CAVE PAINTINGS FROM 20,000 YEARS AGO SHOW game animals with spears sticking out of unmistakably drawn hearts. They may have been the first graphic textbooks—if you want to kill a big animal, that’s where you stab it.
Chinese physicians were writing of the diagnostic implications of patient pulse rates almost 5,000 years ago, and may have guessed that blood circulates. In the West, the two millennia from the Greeks to the European Enlightenment were dominated by Hippocrates’ theory of four “humors,” in which the heart was the source of “vital heat” and blood was more often associated with the liver. Diligent anatomists like Aristotle, Galen, and Avicenna worked out the heart’s internal structures, and had a reasonable understanding of diastolic and systolic blood pressures, the functioning of the valves, and much else. Leonardo da Vinci made gorgeous drawings of the human heart and its major valves in the late fifteenth century, and Andreas Vesalius, a mid-sixteenth-century prosecutor in Padua, and an enthusiastic autopsist, carried cardiac anatomy to near-modern levels of precision.
But it was left to the seventeenth-century Englishman William Harvey to elucidate how all that apparatus really worked, much as his great contemporary Galileo did for astronomy and physics. Harvey conducted the experiments that proved the existence of the capillaries, the circulation of the blood, the direction of its flow, the heart-lung cycle, the action of the heartbeat, the role of the ventricle, and much else—all of which the micro-scopists resoundingly confirmed within a few decades of his first announcements.
At first, the more clinicians learned about the heart, the more they were convinced it was an untouchable organ. During the Napoleonic wars, however, a few adventurous surgeons figured out that when blood or pus from an injury swelled the pericardium (the sheath around the heart) and cut off circulation, they could often cure a patient by making a drainage incision. But they were still careful not to touch the heart itself. By the mid-nineteenth century, however, accumulating autopsy evidence of scars on the hearts of fighting men suggested that the heart might be able to recover from a wound. Animal experiments demonstrated the feasibility of suturing wounds in the heart by the 1880s.
The first successful human heart operation took place in 1896 in Frankfurt, on a young man who had been stabbed in a brawl. The surgeon opened the pericardium to drain suppurative fluids, then closed a 1.5 cm wound of the right ventricle. The man was reported still alive ten years later. The first heart operation in the United States was performed in 1902 on a kitchen table in an Alabama “negro cabin.” The patient was a thirteen-year-old boy who had been stabbed multiple times in the chest. The procedure was much like that in Frankfurt, with a Dr. Luther Hill of Montgomery performing the surgery. Hill pierced and drained a bloody buildup in the pericardium, after which the boy’s pulse noticeably improved, and then he closed a three-eighths-inch stab wound in the heart, packing it, as in Frankfurt, with iodine-soaked gauze to ward off infection. The boy apparently recovered.
The carnage of the First World War brought more impromptu experiments. Although survival rates were very poor, interest kept rising. During the intrawar years, researchers in widely disparate fields began to assemble the technological matrix for reliable cardiac surgical interventions—including the beginnings of dye-based X-ray angiography (injecting X-ray-reflective dye into the heart to locate blockages), rapid strides in both anesthesia and antisepsis, and the discovery of heparin to reduce clotting and of antibiotics to combat infections. The electrical patterns of the heartbeat were being deciphered, and work had commenced on electric pacemakers. Animal experimenters were also starting to understand how resilient the heart is. In one experiment, researchers completely drained a dog’s blood from its body, waited for several minutes, then rein-fused the blood and were amazed to see the heart restart. During World War II, surgeons had some success in removing projectiles from soldiers’ hearts, and cardiology began to emerge as a recognized medical specialty.
Research interest in cardiac medicine was driven by growing alarm over the steady increase in cardiovascular death rates. As the wealthiest people in history, Americans were eating more and more richly, were more likely to have sedentary jobs, and, with the spread of the automobile, did much less walking. By the 1950s, cardiovascular disease was an epidemic of crisis proportions, accounting for more than half of all American deaths.
The technology of cardiac surgery began to assume its current shape through the 1950s and 1960s. Thomas J. Watson, Jr., the chairman of IBM, made a personal project of financing and developing the heart-lung bypass machine, based on a prototype that a surgeon, John Gibbons, had built in 1937. Gibbons performed the first successful operation on a human with the assistance of the bypass machine in 1953. He repaired an atrial septal defect, a hole in the internal wall separating the left and right atria; the machine was built by IBM.
The bypass machine made “direct-vision” heart surgery possible for the first time. With the heart off-line, a surgeon could open it, inspect the problem, and often repair it. Prior to the bypass machine, surgeons were limited to operations that could be performed entirely outside the heart, like suturing wounds, or ones that they could do solely by feel—a balky mitral valve could sometimes be opened by making a tiny incision, sticking in a finger, feeling for the valve, and pushing it open. The first widely adopted bypass-machine protocols were established in a famous series of operations by John Kirklin, at the Mayo Clinic in 1955.
Enthusiasm for on-pump—bypass-machine—surgery was dampened as it became clear that the machine itself could cause serious cardiovascular and cerebral complications. Over time, however, as machine-associated complications were brought down to acceptable levels, the heart-lung bypass machine revolutionized cardiac surgery. As valve replacement became a practical alternative in the 1960s, there was a vast florescence of replacement-valve designs, including valves from human cadavers; equine, bovine, and porcine valves; and dozens of mechanical valves. An early ball-and-cage aortic valve worked reasonably well, but clicked open and shut so loudly that it embarrassed its users.
The most consequential development of the period, however, was the coronary artery bypass graft, or CABG, universally pronounced “cabbage.” Occlusions of the coronaries, the arteries that supply blood to the heart, were identified in the nineteenth century. The occlusive material—calcium, cholesterol, microemboli and other cell detritus—is now known to be a partial correlate of rich diets and minimal exercise. Doctors had long understood the connection between coronary occlusions and angina pain. Symptomatic treatments included amyl nitrate, a vascular relaxant, and in the 1920s and 1930s, thyroid removal. (Excising the thyroid lowered adrenaline production so the heart reacted less quickly to stimuli. Quick ramp-ups in cardiac output often precipitated angina attacks. The underlying occlusion was unaffected.)
Since coronary arteries are usually on the outside of the heart, surgeons could work on them even before the development of the bypass machine. The intrawar years saw multiple attempts at opening and cleaning occluded coronaries, with little success. In the 194s, however, surgeons hit upon the idea of simply implanting one end of a mammary artery directly into the heart. Remarkably, instead of just creating a trapped pool of blood, the implanted artery gradually generated a rich network of new blood vessels within the myocardium. The first mammary implant was performed on a human in 1950 and was a complete success. Three years later, the patient, who had been completely debilitated before the operation, was taking ten-mile hikes. As the technique spread, it appeared that some 70 to 80 percent of surviving patients experienced substantial revascularization within eighteen months or so of the operation. About one in three patients died from the operation, however, which was fairly typical of the heart surgery of the time.
The modern CABG was developed at the Cleveland Clinic in the 1960s, primarily by the Argentinean surgeon René Favaloro, working closely with Frank Sones, a key contributor to modern cardiac angiography. Favaloro performed an unusually successful series of mammary artery implants in 1964, but was bent on finding more direct methods with more immediate results. He performed the first successful CABG on a human in 1967. The procedure entailed excising a vein from the patient’s leg, grafting one end to the diseased coronary artery just below the occlusion and the other end to the aorta. The occlusion was thereby “bypassed” and that portion of the heart once again received a full blood supply. By the following year, Favaloro had performed 171 bypasses with a mortality rate of only 5 percent—at first provoking wide disbelief among his contemporaries.
Having firmly demonstrated the effectiveness of the CABG against angina, the next year Favaloro showed that the same operation, performed within six hours of a heart attack, had a substantial effect in preserving heart muscle. By the end of the year, he had also performed the first double bypass. In the course of his work, Favaloro also established the center-line sternotomy, or breastbone incision, as the standard mode of surgical access, made a number of contributions to improving the bypass machine, and invented the chest retractor. Forty years later, most cardiac surgeons still execute CABGs more or less the way Favaloro did.
By 1970, Favaloro’s breakthroughs had triggered the explosive growth of a new medical industry. There were 60,000 CABG operations in the United States in 1975, and 250,000 in 1985. By the early 1990s, when annual CABG numbers hovered around 350,000, almost every medium-sized city in the country could boast of an open-heart surgery center. Outstanding centers, like those of the great surgeons and bitter rivals Denton Cooley and Michael DeBakey in Houston, became heart surgery Meccas, drawing patients from all over the world. Despite its extraordinary invasiveness and high costs, the CABG became almost fashionable.
The explosion of investment in cardiac intervention had implications far beyond the operating table—rapid-response interventions, tools and techniques to increase diagnostic precision and speed, specialized cardiac care units, better methods of heart protection during surgery, and a steady expansion of the numbers of ailments and patients within reach of the cardiac treatment web. As surgical morbidity and mortality rates dropped to levels that had been unimaginable a decade or so before, patient demographics shifted rapidly to older and riskier patients. Only 4 percent of today’s CABG patients would have been eligible for the surgery under the original guidelines. Mortality rates jumped sharply at first, but quickly settled back to previous levels. One consequence of removing CABG age limits was that women, who tend to contract cardiovascular disease later than men, entered the patient pool in large numbers. By the 1980s, transplant technology, as well, was on the verge of entering the mainstream.
Especially in its high-growth days, the momentum behind CABGs led to substantial overuse, much as may be happening today with stents. (Stents are tiny metal scaffolds that are used to prop open a blocked artery; they are delivered with a catheter inserted through an artery, so they don’t require surgery.) Several long-term randomized studies from the late 1970s and 1980s, however, clearly demonstrated the mortality benefits of the CABG for higher-risk patients—those with either multiple occluded vessels or occlusions in the major arteries of the left ventricle. The CABG also clearly relieved symptoms of severe angina, but with little mortality benefit.
The public health impact from the massive new investment in heart disease infrastructure was substantial. One statistic captures it all. Between 1970 and 1995, heart attack hospitalizations per 100,000 Americans dropped from 530 to 490, about a 7.5 percent decline. Over the same period, the heart attack death rate per 100,000 dropped from 256 to only 70, a 72.8 percent decrease. Stripping out all other factors that might account for the change in heart attack death rates, there is a near-consensus that as much as 70 percent of it was the result of better medical interventions. Just since the mid-1970s, total federal investment in cardiovascular research and treatment infrastructure exceeds $30 billion.
The rapid-growth phase of cardiac surgery ended sometime in the mid-1990s, and the profession began to acquire some of the hallmarks of what stock analysts might call a “maturing” business. But that is another story, to which we will return in Chapter 8.