Attacking the heart attack
It's hard to remember that a heart attack was once a death sentence. These days, nearly 4 out of 5 heart attack victims survive. Emergency physicians treat them with clotbusting medications, their blocked arteries are reopened, and they are sent home, loaded down with pills and finger-wagging admonitions about diet and exercise, to resume the regular rhythms of their lives. It isn't exactly a ho-hum script, but it is the one the public has come to expect.
Yet less than 50 years ago, well within many baby boomers' lifetimes, physicians did not realize that the damage of a heart attack could be minimized and even reversed. Indeed, it wasn't until 1960 that a research team at Northwestern University, led by pathologist Robert Jennings, used experiments with several dozen dogs to demonstrate that radical idea.
A heart attack happens when there is an infarct, or sudden loss of blood flow, to part of the heart's muscular wall--hence heart attack's technical name, myocardial infarction. The Jennings team placed a block in one of the coronary arteries, which supply blood to the heart muscle, for various periods of time and then removed the blockage. Team members found that the blood-starved tissue could be saved if circulation to the area was restored soon enough.
Timing is everything. And "soon enough" didn't have to mean "immediately." The muscle cells lining the interior of the heart wall would die without fresh blood within about 20 minutes, but Jennings discovered that the cells in the outermost layer of the heart could hang on for as long as six hours. It was an epiphany for Jennings. Cell death, he came to understand, moved like a wave through the layers of heart muscle.
The team's discovery, which the American Heart Association described many years later as a "true paradigm shift in cardiology," was published in a then obscure pathology journal. Even so, word spread fast. Researchers were galvanized by the bench-to-bedside possibilities. Coming to a more complete understanding and translating the findings into routines and protocols to apply to real patients did not come easily. But by the early 1980s, thousands of people who would have otherwise dropped dead were walking out of the hospital.
Forty years ago, Jennings was also one of the first cardiac pathologists to use the electron microscope to examine heart muscle cells. It paid dividends. He was able to see tiny holes appear in the cell membrane and correctly identified the point at which they appeared as the moment the cell died. "To this day, that is our best understanding of cell death in the heart," says Charles Murry, director of a pathology laboratory at the University of Washington Medical Center and a former postdoctoral pathology fellow at Jennings's laboratory at Duke University Medical Center. (Jennings left Northwestern in 1986.)
At Duke, a new Jennings-led team, which included Murry, again startled the cardiac community. In another dog study, the team found that episodes of angina, the squeezing chest pain caused by insufficient blood flow to the heart, have a surprising silver lining: They can actually protect the heart against damage inflicted by a later heart attack. The team called the phenomenon "preconditioning." The discovery has stimulated thousands of subsequent studies. In the 1986 study, published in the journal Circulation, Murry was listed as the lead author, but he's the first to credit Jennings for the innovation. "Like a graduate fellow would lead an investigation like that? Oh, sure," he says in amusement. "It was just another way Dr. Jennings showed his generosity."
Intensely driven but no empire builder, Jennings was known at Duke for ducking out of meetings and returning to his lab to pore over tissue samples. "He would chortle about it," says Murry. " 'Ho, ho, I snuck out of a budget meeting.' I didn't understand then, but I do now, that doing bench work was his way of preserving his sanity."
In retirement, bench work has become beach work: For several years, Jennings has cultivated oysters on an artificial reef of oyster shells at his riverfront home on the Chesapeake Bay. It's partly scientific curiosity--and partly that he gets to eat his handiwork.
This story appears in the July 12, 2004 print edition of U.S. News & World Report.
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