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1 of 253523 objects
Blood flow through the aortic valve c.1512-13
Pen and ink on blue paper | 28.6 x 20.5 cm (sheet of paper) | RCIN 919083
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The nominal recto is blank apart from Melzi's inscribed .N. and a small calculation.
On the verso, drawings of the flow and eddies of blood in the heart, with notes on the drawings. In twenty sketches, Leonardo continues to examine the flow of blood through the aortic valve and the eddies in the sinus of Valsalva, whose discovery he had recorded on the previous sheet. Leonardo found the subject of fluid dynamics perennially interesting, and he often attempted to analyse fluid flow in terms derived from both solid dynamics and optics – impetus, percussion, reflection and so on, as here:
We have demonstrated the beating of the heart to be by impetuses. If this were not so, the left [aortic] valve would not be able to shut, and the blood which was at first located above the valve would immediately descend. But the valve being opened by the impetus and percussion of the blood which the left ventricle drives out of itself [in systole], the valve stays open just as long as a small quantity of blood which issues from the heart keeps it free from obstruction. And at the same time the blood above it cannot descend because the wave of blood which percusses it proceeds in an opposite movement throughout all the arteries. And at the same time the remaining impetus of the blood which opened the valves, closes them again with its reflected movement, and the heart opens again [in diastole].
On the reopening of the left ventricle, the blood contained in it ceases to issue from this ventricle, and at that time the blood which had issued from it would return into this ventricle together with that which is placed above it. But the remaining circumvolving impetus which still survives in the ejected blood is that which percusses the sides of the valves and closes them so that this blood cannot descend. And if there were not the revolving of the aforesaid circular movement of the blood newly driven out of the left ventricle, without doubt the penultimate blood driven out of this ventricle would return into the ventricle.
The essential role of the vortices in the sinus of Valsalva in the closing of the aortic valve was not posited again until 1912, and is now well established (see F. Robicsek, ‘Leonardo da Vinci and the Sinuses of Valsalva’, Annals of Thoracic Surgery, LII, 1991, pp. 328-35). Leonardo’s intuitive understanding of this mechanism is highly impressive.
Text from M. Clayton and R. Philo, Leonardo da Vinci: Anatomist, London 2012
Provenance
Bequeathed to Francesco Melzi; from whose heirs purchased by Pompeo Leoni, c.1582-90; Thomas Howard, 14th Earl of Arundel, by 1630; Probably acquired by Charles II; Royal Collection by 1690
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Creator(s)
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Medium and techniques
Pen and ink on blue paper
Measurements
28.6 x 20.5 cm (sheet of paper)
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