, Thomas F. “High blood pressure: new frontiers of an old risk factor.” European Heart Journal (2017) 38, 2791–2794. doi:10.1093/eurheartj/ehx544
- Moser, Marvin. “Historical Perspectives on the Management of Hypertension.” Journal of Clinical Hypertension. 5/22/2007. https://doi.org/10.1111/j.1524-6175.2006.05836.x
- Postel-Vinay, Nicolas, editor. “A Century of Arterial Hypertension 1896-1996.” Wiley. 1996.
- Saklayen, Mohammad G. and Neeraj V. Deshpande. “Timeline of History of Hypertension Treatment.” Frontiers in Cardiovascular Medicine. 2/23/2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4763852/
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:01):
Welcome to Stuff You Missed in History Class, a production
of I Heart Radio. Hello, and welcome to the podcast.
I'm Tracy V. Wilson and I'm Holly Fry. I got
a physical the other day, always the most fun, so
(00:22):
much fun. My blood pressure was high. Not surprising really,
because number one, high blood pressure is just incredibly common.
It is the most prevalent non communicable chronic disease in
the world. But besides that, I'm forty seven and I
have hypertension on both sides of my family. So in
(00:43):
a lot of ways this has felt inevitable. So naturally,
as I have been taking my blood pressure at home,
as instructed by my doctor, I have been pondering how
humanity figured out that this often symptomless disease even exists.
Uh So, today's episode is about how we figured out
(01:05):
how to measure blood pressure and how hypertension became viewed
as a disease. Most of the detail goes up until
the first diuretics were developed, because that marked a big
shift in this and after that, so many things happened
so fast that it's was it felt impossible to include
(01:25):
them all. I did want to note that hypo tension
or low blood pressure that also exists. A lot of
people experience it as orthostatic hypotension, which is what happens
when you stand up too fast and you get that
lightheaded feeling. But a lot of people who have hypotension
for it's a lot more serious and really life disrupting.
(01:45):
But there's not as much historical focus on it because
a lot of the time it is connected to something
else rather than like a condition that's existing on its own.
Um also heads up. Obviously, we're gonna be talking a
out blood a lot, and some animal experimentation and some
stuff about restrictive dieting, and we don't normally give a
(02:09):
heads up about death on the show because death really
comes with the territory of a history podcast. It comes
up almost every episode. But there's a death in here
due to uncontrolled hypertension that I just found a little
unsettling to read, So just know that's coming later on. Yeah. So,
ancient cultures all over the world used the pulse as
(02:32):
a diagnostic tool. This is most documented in ancient Greek
medicine and in traditional Chinese medicine and ayur Veda, which
are still practiced today. It's also been part of indigenous
healing practices in other parts of the world. Many of
these traditional systems of medicine incorporate the idea of a
person's energy or life force or vitality and keeping that
(02:54):
energy balanced. So while a practitioner might be palpating a
person's physical pulse, they might be doing so to assess
something more metaphysical. The first written reference to something that
might have been high blood pressure maybe from the Chinese
Yellow Emperor's Classic of Internal Medicine that dates back to
about b c E. This text describes the pulse as
(03:19):
hardening if there is too much salt in the blood,
and treatments for this hardened pulse include acupuncture and the
removal of blood through things like blood letting and leeches.
There are also references to the pulse being used to
diagnose illnesses in several Egyptian medical texts dating back to
about thirty five hundred years ago. Some of these directly
(03:41):
connect the pulse in other parts of the body to
the beating of the heart and to blood flow. Moving
ahead to the eleventh century c E. Past podcast subject
even Sina, whose name is sometimes westernives does Avicenna wrote
quote the pulse is a movement in the heart and arteries,
which takes the form of alternate expansion and contraction, whereby
(04:04):
the breath becomes subjected to the influence of the air inspired.
The first person to document the circulation of blood throughout
the body was English physician William Harvey in s so
to be clear here, there was already plenty of commentary
on various aspects of the heart, the blood, blood vessels,
(04:24):
and the pulse. But before this point, the conventional wisdom
was at the heart pumped blood out to the tissues,
where it left the blood vessels and was absorbed. Harvey,
on the other hand, described circulation as a closed loop,
with the blood moving through the lungs and out to
the body and back. Yeah. I read a paper that
described him as single handedly discovering circulation, and I was like, nah,
(04:50):
that's a little reductive, building on the work of the
people who came before him. The first measurement of the
pressure inside this system, specifically in an artery, happened more
than a century later, thanks to English clergyman Stephen Hales,
who did experiments in all kinds of subjects related to
plant and animal physiology. Hales was building off of an
(05:14):
invention by past podcast subject Evangelista Torricelli. This was the
manometer that was a device used to measure pressure. Torricelli
used a mercury filled glass tube, but Hale's approach here
was a little bit different. He inserted a brass tube
into the artery of a horse, and he connected that
(05:34):
tube to a long glass pipe. He wrote about this
in his seventeen thirty three treatise Statical Essays containing Hemosthetics.
The horse needed to be euthanized because of a fistula
on its withers, which at the time was not really
a treatable condition, and Hales had it restrained on the
ground for an experiment. He wrote quote, having laid open
(05:57):
the left curl artery about three inches from her belly,
I inserted into it a brass pipe whose bore was
one sixth of an inch in diameter. I fixed a
glass tube of nearly the same diameter, from which was
nine ft in length, then untying the ligature of the artery.
The blood rose in the tube eight ft three inches
(06:18):
perpendicular above the level of the left ventricle of the heart,
but it did not attain to its full height at once.
When it was at its full height, it would rise
and fall at and after each pulse two three or
four inches. So just the note if you go to
look for more about this experiment number one, there is
(06:38):
a widely used illustration of this experiment that shows the
tube and the horse's neck that is incorrect based on
what we just read, But beyond that, the experiment continued
on from here. It is a little disturbing to read.
It resulted in the animal's death, which again the animal
needed to be euthanized, but this would not have been
(06:59):
the most humane way to do it. For a while
after this, most blood pressure measurements were invasive. They involved
putting something inside an artery to take a reading. For example,
Jean leonar Marie Poise did experiments on dogs and wrote
about them in his dissertation recher Left Artique. He placed
(07:23):
a mercury monometer into the dog's artery with a barrier
of potassium carbonate or potash to keep the blood from clotting.
Possoy made a number of observations from this work, including
that dog's blood pressure rose and fell as they breathed
in and out. Through the mid to late nineteenth century,
many doctors and physiologists tried to work out a non
(07:44):
invasive way to measure people's blood pressure. Most of them
involved measuring how much pressure it took to compress a
person's artery until the blood could no longer flow through it,
So sort of like if you pinch a straw until
you can't suck any liquid through it in anymore. This
was a measure of systolic blood pressure, in other words,
how much pressure is exerted on the artery every time
(08:07):
the heart beats. One such doctor was ju Risson, who
wrote a treatise on a device called this phigmometer in
eight five. There were several variations on this device, usually
combining a mercury column, a pressure gauge or dial, and
a piece that would be placed over the radial artery
in a person's inner wrist. Sometimes that piece was a
(08:30):
flat metal disc or a metal ball, but it was
often flexible like a membrane or rubber ball, or a
stretched piece of leather like a drumhead. To use this phigmometer,
a physician would place the device onto a person's wrist
and feel their pulse at a point that was below
the device. Then they would press the device. Usually that
(08:50):
flexible part into the wrist until they could no longer
feel the pulse below it. Then they would look at
the gauge or the dial to get a measurement of
how much pressure they were exerting. This reminds me a
little bit of those tire pressure gauges that have a
little thing that shoots out of the end. So this
device had some pros and cons. It was not invasive,
and compact and portable, but it was also pretty tricky
(09:13):
to read, and eventually it became apparent that it wasn't
very accurate. It was relying on like a person manually
pushing on a thing while feeling something with their fingers.
It was just a little prone to error, much like
those little tire gauges. In eighteen forty seven, German physiologist
Carl Ludwig developed a chemography on which combined amnometer with
(09:35):
a stylus and a revolving drum to record variations in
blood pressure on a graph. Unlike Harrison's figmometer, this was invasive.
The mnometer had to be placed in an artery, and
Ludwig used this for experiments on dogs, but it did
make it possible to record ongoing fluctuations in blood pressure.
(09:55):
As they were happening in the eighteen fifties and sixties,
lots of physicians and physiologists were still trying to find
non invasive ways to measure blood pressure, now, ones that
would be more consistent and more precise than this pigmometer was.
One result was this figma graph that was developed and
improved by multiple people, including German physiologist Carl von der
(10:19):
Roort and French physiologist Etien joul Maray. This was a
device placed over the inner wrist. It used springs and
levers to magnify the movement of the radial pulse and
then all this was connected to a stylist that could
record that movement as a graph. If small weights were
placed onto the device slowly weighing it down, the pulse
(10:42):
would eventually stop, so this could also provide a measurement
for blood pressure. Starting in the eighteen seventies and continuing
until his death in eighteen eighty four, Frederick Akbar Mohammed
researched blood pressure at Guy's Hospital in London. Mohammed was
born in England and was of Irish and in the descent,
and he developed and improved quantitative spygmagraph While he was
(11:04):
still in medical school, and he used this to make
a lot of significant discoveries about blood pressure and circulation
over the course of about a decade. Some of the
patients he worked with were under the care of his
colleague Richard Bright. Mohammed was able to determine that patients
who had kidney disease then known as Bright's disease tended
(11:26):
to have higher blood pressure. He also found that there
were people who had higher blood pressure but no evidence
of kidney dysfunction. He crossed reference to his blood pressure
measurements with autopsy reports to document how high blood pressure
could be related to things like kidney damage, arterial fibrosis,
and youeurysms and enlarged hearts. Sometimes he was credited with
(11:47):
coining the term essential hypertension, although sometimes that credit goes
to physiologist Otto Frank, who was working a few decades later.
Mohammed was one of the first people to suggest that
lowering a per since blood pressure could prolong their life,
and that is something we will get too more after
a sponsor break Frederick Akbar. Mohammed's contributions to the study
(12:18):
of blood pressure and hypertension are notable on their own.
I mean he made a lot of connections that still
hold up today. They're even more impressive considering that he
was using equipment that could be fiddly, encumbersome. Set up
tended to be complicated, it wasn't particularly comfortable for the patient.
Using a spig McGraph often involved strapping the patient's forearm
(12:40):
to a chair in a particular position, and then if
anything was misaligned and those levers and springs, the readings
would be inaccurate. But in the eighteen eighties people started
developing tools to measure blood pressure that are a lot
more in line with what is used today. The first
was Siegfried Karl Ridder von Bosch, who was a Jewish
physician from Austria. In eighteen eighty one, he developed an
(13:02):
inflatable bag that could be pressed against an artery. It
was connected to a pressure gauge, so a physician could
record how much pressure it took to collapse an artery
until blood could no longer pass through. Italian physician Shipione
Riva Rocchi improved on this in eight he created an
inflatable cuff that could be placed around the patient's arm
(13:26):
and then the physician would once again feel the person's
pulse below the cuff. As the cuff was being inflated,
when the pulse stopped, they would measure that number on
a pressure gauge. This was essentially this Figmomme monitor that
is still used to measure blood pressure today. A key difference, though,
was that Riva Rocchi's cuff was pretty narrow, so as
(13:46):
it inflated, it would make a pretty sharp crease in
people's flesh, and that could reduce the accuracy of the readings.
In nineteen o one, German physician hinrichs On Recklinghausen improved
on Riva Rocchi's design by making the cuff eier. Soon
this device was being introduced into other parts of the world.
Theodore Janeway and Harvey Cushing helped popularize it in the
(14:08):
United States. Until this point, most non invasive blood pressure
measurements that involved feeling a person's pulse or less frequently
using some kind of device to create a graph. And
n OH five Nikolai Kortakoff used ascultation, or listening, paying
attention to the sounds of the turbulence in a person's
(14:29):
artery while inflating and deflating the cuff. He noticed a
distinct set of sounds depending on how much pressure the
device was exerting on a person's arm relative to their
blood pressure. He was using a stethoscope to do this. Obviously,
with the cuff on but not inflated, there was no sound.
(14:49):
If the cuff was inflated to a greater amount of
pressure than the person's systolic blood pressure, there would still
be no sound because no blood could get through. But
as he reduced the press sure again he started to
hear sounds as small amounts of blood were able to
get through the artery with each heartbeat. That onset of
sounds marked the person's systolic blood pressure. These sounds went
(15:13):
through a series of changes as he further reduced the
pressure in the cuff, and then the sounds would disappear entirely.
And the point where the sounds disappeared was the person's
diastolic blood pressure. It's the blood pressure in between heartbeats.
I don't think we've said before. These sounds are still
known as corticough sounds today. They are still used when
(15:33):
somebody is measuring blood pressure using us big momentometer and
a stethoscope. There are some variations that exactly when in
the cycle people think is the best time to say
that's the diastolic blood pressure. Though, as has been the
case with so so many other medical innovations on the show,
even though this provided a practical, reliable, noninvasive way to
(15:56):
measure most systolic and diastolic blood pressure, the medical commune
it he did not adopt it right away. Some doctors
just didn't like the idea of using a device like
this in medical practice. In the words of an article
in the British Medical Journal, by using machines as part
of medical diagnosis, quote, we popularize our sense and weaken
(16:16):
clinical acuity. Others just thought that a doctor's fingers were
a better, more sensitive tool than a stethoscope. There were
also people who had been using things like spigma graphs
or other devices, and they felt like the spigmommometer was
making things too easy. Like I said earlier, spigmo graphs
could require a lot of technical skill and precision to
(16:37):
set them up and use them correctly, and so there
was this sense that by being simpler and easier to use,
the sphigmo mimometer would just make the practice of medicine
less prestigious. The sphigmommometer made it much easier to measure
more people's blood pressure, though, so over the first three
decades of the twentieth century, researchers started seeing lots of
(17:00):
connections between high blood pressure and heart diseases, strokes, and death.
This was all happening in spite of the controversy over
this figmomnometer that was playing out in the medical community,
because most of this research was happening actually in another
industry entirely, and that was the life insurance industry. Life
(17:20):
insurance companies wanted to make sure that as often as
possible the people they were covering had a long life
and paid lots and lots of premiums before their policies
had to be paid out. So by the end of
the nineteenth century, assessing a customer's health had become an
established industry practice. If somebody wanted insurance, they would be
examined by an insurance company physician, and then underwriters would
(17:44):
use the physician's report to decide whether ensuring this person
was an acceptable risk for the company. Over time, all
this data would inform things like actuarial tables that the
company could use to estimate how long a person could
be expected to live. Here in the US, it's pretty
much still how it happens today, although there are plans
(18:05):
that don't require physical exams, and a lot of plans
that are offered through employers as an employee benefit don't
require an exam below a certain monetary threshold. In nineteen
o six, Northwestern Mutual Life Insurance Company started measuring the
blood pressure of all of its clients as part of
their insurance applications. Other insurance companies followed suit. In nineteen eleven,
(18:30):
Dr J. W. Fisher, medical director of the Northwestern Mutual
Life Insurance Company, gave an address before the Medical Directors
Association which set, in part quote, no practitioner of medicine
should be without a spigmomanometer. He has in this instrument
a most valuable aid in diagnosis. This figmomanometer is indispensable
(18:51):
in life insurance examinations, and the time is not far
distant when all progressive life insurance companies will require its
use in all examine nations of applicants for life insurance.
By the nineteen thirties, the life insurance industry had gathered
data from more than ten million people. They're putting together
(19:11):
reports on that data, and it showed clear connections between
high blood pressure and other diseases, including cardiovascular diseases and
kidney disease. There was also a clear correlation between high
blood pressure and a shorter life expectancy. This data still
had some big limitations though. Number One, These companies were
(19:31):
primarily ensuring white people, specifically white men, as we talked
about in our episode on Maggie Lena Walker. There were
mutual aid organizations, fraternal orders, and other organizations that offered
insurance to people of color, but they were not included
in this data set. Number two. As the company saw
correlations between hypertension and early death, they started declining coverage
(19:55):
for people whose blood pressure was too high. Number three.
There was a lot of ongoing follow up. People were
either approved for insurance or they weren't, and unless people
wanted to change their coverage and that change required another examination,
the company did not check in on them again until
they died. Although the life insurance industry had a wealth
(20:16):
of data suggesting a connection between high blood pressure and
other diseases and reduced life expectancy, there was still a
lot of debate about all this in the medical community.
Measuring patients blood pressure eventually did become a standard practice
and by the nineteen teams, at least some doctors and
researchers thought high blood pressure should be classified as a disease,
(20:38):
but there was a lot of disagreement about how to define.
High blood pressure is generally measured in millimeters of mercury,
and the idea that one twenty over eighty millimeters of
mercury was normal that showed up pretty early in this
whole process. But some experts in the early twentieth century
thought that normal got higher as people age, and various
(21:01):
researchers cited numbers as high as one eight over one
ten as normal. There also was not a consensus about
what caused high blood pressure, or whether high blood pressure
was really the body's compensation for something else, so a
lot of doctors thought lowering a person's blood pressure might
do them more harm than good, because what if their
(21:22):
blood pressure needed to be that high to move their
circulation through clogged or hardened arteries, for example. To add
to all of that, there weren't really effective treatments for
hypertension at this point, even if a doctor wanted to try.
The idea that salt intake, or more specifically sodium might
cause high blood pressure that had been around since nineteen
(21:44):
o four, when l Umbard and E. Bojard published Cause
de lie potension on arterial so based on that, doctors
often advised patients whose blood pressure was high to reduce
the salt in their diets. But there had been pay
Shans and that first study by Ambard and Bojard whose
blood pressure did not increase with their salt consumption. These
(22:07):
low salt diviots could also be really hard to stick to.
Plus there was i mean evidence going back from this
very first study that they might not work for everybody.
Doctors also tried various drugs to lower blood pressure in
the early twentieth century and found them to be only
somewhat effective at best. On a lot of these drugs
(22:28):
had serious and sometimes dangerous side effects. So with all
of that in mind, a lot of doctors thought that
as long as a patient wasn't showing other symptoms, their
blood pressure should be left alone. In British cartiologist John H.
Hay wrote an article in the British Medical Journal that's said,
in part quote, there is some truth in the saying
(22:50):
that the greatest danger to a man with high blood
pressure lies in its discovery, Because then some fool is
certain to try and reduce it. Sometimes that first part
of the quote is left out, making it seem like
the saying he was quoting was actually his entire statement,
and that he thought it was foolish to try to
reduce blood pressure. But this was in the context of
(23:10):
an article that started quote, no one can now afford
to be indifferent to the problems associated with variations in
blood pressure. For a high pressure is an abnormality which
always demands investigation, supervision, and careful treatment. American cardiologist Paul
Dudley White echoed Hayes sentiments a few years later in
(23:31):
nine seven, quote, the treatment of hypertension itself is a
difficult and almost hopeless task in the present state of
our knowledge, and in fact for aught. We know the
hypertension maybe an important compensatory mechanism which should not be
tampered with, even if it were certain we could control it.
A few years after that, though, President Franklin Delano roosevelt
(23:53):
death brought renewed focus to all of this. We'll talk
more about that after a sponsor break. The death of
President Franklin Delano Roosevelt brought some more public awareness to
the risks of uncontrolled hypertension. Roosevelt was first diagnosed with
(24:17):
hypertension in ninety seven, when he was fifty four. At
that time, his blood pressure was measured at one sixty
two over. No treatment was prescribed for him until four
years later, when his BP was measured at one over
one oh five. As we said earlier, though at this
point treatments for hypertension were really limited, so the President
(24:39):
was put on a low fat, low sodium diet. He
was advised to rest and get massages, and he was
put on the barbiturates phena barbital, which today is most
often used to treat seizure disorders as well as anxiety
and sleeplessness. This course of treatment was not effective, and
in February of nine, Roosevelt's blood pressure was measured at
(25:01):
two sixty over one fifty. He was also starting to
show signs of heart and liver failure. He attended the
Yalta Conference, which was a meeting of Allied leaders to
discuss the post World War two reconstruction, and other people
present expressed concerns about his health, including doubts about whether
he was cognitively alert. During that meeting, Winston Churchill's physician
(25:25):
remarked that Roosevelt looked like a man who only had
a few months to live. His blood pressure was not
the only thing involved in his overall health, but that
is the focus of this episode, so that sort of
sticking to On April twelfth, Roosevelt reported a bad headache
while he was sitting for a portrait. His blood pressure
was recorded at that time at three hundred over one.
(25:50):
Not long after that, he lost consciousness and died at
the age of sixty three. No autopsy was performed, but
his cause of death was reported as a cerebral hemorrhage.
It's a logical conclusion to draw from the symptoms that
were shown at the time. His physician, Admiral Rossty McIntyre,
reportedly said that this quote came out of clear sky.
(26:11):
Even though the president's blood pressure had been escalating for
years and was three day there was still a lack
of medical consensus about what to do about high blood pressure.
Though Tyson's Practice of Medicine is a major medical textbook
and in its edition had this to say about hypertension. Quote,
(26:32):
may not the elevation of systemic blood pressure be a
natural response to guarantee a normal circulation, To the heart, brain,
and kidneys. Essential hypertension. Over zealous attempts to lower the
pressure may do no good and often do harm. Many
cases of essential hypertension not only do not need any treatment,
(26:53):
but are much better off without it, so it was
pretty clear at this point that more medical research was needed.
There was a rice based diet developed by Walter Kempner
that was sometimes effective at reducing a person's blood pressure,
but it was extremely restrictive and not usually sustainable over
the long term. Various drugs are being used to try
(27:14):
to treat hypertension, but at this point they all had
some pretty unpleasant or even dangerous side effects. Ralphina serpentina
or Indian snake root, was developed into an anti hypertension
drug Resurping in India, and while it could lower a
person's blood pressure, it didn't work for everyone, and it
was also associated with things like vomiting, nightmares, and chest pains.
(27:36):
Hadrolyzine was a vasodilator that could cause headaches and rapid heartbeat,
and at large doses could cause a syndrome that resembled lupus.
Hexamathynium was a ganglion blocking agent that had to be
administered as injections, sometimes multiple times a day. There were
also attempts to control people's blood pressure through surgeries. One
(27:57):
was sympathectomy, or severing sympathetic nerves near the spine. Another
involved the removal of the adrenal glands. While a person's
blood pressure might be lower after one of these procedures,
this definitely was not true for everyone, and these procedures
were also really risky and irreversible. There are a lot
of things that were just regarded as quackery also, and
(28:19):
we are not getting into any of that. In President
Harry Truman signed the National Heart Act into law. This
law noted that diseases of the heart and circulatory system
had become the leading cause of death in the United States.
This law established the National Heart Institute and the Public
Health Service, as well as the National Advisory Heart Council.
(28:43):
The Framingham Heart Study was launched soon afterwards with the
goal of determining the causes of heart disease. The Framingham
Heart Study is actually still ongoing today. They're on their
third generation of research participants. Through the Framingham Heart Study
and other large scale long term study ease it became
increasingly clear that hypertension could cause heart and kidney problems,
(29:05):
including issues like left ventricular hypertrophy, and that lowering a
person's blood pressure could help prevent and sometimes even reverse
these issues. But actually reducing people's blood pressure continued to
be really difficult, so many doctors continued to treat hypertension
only if it seemed to be causing some other issue.
(29:25):
When hypertension wasn't being caused by some other disease or disorder,
it was increasingly known as essential hypertension, and many doctors
saw it as just an inevitable part of aging. That
started to change in the fall of nineteen fifty seven
when a clinical trial started for a diuretic called chlorothiazide.
(29:46):
This wasn't intentionally intended to be used as a treatment
for hypertension. Was the diuretic that doctors were prescribing to
patients who had edema due to congestive heart failure. But
when doctors gave their patients this medicine, they noticed that
their blood pressure dropped dramatically in night. This became available
at pharmacies under the brand name di a Ill. This
(30:08):
was during the massive boom in pharmaceutical development that took
place during and after World War two. So many new
drugs and classes of drugs were developed during this period,
several of which have come up on the show before.
Antibiotics entered mass production during the war and flourished afterward.
The first oral contraceptive was approved in nineteen sixty after
(30:31):
having been used to treat various gynecological disorders for a
few years before that. Tranquilizers were also introduced during this era,
which we talked about in our two parter on the litamide.
So Diarill was introduced at a time when there was
just an increasing focus on the idea that chronic illnesses
and conditions could be treated or controlled using pharmaceuticals. It
(30:54):
played a really big part in that shift. At this
point in the United States, the pharmaceutical industry not advertise
drugs directly to consumers, but merk Sharp and Dome, which
was the company that developed Direll, did things like distributing
research reports to science writers, which led to favorable write
ups in publications like Readers. Digest Mark also advertised to
(31:17):
doctors in medical journals, and they created a character called
di a rill Man as part of this campaign. This
was a transparent illustration of a man with the heart
and lungs and urinary system visible in that illustration. Di
arell Man became one of the first examples of a
physical gift that drug sales reps would leave with doctors.
(31:39):
This is a little transparent desk figuring about six inches
tall that had these organs visible on the inside of it,
and it was mostly filled up with water. I want
one so bad now you might be able to find
one on eBay. Oh, I'm gonna go looking. Although di
arell could still cause side effects like lightheadedness and digestive problems,
(32:00):
it was overall more broadly effective than the earlier drugs
that were used to treat hypertension, and those side effects
were generally less serious and more widely tolerated. This made
it possible to get a lot more data about what
worked and what happened when a person's high blood pressure
was lowered. As direl was making its way to market,
(32:20):
Dr Irvine Page proposed the mosaic theory of hypertension. This
built on ideas he had started putting forth as early
as ninety seven, and he argued that there were multiple
interrelated factors at work in maintaining the bodies blood pressure equilibrium.
You thought that blood pressure involved genetic, environmental, anatomical, adaptive, neural, indocrine, humoral,
(32:44):
and hemodynamic factors. You can get a direl man for
just like twenty five bucks. Di arell marked a major
shift in the treatment of hypertension, and thanks to that shift,
it's tricky to do a historical playbi a of all
the new developments since then, even just as highlights, because simultaneously,
(33:05):
so much has happened in terms of drug development and
research into hypertension, and so much is still unknown. Like
diarrhal and other, diuretics were just the first class of
drugs developed to treat hypertension. Today there are at least ten,
including beta blockers, ACE inhibitors, and calcium channel blockers, most
(33:26):
of which were introduced over a period of only about
thirty years. The availability of these drugs and others made
it possible to conduct things like randomized, placebo controlled, double
blind trials of hypertension treatments. The first of these were
conducted through the US Veterans Administration. These studies have provided
(33:46):
clear evidence that reducing moderate and severe hypertension is beneficial
and can prolong people's lives. Based on this and other data,
widespread public education campaign started in the nineteen seventies for
both doctors and the general public. This includes the National
High blood Pressure Education Program, which launched in the US
(34:07):
in nineteen seventy two. There have also been so many
other studies since then, including other studies at the v A.
They've looked at so many questions around things like correlations
with other conditions, race, gender, the efficacy of different drugs, diet, exercise, age,
tobacco used, diabetes, on and on and on. Through this research,
(34:30):
guidelines for how to define high blood pressure and how
to treat it have become increasingly aggressive and specific. For example,
in the US, the Joint National Committee on Prevention, Detection, Evaluation,
and Treatment of High blood Pressure issued its first report
in nineteen seventy seven. This report suggested that a person
(34:50):
who's blood pressure was one sixty over ninety five should
have it checked again in a month, while people fifty
and under should be checked every two to three months.
If their blood pressure was between one forty ninety and
one six probably not how a doctor would approach it today.
It's definitely not how my doctor did. And this report,
(35:11):
treatment was recommended only if a person's dia stylic blood
pressure was greater than or equal to one oh five.
Those numbers have dropped repeatedly since the seventies. Most recently
in seventeen, the American Heart Association and the American College
of Cardiology announced new guidelines that defined normal blood pressure
(35:31):
has less than one twenty over eighty, and everything above
one thirty over eighty is classified as some variety of hypertension.
A systylic reading above one eighty and a dia stylic
reading above one twenty either of those that's classified as
a hypertensive crisis, and the American Heart Association advises people
(35:51):
to contact their doctor immediately if this happens to them.
This is so radically different from earlier eras when there
were studies that classified one eight over one ten as normal.
There is also various conventional wisdom around hypertension that still
isn't fully supported or understood. We noted earlier that a
possible connection to sodium was first proposed in nineteen o four.
(36:15):
Today you can read all kinds of extremely authoritative, yet
totally contradictory, peer reviewed papers that describe sodium as everything
from the single biggest contributor to hypertension in the entire
world to something that can contribute to hypertension in some people,
but only if they are sensitive to sodium yets. I
(36:37):
found this very frustrating as I was trying to get
to this part of the episode. Another bit of conventional
wisdom has involved associating high blood pressure with being overweight,
and with recommendations for people to lose weight included as
a way to try to control their blood pressure. But
that is seemingly not as straightforward as all that number
(36:58):
one and abody can have high blood pressure regardless of
how much they weigh and number two. For a long time,
there was really only one size of blood pressure cuff
that was being used, and it was really too small
for people with bigger arms. It gave artificially high readings
for people who weighed more. Blessed people tends to weigh
(37:19):
more as they get older, and some of the very
earliest actuarial reports about this noted that quote the increase
of blood pressure with increasing percentage of overweight is exaggerated
because of that interaction between people's age and their weight. Today,
researchers are looking at people's genetics, salt sensitivity, congenital factors
(37:40):
like birth weight and stress during fetal development and so
many other factors. But the reality at this point is
that for the overwhelming number of people who have hypertension,
we don't know exactly why. We really don't know. It's
also frustrating. Also, while the blood pressure cuff has been
a stay entered piece of equipment for doctors and nurses
(38:02):
and various other health and medical practitioners for more than
a century, there are improvements in the works for that
as well. So beyond just cuffs that inflate themselves and
then give a readout of blood pressure and pulse on
a screen like I've been using at home as my
doctor instructed, there are also efforts to make noninvasive blood
pressure measurement tools that don't actually require a cuff at all.
(38:26):
They would work a little more like a pulse oxometer
that goes on a person's fingertip. That technology also needs
some work. Uh. We know at this point that pulse
oxometers often don't give readings that are correct on people
with darker skin, So there's there's a whole confluence of
things to keep in mind. There there are some finger
monitors that have already hit the market at various points,
(38:48):
but they've generally been seen as less accurate than monitors
that use a cuff, and then rist monitors that are
also on the market today are similarly seen as less
accurate than ones go around the upper arm. Um. There
would be a lot of pluses to having an accurate
way to measure blood pressure that didn't require a cuff,
(39:11):
in part because try and put a cuff on yourself
is annoying. So that's um. That's the brief history of hypertension,
especially up through the introduction of di rill. Uh. This
is not a solicitation for advice about my blood pressure.
Please and thank you. Tracy has a doctor. I sure
(39:35):
my doctors on the ball with my blood pressure. Do
you also have listener mail I do? This is from Samantha.
This is one of many, many, many notes that we
got about this. It was something that had crossed my
radar first thing in the morning. Um, and I'm sure
I will say it again on a future installment of
on Earth, but this the next Unearthed, is all the
(39:56):
way in October, and I would rather say something about
it now. So Samantha wrote, hello there. I came across
this article today and remembered that you both had done
an episode to part if I remember correctly on Jim Thorpe.
You probably already saw it, but I thought i'd pass
it along just in case. I'm always behind on the podcast,
so my apologies if it's already been mentioned. Can't wait
to hear more. And Samantha sent an article about Jim
(40:20):
Thorpe's Olympic record being restored. Jim Thorpe is the subject
of the only three parter we have ever done on
the show so far, and one of the things that
we talked about was a whole controversy involving whether some
of his athletic participation disqualified him from being an amateur athlete.
(40:41):
And so just on I think what was gonna be
the one anniversary of one of his Olympic wins, um
his Olympic record was restored. So uh, I'm sure I
will have a more thorough discussion of that at the
next un Earth, which is not until October, so it
(41:02):
was too good of a thing to wait until them.
If you would like to send us a note about
this or any other podcast, where a history podcast that
I heart radio dot com and we're all over social
media at miss in History. You'll find us there for
your Facebook, Twitter, Pinterest, and Instagram, and you can subscribe
to our show on the I heart Radio app and
wherever else you like to get podcasts. Stuff you Missed
(41:27):
in History Class is a production of I heart Radio.
For more podcasts from I heart Radio, visit the i
heart Radio app, Apple Podcasts, or wherever you listen to
your favorite shows.
Welcome to Stuff You Missed in History Class, a production
of I Heart Radio. Hello, and welcome to the podcast.
I'm Tracy V. Wilson and I'm Holly Fry. I got
a physical the other day, always the most fun, so
(00:22):
much fun. My blood pressure was high. Not surprising really,
because number one, high blood pressure is just incredibly common.
It is the most prevalent non communicable chronic disease in
the world. But besides that, I'm forty seven and I
have hypertension on both sides of my family. So in
(00:43):
a lot of ways this has felt inevitable. So naturally,
as I have been taking my blood pressure at home,
as instructed by my doctor, I have been pondering how
humanity figured out that this often symptomless disease even exists.
Uh So, today's episode is about how we figured out
(01:05):
how to measure blood pressure and how hypertension became viewed
as a disease. Most of the detail goes up until
the first diuretics were developed, because that marked a big
shift in this and after that, so many things happened
so fast that it's was it felt impossible to include
(01:25):
them all. I did want to note that hypo tension
or low blood pressure that also exists. A lot of
people experience it as orthostatic hypotension, which is what happens
when you stand up too fast and you get that
lightheaded feeling. But a lot of people who have hypotension
for it's a lot more serious and really life disrupting.
(01:45):
But there's not as much historical focus on it because
a lot of the time it is connected to something
else rather than like a condition that's existing on its own.
Um also heads up. Obviously, we're gonna be talking a
out blood a lot, and some animal experimentation and some
stuff about restrictive dieting, and we don't normally give a
(02:09):
heads up about death on the show because death really
comes with the territory of a history podcast. It comes
up almost every episode. But there's a death in here
due to uncontrolled hypertension that I just found a little
unsettling to read, So just know that's coming later on. Yeah. So,
ancient cultures all over the world used the pulse as
(02:32):
a diagnostic tool. This is most documented in ancient Greek
medicine and in traditional Chinese medicine and ayur Veda, which
are still practiced today. It's also been part of indigenous
healing practices in other parts of the world. Many of
these traditional systems of medicine incorporate the idea of a
person's energy or life force or vitality and keeping that
(02:54):
energy balanced. So while a practitioner might be palpating a
person's physical pulse, they might be doing so to assess
something more metaphysical. The first written reference to something that
might have been high blood pressure maybe from the Chinese
Yellow Emperor's Classic of Internal Medicine that dates back to
about b c E. This text describes the pulse as
(03:19):
hardening if there is too much salt in the blood,
and treatments for this hardened pulse include acupuncture and the
removal of blood through things like blood letting and leeches.
There are also references to the pulse being used to
diagnose illnesses in several Egyptian medical texts dating back to
about thirty five hundred years ago. Some of these directly
(03:41):
connect the pulse in other parts of the body to
the beating of the heart and to blood flow. Moving
ahead to the eleventh century c E. Past podcast subject
even Sina, whose name is sometimes westernives does Avicenna wrote
quote the pulse is a movement in the heart and arteries,
which takes the form of alternate expansion and contraction, whereby
(04:04):
the breath becomes subjected to the influence of the air inspired.
The first person to document the circulation of blood throughout
the body was English physician William Harvey in s so
to be clear here, there was already plenty of commentary
on various aspects of the heart, the blood, blood vessels,
(04:24):
and the pulse. But before this point, the conventional wisdom
was at the heart pumped blood out to the tissues,
where it left the blood vessels and was absorbed. Harvey,
on the other hand, described circulation as a closed loop,
with the blood moving through the lungs and out to
the body and back. Yeah. I read a paper that
described him as single handedly discovering circulation, and I was like, nah,
(04:50):
that's a little reductive, building on the work of the
people who came before him. The first measurement of the
pressure inside this system, specifically in an artery, happened more
than a century later, thanks to English clergyman Stephen Hales,
who did experiments in all kinds of subjects related to
plant and animal physiology. Hales was building off of an
(05:14):
invention by past podcast subject Evangelista Torricelli. This was the
manometer that was a device used to measure pressure. Torricelli
used a mercury filled glass tube, but Hale's approach here
was a little bit different. He inserted a brass tube
into the artery of a horse, and he connected that
(05:34):
tube to a long glass pipe. He wrote about this
in his seventeen thirty three treatise Statical Essays containing Hemosthetics.
The horse needed to be euthanized because of a fistula
on its withers, which at the time was not really
a treatable condition, and Hales had it restrained on the
ground for an experiment. He wrote quote, having laid open
(05:57):
the left curl artery about three inches from her belly,
I inserted into it a brass pipe whose bore was
one sixth of an inch in diameter. I fixed a
glass tube of nearly the same diameter, from which was
nine ft in length, then untying the ligature of the artery.
The blood rose in the tube eight ft three inches
(06:18):
perpendicular above the level of the left ventricle of the heart,
but it did not attain to its full height at once.
When it was at its full height, it would rise
and fall at and after each pulse two three or
four inches. So just the note if you go to
look for more about this experiment number one, there is
(06:38):
a widely used illustration of this experiment that shows the
tube and the horse's neck that is incorrect based on
what we just read, But beyond that, the experiment continued
on from here. It is a little disturbing to read.
It resulted in the animal's death, which again the animal
needed to be euthanized, but this would not have been
(06:59):
the most humane way to do it. For a while
after this, most blood pressure measurements were invasive. They involved
putting something inside an artery to take a reading. For example,
Jean leonar Marie Poise did experiments on dogs and wrote
about them in his dissertation recher Left Artique. He placed
(07:23):
a mercury monometer into the dog's artery with a barrier
of potassium carbonate or potash to keep the blood from clotting.
Possoy made a number of observations from this work, including
that dog's blood pressure rose and fell as they breathed
in and out. Through the mid to late nineteenth century,
many doctors and physiologists tried to work out a non
(07:44):
invasive way to measure people's blood pressure. Most of them
involved measuring how much pressure it took to compress a
person's artery until the blood could no longer flow through it,
So sort of like if you pinch a straw until
you can't suck any liquid through it in anymore. This
was a measure of systolic blood pressure, in other words,
how much pressure is exerted on the artery every time
(08:07):
the heart beats. One such doctor was ju Risson, who
wrote a treatise on a device called this phigmometer in
eight five. There were several variations on this device, usually
combining a mercury column, a pressure gauge or dial, and
a piece that would be placed over the radial artery
in a person's inner wrist. Sometimes that piece was a
(08:30):
flat metal disc or a metal ball, but it was
often flexible like a membrane or rubber ball, or a
stretched piece of leather like a drumhead. To use this phigmometer,
a physician would place the device onto a person's wrist
and feel their pulse at a point that was below
the device. Then they would press the device. Usually that
(08:50):
flexible part into the wrist until they could no longer
feel the pulse below it. Then they would look at
the gauge or the dial to get a measurement of
how much pressure they were exerting. This reminds me a
little bit of those tire pressure gauges that have a
little thing that shoots out of the end. So this
device had some pros and cons. It was not invasive,
and compact and portable, but it was also pretty tricky
(09:13):
to read, and eventually it became apparent that it wasn't
very accurate. It was relying on like a person manually
pushing on a thing while feeling something with their fingers.
It was just a little prone to error, much like
those little tire gauges. In eighteen forty seven, German physiologist
Carl Ludwig developed a chemography on which combined amnometer with
(09:35):
a stylus and a revolving drum to record variations in
blood pressure on a graph. Unlike Harrison's figmometer, this was invasive.
The mnometer had to be placed in an artery, and
Ludwig used this for experiments on dogs, but it did
make it possible to record ongoing fluctuations in blood pressure.
(09:55):
As they were happening in the eighteen fifties and sixties,
lots of physicians and physiologists were still trying to find
non invasive ways to measure blood pressure, now, ones that
would be more consistent and more precise than this pigmometer was.
One result was this figma graph that was developed and
improved by multiple people, including German physiologist Carl von der
(10:19):
Roort and French physiologist Etien joul Maray. This was a
device placed over the inner wrist. It used springs and
levers to magnify the movement of the radial pulse and
then all this was connected to a stylist that could
record that movement as a graph. If small weights were
placed onto the device slowly weighing it down, the pulse
(10:42):
would eventually stop, so this could also provide a measurement
for blood pressure. Starting in the eighteen seventies and continuing
until his death in eighteen eighty four, Frederick Akbar Mohammed
researched blood pressure at Guy's Hospital in London. Mohammed was
born in England and was of Irish and in the descent,
and he developed and improved quantitative spygmagraph While he was
(11:04):
still in medical school, and he used this to make
a lot of significant discoveries about blood pressure and circulation
over the course of about a decade. Some of the
patients he worked with were under the care of his
colleague Richard Bright. Mohammed was able to determine that patients
who had kidney disease then known as Bright's disease tended
(11:26):
to have higher blood pressure. He also found that there
were people who had higher blood pressure but no evidence
of kidney dysfunction. He crossed reference to his blood pressure
measurements with autopsy reports to document how high blood pressure
could be related to things like kidney damage, arterial fibrosis,
and youeurysms and enlarged hearts. Sometimes he was credited with
(11:47):
coining the term essential hypertension, although sometimes that credit goes
to physiologist Otto Frank, who was working a few decades later.
Mohammed was one of the first people to suggest that
lowering a per since blood pressure could prolong their life,
and that is something we will get too more after
a sponsor break Frederick Akbar. Mohammed's contributions to the study
(12:18):
of blood pressure and hypertension are notable on their own.
I mean he made a lot of connections that still
hold up today. They're even more impressive considering that he
was using equipment that could be fiddly, encumbersome. Set up
tended to be complicated, it wasn't particularly comfortable for the patient.
Using a spig McGraph often involved strapping the patient's forearm
(12:40):
to a chair in a particular position, and then if
anything was misaligned and those levers and springs, the readings
would be inaccurate. But in the eighteen eighties people started
developing tools to measure blood pressure that are a lot
more in line with what is used today. The first
was Siegfried Karl Ridder von Bosch, who was a Jewish
physician from Austria. In eighteen eighty one, he developed an
(13:02):
inflatable bag that could be pressed against an artery. It
was connected to a pressure gauge, so a physician could
record how much pressure it took to collapse an artery
until blood could no longer pass through. Italian physician Shipione
Riva Rocchi improved on this in eight he created an
inflatable cuff that could be placed around the patient's arm
(13:26):
and then the physician would once again feel the person's
pulse below the cuff. As the cuff was being inflated,
when the pulse stopped, they would measure that number on
a pressure gauge. This was essentially this Figmomme monitor that
is still used to measure blood pressure today. A key difference, though,
was that Riva Rocchi's cuff was pretty narrow, so as
(13:46):
it inflated, it would make a pretty sharp crease in
people's flesh, and that could reduce the accuracy of the readings.
In nineteen o one, German physician hinrichs On Recklinghausen improved
on Riva Rocchi's design by making the cuff eier. Soon
this device was being introduced into other parts of the world.
Theodore Janeway and Harvey Cushing helped popularize it in the
(14:08):
United States. Until this point, most non invasive blood pressure
measurements that involved feeling a person's pulse or less frequently
using some kind of device to create a graph. And
n OH five Nikolai Kortakoff used ascultation, or listening, paying
attention to the sounds of the turbulence in a person's
(14:29):
artery while inflating and deflating the cuff. He noticed a
distinct set of sounds depending on how much pressure the
device was exerting on a person's arm relative to their
blood pressure. He was using a stethoscope to do this. Obviously,
with the cuff on but not inflated, there was no sound.
(14:49):
If the cuff was inflated to a greater amount of
pressure than the person's systolic blood pressure, there would still
be no sound because no blood could get through. But
as he reduced the press sure again he started to
hear sounds as small amounts of blood were able to
get through the artery with each heartbeat. That onset of
sounds marked the person's systolic blood pressure. These sounds went
(15:13):
through a series of changes as he further reduced the
pressure in the cuff, and then the sounds would disappear entirely.
And the point where the sounds disappeared was the person's
diastolic blood pressure. It's the blood pressure in between heartbeats.
I don't think we've said before. These sounds are still
known as corticough sounds today. They are still used when
(15:33):
somebody is measuring blood pressure using us big momentometer and
a stethoscope. There are some variations that exactly when in
the cycle people think is the best time to say
that's the diastolic blood pressure. Though, as has been the
case with so so many other medical innovations on the show,
even though this provided a practical, reliable, noninvasive way to
(15:56):
measure most systolic and diastolic blood pressure, the medical commune
it he did not adopt it right away. Some doctors
just didn't like the idea of using a device like
this in medical practice. In the words of an article
in the British Medical Journal, by using machines as part
of medical diagnosis, quote, we popularize our sense and weaken
(16:16):
clinical acuity. Others just thought that a doctor's fingers were
a better, more sensitive tool than a stethoscope. There were
also people who had been using things like spigma graphs
or other devices, and they felt like the spigmommometer was
making things too easy. Like I said earlier, spigmo graphs
could require a lot of technical skill and precision to
(16:37):
set them up and use them correctly, and so there
was this sense that by being simpler and easier to use,
the sphigmo mimometer would just make the practice of medicine
less prestigious. The sphigmommometer made it much easier to measure
more people's blood pressure, though, so over the first three
decades of the twentieth century, researchers started seeing lots of
(17:00):
connections between high blood pressure and heart diseases, strokes, and death.
This was all happening in spite of the controversy over
this figmomnometer that was playing out in the medical community,
because most of this research was happening actually in another
industry entirely, and that was the life insurance industry. Life
(17:20):
insurance companies wanted to make sure that as often as
possible the people they were covering had a long life
and paid lots and lots of premiums before their policies
had to be paid out. So by the end of
the nineteenth century, assessing a customer's health had become an
established industry practice. If somebody wanted insurance, they would be
examined by an insurance company physician, and then underwriters would
(17:44):
use the physician's report to decide whether ensuring this person
was an acceptable risk for the company. Over time, all
this data would inform things like actuarial tables that the
company could use to estimate how long a person could
be expected to live. Here in the US, it's pretty
much still how it happens today, although there are plans
(18:05):
that don't require physical exams, and a lot of plans
that are offered through employers as an employee benefit don't
require an exam below a certain monetary threshold. In nineteen
o six, Northwestern Mutual Life Insurance Company started measuring the
blood pressure of all of its clients as part of
their insurance applications. Other insurance companies followed suit. In nineteen eleven,
(18:30):
Dr J. W. Fisher, medical director of the Northwestern Mutual
Life Insurance Company, gave an address before the Medical Directors
Association which set, in part quote, no practitioner of medicine
should be without a spigmomanometer. He has in this instrument
a most valuable aid in diagnosis. This figmomanometer is indispensable
(18:51):
in life insurance examinations, and the time is not far
distant when all progressive life insurance companies will require its
use in all examine nations of applicants for life insurance.
By the nineteen thirties, the life insurance industry had gathered
data from more than ten million people. They're putting together
(19:11):
reports on that data, and it showed clear connections between
high blood pressure and other diseases, including cardiovascular diseases and
kidney disease. There was also a clear correlation between high
blood pressure and a shorter life expectancy. This data still
had some big limitations though. Number One, These companies were
(19:31):
primarily ensuring white people, specifically white men, as we talked
about in our episode on Maggie Lena Walker. There were
mutual aid organizations, fraternal orders, and other organizations that offered
insurance to people of color, but they were not included
in this data set. Number two. As the company saw
correlations between hypertension and early death, they started declining coverage
(19:55):
for people whose blood pressure was too high. Number three.
There was a lot of ongoing follow up. People were
either approved for insurance or they weren't, and unless people
wanted to change their coverage and that change required another examination,
the company did not check in on them again until
they died. Although the life insurance industry had a wealth
(20:16):
of data suggesting a connection between high blood pressure and
other diseases and reduced life expectancy, there was still a
lot of debate about all this in the medical community.
Measuring patients blood pressure eventually did become a standard practice
and by the nineteen teams, at least some doctors and
researchers thought high blood pressure should be classified as a disease,
(20:38):
but there was a lot of disagreement about how to define.
High blood pressure is generally measured in millimeters of mercury,
and the idea that one twenty over eighty millimeters of
mercury was normal that showed up pretty early in this
whole process. But some experts in the early twentieth century
thought that normal got higher as people age, and various
(21:01):
researchers cited numbers as high as one eight over one
ten as normal. There also was not a consensus about
what caused high blood pressure, or whether high blood pressure
was really the body's compensation for something else, so a
lot of doctors thought lowering a person's blood pressure might
do them more harm than good, because what if their
(21:22):
blood pressure needed to be that high to move their
circulation through clogged or hardened arteries, for example. To add
to all of that, there weren't really effective treatments for
hypertension at this point, even if a doctor wanted to try.
The idea that salt intake, or more specifically sodium might
cause high blood pressure that had been around since nineteen
(21:44):
o four, when l Umbard and E. Bojard published Cause
de lie potension on arterial so based on that, doctors
often advised patients whose blood pressure was high to reduce
the salt in their diets. But there had been pay
Shans and that first study by Ambard and Bojard whose
blood pressure did not increase with their salt consumption. These
(22:07):
low salt diviots could also be really hard to stick to.
Plus there was i mean evidence going back from this
very first study that they might not work for everybody.
Doctors also tried various drugs to lower blood pressure in
the early twentieth century and found them to be only
somewhat effective at best. On a lot of these drugs
(22:28):
had serious and sometimes dangerous side effects. So with all
of that in mind, a lot of doctors thought that
as long as a patient wasn't showing other symptoms, their
blood pressure should be left alone. In British cartiologist John H.
Hay wrote an article in the British Medical Journal that's said,
in part quote, there is some truth in the saying
(22:50):
that the greatest danger to a man with high blood
pressure lies in its discovery, Because then some fool is
certain to try and reduce it. Sometimes that first part
of the quote is left out, making it seem like
the saying he was quoting was actually his entire statement,
and that he thought it was foolish to try to
reduce blood pressure. But this was in the context of
(23:10):
an article that started quote, no one can now afford
to be indifferent to the problems associated with variations in
blood pressure. For a high pressure is an abnormality which
always demands investigation, supervision, and careful treatment. American cardiologist Paul
Dudley White echoed Hayes sentiments a few years later in
(23:31):
nine seven, quote, the treatment of hypertension itself is a
difficult and almost hopeless task in the present state of
our knowledge, and in fact for aught. We know the
hypertension maybe an important compensatory mechanism which should not be
tampered with, even if it were certain we could control it.
A few years after that, though, President Franklin Delano roosevelt
(23:53):
death brought renewed focus to all of this. We'll talk
more about that after a sponsor break. The death of
President Franklin Delano Roosevelt brought some more public awareness to
the risks of uncontrolled hypertension. Roosevelt was first diagnosed with
(24:17):
hypertension in ninety seven, when he was fifty four. At
that time, his blood pressure was measured at one sixty
two over. No treatment was prescribed for him until four
years later, when his BP was measured at one over
one oh five. As we said earlier, though at this
point treatments for hypertension were really limited, so the President
(24:39):
was put on a low fat, low sodium diet. He
was advised to rest and get massages, and he was
put on the barbiturates phena barbital, which today is most
often used to treat seizure disorders as well as anxiety
and sleeplessness. This course of treatment was not effective, and
in February of nine, Roosevelt's blood pressure was measured at
(25:01):
two sixty over one fifty. He was also starting to
show signs of heart and liver failure. He attended the
Yalta Conference, which was a meeting of Allied leaders to
discuss the post World War two reconstruction, and other people
present expressed concerns about his health, including doubts about whether
he was cognitively alert. During that meeting, Winston Churchill's physician
(25:25):
remarked that Roosevelt looked like a man who only had
a few months to live. His blood pressure was not
the only thing involved in his overall health, but that
is the focus of this episode, so that sort of
sticking to On April twelfth, Roosevelt reported a bad headache
while he was sitting for a portrait. His blood pressure
was recorded at that time at three hundred over one.
(25:50):
Not long after that, he lost consciousness and died at
the age of sixty three. No autopsy was performed, but
his cause of death was reported as a cerebral hemorrhage.
It's a logical conclusion to draw from the symptoms that
were shown at the time. His physician, Admiral Rossty McIntyre,
reportedly said that this quote came out of clear sky.
(26:11):
Even though the president's blood pressure had been escalating for
years and was three day there was still a lack
of medical consensus about what to do about high blood pressure.
Though Tyson's Practice of Medicine is a major medical textbook
and in its edition had this to say about hypertension. Quote,
(26:32):
may not the elevation of systemic blood pressure be a
natural response to guarantee a normal circulation, To the heart, brain,
and kidneys. Essential hypertension. Over zealous attempts to lower the
pressure may do no good and often do harm. Many
cases of essential hypertension not only do not need any treatment,
(26:53):
but are much better off without it, so it was
pretty clear at this point that more medical research was needed.
There was a rice based diet developed by Walter Kempner
that was sometimes effective at reducing a person's blood pressure,
but it was extremely restrictive and not usually sustainable over
the long term. Various drugs are being used to try
(27:14):
to treat hypertension, but at this point they all had
some pretty unpleasant or even dangerous side effects. Ralphina serpentina
or Indian snake root, was developed into an anti hypertension
drug Resurping in India, and while it could lower a
person's blood pressure, it didn't work for everyone, and it
was also associated with things like vomiting, nightmares, and chest pains.
(27:36):
Hadrolyzine was a vasodilator that could cause headaches and rapid heartbeat,
and at large doses could cause a syndrome that resembled lupus.
Hexamathynium was a ganglion blocking agent that had to be
administered as injections, sometimes multiple times a day. There were
also attempts to control people's blood pressure through surgeries. One
(27:57):
was sympathectomy, or severing sympathetic nerves near the spine. Another
involved the removal of the adrenal glands. While a person's
blood pressure might be lower after one of these procedures,
this definitely was not true for everyone, and these procedures
were also really risky and irreversible. There are a lot
of things that were just regarded as quackery also, and
(28:19):
we are not getting into any of that. In President
Harry Truman signed the National Heart Act into law. This
law noted that diseases of the heart and circulatory system
had become the leading cause of death in the United States.
This law established the National Heart Institute and the Public
Health Service, as well as the National Advisory Heart Council.
(28:43):
The Framingham Heart Study was launched soon afterwards with the
goal of determining the causes of heart disease. The Framingham
Heart Study is actually still ongoing today. They're on their
third generation of research participants. Through the Framingham Heart Study
and other large scale long term study ease it became
increasingly clear that hypertension could cause heart and kidney problems,
(29:05):
including issues like left ventricular hypertrophy, and that lowering a
person's blood pressure could help prevent and sometimes even reverse
these issues. But actually reducing people's blood pressure continued to
be really difficult, so many doctors continued to treat hypertension
only if it seemed to be causing some other issue.
(29:25):
When hypertension wasn't being caused by some other disease or disorder,
it was increasingly known as essential hypertension, and many doctors
saw it as just an inevitable part of aging. That
started to change in the fall of nineteen fifty seven
when a clinical trial started for a diuretic called chlorothiazide.
(29:46):
This wasn't intentionally intended to be used as a treatment
for hypertension. Was the diuretic that doctors were prescribing to
patients who had edema due to congestive heart failure. But
when doctors gave their patients this medicine, they noticed that
their blood pressure dropped dramatically in night. This became available
at pharmacies under the brand name di a Ill. This
(30:08):
was during the massive boom in pharmaceutical development that took
place during and after World War two. So many new
drugs and classes of drugs were developed during this period,
several of which have come up on the show before.
Antibiotics entered mass production during the war and flourished afterward.
The first oral contraceptive was approved in nineteen sixty after
(30:31):
having been used to treat various gynecological disorders for a
few years before that. Tranquilizers were also introduced during this era,
which we talked about in our two parter on the litamide.
So Diarill was introduced at a time when there was
just an increasing focus on the idea that chronic illnesses
and conditions could be treated or controlled using pharmaceuticals. It
(30:54):
played a really big part in that shift. At this
point in the United States, the pharmaceutical industry not advertise
drugs directly to consumers, but merk Sharp and Dome, which
was the company that developed Direll, did things like distributing
research reports to science writers, which led to favorable write
ups in publications like Readers. Digest Mark also advertised to
(31:17):
doctors in medical journals, and they created a character called
di a rill Man as part of this campaign. This
was a transparent illustration of a man with the heart
and lungs and urinary system visible in that illustration. Di
arell Man became one of the first examples of a
physical gift that drug sales reps would leave with doctors.
(31:39):
This is a little transparent desk figuring about six inches
tall that had these organs visible on the inside of it,
and it was mostly filled up with water. I want
one so bad now you might be able to find
one on eBay. Oh, I'm gonna go looking. Although di
arell could still cause side effects like lightheadedness and digestive problems,
(32:00):
it was overall more broadly effective than the earlier drugs
that were used to treat hypertension, and those side effects
were generally less serious and more widely tolerated. This made
it possible to get a lot more data about what
worked and what happened when a person's high blood pressure
was lowered. As direl was making its way to market,
(32:20):
Dr Irvine Page proposed the mosaic theory of hypertension. This
built on ideas he had started putting forth as early
as ninety seven, and he argued that there were multiple
interrelated factors at work in maintaining the bodies blood pressure equilibrium.
You thought that blood pressure involved genetic, environmental, anatomical, adaptive, neural, indocrine, humoral,
(32:44):
and hemodynamic factors. You can get a direl man for
just like twenty five bucks. Di arell marked a major
shift in the treatment of hypertension, and thanks to that shift,
it's tricky to do a historical playbi a of all
the new developments since then, even just as highlights, because simultaneously,
(33:05):
so much has happened in terms of drug development and
research into hypertension, and so much is still unknown. Like
diarrhal and other, diuretics were just the first class of
drugs developed to treat hypertension. Today there are at least ten,
including beta blockers, ACE inhibitors, and calcium channel blockers, most
(33:26):
of which were introduced over a period of only about
thirty years. The availability of these drugs and others made
it possible to conduct things like randomized, placebo controlled, double
blind trials of hypertension treatments. The first of these were
conducted through the US Veterans Administration. These studies have provided
(33:46):
clear evidence that reducing moderate and severe hypertension is beneficial
and can prolong people's lives. Based on this and other data,
widespread public education campaign started in the nineteen seventies for
both doctors and the general public. This includes the National
High blood Pressure Education Program, which launched in the US
(34:07):
in nineteen seventy two. There have also been so many
other studies since then, including other studies at the v A.
They've looked at so many questions around things like correlations
with other conditions, race, gender, the efficacy of different drugs, diet, exercise, age,
tobacco used, diabetes, on and on and on. Through this research,
(34:30):
guidelines for how to define high blood pressure and how
to treat it have become increasingly aggressive and specific. For example,
in the US, the Joint National Committee on Prevention, Detection, Evaluation,
and Treatment of High blood Pressure issued its first report
in nineteen seventy seven. This report suggested that a person
(34:50):
who's blood pressure was one sixty over ninety five should
have it checked again in a month, while people fifty
and under should be checked every two to three months.
If their blood pressure was between one forty ninety and
one six probably not how a doctor would approach it today.
It's definitely not how my doctor did. And this report,
(35:11):
treatment was recommended only if a person's dia stylic blood
pressure was greater than or equal to one oh five.
Those numbers have dropped repeatedly since the seventies. Most recently
in seventeen, the American Heart Association and the American College
of Cardiology announced new guidelines that defined normal blood pressure
(35:31):
has less than one twenty over eighty, and everything above
one thirty over eighty is classified as some variety of hypertension.
A systylic reading above one eighty and a dia stylic
reading above one twenty either of those that's classified as
a hypertensive crisis, and the American Heart Association advises people
(35:51):
to contact their doctor immediately if this happens to them.
This is so radically different from earlier eras when there
were studies that classified one eight over one ten as normal.
There is also various conventional wisdom around hypertension that still
isn't fully supported or understood. We noted earlier that a
possible connection to sodium was first proposed in nineteen o four.
(36:15):
Today you can read all kinds of extremely authoritative, yet
totally contradictory, peer reviewed papers that describe sodium as everything
from the single biggest contributor to hypertension in the entire
world to something that can contribute to hypertension in some people,
but only if they are sensitive to sodium yets. I
(36:37):
found this very frustrating as I was trying to get
to this part of the episode. Another bit of conventional
wisdom has involved associating high blood pressure with being overweight,
and with recommendations for people to lose weight included as
a way to try to control their blood pressure. But
that is seemingly not as straightforward as all that number
(36:58):
one and abody can have high blood pressure regardless of
how much they weigh and number two. For a long time,
there was really only one size of blood pressure cuff
that was being used, and it was really too small
for people with bigger arms. It gave artificially high readings
for people who weighed more. Blessed people tends to weigh
(37:19):
more as they get older, and some of the very
earliest actuarial reports about this noted that quote the increase
of blood pressure with increasing percentage of overweight is exaggerated
because of that interaction between people's age and their weight. Today,
researchers are looking at people's genetics, salt sensitivity, congenital factors
(37:40):
like birth weight and stress during fetal development and so
many other factors. But the reality at this point is
that for the overwhelming number of people who have hypertension,
we don't know exactly why. We really don't know. It's
also frustrating. Also, while the blood pressure cuff has been
a stay entered piece of equipment for doctors and nurses
(38:02):
and various other health and medical practitioners for more than
a century, there are improvements in the works for that
as well. So beyond just cuffs that inflate themselves and
then give a readout of blood pressure and pulse on
a screen like I've been using at home as my
doctor instructed, there are also efforts to make noninvasive blood
pressure measurement tools that don't actually require a cuff at all.
(38:26):
They would work a little more like a pulse oxometer
that goes on a person's fingertip. That technology also needs
some work. Uh. We know at this point that pulse
oxometers often don't give readings that are correct on people
with darker skin, So there's there's a whole confluence of
things to keep in mind. There there are some finger
monitors that have already hit the market at various points,
(38:48):
but they've generally been seen as less accurate than monitors
that use a cuff, and then rist monitors that are
also on the market today are similarly seen as less
accurate than ones go around the upper arm. Um. There
would be a lot of pluses to having an accurate
way to measure blood pressure that didn't require a cuff,
(39:11):
in part because try and put a cuff on yourself
is annoying. So that's um. That's the brief history of hypertension,
especially up through the introduction of di rill. Uh. This
is not a solicitation for advice about my blood pressure.
Please and thank you. Tracy has a doctor. I sure
(39:35):
my doctors on the ball with my blood pressure. Do
you also have listener mail I do? This is from Samantha.
This is one of many, many, many notes that we
got about this. It was something that had crossed my
radar first thing in the morning. Um, and I'm sure
I will say it again on a future installment of
on Earth, but this the next Unearthed, is all the
(39:56):
way in October, and I would rather say something about
it now. So Samantha wrote, hello there. I came across
this article today and remembered that you both had done
an episode to part if I remember correctly on Jim Thorpe.
You probably already saw it, but I thought i'd pass
it along just in case. I'm always behind on the podcast,
so my apologies if it's already been mentioned. Can't wait
to hear more. And Samantha sent an article about Jim
(40:20):
Thorpe's Olympic record being restored. Jim Thorpe is the subject
of the only three parter we have ever done on
the show so far, and one of the things that
we talked about was a whole controversy involving whether some
of his athletic participation disqualified him from being an amateur athlete.
(40:41):
And so just on I think what was gonna be
the one anniversary of one of his Olympic wins, um
his Olympic record was restored. So uh, I'm sure I
will have a more thorough discussion of that at the
next un Earth, which is not until October, so it
(41:02):
was too good of a thing to wait until them.
If you would like to send us a note about
this or any other podcast, where a history podcast that
I heart radio dot com and we're all over social
media at miss in History. You'll find us there for
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wherever else you like to get podcasts. Stuff you Missed
(41:27):
in History Class is a production of I heart Radio.
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Hosts And Creators
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Tracy Wilson
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