Leonardo da Vinci and His Study of the Heart

A 500-year Anniversary Appreciation of a Maestro

Marco Cambiaghi; Heidi Hausse

Disclosures

Eur Heart J. 2019;40(23):1823-1826. 

"How in words can you describe this heart without filling a whole book? (Quaderni 11 1 r.)"

The 500th anniversary of the death of Leonardo da Vinci (1452–1519, Figure 1) this spring is a fitting moment to reflect on the passionate efforts of this larger-than-life figure to study the human heart. Leonardo was a famous artist but also an innovative engineer, inventor, and early modern scientist.[1] His scientific explorations of the body, while in many ways grounded in the beliefs of his own time, show both his particular genius in observation and deduction, and an underlying empiricism that resonates deeply with the approaches of modern biology. Leonardo's findings on the anatomy and physiology of the heart, preserved in his private sketches and notes, reveal a remarkable period of transition in the early history of cardiology.

Figure 1.

Leonardo da Vinci self-portrait (c.1515–1516), red chalk on paper. Credit: ©Musei Reali—Biblioteca Reale di Torino.

At the time of Leonardo's birth in the mid-fifteenth century, the prevailing understanding of the structures and functions of the heart in Europe derived from ancient authorities, particularly Aristotle and Galen, whose contradictory views were synthesized for Europeans through the influential work of the Arabic physician Avicenna.[2] While many different theories of the heart and its functions persisted side by side, one tradition imagined the heart as a three-chambered organ in which venous and arterial blood were separate. Furthermore, the diastole was considered the active phase of the cardiac cycle, pulling blood from the veins, while the lungs delivered air to the left ventricle through the pulmonary vein.[3,4] At the same time, the heart had an almost spiritual role.[2] It was in the heart that the vital virtue or spiritus, which safeguarded life itself, was produced and then spread throughout the body.[5]

The developing artistic style of Renaissance Italy, which emphasized naturalistic portrayals of human figures, spurred interest among artists to learn anatomy.[5] Leonardo first approached gross anatomy through his early artistic studies and he took part in many post-mortem examinations of human bodies during his apprenticeship in the workshop of the sculptor Andrea del Verrocchio (c.1435–1488).[6,7] However, this early work was an attempt to understand the architecture of the body primarily for the purpose of artistic representation rather than scientific exploration.[8]

By the 1490s, Leonardo's interest in anatomy had grown into an independent area of investigation. The artist developed a special curiosity for human morphology and physiology. His studies sought to connect what he considered to be inseparable: bodily structures and their functions.[8] In his drawings of the human body, the artist embarked on in-depth explorations into the anatomy and functions of specific organs—including the heart.[7] Endowed with a pulsatile faculty, the heart fascinated Leonardo, who called it an instrumento mirabile, invenzionato dal sommo maestro (12 R),[9] a 'wonderful instrument invented by the Supreme Master'.

The vast majority of his observations on the heart are reported in drawings and notes he produced while working in Milan from 1508 to 1513, though afterwards he continued to work on the physiology of the heart while in Rome.[10,11] Notably, most of Leonardo's initial drawings from 1508 were based on studies of the hearts of oxen or pigs; only later did the artist gain access to human cadavers for dissection.[8]

Leonardo's anatomical knowledge was an amalgamation drawn from textual sources and first-hand experience. In addition to the influence of Galenic theories, the artist was familiar with Mondino de' Liuzzi's medieval handbook on dissection, entitled Anothomia (1316).[12,13] Significantly, Anothomia was well-regarded by Mondino's contemporaries for its references to the author's own dissections.[5,14] In the medieval period, dissections of human cadavers were largely performed in the nature of an autopsy for legal purposes and, over time, dissection also became part of medical education.[5,15]

During the Renaissance, Italian universities built anatomy theatres to hold public dissections of executed criminals.[15,16] Artists such as Antonio di Jacopo Pollaiuolo (ca. 1431–98) also began to perform their own dissections in order to investigate human anatomy more thoroughly.[17] Leonardo himself became a master of human dissection over several years. Before the age of 40, he referred to dissecting more than 10 human bodies. By his death, the number climbed to 'over thirty'.[7]

One such dissection took place in 1506 at the hospital of Santa Maria Nuova, in Florence. Leonardo dissected the body of a 100-year-old man whose death the artist had witnessed firsthand.[18,19] With the intention of understanding the cause of sì dolce morte ('so sweet a death') (10 R),[9] he reported what has at times been credited as the first known description of artery disease.[20] By comparing these results with his findings from a dissection, he performed on a child of 2 years of age, Leonardo 'found everything opposite to that of the old man' (10 R).[9] Due to his knowledge of hydrodynamics and anatomy, the artist was able to interpret the physical basis of such a natural death to the arteriosclerosis of old age.[19,20] Indeed, Leonardo correctly deduced that the tortuosity and thickening of blood vessels caused a reduced blood supply to the heart, contributing to its dysfunction (Figure 2).[8]

Figure 2.

Increasing tortuosity and constriction of the vessels in the elderly (c.1508). Bottom of RL919028. Credit: Royal Collection Trust/© Her Majesty Queen Elizabeth II 2019.

Though Leonardo's interpretations were not a completely new departure in Renaissance anatomy or in medical theory, the artist did make many observations that were at odds with classical teachings.[10] He believed that the heart consisted of four chambers, two upper and two lower, with a functional distinction between the atria and ventricles (Figures 3 and 4).[4,8] Leonardo also showed that the heart does not draw air from the lungs, opposing Galen's teachings on the function of the pulmonary vein.[10] His excellent skill as an anatomist enabled him to detect even rare congenital cardiac anomalies, such as a quadricuspid semilunar valve that he sketched in detail, even if he did not recognize it as a functional impairment.[21]

Figure 3.

Dissections of the heart and its ventricles, with numerous notes on the supremacy of mathematics (c.1513). Top of RL919084. Credit: Royal Collection Trust/© Her Majesty Queen Elizabeth II 2019.

Figure 4.

Sections of the ventricles (c.1511–13). RCIN 919073. Credit: Royal Collection Trust/© Her Majesty Queen Elizabeth II 2019.

Leonardo's studies on water flow may have contributed to his ideas about the heart's functions and anatomy.[19] Unaware of the circulatory system that would not be fully demonstrated until 1628 by William Harvey, Leonardo's understanding followed Galenic precepts: the blood was produced in the liver, cooled by the lungs and pumped by the heart in order to nourish the muscles and be consumed there.[10] To explore the workings of the heart, Leonardo injected warm wax into a bull's heart to examine the valves' forms in their natural state (Figure 5).[20] He then created a glass model of the heart to study the hydraulic characteristics of the blood flux and the function of valves.[6] In so doing, Leonardo intuited that the valves were key to the functioning of the heart, considering them as a perfect model of the mathematical and geometrical essence present in all the workings of nature (Figure 2).[8]

Figure 5.

The aortic valve. Notes on the valves of the heart and the flow of blood within it and a drawing of a mould for the making of a glass model of the pulmonary or aortic valves. (c.1512–13). RCIN 919082. Credit: Royal Collection Trust/© Her Majesty Queen Elizabeth II 2019.

There are more instances in which Leonardo's observations can be considered as truly pioneering in the history of cardiology. In one of his most beautiful drawings, seen in figure (Figure 6), Leonardo authored what has been called the first known representation of the coronary arteries.[22] Furthermore, in his attempts to explain heart fluid dynamics, Leonardo accurately predicted the formation of vortices between the aortic valve cusp and the sinus wall in controlling the mechanism of closure of the aortic valve. This phenomenon was clearly explained only in 1968 in a Nature paper by Bellhouse and Bellhouse, in which the authors cited only one previous description, the one made by Leonardo more than four centuries earlier.[23]

Figure 6.

The heart and coronary vessels. Drawings of varying size of the heart showing the origin of the coronary arteries and their course; details of semilunar valves (c.1511–13). RCIN 919073 v and 919074. Credit: Royal Collection Trust/© Her Majesty Queen Elizabeth II 2019.

Leonardo da Vinci is a remarkable historical figure not only for his talent and genius as an artist and engineer, or even for the wonderful imagination of his flying machine. Leonardo's study of the heart reveals an individual who possessed an extraordinary curiosity about the world, and who found in the human body and in the human heart a microcosm of that world. His investigations into the workings of the human body present a scientist increasingly driven to discover for the sake of discovery. Leonardo's explorations of the heart were contained in his private notebooks, which were published posthumously and did not themselves strongly develop anatomical study in his own lifetime.[5,24]

Yet, looking back 500 years after his death, we can see that Leonardo's experiments, observations, and sketches underscore a gradual yet weighty shift in the history of medicine—a time when ancient authorities began to be questioned as hands-on experimentation uncovered flaws in traditional knowledge. As a 'Renaissance cardiologist', Leonardo is both a representative of the transformative moment of his own time and an inspirational reflection of the hunger for discovery that drives medical professionals today.

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