A heart attack can have salutary effects. In some instances, it helps us to reexamine our lives and reorder our priorities. The same is true for medicine.
Petr Josek Snr/Reuters
One of medicine's greatest challenges is heart failure. Nearly all of the human body's tens of trillions of cells depend on a constant supply of blood, and failure of the heart to meet this demand represents one of the gravest threats to health and life. It is estimated that heart failure afflicts over 5 million Americans, and it represents the most common reason for hospital admission in patients over 65 years of age.
We can live without a hand, an eye, or even a kidney or lung, but the heart is absolutely indispensable. It reliably contracts 100,000 times each day, for a total of 2.5 billion beats over the course of a life time. It pumps blood through a network of vessels that, if each were stretched out and laid end to end, would measure over 60,000 miles in length. Cessation of cardiac function remains one of the most important indicators that life has ended.
The scientific and rhetorical proof of the heart's role in circulating the blood constituted one of the greatest triumphs in the history of medicine. William Harvey (1578-1657), perhaps the greatest English-speaking physician who ever lived, was not the first to suspect that the blood moves in a circuit, but he was the first to provide rigorous experimental proof. Yet even Harvey's demonstration had holes. Lacking a microscope, he could not explain how the blood finds its way from the arteries to the veins.