We all know the heart is a vital organ. If it stops functioning (such as during cardiac arrest), your body begins systematically shutting down. But did you know the history of cardiac anatomy was widely influenced by 4 intellects, some names which may be familiar and some which may not. Still, all contributed significantly to our understanding of the heart and its functions.
400-300 BC
Ancient Greeks held the heart as the center of the soul and the source of heat within the body. In the fourth century B.C., Greek philosopher Aristotle (384-322 BC) believed the heart to be the most important organ in the body that controlled all others, including mental processes. Aristotle described the heart as having three chambers and being the center of vitality. According to Aristotle, the surrounding organs like the brain and lungs existed only to cool the heart.
100-300 AD
In the 2nd century AD, the prolific Greek physician Claudius Galenus, known as Galen, (129- 216 AD), contributed significantly to the anatomical and physiological knowledge of the cardiovascular system. In AD 157, at the age of 28, he was chief physician to the gladiators in Pergamon (modern day Turkey), where he watched the still-beating hearts of fighters who lay dying, their chests ripped open by their opponents' blades. Later when he moved to Rome, he became the personal physician to the Roman emperor Marcus Aurelius. Galen was the originator of the experimental method in medical investigation carrying out vivisections, (surgery conducted for experimental purposes on a living organism, typically animals with a central nervous system, to view living internal structure) on monkeys and pigs, in order to observe the pulmonary circulation. He was the first to identify the physiological difference between veins and arteries. While Galen correctly recognized that blood passes from the right to the left side of the heart, he incorrectly decided this was accomplished through tiny pores (holes) in the septum (wall separating the two chambers of the heart), rather than through the pumping action of the heart. Galen also believed that blood formed in the liver and was circulated from there throughout the body in the veins. Many of his theories concerning the heart and blood circulation dominated European medicine for 1,500 years until they were refuted by William Harvey.
1400- 1550
For Italian Leonardo da Vinci (1452-1519), investigations of the human form were a lifelong interest. His diagrams and sketches of the skull, skeleton, muscles, and major organs fill countless notebooks, while his theories on how they function fill many more pages. But in his 50s, the heart appeared to be a source of interest. When Leonardo da Vinci was born (around the mid-fifteenth century), most of the understanding of the heart in Europe was derived from the works of Aristotle and Galen, who both had contradictory views. Not only was the heart's physical structure perceived to be different (some said it was a three-chambered organ), but the heart also had a spiritual role in those days, as it was believed that it was the heart that safeguarded life and carried our virtue or spiritus.
It was da Vinci who said that the heart had four chambers, two upper and two lower and that there was a functional distinction between the atria and ventricles. He also demonstrated that the heart did not draw air from the lungs. It was also da Vinci who showed that the valves of the heart were critical to its function. da Vinci also seems to have been the first to recognize that the heart is a muscle and that systole is the active phase of the pump. Leonardo da Vinci's observations about the heart can be deemed pioneering in the history of cardiology.
1550-1700
William Harvey (1578 -1657) was an English physician who was the first to recognize the full circulation of blood in the human body and to provide experiments and arguments to support this idea. Harvey taught and practiced medicine until age 40, when in 1618, he became the royal physician, serving both James I and his successor, Charles I.
Harvey was the first scholar to question traditional beliefs about the heart and its circulation dating back to Galen, 1500 years earlier. Galen's theories, widely accepted and taught in all universities as irrefutable truths up to the 17th century, postulated that blood was made in the liver from digested food.
Through his teachings and observations, Harvey developed a new theory to explain how blood flowed through the body. Before Harvey, blood was not thought to circulate in the body—it was believed to be consumed by the body at the same rate that it was produced. Theories were accepted as valid just because Aristotle and Galen said so, not because they were verified empirically. Harvey, however, refused to believe what he was taught and insisted on relying on his experimental observations. Harvey applied rigorous standards to his research and only accepted conclusions as proven when they were based on evidence from repeated experiments. He collected data from phlebotomies and conducted thorough research, including numerous dissections of human beings and as many as 40 animal species. Analyzing all the experimental results and data, Harvey compiled and published his theories in 1628, leading to a huge milestone in understanding the body and blood circulation.
Harvey's approach to this discovery was genuinely revolutionary in the 17th century, and his promotion of critical thinking and experimental testing of ideas was a groundbreaking contribution to science.