The Man Who Touched His Own Heart

by Rob Dunn

  I don’t think the relative neglect of basic biological studies of the heart (or any other organ) will change, and so, rather than bemoan the situation, I have a recommendation. If you are a young person and want to grow up to understand the heart, to make a great discovery the elegance of which people can only begin to contemplate now, study the heart’s ecology and evolution. Study hearts around the world. Study the hearts of frogs and turtles and, especially, as it turns out, snakes. Study the biology of wild nature in general. This course of action is not likely to make you rich or famous, but it may well lead to a moment, somewhere in a small lab, or better yet in the middle of jungle, in which you suddenly realize something about the heart that no one else, no one in the history of science or society, had even considered. That thrill will be worth it, worth some sacrifice. That thrill will give you goose bumps that never quite go away.

  But back to the snakes. I love snakes. I think there is a convincing case to be made that they have shaped our evolution, so great was their historical impact on human life and death. As a result, a kind of wild fear of snakes is come by honestly. Yet it does not take much inspection of a snake to realize that magic dwells in its armless existence. Arms and legs took hundreds of millions of years to evolve, and the snakes, who once had them, decided to do without. They slither. Their backs bend in remarkable shapes, thanks to a multitude of vertebrae. Their jaws expand to envelop prey bigger than their heads. Their tongues reach out to gather scent in the air and then return it to a special organ in which those scents can be stored and interpreted. Snakes are special, and this specialness, it has recently been discovered, extends to their hearts.

  Snakes have three-chambered hearts—two atria and one ventricle. The heart of a snake works similarly to that of a human with a ventricular-septal defect. Each time the ventricle pumps, some blood goes to the lungs, some to the body. It is a sloppy business, but functional.

  When snakes are dissected, even snakes of a single species, their hearts are sometimes found to be enormous, and sometimes small. It was noted that the heart seemed bigger after the snake had eaten a meal. Appearances and anecdotes are not to be trusted, though. The idea of the snake’s heart growing during digestion is clearly ridiculous.

  Human hearts can change some in size, but they do it slowly. When the heart is injured, some cells divide and others expand. The heart remodels itself, although to a very modest extent. Bigger changes occur during pregnancy, when a woman’s heart expands to pump blood through two bodies; during development, when a newborn’s heart grows rapidly; and during prolonged exercise, when the heart expands to move blood. But even these beneficial changes are small, a 10 or 20 percent increase in size at most, and the higher percent only a freak-show potentiality.

  There is no model snake for biological research, but Burmese pythons (Python molurus bivittatus) seem to have been studied as well as any. These pythons, which can grow as long as nineteen feet, can go an entire year without feeding. They live slow lives, except for those voracious moments when they don’t, those moments in which they seize prey, sometimes as big as they are. The muscles of Burmese pythons speed up when they attack prey, but the real shift comes during digestion. Steven Secor, a professor at the University of Alabama, Tuscaloosa (and a reptile chaser by native inclination), and his former adviser Jared Diamond, of Guns, Germs, and Steel fame, discovered that the metabolic rate of Burmese pythons during digestion is forty-four-fold what it is when they are hungry. It might be advantageous, then, for these big snakes to be able to expand their hearts after they eat. Having eaten, they need more blood and oxygen for digestion. Having eaten, they have more amino acids, triglycerides, and free fatty acids to move around. Having eaten, their bodies have a great deal to do. Sure enough, a recent series of studies by Secor and colleagues has shown that forty-eight to seventy-two hours after a snake eats, its heart expands by 40 percent (its liver, intestines, and kidneys also expand). With the increase in heart size, the snake’s output of blood goes up fivefold.3

  The enlarging of the python heart appears to be due to increases in the size of individual cells. One of the things that changes in the python’s heart and blood during the expansion of these cells is the number of fatty acids in the blood; they go up dramatically (as much as fiftyfold), which appears to trigger the growth of the heart cells. All of this is the obscure business of snake biologists such as Stephen Secor, merely a lovely story about the eccentricities of our legless friends. Or it would be. But one of the teams of researchers studying the python heart, a team collaborating with Secor, decided to inject the same cocktail of fatty acids that are found in snake blood into the hearts of lab mice. The heart cells in those mice grew,4 as did rat-heart cells in culture. Our own heart cells, it seems clear, might too.

  The ability to make heart cells grow larger might hold therapeutic value. One of the problems with diseased human hearts is that they become hypertrophic (overly large), and in part, this hypertrophy is due to the expansion of cells. Understanding how the python-fat elixir makes cells grow might allow scientists to better understand such growth in diseased human hearts and, perhaps, find a way to prevent it. It might also offer some benefit in cases of atrophy, in which the growth of heart cells would be helpful. Compounds from other reptiles are already being used medically. A compound in Gila monster saliva, for example, is the active ingredient in the diabetes drug Byetta. There is much to learn, and some things we will learn from aggressive study of humans and from big medical experiments, but bigger discoveries dwell in the bodies of snakes and the millions of species we don’t yet understand. The light of our inquiry remains humble relative to the grandeur of existence.

  As for me, one of the great joys of being a scientist and a writer is that when I realize we don’t know very much about something, I can just go study it. In the next months, I may begin a study of the bacteria and viruses found in heart tissue. We know little about the microbes of the heart other than that they are almost undoubtedly there, dividing, thriving, doing whatever they do. Are they the same ones found in other primates? We don’t know. Perhaps we will need to study the hearts of chimpanzees or gorillas. Perhaps the viruses and bacteria in the heart come from the gut. Whatever we find, I predict it will be fascinating and new. Here, I am not just guessing; I am betting on the prediction that always seems to hold—namely, that we find something new each time we look, especially when we consider a great and poorly trammeled wilderness such as ourselves.

  ACKNOWLEDGMENTS

  Later in his life, my great-grandfather, who was active in his Methodist church in Greenville, Mississippi, was asked to comment on the history of that church. I recently discovered his response in a box of old family letters. He wrote, “In commenting upon the history of the Methodist church in Greenville, I would be remiss if I did not comment upon the history of the Methodist church more generally. In commenting upon the history of the Methodist church more generally it behooves me to speak to the history of Christianity and, of course, no discussion of the history of Christianity would be complete if it did not include a discussion of the religions of the world.”

  I come from a long line of people who, when telling a story, back way up to the beginning. For that same tendency in my own writing, I thank my great-grandfather. I thank my grandfather, his son, for the joy I find in exploring everything. I hope you, the reader, find some of his joy in this book. I thank my grandmother who grew up living in the building at the University of Mississippi where the biggest telescope in the world was supposed to go except that the telescope was built in the North and not yet delivered when the Civil War started (and so never delivered). Instead of being able to see out into space, she grew up listening to Faulkner tell stories on her front porch. As a result, she could instead see far into the universe of people, and for that I thank her. My mother allowed me to share the story of her heart. My dad read the book and reminded me when I was being too much of a scientist. Thanks to them both also for loving everything I write,
even early on in my writing when, in retrospect, it is clear that when they told me that, they were lying.

  My wife gave me the guts to tackle a topic as central as the heart. She also put up with the consequences of that confidence: thousands of conversations about the characters in this book (and an even larger number that never made it in), characters that, while fascinating, are a little much for dinner conversation every week for two years. Thank you, Monica, for your push, forbearance, wisdom, keen editorial eye, all the funny parts of the book, and everything else. My kids too listened to stories about the heart; Lula and August know more about blood vessels than any eight-and four-year-old really need to.

  Many people have read parts of this book or responded to interview requests.

  Bill Parker (the man who, in my last book, discovered the true function of the human appendix) read the book and added to it his special bit of magical brilliance. Colleen Farmer, Keith Myles, Will Kimler, Abell Assam, Ajit Varki, Nissi Varki, Kathie Hodge, Mariano Vázquez, Mohammadali M. Shoja, Nick Haddad, Stephen Secor, Geoffrey Donovan, Sarah Tracy, Herbert Cohn, Chris Gould, George Forssmann, Anne Murphy, Jie Jack Li, Kymberleigh Romano, Mizuki Takahashi, Harry Greene, Andrew Latimer, James Waters, Pajaro Morales, and Mette Olufsen all read sections of the book, in nearly all cases more than I asked them to. Dr. Bill Haynos read the book at the last minute, frantically, late at night, even when he had to get up early the next morning to look at his patients’ hearts. Thank you, Bill. Thank you also to Steve Jordan for the introduction and for being a supporter of this arcane work of turning words into books. Amanda Moon and T. J. Kellerer provided thoughts on what worked with the concept of the book that were very useful. Marko Pecaravic provided a balcony in Croatia on which I wrote part of this book. Michelle Trautwein and Ari Lit listened to these heart stories again and again, pretending the stories were interesting even before they were. Steve Frank listened to these stories while walking around his neighborhood late at night.

  John Parsley and Malin von Euler-Hogan wielded an ax where necessary and a fine carving tool everywhere else. Thank you, John and Malin, for your patience, vision, and extraordinarily clear thinking. Thank you also for finding Tracy Roe, a copyeditor who’s also a physician. Who knew such people existed? Thank you, Tracy. Victoria Pryor helped with everything, even when she was busy, even when it wasn’t her job. Every part of the book is better for it.

  And then I also need to thank my lab. Thank you, Holly Menninger, Lea Shell, Clint Penick, De Anna Beasley, Amy Savage, Amanda Traud, Magdalena Sorger, MJ Epps, and everyone else for being wonderfully patient when I disappeared into a coffee shop, library, or basement for days on end to write. Thank you especially, Emily and Megan, for reminding me, with your stories, of the ordinary urgency of heart problems. And thank you, lab, because, as you all know from experience, when I write a book, the mysteries revealed in a book come back to the lab. How could I not go back to the lab and study those things that appear unknown and yet knowable? And so thanks in advance for everything you help with in trying to understand the mysteries of the heart, mysteries that began, as my great-grandfather would have pointed out, thousands of years ago and yet, if we have some luck, might end in our third-floor lab (only, of course, to spawn new mysteries).

  ABOUT THE AUTHOR

  Rob Dunn is an associate professor in Ecology and Evolution in the Department of Biological Sciences at North Carolina State University. He’s the author of The Wild Life of Our Bodies and Every Living Thing, and his magazine work is published widely, including in National Geographic, Natural History, New Scientist, Scientific American, and Smithsonian. He has a PhD from the University of Connecticut and was a Fulbright Fellow. He lives in Raleigh, North Carolina.

  Also by Rob Dunn

  The Wild Life of Our Bodies

  Every Living Thing

  ENDNOTES, REFERENCES, AND A FEW ANECDOTES

  1. The Bar Fight That Precipitated the Dawn of Heart Surgery

  1. An early perspective on Williams’s story can be found in W. M. Cobb, “Daniel Hale Williams—Pioneer and Innovator,” Journal of the National Medical Association 36 (1944): 158. For perspective on Williams’s broader career, see W. K. Beatty, “Daniel Hale Williams: Innovative Surgeon, Educator and Hospital Administrator,” Chest 60 (1971): 175–82.

  2. Provident Hospital is described by some as the very first interracial hospital in the United States. See W. M. Cobb, The First Negro Medical Society (Washington, DC: Associated Publishers, 1939). Whether or not it was first, it was certainly among the first.

  3. Emma Reynolds would go on to obtain her MD at the Woman’s Medical College of Chicago in 1895. She then moved to Waco, Texas, and, later, New Orleans, where she would practice medicine until her death in 1917.

  4. Details about Cornish’s night in the bar come from S. Cohn, It Happened in Chicago (Guilford, CT: Morris Book Publishing, 2009).

  5. Also lacking at this point were antibiotics, a heart-lung machine, blood transfusions, and intravenous anesthesia, to name just a few items.

  6. Sounds, like sights, tell stories. We have all heard someone trying to replicate a sound his car makes: “It goes flappa, flappa, flappa,” or “It’s like ticka, tank, ticka, tank, squeee!” Our bodies too tell stories of our well-being. They tell them via their appearances and odors but also via their sounds, which were once used extensively to make diagnoses. Doctors would actually put an ear against the patient’s chest to listen to his heart. Then, in 1816, a Parisian named René-Théophile-Hyacinthe Laennec invented the stethoscope. Laennec had been watching children play a game in which they scratched a long, hollow, flutelike stick on one end with a pin and then listened for the scratch at the other end. This, he thought, might also allow him to listen to hearts. Laennec promptly went back to his office to experiment with a kind of flute, a long tube that he might hold to the chest. With this device, the first stethoscope, many of the mechanical problems of the heart could be differentiated by sound. An audio archive is now available to teach new doctors the art of listening to the heart’s problems through stethoscopes, though most doctors aren’t skilled in listening to the heart; technology has allowed the practice to fall by the wayside.

  7. For these estimates see J. L. Halperin and R. Levine, Bypass (New York: Times Books, 1985).

  8. D. H. Williams, “Stab Wound of the Heart and Pericardium—Suture of the Pericardium—Recovery—Patient Alive Three Years Afterward,” Medical Record 51 (1897): 439.

  9. H. C. Dalton, “Report of a Case of Stab-Wound of the Pericardium, Terminating in Recovery After Resection of a Rib and Suture of the Pericardium,” Annals of Surgery 21 (1895): 148.

  10. L. Rehn, “On Penetrating Cardiac Injuries and Cardiac Suturing,” Archiv für klinische Chirurgie 55 (1897): 315.

  11. “Heartbeats,” Time 1 (1923).

  2. The Prince of the Heart

  1. And just as often of the terribleness of his mother, who, he claimed, “bit the servants.”

  2. One sometimes needs to be a bit circumspect in considering Galen’s biography. He wrote most of it. In fact, while he was alive, he wrote most of what was written in the Roman Empire having to do with medicine—millions of words.

  3. One place we do find pan-cultural knowledge of the heart is on the dinner table. Hearts are (and, one presumes, have long been) cooked in cultures around the world. As Steven Vogel, in his excellent book Vital Circuits, points out, hearts are not easy to cook because they are full of collagen (the original source of glue, which Vogel also notes). Collagen is chewy and hard to eat. The best way to deal with collagen is to break it down molecularly, which can be done by leaving the collagen in acidic solutions such as vinegar, lemon juice, or tomato sauce. Then, of course, add some red pepper, cloves, cumin, and the like for flavor, and cook.

  4. It was for this reason that in some groups, the kidney fat was the part of the body most relished in acts of ritual cannibalism. In eating the kidney fat, one consumed a soul.

  5. The Egyptians
actually had two separate words for the heart, one for the spiritual heart, ib, and one for the physical organ, haty.

  6. R. Van Praagh and S. Van Praagh, “Aristotle’s ‘Triventricular’ Heart and the Relevant Early History of the Cardiovascular System,” Chest 84 (1983): 462–68.

  7. Herophilus is also sometimes described as the most prolific vivisectionist in history. Tertullian describes Herophilus as having dissected six hundred living criminals, though if this was really true, it seems as though Herophilus would have figured out more about how the heart works, having seen so many beating their exposed, last beats.

  8. In a rare moment of modesty, he confessed to the limits of his knowledge, admitting to never having dissected an ant, a louse, or a flea.

  9. Because only a portion of what Galen wrote has survived, much of it in secondhand translations, it is sometimes difficult to disentangle exactly what he believed.

  10. Nor were these treatments the extent of Galen’s lingering influence. For example, the practice of dissecting animal bodies in anatomy classes in order to reveal the truths in biology textbooks is simply revisiting the ancient Galenic practice.

  3. When Art Reinvented Science

  1. S. J. Martins, “Leonardo da Vinci and the First Hemodynamic Observations,” Revista Portuguesa de Cardiologia 271 (2008): 243–72.

  2. All of that said, da Vinci did have preconceived notions as to the causes of death in old age. In scholar Kenneth Keele’s read, what da Vinci imagined he was looking for was whatever prevented the movement of “vital heat and humors” through the body. In other words, he started off looking for blockages of one kind or another. Lack of movement was like stagnant water that putrefied. Here, then, the Galenic perspective on the body (a perspective in which vital heat and its movement was key) actually predisposed da Vinci to see the truth. It is also interesting to note that da Vinci’s analogy of stagnant water to blocked blood flow is, in its way, quite apt. Stagnant water is devoid of oxygen, and blocked blood flow leads to the inability of oxygen to reach the body. See K. D. Keele, “Leonardo da Vinci’s Views on Atherosclerosis,” presented at the Twenty-Third International Congress of the History of Medicine, London, September 2–9, 1972.