Pt1. In the Spirit of the Heart Work of Leonardo
Among the near-infinite areas Leonardo showed a profound interest, his unparalleled studies was more than just an extreme fixation about water flow and its dynamics. These led to one of his foremost discoveries about the anatomy of the heart, the intracardiac flows and the precisely and correctly denoted functionality of the heart valves. Some medical historians herald Leonardo’s intracardiac fluid dynamics and valvular mechanisms as his perhaps greatest anatomical discoveries. As recently as nine years ago in 2014 scientists could confirm that Leonardo was right about cardiac fluid dynamics and the balance of pressure across cardiac chambers.
His intricate observations about rivers and water flow were used to understand hemodynamics further. In one of his notebooks, he observed over seven hundred (700) phenomena in flowing water. Leonardo’s combination of scientific curiosity and artistic virtuosity has bequeathed to us aesthetic drawings of a whole array of anatomical angles, accompanied by notes which are based on practical experiments and intricately scientific observation. He had a long-lasting focus on spirals and curls, visible in portraits and his fluid dynamic drawings. The forces creating water eddies in a flowing current or hair curls in a portrait of a woman, or a sketch of his friends’ heads, were parallel in his world. He enjoyed connecting patterns, and his sharp observations made him observe an unparalleled number of scientific areas hundreds of years before others; and stumblingly close to, e.g., Newton, Galileo and Darwin, to name a few.[i]
Leonardo could for instance, study how water falls into a pond, how a water column reacts to various forces, how submerged water bubbles behave, and even build transparent anatomical models to study blood flow and its dynamics. In water he studied how bubbles pop at the surface and sharply observed that the eddies that begin on the surface are filled with air, and those with an origin within the water, are filled with water, and that those are more long lasting, since water within water has no weight. He made hundreds of such observations, then mirrored in haemodynamics, in art and engineering, e.g., in the attempt to divert the Arno. His curiosity went beyond the scientific necessity and went on into the obsession of a genius.
He studied what happens to water blocked by obstacles, subsequent diverted forces, vortices, percussions, impetus, curves and spirals. He understood the nature of waves, and tremors as he called some of them, understood how these propagate in a medium and concluded that sound and light travels in waves.
Leonardo’s superb analogy even transferred waves into emotions, also expressed in the Last Supper, where Jesus causes turbulence by announcing that one of them would betray him – the apostles, symmetrically grouped three by three on either side, all react individually. They form waves of depicted emotions around the epicentre of the harmony disturbing announcement.
One key sign of a great mind is the ability the change and modify the thoughts. Leonardo changed his mind about heart anatomy and fluid dynamics many times – adapting theory after experiment and experience, when they conflicted. Often, he considered several theories, as visible in the Codex Leicester, where we denoted on a large folio twelve parallel theories on river water dynamics. He studied how springs could transport water into rivers, the veins of earth, into the sea, when “logically” water should gravitate and stay at sea level – he eventually understood how the entire water circulation on earth depends on water evaporated from the surface into clouds, and how the same water vapor is also responsible for why the sky is blue. His open-mindedness, willingness to dismiss incorrect theories led him to the correct answers in medicine, geology, physics, and many other areas.[ii]
Leonardo’s Notes on Heart Fluid Dynamics
Leonardo’s anatomical notebooks are full of passion and precision revealing almost more about his personality, than about science. In other words, it has more detail than necessary to explain his findings, and the text is more precise and artistically beautiful than “required” for a scientific publication. In essence, there is abundant evidence of a thriving, unhindered and curious universal genius.
On the recto face of Image 1 Leonardo depicts a bovine heart, including the major vessels and parts of the respiratory system with the tracheal cartilage and bronchial tree. The drawings are, as always, accompanied by richly explaining texts, here on the interactions and actions of respiration vs. the heart. Most of his depictions were made on an ox. The image depicts the heart and vessels from a posterior view. He clearly depicts the sinus coronarius and ramus circumflex branch of arteria coronaria sinistra, in the posterior left atrioventricular groove, with the middle cardiac vein and posterior interventricular artery descending in the posterior interventricular groove. Leonardo draws how the bronchiare branched, and how their C-shaped cartilaginous tubes decrease down to smaller and smaller bronchi. He shows the correct patterns of surrounding veins and arteries in the respiratory tract, including the bronchial arteries originating from the aortic arch. It can be noted Leonardo used the trachea to any air passage in the respiratory tract.[i]
For instance, Leonardo’s extensive notes on cardiopulmonary phenomena, he answers to the then conundrum of how we breathe, under the headline, whether air penetrates into the heart or not in this passage:
To me it seems impossible that any air can penetrate into the heart through the trachea [ie. bronchi], because if one inflates [the lung], no part of the air escapes from any part of it. And this occurs because of the dense membrane with which the entire ramification of the trachea is clothed. This ramification of the trachea as it goes on divides into the most minute branches together with the most minute ramification of the veins which accompany them in continuous contact right to the ends. It is not here that the enclosed air is breathed out through the fine branches of the trachea and penetrates through the pores of the smallest branches of these veins. But concerning this I shall not wholly affirm my first statement until I have seen the dissection which I have in hand.[ii]
Image 1: Leonardo da Vinci (Vinci 1452-Amboise 1519). The heart, bronchi and bronchial vessels (recto); A sketch of the heart and great vessels (verso) c.1511-13.
Leonardo changed his mind several times, all depending of experimental outcome. At first, he did not support the traditional belief of air passing from the lungs into the heart, which he though illustrates on the ventral side of image 1 – here air mixes directly with blood anywhere in the cardiopulmonary system. His skepticism was based on his form belief in experiments, and he often held a provisional hypothesis, as a genuine scientist should do. Four lines from the bottom of the image, Leonardo could have given us a correct rendering of the gaseous exchange in the alveolar membrane. But still, he kept the word not in his text.
Coda
In 2019, five years after Oxford team’s ultimate in-vivo confirmation of Leonardo’s explanation of the fluid dynamics and intracardiac pressure circumstances, and 500 years after his heart drawings and texts, emerged the AI-empowered concept of wireless, non-invasive, intracardiac pressure monitors (ICPM).
After half a millennium medical science, empowered with artificial intelligence, is ready to move on with intracardiac pressure and fluid dynamics, where Leonardo left us. With non-invasive intracardiac pressure monitors we will be able to optimise heart failure treatment, amplify resources and widen our understanding and satisfy our creative curiosity – all in the spirit of Leonardo.
Next week we will explore three ways Leonardo was right about the structure and working of the Heart and Valves.