Matteo Realdo Colombo was an Italian anatomist and became Vesalius' assistant in 1541. Later he became his successor as Professor of Anatomy at the prestigious University of Padua.
Colombo made numerous original contributions to the knowledge of the anatomy as he performed a significant number of dissections and vivisections throughout his career. From historical point of view, he is credited with the first description of the pulmonary circulation.
Colombo's observations were published in a book under the title, "De re Anatomica," in 1559 posthumously. A second edition of this work appeared in Paris in 1562. This book consists of fifteen sections and the chapter seven primarily discusses the pulmonary circulation. In chapter fourteen, Colombo described his observations in vivisection.
Realdo Colombo first gave a detailed description denying any communication between the right and left ventricle via the interventricular septum. He then described precisely the pulmonary or lesser circulation based on almost a thousand dissections or vivisections:
"Between these ventricles is the septum through which almost all think there is a way from the right ventricle to the left, so that the blood in transit may be rendered subtle by the generation of the vital spirits in order that the passage may take place more easily. But they are in great error, for the blood is carried through the pulmonary artery to the lung and is there attenuated; then it is carried, along with air, through the pulmonary vein to the left ventricle of the heart. Hitherto no one has noticed this or left it in writing, and it especially should be observed by all. Wherefore I cannot wonder enough that anatomists have not observed a matter so clear and of such importance. For them it suffices that Galen Said so. There are some in our time who swear by the opinions of Galen and assert that he should be taken as gospel and that there is nothing untrue in his writings."
Colombo showed by vivisection that the pulmonary veins and the left atrium contained blood. He also suggested that the blood and air were mixed in the lungs rather than in the heart.In addition to the pulmonary circulation, he also described precisely the function of the cardiac valves. He explained that the cardiac valves allowed the blood to move in one direction and disproved the Galenic concept of relative incompetency of the cardiac valves:
"...Two of them have been constructed so that they carry [blood] inwardly to the heart, that is, when the heart is dilated [in diastole]; but the other two carry [blood] outward when the heart is constricted [in systole]. Therefore when it is dilated, and those membranes are loosened and yield ingress, the heart receives blood from the vena cava into the right ventricle, and also prepared blood from the pulmonary vein, as we said, along with air into the left ventricle. And when the heart is compressed [in systole], these valves are closed lest the vessels receive anything regressing along the same path; and at the same time the valves of both the aorta and the pulmonary artery are opened; they permit the passage of the outgoing spirituous blood which is diffused through the whole body and of the natural blood which is carried to the lungs; and it is always thus when the heart is dilated, as we noted before: [that the] other [valves] open and then shut. And so you will find that the blood which has entered the right ventricle is unable to return to the vena cava."
Chapter seven and fourteen are reproduced entirely in the original Latin version.
Although he conceived the pulmonary circulation, Colombo did not fully understand the mechanism of blood circulation. Adhering to the Galenic teaching, he believed that the liver was the centre of cardiovascular system. He was also of the opinion that nutritive blood containing natural spirits was transported from the liver to the entire body throughout the venous system.
Historians have debated over centuries on the designation of the author who first described the pulmonary circulation and have questioned the originality of Colombo's contribution.
In 1553, Michel Servetus published his "Christianismi Restitutio". In this large theological book, he described the passage of the blood from the right ventricle through the lungs and not through the interventricular septum. As most of Servetus writing was against the religious belief of his time, he was condemned to death and his book was entirely burned and destroyed. Most historians believe that Colombo did not have access to "Christianismi Restitutio", and did his observations on pulmonary circulation independently, despite strong similarities between the two texts.
Ibn-Al-Nafis also questioned the existence of pores in the septum in the 13th century and his text provided an accurate description of the pulmonary circulation. According to most historians, Colombo did not have knowledge of this text.
Ibn-Al-Nafis (1210-1288). Ibn an Nafis und seine Theorie des Lungenkreislaufs. Von Max Meyerhof. Quell.Stud. Gesch. Med., 1933,4, 37-88
Michael Servetus (1511-1553). Christianismi restitutio. (Vienne, Balthasar Arnollet), 1553
Moes RJ, O'Malley CD. Realdo Colombo: On those things rarely found in anatomy. An annotated translation from his De Re Anatomica(1559). Bull His Med 1960;34:508-528
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Fye WB. Profiles in Cardiology: Realdo Colombo. Clin Cardiol 2002;25:135-137