It turns out that the classic red heart symbol we see almost everywhere around Valentine's Day doesn't look much like a real human heart at all.
"Of all the theories about where that symbol comes from, my favorite is that it is a representation of a sixth century B.C. aphrodisiac from northern Africa," says Stephen Amidon, a novelist and co-author of The Sublime Engine: A Biography of the Human Heart. "And I kind of like that history because it sort of suggests that early on, people sort of understood the connection between love and the heart."
Stephen Amidon wrote the book — which traces the story of the human heart through the world of science, history, culture and our bodies — with his brother, Thomas, a practicing cardiologist in Montana and a former medical director of The Hope Heart Institute.
"Ironically, I did an angiogram on a patient last week who had very calcified and hardened arteries that were almost precisely in the shape of the Valentine heart," Thomas tells NPR's Scott Simon. "But I don't think the early depicters of that heart shape had access to the same view of the heart that I have."
A Heart Without Feeling?
Some of the early physicians of the Renaissance didn't have the medical skill or knowledge to care for traumatic injuries to the heart. And in some cases, they didn't even know what they were looking at inside the body.
Stephen Amidon recounts the story of Hugh Montgomery, a young 17th-century Irish nobleman who fell from his horse onto a fence, opening a hole in his chest that doctors couldn't close. But the young rider didn't die — he actually got better.
"And yet he had a hole in his chest, which exposed some inner workings," Stephen says. Later in life, the boy's father fashioned a metal plate to cover the injury. "But if you took that metal plate off, you could actually see something in there."
Until his young adulthood, people thought it was his lung. The boy toured Europe, selling out theaters where he would remove the plate to show the insides of his body working.
"It wasn't until Sir William Harvey, the greatest of all cardiologists, took a look inside his chest that he realized it wasn't the lung at all that they were looking at — it was the heart," Stephen says. "And this was really the first time anyone had seen the actual working of the heart."
He'd even let people reach in and touch his heart — and he wouldn't feel anything.
"I encounter this on a regular basis when I perform procedures on patients," says Thomas Amidon, the cardiologist. "When I put catheters inside them, they're amazed to realize that they're not going to feel it inside their body. They may feel the initial needle puncture when I put a catheter in their artery, but when I'm up inside placing catheters inside the heart, taking pictures inside the heart, there is no innervation on the inside of the heart — you don't feel it at all."
Technological Advancements In Cardiology
Weighing in at a mere 15 ounces, the heart beats roughly once per second — that's about 2.5 billion times during an average lifetime — and it pumps 74 gallons of blood through the adult body every hour, the Amidons write.
Thomas says that one of the remarkable advances in medical technology was the ability to stop the heart during an operation. It was the development of the heart-lung machine in the 1950s, he says, that allowed surgeons to stop the heart and operate on it.
This technique was crucial for a Minnesota surgeon named C. Walton Lillehei, who pioneered the treatment of congenital heart defects. In 1954, Lillehei needed to patch a hole in the heart of an 11-year-old boy. He began the operation by connecting the circulatory system of the boy to his father.
"So the father actually became the heart-lung machine that allowed Lillehei to have the 18 minutes or whatever it took for him to fix the hole in the boy's heart," Stephen says. He went on to perform the operation on numerous sick and dying children — many of them babies. The practice of cross-circulation, as it was known, was later abandoned because it became too risky for both the adult and the child.
"The irony, of course, is that now, in 2011, we're working diligently on techniques to operate on the heart without having to stop it," Thomas says.
As for artificial hearts, Thomas says the difficulty isn't in devising a pump — "that's been pretty well worked out," he says — it's finding a way to have the blood that flows through the system not cause problems, like blood clots.
The Heart's Staying Power
But as heart transplants, surgical techniques and mechanization become more commonplace, will the heart lose any of its cultural and metaphorical significance? Stephen Amidon doesn't think so.
"One of the things that surprised me during the course of writing this book was how durable the heart's metaphorical power has been — not just in the past 50 years in the great explosion of cardiology, but in the past 500 years since the great anatomists of the Renaissance began opening up bodies and began looking at the physical heart," he says.
Even as all this was happening, the heart has retained its metaphorical power.
"So perhaps there will be a day when we no longer touch our chest and kind of nod, and people understand we're talking about qualities that can't be explained by medicine — we're talking about courage or devotion or inspiration," he says. "You can have a situation where someone receives an artificial heart, and afterward goes to their surgeon and says, 'I thank you for this from the bottom of my heart.' This will make complete sense to us."