In much of modern medical literature, the discovery is credited to English physician William Harvey (1578 – 1657 CE) based on the comprehensive completeness and correctness of his model, despite its relative recency.

At the time, the Egyptians believed that the heart was the origin of many channels that connected different parts of the body to each other and transported air – as well as urine, blood, and the soul – between them.

[24] A second scroll, the Ebers Papyrus (c. 1550 BCE), also emphasized the importance of the heart and its connection to vessels throughout the body and described methods to detect cardiac disease through pulse abnormalities.

His descriptions built substantially on previous and contemporaneous efforts but, by modern standards, his conceptions of pulmonary circulation and of the functions of the parts of the heart were still largely inaccurate.

[23] Greek physician Erasistratus (315 – 240 BCE) agreed with Hippocrates and Aristotle that the heart was the origin of all of the vessels in the body but proposed a system in which air was drawn into the lungs and traveled to the left ventricle via pulmonary veins.

Galen further proposed that the heat of the blood arriving in the heart produced noxious vapors that were expelled through the same pulmonary veins that first brought the pneuma.

[19] The Arab physician, Ibn al-Nafis, wrote the Commentary on Anatomy in Avicenna's Canon in 1242 in which he provided possibly the first known description of the system that remains substantially congruent with modern understandings, in spite of its flaws.

[22] However, like Aristotle and Galen, al-Nafis still believed in the quasi-mythical concept of vital spirit and that it was formed in the left ventricle from a mixture of blood and air.

Despite the enormity of Ibn al-Nafis's improvements on the theories that preceded him, his commentary on The Canon was not widely known to Western scholars until the manuscript was discovered in Berlin, Germany, in 1924.

[19][22] In 2021, several researchers described a text predating the work of al-Nafis, fargh- beyn-roh va nafs, in which there is a comparable report on pulmonary circulation.

The researchers argue that its author, Qusta ibn Luqa, is the best candidate for the discoverer of pulmonary circulation on a similar basis to arguments in favour of al-Nafis generally.

Italian polymath Leonardo da Vinci (1452 – 1519 CE) was one of the first to propose that the heart was just a muscle, rather than a vessel of spirits and air, but he still subscribed to Galen's ideas of circulation and defended the existence of interventricular pores.

[23] The Flemish physician Andreas Vesalius (1514 – 1564 CE) published corrections to Galen's view of circulatory anatomy, questioning the existence of interventricular pores, in his book De humani corporis fabrica libri septem in 1543.

In subsequent centuries, he has frequently been credited with the discovery, but some historians have propounded the idea that he potentially had access to Ibn al-Nafis's work while writing his own texts.

[19] Servetus published his findings in Christianismi Restituto (1553): a theological work that was considered heretical by Catholics and Calvinists alike.

[19] Italian physician Realdo Colombo (c. 1515 – 1559 CE) published a book, De re anatomica libri XV, in 1559 that accurately described pulmonary circulation.

It is still a matter of debate among historians as to whether Colombo reached his conclusions alone or based them to an unknown degree on the works of al-Nafis and Servetus.

[19][23] Finally, in 1628, the influential British physician William Harvey (1578 – 1657 AD) provided at the time the most complete and accurate description of pulmonary circulation of any scholar worldwide in his treatise Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus.