Realizing what arteries do...
If we take the wayback machine to well... wayback, people didn’t know how the heart worked, what arteries do or even that their dysfunction could cause disease. Of course, people have been talking or writing about arteries for millenia. At first, arteries weren’t really seen for what they are. They were felt as the pulse. Chinese physicians pored over the pulse to seek any clue to internal disquiet. Was it fast, slow, regular, irregular, strong or weak? Did it push hard or simply tap and how did it change? Greeks physicians were equally interested but only briefly and moved on to other pursuits. On both fronts, there were some interesting observations. They gave pulses a host of clever names (some of which we still use) and realized that something about the pulse was important. They just were not certain exactly what that important thing might be.
The general sense of things (in this discussion, things are the heart and arteries, mostly) went something like this. From food and air, our bodies somehow distilled an essence that fueled life. This mixed in blood which contained life’s most basic and necessary essence. Blood moved, partly of its own accord. It animated the body and provided the fuel for physical activity. In doing so, blood also provided the essential nature of what we are, how we feel and behave. The dispensation of life into the body could be felt in the pulse. The heart was somewhere in this mix. Exactly what it was doing wasn’t completely clear. Altogether, this scenario is pretty decent guesswork, considering that there was not a wealth of information to guess from.
Leonardo looks for life and points at arteries
Fast forward to the Renaissance. By this time, most people who were interested in the human body had taken the old understanding of how things worked and found the explanations to be seriously wanting. In part, this was because many of the “experts” expounding upon how things worked liked to sprinkle their writing with personal opinion and some seriously bizarre ideas. The weight of crazy so badly encumbered explanations of the natural world that the scientific method of thought was born. Scientific method meant that if you wanted to put forth an idea, you had to let other people–who might not buy your explanations or even like you–test it and make fun of you when you were wrong.
Leonardo da Vinci (just Leonardo apparently) was of this time. In some respects, he probably is the best representative of this time, in that he observed, he described and he explored ideas by putting them to the test. One of his most important contributions to the new way of thinking was to accurately describe normal and variant human anatomy. His beautiful drawings capture his exploration of the mechanics of how and why different parts of us work as they do.
At the time, there was a general understanding that blood moved through the body with arteries as the highways. The heart was in some way integral to the process, but the mechanics were a mystery. In Leonardo’s drawings and writing concerning circulatory anatomy, it is clear that he knew of heart valves, that blood really went in only one direction and that arteries were responsible for the distribution of energy. With energy, he included the body’s heat, the still undefinable essence of life because it was all too clear that, should blood escape through an open artery, the heat of life would go with it.
Famously curious and undoubtedly consulted to explain any mystery, Leonardo’s interest was piqued when he was offered the opportunity to examine an old man who had died peacefully. His purpose was to find where life’s heat escaped at a peaceful end. He examined the anatomy in great detail and reported his observations and musings. From the many observations, one stands out as the beginnings of an idea. Leonardo reported that the supple, straight vessels of youth had been thickened, gnarled, and bent with age, leaving little room remaining for blood.
In today’s world, we would interpret this description as evidence of arterial disease. The old man died peacefully, probably having a heart attack as he slept. Thickened and deformed arteries probably signified more than simply age, but also atherosclerosis, the disease of arteries that plagues so many of us. No one really knows what conclusions Leonardo drew from his observations about arteries. He may very well have believed that part of our aging is an attenuation of the channels blood can take to keep us moving and alive. What is most important is that his observations represent the the first inkling that arteries might fail of their own accord and cause disease.
Within a relatively short time (in historical terms) arterial failure would be seen more clearly and blamed for an odd type of chest discomfort that eventually became known as heart attack.