1
DARKNESS BEFORE DAWN
The human heart has hidden treasures,
In secret kept, in silence sealed.
—Charlotte Brontë, “Evening Solace,” 1846
Before I walked into my patient’s room, I huddled outside with the rest of the team to make sure we were all on the same page. He had come to the hospital after he had caught a serious infection while on a cruise with his wife in the Caribbean. Tests confirmed that he had bacteria growing in his blood, which he had likely contracted from using a catheter to urinate while on the cruise. We treated his infection with antibiotics, but what we couldn’t fix was his heart. He had been seeing a cardiologist regularly for his feebly beating heart, had been taking heart medications for decades, had even received a special pacemaker to help his heart beat synchronously. Despite all that had gone into trying to overcome his weakening heart, he was now fast approaching what seemed to be an imminent end. The entire medical team was convinced he didn’t have long to live, maybe a few months at best. Everyone nodded in agreement one final time, like a football team about to take the field or a group of paratroopers about to leap from the back of a plane. After we filed into his room and made the customary introductions, the team settled in like a dense air freshener. As we had decided, I started talking, slowly.
“While you have recovered well from your infection, the one thing we cannot help you recover from is your heart failure.”
“Wait—what—I have heart failure?” he asked abruptly. Startled, he looked to his wife, who started crying. “He has heart failure? No one told us he has heart failure! What is heart failure?” she wailed.
I was completely taken aback. These conversations can sometimes take their time to come to a full boil, but in this instance, it had bubbled over almost as soon as the stove was lit. The patient had been living with heart failure for almost two decades, and by all accounts, his cardiologist had been managing his heart failure diligently, yet somehow, the man had no idea what it was or what it meant, and worst of all, it appeared as if no one may have ever told him either. For some reason, the words heart failure had never been used around him. I had to back up, change gears immediately, and scrap the conversation about his mortality for another day. But that day never came—he died two weeks later in the intensive care unit.
More people die of heart disease than any other disease in the world, including even cancer. In fact, deaths from heart disease are on the rise around the world and in the United States as well.1 When any heart disease becomes advanced enough, it frequently results in the development of heart failure. In the United States, heart failure is the most common reason for admission to the hospital.2 Heart failure strikes both the abject and the affluent, the young and the old. In the past few years, both the pop singer George Michael and former first lady Barbara Bush died of heart failure. And yet, in many ways, heart failure is a disease few know about and fewer still understand. Even though the words heart failure are more likely to show up in common use these days than in times prior, many continue to ask the same question as my patient’s wife—what is heart failure?
Heart disease, in many ways, is the overlooked affliction of our times. That seems like a curious thing to say for a disease that touches so many, young and old, man or woman, black or white, rich or poor. And even as the number of people dying from heart disease continues to rise. Many proclamations of the end of heart attacks have been made. And such pronouncements are having an effect; funding for research for heart disease and the development of new innovations for heart disease continues to lag behind other diseases such as cancer.3 Fewer therapies are in development for heart disease today than before.4 This is driven by many thinking of heart disease as a battle that has already been won, with funding being increasingly diverted to other conditions such as cancer, dementia, and diseases such as amyotrophic lateral sclerosis (ALS). Breast cancer, for example, receives seven times more research funding than heart disease for every death that it causes.5 The media is far more likely to play up incremental and unproven advances in other diseases while ignoring proven and lifesaving therapies for heart disease.6 Many people think that when people get heart disease, it is their fault and, increasingly, as treatments get better for heart disease, people acquire it in older age rather than in their younger years.7 Even some of the leading experts in cardiovascular research are not optimistic about the future of research in heart disease. And despite the amazing reduction in the death rate from heart disease over the past few decades, the last few years have seen that progress effectively plateau and even some disconcerting reversal occur in the rate of death from heart disease.8
And yet, the present and future of how we can treat and prevent heart disease have truly never been more awe-inspiring. There is almost no parallel in human progress that mirrors how we have managed to change a heart attack from a death sentence to something that for the most part can be managed safely. Just over the past few years, I have seen technology become commonplace that could easily have been conflated with science fiction.
The heart, that muscular organ beating in your chest as you read, sending pulsations throughout your body, is perhaps the part of the body most associated with life at both ends of human existence. Hearing a heartbeat has become a rite of passage for anyone who becomes pregnant. When my wife got pregnant, it wasn’t until our visit to the gynecologist at the eight-week mark that we heard that machine-gun-like heartbeat and the pregnancy was truly confirmed and we breathed a sigh of relief.
On the other end of existence, when someone falls to the ground unconscious, the reflex of anyone with an ounce of knowledge about the human body will be to reach for their wrist and feel for a pulse. If there is a pulse, there is life. If there is no pulse, there is no life, and hopefully someone is straightening out their elbows and locking their fingers as they get ready to perform cardiopulmonary resuscitation.
The pumping heart keeps the circulation of the body going. Blood seeping through the vine-like arterioles webbed through the lungs picks up oxygen that we breathe in. These vines then merge to form bigger vessels, which lead into the left side of the heart. The left side of the heart, the most muscular part of the heart, then pushes the blood to every part of the human body, from the kidneys, to the intestines, to the limbs, and all the way to the tips of the toes and fingers, but most importantly, to every vital nerve cell in the brain. These organs suck out oxygen from the blood like you would the last bit of that Slurpee with a spiral straw. This oxygen-deprived blood is sucked all the way back to the right side of the heart, which then squeezes this oxygen-poor blood into the vine-like arterioles lacing the lungs to fill up on oxygen.
The constant circulation of blood is like a divine, life-giving pilgrimage. When blood reaches the lungs, the temple of life, each red blood cell—all five million or so of them—squeezes into teeny-tiny alleys as opposed to the large highways it drove in from. These tiny alleys are called capillaries. It is in these capillaries that each and every red blood cell comes face-to-face with the invisible source of life—air. The air that we breathe in remains confined to tiny sacs of air called alveoli, which look like a bunch of grapes at the end of a stem. These alveoli are wrapped by the capillaries. So here the capillaries and alveoli come up right against each other, but they never mix, never touch the other. And yet, because of how thin the membranes that separate the two are, the red blood cells are able to absorb oxygen from the air, while unloading the carbon dioxide they are burdened with in exchange for the oxygen they have previously delivered to the tissues of the body. In essence, each and every one of the millions of red blood cells is cleansed, and their sheen so visible, so evident, that the blood actually changes color, from the dull and murky maroon of oxygen-deprived blood in the veins to the flush and vibrant crimson of oxygen-rich blood cruising through the arteries.
The heart is not the temple, but it is the stream that keeps this pilgrimage flowing uninterrupted. The heart is so essential to life that within seconds of its stopping, the body starts to undergo irreversible damage. It is a miracle that the heart, which beats more than two billion times in an average human being’s lifetime, doesn’t ever stop unless catastrophe happens.
The heart is one of the most complex structures in the human body, in charge of an incredibly high-stakes job. It is one of the first organs that forms in the growing human fetus. Although initially it starts off as one long tube while in the fetus, the heart folds in on itself, undergoing a dramatic but meticulous transformation, emerging as the four-chambered heart we are familiar with. The more one studies it, though, the more one is drawn into its complex yet elegant mechanisms. Every bit of the heart serves a purpose, and any small deviation can result in life-threatening consequences. This is particularly true when the heart is forming in the fetus.
How the fetus just knows what to do as it constructs itself out of a single embryonic cell into the most complex piece of organic machinery in the known universe is something that is worth pausing for. Without almost any outside guidance, within every human embryo lies all the knowledge needed to build itself. It’s like an IKEA cabinet that can assemble itself just from a single piece of paper with directions on it. The worst a poorly assembled chest of drawers can do is not operate as smoothly as one would like. A poorly assembled heart with even the slightest flaw can be fatal.
Nature gets the heart right 99 percent of the time.9 That sounds pretty great until you realize that in the United States, the 1 percent of children born with congenital heart defects amounts to forty thousand babies a year.10 Most of these defects are not life-threatening and can be easily repaired or, in many cases, simply observed. A quarter of that 1 percent, though, almost ten thousand infants, have critical congenital heart disease, requiring major surgery within the first year of life.
The smallest aberrancy in the human heart can have devastating consequences. Recently, I took care of a woman who had a coronary artery, the teeny blood vessels that supply oxygen to the heart itself, taking a slightly different route. Instead of falling right onto the heart, it coursed between two large blood vessels. This simple rerouting meant that the lifeline to her heart could be blocked off at any given moment as the large vessels pulsated, sandwiching the coronary artery between them, and she needed to have it surgically corrected. Yet advances in surgery now mean that the vast majority of babies born with defected hearts can live into adulthood.
For the rest of the 99 percent, those without any obvious defects at birth, it is easy to think of the heart as perfect. Yet, in nature, there is no such thing as one perfect heart, for there is a different type of perfect heart for every different organism.
Just like there are many animals on the planet, there are different types of hearts.11 A hummingbird has a heart that beats a thousand times a minute, while that of an elephant beats only about thirty times a minute. The heart of a blue whale weighs 1,300 pounds, is as big as a car, and pumps 92 gallons with every contraction, while the human heart pumps only about 70 milliliters with every squeeze. Octopuses have three hearts, two for each gill that serves as a lung, and one for the rest of the body. The Burmese python’s heart can double in size within a day after it has a nice meal like a mouse or even a deer to accommodate for the sudden boost in metabolism before shrinking back to its previous dimensions. And dogs have a bigger heart relative to the size of their bodies than any other mammal, a fact that many dog owners might have already intuited.
So there is no one perfect heart, but each heart seems to be perfect for the body that it dutifully serves. But if the heart is so perfect, why is it that to this day, there are organisms that can exist just fine without one? While many readers have, at various points in their lives, been accused of being so, the truth is that when life started out, all the beasts that wandered the earth or swam in the oceans were heartless. Many of those exist as such to this day, but they are mostly tiny invertebrates. Some heartless organisms, such as sea spiders, actually move oxygen-rich blood within their bodies with the help of their pulsating guts.12 The question—one that is starting to take on even more import as we humans advance to a stage where we can effectively replace people’s hearts—is why do we even need the heart to begin with?
While many think of the heart in isolation, the truth is that the heart is in fact just the most visible part of the entire cardiovascular system. Focusing on the heart is like focusing on the air traffic control tower and ignoring the rest of the airport. Each and every blood vessel in your body, from the artery in your foot that you can feel between the webbing of your big toe and the second digit to the vessels supplying blood to your eyeball, is connected to the heart.
The heart is central to what it means to be human, yet modern medicine, having fundamentally changed how we live in so many ways, is now on the verge of unseating the heart from its throne. Over the past decade, new technology has been developed that allows people to live far beyond when their hearts fail. Heart failure, which used to be a terminal diagnosis, has been effectively transformed into a chronic disease that people live many years with. This technology effaces some of the most elemental aspects of what the heart does. Left ventricular assist devices (LVADs) are mechanical pumps that are surgically sewn into patients’ hearts and take over the pumping function of the heart. If you put your fingers on the wrist of a patient with an LVAD, most of the times you will not feel a pulse. If you put your ear on an LVAD patient’s chest, you will actually hear the pump humming, not the heart beating. When patients with LVADS get really sick, sometimes they don’t need a doctor or a surgeon—they need a mechanic. LVADs are not only changing how patients with heart disease are being treated, they are changing what it means to be human.
Over the past century, heart disease has been the focus of intense scientific scrutiny, and the journey to rid the world of heart disease is very much reflective of the journey of medical science at large. So many issues that are relevant to science—the introduction of empirical testing, the industrialization of the scientific vocation, the epidemic of “fake news” and hype—are most apparent when it comes to heart disease. In understanding how our knowledge of the heart evolved, we inevitably trace the twisting and turning road all the way back, which allowed us to reach our present understanding of our biology and ourselves.
Just during my own training, I have seen the treatments for heart disease change in unimaginable ways. Take, for example, a condition in which the valve of the heart that connects the heart to the rest of the body, the final door the blood has to pass through as it enters the great vessel supplying the body with oxygenated blood, the aorta, becomes really tight. Aortic stenosis most commonly affects us as we get older, typically resulting in the soft and pliable aortic valve becoming hard and calcified. When it’s severe, aortic stenosis can cause very high pressures the heart has to beat against, and it can limit how much blood can be ejected from the heart. Not too long ago, severe aortic stenosis was a death sentence. Then one doctor, who saw one case and was asked one simple question, changed all of that.
Eugene Braunwald is almost ninety years of age and to this day is one of the most prolific cardiology researchers around. Back in 1958, he was working at the National Institutes of Health, in Bethesda, Maryland, and a patient with aortic valve disease was seen by him and a heart surgeon. Aortic valve surgery, which was done through the placement of an artificial heart valve after open-heart surgery, was just in its nascent stage, and the surgeon asked Braunwald, “What would you expect would be his prognosis in five to ten years if we don’t operate?” Braunwald was caught off guard because no one really knew what the answer was. “What the hell are you good for?” he recalled the surgeon telling him when I spoke with Braunwald recently. “You can’t fix the valve, and you can’t even tell me what will happen to this patient if I don’t fix it.” Braunwald then launched a project to understand what happens to patients with severe aortic stenosis and found that once patients develop symptoms such as chest pain, fainting, or heart failure, they pretty much fall off a cliff and die within weeks to months, effectively defining the natural history of the disease.13 Aortic valve surgery, the culmination of decades of technological developments that would have previously been unimaginable, was able to yank people off that ledge and provide them long and healthy lives.
Yet for many patients, aortic valve surgery was a tall task, and too many patients were too sick to be able to get this procedure. On the other side of the Atlantic, the French cardiologist Alain Cribier was planning an entirely radical treatment for severe aortic stenosis. He had devised a procedure in which, through a small incision in the leg, he would introduce a long, thin plastic catheter that would reach all the way up to the patient’s heart and then blow up a balloon across the stiff aortic valve. After Cribier first performed this procedure in 1985, it spread around the world like pandemic flu, but the excitement was short-lived.14 “The procedure appeared to provide only a temporary improvement in symptoms and, at best, a modest survival benefit,” he told me in an email. Blowing a balloon open in a diseased valve was a Band-Aid at best. Cribier’s eventual goal was much loftier: he wanted to transform aortic valve replacement from open-heart surgery to a minimally invasive procedure by “implanting a valve prosthesis within the diseased calcific native valve, on the beating heart, using catheter-based techniques and local anesthesia.” He faced extensive challenges to be able to even imagine what this might look like, but the biggest one had nothing to do with science and technology. “The negative opinion of experts was definitely the greatest barrier,” he wrote to me. “The idea was even considered the most stupid idea ever heard.”
Cribier, though, was never going to take no for an answer. He developed a cylindrically shaped wire frame a few inches in length that housed a valve taken out of a pig or a cow. After a series of experiments in cadavers and animals, in April 2002, he implanted the first such valve in a fifty-seven-year-old man who was dying of severe aortic stenosis and was too high risk for surgery.15 The procedure was so well tolerated that Cribier’s team, in very French fashion, drank “champagne with him, in his room, on the same day.”
Fast-forward to 2010, and I found myself standing in the operating room at Beth Israel Deaconess Medical Center in Boston, where I was doing research, and the first-of-its-kind transcatheter aortic valve similar to the one developed by Cribier was being placed in a patient. It was the first implantation of this valve in the United States as part of a large clinical trial that was just kicking off. The operating room was full of dozens of people with multiple cardiologists, surgeons, and anesthesiologists in attendance. Tension was high, but there was a sense that history was being made. Since then, hundreds of thousands of people have avoided open-heart surgery to receive this procedure that has single-handedly transformed the fate of patients with this life-limiting diagnosis.
To many, the best years of heart science are in our rearview mirror. Eugene Braunwald said, “If I were to start over today, I would choose a career in neuroscience, because the next forty or fifty years will be the golden period for discoveries in treatment of neurologic disorders, just as the last half century has been the golden period of cardiology, even though we have a long way to go.” Yet, as you will find out, the golden age of cardiology is only just beginning, and it could end not by elevating the status of the heart but by entirely usurping it, effectively developing devices that can replace the human heart. Heart disease has been around for a while, but the type of heart disease people have, why they have it, and how it’s treated is changing. And with treatments of heart disease altering the very definitions of human life and death, there is no better time to look at the present and future of heart disease, the doctors and nurses who treat it, the patients and caregivers who live with it, and the stories they hold close to their chests.
2
THE HEART—A LOVE STORY
Hearts are wild creatures,
That’s why our ribs are cages.
—Elalusz
I was sitting in a coffee shop with my wife and baby daughter, our table awash with sunlight, when the barista tiptoed over, delicately balancing the latte my wife had ordered. As he placed the large ceramic cup in front of her, something instantly made us smile. Beneath the reams of steam rising from the coffee, he had drawn an immaculate and whimsical heart in the foam. It made our day.
The heart is as much an organ that keeps us alive as it is a metaphor that helps define some of the most powerful, at times irrational, impulses we feel. It aids songwriters at wit’s end, helping finish unwritten songs. It helps lovers put down in words what only the other can see, the other can feel. One doesn’t even need to know how the heart works, how the heart comes to be formed, and all the beautiful mechanics that constitute its immaculate design to be bathed in its self-evident splendor.
The heart, though, is not just a symbol of beauty or love; the more you understand its actual function, its day-to-day existence manifest in every beat, the more its actual living beauty is actualized. Cardiologists dedicate their lives to appreciating what the heart is and then using that understanding to mend people’s hearts—as much in allegory as in actuality. Between medical school and clinical training, it takes more than a decade to gather all the knowledge needed to be able to diagnose, prevent, and treat all the afflictions the heart can gather over a lifetime of hard, incessant labor.
There are many perks to being a cardiologist, but the one thing that unites us all is our fascination with the sheer, untainted beauty of the heart. Like a labyrinth that goes deeper and deeper, like a code that can never be cracked, the heart is so obvious in its magnificence that it is in its enigmatic details that its intricacy emerges. On any given day, using several different advanced imaging technologies, we get to see the hearts of many beat away, in radiographic loops that seamlessly flow in infinite cycles. At the same time, we talk to patients and their families at length about their cardiac health, the treatments they may or may not be able or willing to get. Interventional cardiologists who do invasive procedures, including inserting miniscule metal stents to open up the blood vessels supplying the heart, get even more up close and personal with the heart. And perhaps, no one is closer to the human heart, and is more aware of its maze of vessels and chambers, than the surgeon who can hold the heart of another in their hands with the human chest splayed wide open.
There are a variety of reasons behind why many choose to go down this path of training, and most of them are less romantic. During the first year of my cardiology training in the middle of the night in Durham, North Carolina, while I slept, on the very other end of the planet in Pakistan, a man in his mid-sixties started to sweat profusely early in the morning. He then felt light-headed and had to sit down to gain composure, not knowing what was going on. His wife, my mom, knew: my dad was having a heart attack. There was no one else at home. She didn’t call the ambulance. She put him in the back of the car and rushed him to the nearest hospital.
About an hour after they had reached the emergency room, my mom called me. During that hour, he’d had an electrocardiogram, which was read by a cardiologist who immediately knew that he was having a heart attack—a serious one. The cardiologist activated the cardiac catheterization lab team, who swooped in and took Dad right in. Within minutes of him getting there, through a small puncture in his leg—using a long, slim, plastic-based catheter—they had made it all the way up to his heart, where they saw a blood clot completely obstructing the main blood vessel supplying it. They deployed a small metallic stent in the blocked blood vessel, restoring blood flow.
When I talked to Dad only moments after the procedure was over, he told me how everyone seemed so calm, that there was no commotion, that they just went ahead and did their jobs. In this instance, their job saved his life, and their timely response ensured that his heart was not affected in any way. All this happened while I was still asleep seven thousand miles away. In modern medicine, where chronic disease dominates, there are few moments one can look back on and truly feel like they saved a life. For those taking care of patients with heart disease, moments like these are not an exception—it is their very job. More than anything, it is for moments such as these that many embark on this journey.
Not all love stories have happy endings, though. My first memory of being in a cardiac hospital is very vivid to this day. I was around six or seven when one of my uncles was admitted to that very same hospital my mom drove my dad to after his heart attack. When I went with my parents to visit my uncle, a curious sign greeted us at the entrance: Children are not allowed in the hospital, it proclaimed. It was too late for us to turn around, so my parents snuck me in, something that was perhaps not so out of the ordinary back in Pakistan. I was walking down the main hallway when suddenly, I heard a loud shriek. Ahead of us, I saw a young woman wrapped in a large shawl who was running from side to side in the hallway, flailing her arms, until she collapsed to the ground. Her family rushed to her and tried to lift her off the floor, but she fought for her right to stay down. She was wailing in a way I could never have imagined would be possible. I had never heard sounds like that coming from a human being, and that traumatic sight lives with me to this day. She had not been as lucky as I would be almost two decades into the future. Her dad never called her after the heart attack—and he never would again.
With time, as our understanding of the heart’s mechanics has changed, this knowledge has also changed the arc of the metaphorical heart. The heart is no longer hallowed ground, but a machine, which breaks down and needs a tune-up once in a while, with pipes that get clogged and that frequently need to be opened up by plumbers. When the heart is weak, the heart doesn’t need love, it needs rocket fuel. In that way, the heart as metaphorical symbol has experienced as much of an arc as has the biological organ it represents.
For physicians and romantics alike, the heart has always been an irresistible, shimmering mirage on the horizon, forever drawing both toward it. The connection between us humans and our hearts always come down to anguish or elation, agony or exhilaration, affliction or enchantment. Never one for the fainthearted, many have trodden this path to unlock the secrets of the heart so as to conquer it, through words or verse and analysis and experiment. Walking back down these footsteps leads us all the way back to ancient Egypt, where the first records of our study of the human heart were unearthed.
* * *
Physicians and surgeons are frequently accused of having a god complex. Not too long ago, though, perhaps many did feel like they were the ultimate authority over their patients and what was best for them. If you look even further back, such as during the time of the pharaohs, physicians were very literally considered gods. Yet it is during that time, thousands of years ago, that we started to take baby steps into understanding the basic fundamentals of how our body works. What is intriguing is that for a long time, we were much better at understanding the universe around us, the one in which we are mere specks, than the universe that existed within.
The unassuming plant growing extensively in the Nile River delta wetlands, Cyperus papyrus, which was used to create the scrolls that allowed for the documentation and preservation of information, is why we can go back in time and tap into the vast wealth of knowledge that was being generated in Egyptian society, which was obsessed with medicine, chemistry, architecture, metaphysics, and the arts. What the Egyptians left behind was not just some of the first formal observations of medical science and the birth of the physicians’ profession but something much greater. Sir William Osler (1849–1919), the famous physician who was one of the founding professors of Johns Hopkins, said in 1913, “In records so marvelously preserved in stone we may see, as in a glass, here clearly, there darkly, the picture of man’s search after righteousness, the earliest impressions of his moral awakening, the beginnings of the strife in which he has always been engaged for social justice and for the recognition of the rights of the individual. But above all, earlier and more strongly than in any other people, was developed the faith that looked through death, to which, to this day, the noblest of their monuments bear an enduring testimony.”1
No one is more singularly associated with the birth of medicine than Imhotep, who lived during the twenty-seventh century B.C. and was one of only two commoners ever elevated to the honor of full deification.2 Considered the Egyptian god of medicine by the people of his time, he was outlived by temples erected in his honor, where the sick and debilitated would come for healing. These facilities were precursors to the modern hospital. Imhotep was much more than a physician: he was the chief minister to Pharaoh Djoser and was the principal designer of the step pyramid, the oldest hewn stone monument still left standing in the world. He truly was a god among men.
While no medical work is directly attributed to him, Imhotep’s legacy was best documented in the Edwin Smith Papyrus, which gives us a glimpse into how medicine was practiced five thousand years ago.3 While dated to the seventeenth century B.C., it is believed to have been copied from a document written possibly by Imhotep himself between 3000 and 2500 B.C.4 The Edwin Smith Papyrus is a methodical analysis of forty-eight cases, ranging from infections to wounds, from the head to the feet, presented in what can now be considered a classic format. Every case has a title, followed by findings on physical examination, followed by one of three proclamations by the physician. When the ailment is one such as a chest infection (case 39), the physician “can handle it,” and treatment is described. When the physician faces an ailment in which cure is not guaranteed, such as a chest tumor (case 45), the physician says that they “can fight with” or “contend with” it. Finally for ailments that just require observation, such as a rib fracture (case 44), these cases are described as those for which “nothing is done.”
The Egyptians got much wrong about how the body works, and those misunderstandings would not be corrected for several thousand years, but they also got much right. The Egyptians were correct in understanding the centrality of the heart in human circulation, and the Edwin Smith Papyrus provided the first account of the human pulse linked to the heart. In poetic hieroglyphs they wrote, “It [the heart] … speaks in every vessel, every part of the body.”5 This might sound intuitive now, but almost a thousand years later, the Greek physician Hippocrates was still adamant that the circulation of blood started in the liver and not the heart.
But what was the heart circulating? The Egyptians thought that the heart was the central organ connected to channels spread throughout the body, transporting air, blood, bile, feces, semen, the spirits, and even the soul to every part of the body.6 They also thought that it was air in the vessels that causes them to pulsate rather than a literal conduction of the heart’s contraction through the arteries of the body. Furthermore, Egyptians, like many others to this day, had difficulty separating the fantastical from the empirical when it came to the heart. Blood, air, and all sorts of other bodily fluids were brought to the heart through a receptor vessel, likely the aorta, and were then transported to organs around the body, never to come back. The soul, while centered around the heart, also had another collection zone around the anus, which is why keeping the anus clean was an essential ritual necessary to cleanse one’s soul.
Over the course of their civilization, the Egyptians continued to keep a magnifying glass on the heart, and their understanding evolved. Even how they drew the heart changed, starting from a blob with eight vessels looking like a latex glove blown up like a balloon to a more realistic jar-like shape. The heart was the seat of emotion and the spirit, a living record of one’s deeds both good and bad, so essential that it was left behind in the chest when bodies were mummified. It was believed that when the deceased were ushered into the hereafter for judgment by Anubis, the canine-headed Egyptian god of the afterlife, the heart of the dead person was weighed on a scale against an ostrich feather. A heart weighed down by sin would be fed to the devourer of the dead, Ammit, the crocodile-lion-hippopotamus hybrid, and the deceased could no longer enter the afterlife and were damned to eternal restlessness. A heart devoid of debauchery, floating like a feather, would allow the deceased entry into the eternal underground, promising an unending life of peace.
Sin didn’t just burden the heart in the afterlife but could actually lead to disease in the mortal life. This concept formed the basis of seminal descriptions of some of the most common heart conditions, such as heart failure, that we see and struggle to treat to this very day.7 These diagnoses were documented in the Ebers Papyrus—one of the longest-surviving papyruses, written almost 1,500 years after the Edwin Smith Papyrus, around 1,500 B.C.—bought in 1873 by the German Egyptologist Georg Ebers from its Egyptian owner and translated by Heinrich Joachim. Many think of heart disease as a modern disease, and yet it has continued to maim men and women for as long as they have had hearts.
* * *
For many, a single degree connects them to the earliest accounts of heart disease and the most primitive ideas about how the body was assembled. For me, it is the wedding ring I have worn so long on my finger that the skin underneath it is slick and several shades fairer than the uncovered rest of my hand. What dates back even longer than my marriage is the tradition underlying why exactly so many wear wedding rings on the fourth digit on their left hands. The answer to that may lie in a roll of papyrus a hundred pages long, written in 1555 B.C. The Ebers Papyrus contains an encyclopedic amount of information, from treatments for night blindness (ox liver) to some of the first descriptions of diabetes, yet it was its description of different types of heart disease that cemented its place in human history.
To this day, there is no image more classically associated with potentially fatal heart disease than a man or woman clutching their chest in pain. The clenched fist over the breastbone, referred to as the Levine sign, is almost synonymous with angina pectoris. Angina, the pressure-like feeling in the chest that frequently travels down one’s left arm and up the neck, occurs when there is a restriction in the blood supply of the heart, which, if it continues unabated, represents a heart attack.
It is important to understand here that even though the heart is pumping blood at all times, this blood does not actually supply the heart itself with oxygenated blood. In fact, the heart muscle is supplied with oxygenated blood from a system of blood vessels referred to as the coronary circulation. Derived from crown, the coronary arteries emerge right from where the aorta leaves the heart and descend on it like ivy embedded in the heart’s wall like termite tunnels. It is these tiny vessels on the outside of the heart where blockages from cholesterol in the blood vessels can cause heart attacks and result in people feeling pain or a pressure-like sensation in their chests. For most of modern times, the discovery and initial description of angina was attributed to British physician William Heberden (1710–1801), in his very vaguely titled paper, “Some Account of Disorder of the Breast,” which he presented to the Royal College of Physicians in London in 1768; it was published in 1772.8 Heberden provided an arresting and incredibly accurate description based off an analysis of only twenty patients: “Those who are afflicted with it, are seized while they are walking with a painful and most disagreeable sensation in the breast, which seems as if it would extinguish life if it were to increase.” While these patients had angina, Heberden felt their pulse and, given the lack of any abnormalities there, incorrectly determined that the pain was not from the heart but from an ulcer in the stomach, yet despite this misattribution, he knew what happened when angina went on unabated. “If … the disease goes on to its height, the patients all suddenly fall down, and perish almost immediately.” After not finding any abnormalities in autopsies in patients suffering angina, having again missed the coronary circulation, Heberden concluded, “Since it was not due owing to any malconformation, or morbid destruction of parts necessary to life, we need not despair of finding a cure.”
Heberden, though, was far from the first to describe angina. In fact, several thousand years ago, an equally compelling description of angina was noted in the Ebers Papyrus, also predicting a grim ending: “And if thou examinst a man for illness in his cardia and he has pains in his arms, in his breast, and in side of his cardia … it is death that threatens him.”9 In fact, the Egyptians were likely a step ahead since the left fourth digit, the very finger many people wear rings on as signs of sexual and emotional commitment, where the pain of angina frequently radiates to, was widely referred to as the “heart” finger. They believed that angina was related to the heart and not in fact the stomach or intestines as Heberden did. In fact, it was later hypothesized, and widely believed to this day, that a special vein, the so-called vena amoris, forms a direct connection between the heart and the fourth finger.
While angina occurs because of restricted blood flow supplying the heart muscle, the Egyptians also provided the first description of a different type of heart disease, one that is rearing its head today more than ever before—heart failure.10,11 The papyrus describes it as a weakening of the heart muscle, which it calls in other places a “weakness or feebleness” of the heart, a “kneeling of the heart.” Elsewhere, the author states “his heart is bored,” although the cause of this boredom was perhaps misattributed: “This means that his heart is weak because of heat of the anus.” Many patients with heart failure develop swelling of the legs and can collect fluid in their lungs, causing difficulty breathing and a wet cough, and this, too, was addressed. “His heart is flooded. This is the liquid of the mouth. His body parts are all together weak.” And finally, the unknown author of the Ebers Papyrus also reported on the fatal final act of heart failure for many patients, which takes lives without announcement to this day: ventricular fibrillation. “When the heart is diseased, its work is imperfectly performed; the vessels proceeding from the heart become inactive so that you cannot feel them.… If the heart trembles, has little power and sinks, the disease is advancing.” This trembling of the heart, which effectively leads to a stoppage of the circulation of blood, occurs when an abnormal heart rhythm originating from the pumping chambers of the heart, the ventricles, causes the heart to rapidly quiver, at times more than two hundred times a minute, and can be fatal within seconds. Patients with heart failure are at particularly high risk of developing ventricular tachycardia or fibrillation.
These breathtaking discoveries, these complex descriptions of heart disease, in all their different forms, though, would remain unknown for centuries. While much of Western medicine draws a straight line back to the Egyptians, in many ways, much of what was learned in the cradle of human civilization was lost, and many of these conditions, such as angina or heart failure, would not be “discovered” until centuries after they had already been recognized. It was our inability to comprehend their ancient language that prevented these findings from being transmitted and built upon rather than buried underneath the ruins of time.
These discoveries could still have been outside our reach were it not for one of the most serendipitous moments of human history. During Napoleon’s Egyptian campaign in 1799, Pierre-François Bouchard, a French soldier, was put in charge of rebuilding Fort Julien, an old Ottoman fort near the Egyptian town of Rashid. He came across a large granite slab, which was being used as fill, but there was something quite remarkable about it. On the slab was inscribed ancient text, which was subsequently revealed to be three versions of the same royal decree. The top two texts were in ancient Egyptian scripts while the bottom one was in ancient Greek. The stone was captured by the British, who transported it to the British Museum, and almost twenty years after it was first discovered, using his knowledge of the ancient Greek language, the texts were transliterated by the French Egyptologist Jean-François Champollion, opening up the entire Egyptian civilization and its myriad time capsules jotted on hardy papyruses to our comprehension.
By the time the Rosetta stone blew humanity’s collective minds, Egyptian knowledge had gathered two millennia worth of dust, and it was the Greeks and Arabs who came to define our modern knowledge of the heart and the human circulation. A scientific theory originating in ancient Greece and popularized by the scholars Hippocrates and Galen defined not only how we thought of the human body but also the human soul. For the almost two millennia that separated the creation of the Rosetta stone to its eventual rediscovery, civilization found itself neck deep in blood, phlegm, black bile, and yellow bile—the four humors.
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Before a time when we could go online and take a quiz to figure out “Which Game of Thrones character am I?” many looked to the concept of the four humors to explain one’s temperament. While the humors were used to organize all of human existence into one theorem, at their core they were a personality test, one that persists to this day, and you can go online and take it for free. Different tests, though, gave me a different personality type, with one defining me as sanguine while another found me to be phlegmatic. The four temperaments associated with the humors form the backbone of some more widely used tests, such as the Myers-Briggs Type Indicator.
The humors centered around the number four.12 There were four primary qualities in nature—hot, cold, dry, and wet. There were four central elements—earth, wind, fire, and water. Corresponding to these elements and qualities were the four temperaments of human nature—melancholic, sanguine, choleric, and phlegmatic. And finally, these temperaments were linked to the four humors—black bile, blood, yellow bile, and phlegm. An imbalance in the humors was the source of all disease. While this theory existed in ancient Egypt before the time of Hippocrates and Galen, these Greek physicians helped to legitimize it and were responsible for its longevity past their own deaths.
Galen (A.D. 129–210), a disciple of Hippocrates, was born in what is now western Turkey and had a long education, including at Alexandria in Egypt, where he was able to pick up and carry forward the torch of Egyptian medicine, eventually ascending to being the physician to the Roman emperor.13 He was a strong proponent of the body’s circulation being an “open” system. What does that mean? Galen held that nutrients were absorbed from the food in the intestines and converted into blood in the liver. He hypothesized that all the vessels of the body emerged from the liver. The blood then moved via the veins to all the organs, where it would be absorbed. The blood that went to the right side of the heart, instead of going to the lungs, being oxygenated and coming back, just diffused from the right side of the heart directly to the left side through small pores in the septum that separated the two sides, he posited. Essentially, he theorized that the movement of blood was one-way rather than circular. Air was directly ingested into the left side of the heart, where it mixed with blood that had diffused through said invisible pores. Galen, like others at his time, believed that the chief function of the heart was not to pump blood but to provide innate heat, and that the primary function of breathing was to cool the body.
The theories that Galen held would become the staple of medical science in the civilized world throughout Europe, spreading all the way to the Arab and Byzantine empires. Though Galen was perhaps the most influential physician-scientist of all time, far from moving science forward, Galen only reinforced preexisting incorrect notions. Galen did not distinguish himself by performing experiments that were validly executed. In fact, he never dissected a human body in his entire life. And the timing of his rise in influence could not have been worse. In the years after his death, religious forces completely took over the sciences, bringing an ignominious end to any further empirical investigation for centuries in Europe. Galen’s theory of the humors was so easily coopted by theology that it would be a few thousand years until enlightenment would return to Western civilization and the Dark Ages would dissipate.
It was during these Dark Ages that the mantle of intellectual pursuit was taken up by the Arab civilization. Ibn al-Nafis (1210–1288), born around Damascus in Syria, was a polymath, like so many other intellectuals of his time, but his main specialty was the eye.14 His investigative nature, however, led him to overcome the overwhelming influence of Galen and his own mentor, Ibn-Sina (980–1037), also called Avicenna in the West.15 Galen had theorized that blood in the right side of the heart does not go to the lungs and come back flush with oxygen. The heart did not pump blood; rather, blood moved passively from the right to left side through small, invisible pores in the septum that separated the two sides. But of course, given that he had never dissected a human body or opened a human heart, this was all conjecture.
Even today, when we can get microscopic views of the beating heart without a scalpel in sight, there is so much an actual dissection of the heart can reveal that even the highest-resolution imaging cannot. While they are rarely performed in modern medicine, autopsies can transform disease from an existential threat to a real entity you can touch and feel. Whether that is poking the hardened muscle of the heart that suffered a heart attack or actually seeing the tiny clot obstructing a stent that had been previously placed in a patient’s coronary artery, there is almost no substitute to seeing humanity’s nemeses in the flesh.
Unlike those before him, Ibn al-Nafis did open a human heart, and he realized that there was in fact no connection between the right and left side of the organ. Blood that went to the lungs from the right side received vital spirit from the air we breathed in and returned to the left side of the heart to be circulated to the body.16 While he never fully divorced himself from Galen’s general ideas, he was quite clear about what he thought about prevalent ideas of the circulation: “Therefore the contention of some persons to say that this place is porous, is erroneous; it is based on the preconceived idea that the blood from the right ventricle had to pass through this porosity—and they are wrong!”17
Ibn al-Nafis’s accounts, though, while accepted in the Islamic world, failed to convince many Europeans, including Leonardo Da Vinci, who also was housed in the Galenic view of the world. Galen’s influence consumed medical science, and it persisted until an English physician, William Harvey, appeared on the scene in the seventeenth century and who debunked centuries of dogma. His story, and the reaction to his findings, have important lessons about the scientific process, the brutality of the status quo, and what it takes to overcome the toxic mix of scientific and religious ideas. Fake news has become a buzzword recently, but it has been around as long as there have been mouths that speak and ears that hear.
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William Harvey, born in 1578, in Kent, England, went to Gonville & Caius College in Cambridge, but to receive the best medical education in the world, he had to pack his bags and travel to Padua, Italy, which one might say was the Harvard of medical schools back then. At the same time that Harvey was there, Galileo was the chair of the mathematics department. After finishing his studies, Harvey returned to England, where he eventually ascended to being the personal physician to King James in 1618.
By all accounts, Harvey was not a renegade. He did not set out to upend centuries of doctrine. In fact, he rejected many of the mathematical discoveries that were being made at that time and was fully invested in the theology of the vital spirit. What he was, though, was a scientist in perhaps the truest form. In his magnum opus, Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (Anatomical Exercises on the Motion of the Heart and Blood in Animals), published in 1628, he wrote, “I profess to learn and teach the anatomy not from books but from dissections, not from the tenets of philosophers but from the fabric of nature.” He was interested not merely in receiving the truth but in testing it with a hypothesis in mind. And unlike the cosmos, where the truth could lie completely out of reach, you didn’t have to go far to examine and investigate the human body.
Before Harvey’s time, the very flow of life was thought to be linear, from point A to B, never to return. Nutrition obtained from food in the intestines was converted to blood and moved to the tissues, where it was consumed and was never to be seen again. Yet this was also the time of Copernicus, who had postulated that far from being stationary, the earth was constantly revolving in circular motion around the sun. There was something so elegant and efficient about circular movement that it must have struck a chord with Harvey.
To test his hypothesis that blood traveled circularly through the body, and that arteries taking bright blood away from the heart were in fact connected to the veins bringing dark blood back to the heart, he devised an experiment so simple yet elegant that not only could an eight-year-old design it, they would be able to understand what it meant.18
The heart pumps oxygenated blood into the arteries. The arteries have thick walls to withstand the pressure of the heart’s pulsations and to transmit those pulsations all the way down their course. Veins, on the other hand, carry blood at low pressures, since they are not connected directly to the pumping chamber of the heart and, as Harvey observed, have valves to prevent blood from flowing back toward the tissues. Arteries and veins are connected by microscopic vessels called capillaries, which look like interlocked fingers surrounding tissues in their webs. It is through these thin-walled capillaries that blood can deliver oxygen and take up carbon dioxide, which is waste produced after the oxygen is used to create the building blocks of energy in the human body.
Harvey tied a band tightly around a man’s elbow—so tight that it occluded both the artery taking blood to the hand and the vein bringing blood back. This caused blood to start accumulating in the throbbing artery in the arm above the band, since it couldn’t cross the tight band, and the pulse in the wrist to disappear in that same artery downstream.
Harvey then repeated this experiment, but this time with the elbow band only tight enough to compress the vein but not the artery. In this case, the man still had a pulse in the wrist since arterial blood was still making its way to the hand past the elbow. Yet because blood in the veins from the hand could not return back to the heart, it started collecting there, causing the hand to become swollen and distended.
Having proved that the arteries and veins were connected, with arteries moving blood toward the fingers and away from the heart, and the veins vice versa, he then devised another incredibly simple experiment to establish that the heart was central to this connection.19 In a still-living fish, Harvey tied off the veins draining into the fish heart. The fish heart almost immediately emptied out since it was continuously pumping blood forward, and it started accumulating blood behind the ligature on its way back. In a snake, he pinched the aorta, the great artery emerging out of the heart. Immediately, the heart became swollen and distended, a change that resolved as soon as he let go. Even though the hearts of humans and fish are not identical, how they work is similar enough to support the veracity of this experiment.
Therefore, with a band here and a pinch there, Harvey proved quite simply that all the blood in the body was traveling, constantly and relentlessly, in one big loop, over and over and over again, incessantly, in both humans and animals, driven by the heart, the captain of this crazy train.
After centuries of dabbling in dubious distortions, how would humanity even react to the truth? Galen’s words and theories by Harvey’s time had acquired a divine power that was above question from even the brightest of minds. What would it take for people to realize that not only was everything a deviation from the truth but manifestly false in every imaginable manner? The story of William Harvey is important because if you are an optimist, it demonstrates the natural history of the truth coming to light and being accepted for what it is. In an address in 1906, Sir William Osler said, “By no single event in the history of science is the growth of truth, through the stages of acquisition, the briefer period of latent possession, and the glorious period of conscious possession, better shown than in the discovery of the circulation of the blood.”20 But if you are a pessimist, you realize just how strong a grip falsehoods can have, especially when so many are so invested in them.
Harvey, who was incredibly powerful at the time of the publication of his work, knew that he was not immune to retribution. In De Motu Cordis, he wrote, “What remains to be said on the quantity and source of this transferred blood, is so strange and undreamed of that not only do I fear danger to myself from the malice of a few, but I dread lest I have all men as enemies, so much does habit or doctrine once absorbed become second nature, and so much does reverence for antiquity influence all men.”
Harvey did find some supporters, but they were greatly outnumbered by his opponents, who spanned the entire European continent.21 René Descartes approved of Harvey’s theory in Discourse on the Method (1637), but he believed that blood did not flow due to the pumping of the heart but by the natural heat implanted by God in the heart, causing the blood to expand and move forward.22 The one thing that was common to all those opposing Harvey was that they didn’t actually perform experiments to disprove his claims. In fact, one of the only adversaries of Harvey who used physical experiments to challenge his claims actually converted to Harvey’s theory of circulation, convinced by his own experimentation.23 Eventually, though, given his proximity to the royal family and prominent position in the Royal College of Physicians, William Harvey’s theory found acceptance during his lifetime. Harvey was also a careful man—he published his book in Frankfurt and not in England so as to not arouse the ire of his direct peers. He also accepted most of the theological assertions of his time and used his political connections to protect himself. He fared much better than Galileo, who was placed under house arrest and accused of heresy by the pope.
Harvey’s greatest legacy, however, was perhaps not so much his discovery as how he got to it in the first place. His true gift was introducing the art of scientific experimentation and observation into medical education and research. Many of the young doctors he influenced went on to repeat his experiments and then become seeped in a tradition of generating new data through hypothesis-driven testing. While that tradition continues unabated to this day, much of what Harvey stood for appears to be under siege once again. In the Western world and particularly in the United States, anti-intellectualism and a disdain for science have begun to rear their long-dormant heads. Disruptive science is not only attacked by those for whom scholarship is but a convenient companion but by other scientists with competing financial or intellectual biases. Climate science comes instantly to mind, as many with vested interests or entrenched biases seek to redirect the march of science. Only these days, instead of pitchforks, heated battles are waged over Twitter and through legislation passed by government. While the body count is thankfully sparse, the damage to the spread of knowledge is constant and worrisome.
As we progressed toward a more accurate understanding of the physiological function of the heart and how it relates to us, a parallel and equally important journey was taking place: the role the heart plays in artistic, literary, social, and religious discourse. The heart has always played an outsize role beyond its biologic function. When most people talk about the heart, to this day, it represents something far more than a thoughtless pump, mindlessly churning blood through the body; it represents the very core of human life in its myriad layers in all cultures and at every point of human history.
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The metaphorical heart, rarely swayed by the winds of time, was shaken forever by William Harvey’s De Motu Cordis. Harvey not only changed how physicians and biologists think about the heart but how poets, philosophers, and novelists contemplate it and its role in our lives and the qualities that it represents. From an organ that provided warmth to the body, the heart now became a muscular pump, circulating blood throughout the body. This represented not just a new function but a new character. In his book The Language of the Heart, 1600–1750, Robert Erickson posited that while the Galenic heart had a “strongly receptive or ‘feminine’ function,” given that it attracted and then warmed the blood, William Harvey’s heart, given its throbbing dilations and constrictions, performed a “more ejaculatory and ‘masculine’ function.”24 Through his scientific findings and editorial overlays, Harvey developed an “implied allegory of an erotic and divine harmony between the husband heart and the bodily wife.”
From being an organ that was the key to understanding not only human nature but divine nature, the heart was increasingly seen as a laborer, a cog in a conveyer belt. Advances in knowledge about the nervous system led to the recognition that the brain was more than just a filler between the ears. It was Charles Darwin who, in 1871, took the crown from the heart and placed it firmly on the brain, calling it “the most important of all the organs.” To many, the heart was no more than a mule, slogging away in the mud, carrying the load without asking questions. In Illness as Metaphor (Farrar, Straus and Giroux, 1978), Susan Sontag wrote, “Cardiac disease implies a weakness, trouble, failure that is mechanical.”
As we continue to move forward, the long and eventually fruitful development of the theory of circulation, which overcame centuries of missteps and untruths, has important lessons for us today, leaving many unanswered questions: What do we believe in today that will be the equivalent of Galen’s invisible pores in years to come? How do we even go about that search? To do that, let’s look at what we know about the heart today, the culmination of a portrait centuries in the making, put together by scientists and artists alike, yet still as mysterious and ambiguous as Mona Lisa’s smile.
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The heart sits behind the rib cage slightly to the left of the breastbone with its tip pointing down and to the left. The human body has many valuable organs, yet few are as well protected as the heart. As big as your closed fist, the heart is unlike any other organ because it is always beating, always moving, and, to make sure that it is provided the best possible environment to be able to do that, it is surrounded by a thin, double-walled fibrous sac called the pericardium. The pericardial sac contains about 30 milliliters of a transparent fluid called pericardial fluid. The pericardium does many things—it lubricates the heart, allowing it to continue pumping while expending the least amount of excess energy. The pericardium also shields the heart from infections that might occur in the tissues around the heart. Unlike the heart, which floats like a fetus in its sac, the pericardium is attached to the tissues and bones around it, effectively anchoring the heart in place, which would otherwise just be flopping around in the chest. And finally, because of its inelastic nature, the pericardium restricts the heart from ballooning out of control.
The heart itself is made up of four chambers, two smaller, thin-walled atria on top, and larger, thick-walled ventricles below. The left and right atria are separated by a thin septum, while the ventricles are separated by a much thicker septum.
The largest two veins in the body—called the vena cava, one coming down from the head, the other coming up from the body—converge at the right atrium, bringing venous blood from the body to the heart. Blood flows from the right atrium, across the tricuspid valve, into the right ventricle. The heart valves are meant to prevent blood from going in reverse gear and keep blood moving in the right direction. The right ventricle, much smaller than the left ventricle, is connected directly to a large artery called the pulmonary artery that leads this venous blood to the lungs. As soon as the pulmonary artery emerges out of the right ventricle, pointed up toward the head, it splits into the right and left pulmonary arteries like a T. These pulmonary arteries then keep splitting like cracks in a frozen lake until they become tiny capillaries wrapping around alveoli, the tiny sacs where air drawn in from the lungs comes face-to-face with the blood without actually touching the other. These capillaries, now with blood brightened with oxygen, merge into other smaller veins, eventually ending up as four large pulmonary veins, bringing juiced-up blood back to the heart, draining into the left atrium. This blood then moves down the mitral valve into the left ventricle, the largest and most powerful part of the heart, responsible for pumping blood to the entire body, unlike the right ventricle, which only pumps blood to the lungs. With every contraction, blood leaves the left ventricle through the aortic valve and into the aorta, which then branches off into vessels leading to each and every part of the body.
The small and wispy atria and the large and powerful ventricles engage in a rhythmic dance that starts from the first heartbeat to the last. When the atria relax and dilate, causing blood to rush in from the body on the right and the lungs on the left, the ventricles are contracting, pushing blood out of the heart. They are separated by the valves, which ensure that the pressure generated in the ventricles during their contraction, called systole, does not travel back toward the atria, which would interrupt them filling with blood. Therefore, the atria exist to ensure that the heart is filling with blood at all times. After the ventricles are done contracting, they relax, actively sucking blood in from the atria across the tricuspid valve on the right and the mitral valve on the left. To maximize filling of the ventricles, the atria contract while the ventricles are relaxing in diastole, providing an additional kick of blood flow into the ventricles. This ensures that the ventricles are nice and full when they beat next. And because the atria are full when the ventricles contract and the ventricles are full when the atria contract, the overall size of the heart only varies by about 5 percent during the entire cardiac beating cycle. The dance between the atria and the ventricles also means that blood in the body is always moving forward, either out the aortic valve and into the aorta, or up and down the vena cava and into the right atrium.
What is important to realize is that even though the heart is always full of blood, it does not derive any nourishment from the blood that courses through it. The heart gets its own oxygen from the blood in the coronary arteries, which originate just past the aortic valve from the wide mouth of the aorta. The right coronary artery emerges from the right side, supplying the right ventricle and the inferior portion of the left ventricle, while the left coronary artery splits into two large vessels, the left anterior descending and left circumflex arteries. Of these, the left anterior descending artery supplies the entire front face of the left ventricle, all the way from the top to its pointy end, called the apex, and then wraps around it. The left anterior descending is affectionately called the widow-maker—not only is it the most common of the three coronary arteries to be affected by blockages causing heart attacks, but an occlusion in the left anterior descending is also the most dangerous since it supplies the greatest territory of heart muscle.
Disease can affect each and every part of the heart described here, from the pericardium to the electrical conduction system within the heart, and for the most part, we have figured out ways to treat, manage, and in some cases, cure, most of those pathologies. This progress represents one of the single most impressive achievements of our race.
The truth, though, is that much of what I described here, the foundation on which we have built modern cardiovascular medicine, might be completely false. What science has taught us to date so far is that nothing is absolute, yet the past fifty years have yielded more tangible progress in culling the progress of cardiovascular disease than any other time in our history. Furthermore, what the history of the heart also teaches us is the fragility and reversibility of scientific progress. Ancient civilizations went from being this close to putting the theory of human circulation together, perhaps being one tourniquet around the elbow from revealing the true nature of the cardiovascular system, to descending into almost fifteen hundred years of darkness. How can such progress be so brittle? Perhaps, as in the case of vaccines, its effectiveness at preventing diseases such as measles, polio, smallpox, and whooping cough obscures to people what we have worked so hard to overcome. Sometimes, progress can be prevented due to disinformation. Until recently, the sugar and tobacco industries were actively suppressing research suggesting that their products caused harm. Our history makes clear that we must always remain vigilant and protect what we now finally know after millennia of setbacks.
Science, too, runs the risk of becoming what it was made to overcome. William Harvey and others used the scientific method to change how we interrogate reality, not to believe what has been passed down but to empirically figure it out for ourselves; many scientists and physicians, however, cling to ideas like they are religious texts that cannot be questioned even though this was exactly what the scientific method was supposed to overcome.
For now, though, we can bask in the light illuminating every crevice of the heart. And to get things started, let’s squint into some of the tiniest blood vessels in the human body. The heart is always full of blood that is used by the rest of the body, yet the blood that the heart itself needs for oxygenated nourishment fills the coronary arteries that cover it like paper covers rock. In the most important real estate in the human body, a millimeter of plaque can be the difference between life and death.
Copyright © 2019 by Haider Warraich
