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Heart attacks are the number 1 cause of death worldwide in the 21st century.
And based on studies of mummies and written records from various civilizations,
this is nothing new:
People seem to have been suffering heart attacks since ancient times.
But for most of human history, heart attacks were basically a mystery.
All anyone knew was that people could get sudden chest pains and sometimes,
but not always, that killed them.
Luckily, a lot has changed.
We now have an intimate understanding of how the heart works, and how it can fail.
And how we got here is pretty remarkable.
For most of human history, the chest was a bit of a black box.
It took time for scholars, including Arab and Renaissance European folks
starting around the 1200s, to break down various cultural and religious taboos
around autopsies and make them more of a thing.
By the end of the 18th century, a number of doctors and scientists had noticed
a possible connection between fatal chest pains and problems
in the blood vessels surrounding the heart.
For instance, some, like British physician Edward Jenner, noticed that the arteries
that fed the heart could become narrow, stiff, and full of fatty plaque.
This blockage could cut off part or all of the blood flow to the heart.
And by the late 1800s, this narrowing of the arteries
was recognized as the cause of fatal heart attacks.
This was a huge step forward. But there were still a lot of questions.
Like, doctors kind of assumed this sort of blockage would always be fatal, so they
weren’t sure what was going on in people who survived this kind of chest pain.
Some people had also noticed the presence of blood clots
in these blood vessels during autopsies, but not always.
And it wasn’t clear if clots were a cause of the heart attack or an effect.
We also didn’t really have a lot of good ways to investigate these questions
in living people, but that changed soon,
thanks to both more observation and a few advances in technology.
One important advance came in the early 1900s, with the invention
and adoption of the electrocardiogram, known by the initials ECG or EKG.
This device records the heart’s electrical signals.
A healthy, working heart would produce a repeating, predictable pattern
on an ECG, but in heart disease produced different patterns.
This made it possible for doctors to distinguish
hearts with heart disease from healthy ones.
Another breakthrough came when doctors discovered they could inject dyes into
the arteries around the heart and then use X-rays to see how blood was flowing.
The first time they did this was actually an accident, and the doctors who did it
were afraid that they had killed their patient, but they did not.
And their discovery would go on to help other doctors see blockages in living people.
Over time, these tools combined with other lines of evidence
proved that people could, in fact, survive certain blockages.
It also gave doctors better ways to diagnose heart attacks as a specific problem
separate from other conditions that can cause chest pains, like an injured rib or a hernia.
It also helped them identify risk factors and ways to help people survive attacks.
There was still the question of those blood clots, though,
like the ones Edward Jenner noticed way back when he was doing autopsies.
Like, were they part of the cause?
Something that happened later?
What was going on with them?
By the 1970s, scientists had started to believe they might be part of the cause,
but a 1980 study really sealed the deal.
In it, doctors used X-rays to examine the hearts of over 300 heart attack survivors,
within 24 hours of an attack.
And they almost always found clots that seemed to clear up over time.
That pretty clearly suggested that the clots were causing the heart attack
and not just happening hours or days after the fact.
If they were developing after the attack,
the scientists would expect to see them get worse over time, not better.
So, finally, after centuries of work, scientists had figured out the cause of heart attacks.
It wasn’t always a linear process, but in the end, we had a clear picture.
The heart is fed by blood vessels that bring oxygen and nutrients to the muscle
cells and take away waste, but these blood vessels can become stiff
and narrow over time, often due to a build-up of plaque.
If this blocks blood flow, or if a blood clot forms and gets stuck
in the narrowed artery, the muscle cells in the heart
can quickly become starved and begin to die, causing a heart attack.
That was over four decades ago, but even though we can now definitively say
what heart attacks are and what causes them, there’s still a lot of work to be done
before they’re no longer topping those cause of death statistics.
Fortunately, what we have learned makes it possible for doctors
to keep an eye out for people who are developing blockages
and offer them ways to protect their hearts before it is too late.
Which is a good reminder of how astounding it is to live in a time
where we know just so much about the human body.
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