HISTORICAL DEVELOPMENT OF CARDIOVASCULAR PHYSIOLOGY 



cise description of the pulmonary circulation and also 

 of the simultaneous beat of the two ventricles of the 

 heart. Harvey quotes Colombo, and also credits him 

 with claiming that blood mixes with air in the lungs 

 instead of in the heart as the Galenical doctrine postu- 

 lates. However, Colombo did question the dogma 

 about pores in the cardiac septum. This was beginning 

 to be a crucial problem for the validity of scholastic 

 cardiovascular theory. Actually Galen may have seen 

 the Thebesian vessels, named for Adam Christian 

 Thebesius {1686-1732), which however drain venous 

 sinuses from the coronary vessels. The error in the 

 interpretation of these endocardial openings was 

 paramount in scholastic dogma, and, when fully ex- 

 posed, led to its repudiation. 



Andrea Cesalpino (1519-1603) raised the question 

 of blood circulation academically, but decided against 

 it on the basis of Galenical theory. Yet he showed the 

 centripetal flow of blood in veins, without however 

 impressing his contemporaries or his followers. He 

 noted the differences in structure between the pulmo- 

 nary arteries and the pulmonary veins with reflections 

 on their function, in comparison with systemic arteries 

 and veins. He showed connections between portal 

 veins and the vena cava, and described the reciprocal 

 relations between cardiac contraction and arterial 

 dilatation. Further, he raised the question of possible 

 communications between arteries and veins. - 



Meanwhile, critical study was gaining a following 

 in anatomy. Gabriele Falloppio (1523-1562), a pupil 

 and successor of Vesalius at Padua, corrected his 

 teacher's account of the course of cerebral arteries, 

 and described a nerve plexus in the heart. Giulio 

 Cesare Aranzio (1530- 1589), another of the great 

 Bolognese anatomists, noted the fetal ductus arteriosus 

 and ductus venosus. He also observed the corpora 

 aranlii in heart valves. The fetal heart was further 

 described by Arcangelo Piccolomini (i 525-1 586), 



^ In discussing Cesalpino's studies, S. Peller emphasizes how 

 Harvey's quantitative reasoning led him flashingly to go beyond 

 Cesalpino's cautious approach to the irrefutable demonstration 

 of blood circulation {Bull. Hut. Med. '23: 213—235, 1949). How- 

 ever, W. Pagel shows clearly how the ancient Aristotelean doc- 

 trine of circular motion was part of the philosophical climate 

 of the late Renaissance and greatly influenced both Cesalpino 

 and Harvey. The symbol of a circle was applied to blood move- 

 ment by Plato (427-347 B.C.), and elaborated by Giordano 

 Bruno (1548- 1600); it was applied scholastically to a cyclical 

 movement of the heart by Thomas Aquinas (i225?-i274). In- 

 deed, as F. Boenheim suggests iJ. Hist. Med. 12: 181-188, 

 1957), the circular philosophy was implied in very ancient 

 Chinese ideas on the similarities between motions in the macro- 

 cosm (the universe) and the microcosm (man). 



with an account of the foramen ovale. Piccolomini 

 correctly ascribed the arrangement of valves in the 

 jugular veins, and in veins in the limbs, to the function 

 of preventing reflux of blood on change of position. 

 Thus there was much in the state of knowledge at the 

 time to prepare the way for such a conceptual syn- 

 thesis as Harvey achieved. 



H.^RVEV S ACHIEVEMENT 



A great medical teacher was Girolamo Fabrizzi 

 (1537-16 1 9), who attracted students from all Europe 

 to his anatomical demonstrations in Padua. Some, 

 like the keen young Englishman, William Harvey 

 (1578-1657), helped him with experiments on the 

 developing chick and with his dissections of the valves 

 of the veins. Long he puzzled over the possible func- 

 tion of these structures. Perhaps he passed his curiosity 

 to his famed pupil. Harvey had returned to London 

 when his master's book, De venarum ostiolis, appeared in 

 1603. Long afterward Harvey acknowledged the 

 inspiration received from Fabrizzi. He must have 

 been considering the complicated matter of blood flow 

 by the time he was appointed Lumleian Lecturer to 

 the Royal College of Physicians in 16 15, for his manu- 

 script notes for the first "visceral" lecture in 1616, 

 given the very month Shakespeare died, raised the 

 question of the systemic circulation, with preliminary 

 observations to justify it. 



It was not until twelve years later that Harvey 

 published his famed De rnotu cordis from an obscure 

 Frankfurt printer, William Fitzer. It is a remarkable 

 item of only 70 pages comprising a preface, introduc- 

 tion and 17 chapters. It not only established the 

 central principle of modern physiology and indeed of 

 medicine, but it also demonstrated the most effective 

 method of procedure in the natural sciences: a) care- 

 ful and accurate observation and description of a 

 phenomenon; b) a tentative explanation of how the 

 phenomenon occurs; c) a controlled testing of the 

 hypothesis, and d) conclusions based on the results of 

 the experiments. In addition, he introduced the 

 method of quantitative reasoning which forced 

 validity of the conclusions. 



For all the greatness of the achievement, the eff'ort 

 may be severely criticized in the light of our present 

 practices, as Wiggers has done. However, Harvey was 

 a pioneer and had no example to follow. In spite of 

 his occasional fumbling logic, in spite of his failure to 

 deal eff"ectively with the pulmonary circulation, and 



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