Friday, September 11, 2015

625-690: What did the ancients know of the cardiovascular system?

Sometime during the 7th century A.D. Paulus Aegineta recorded all he knew about ancient medicine.  It is from his works that we can gather a sense for what the ancient physicians thought about the heart and lungs.

The lungs were essential to life, as they provided for the breath that was necessary for the inhalation of a spirit, or pneuma, that was essential for the establishment of life, or a soul.  Yet the main purpose of the lungs were to facilitate the heart with nutrients, and to make sure it doesn't become too hot.

Aegineta noted what he learned about the heart.  I will break down what he said to make for easier reading.  He said:

"These are the marks of an unusually warm heart:
  • Largeness of respiration
  • Quickness and density of pulse
  • Boldness and maniacal ferocity
  • The chest is covered with hair, particularly the breast, and usually the parts of the hypochondriac regions adjoining to it
  • The whole body is hot, unless the liver powerfully antagonise. 
  • And capacity of chest is also a mark of heat, unless the brain in that case antagonise. 
"But an unusually cold heart has the pulse smaller than moderate, and such persons are timid and spiritless, more especially if there be no hairs on the breast.

"Dryness of the heart renders the pulse hard, and the passions ungovernable, fierce, and difficult to quell; and, for the most part, the whole body is drier than usual, unless the parts about the liver antagonise. 

"These are the marks of a more humid temperament: 
  • A soft pulse
  • A disposition easily roused to anger and easily pacified, 
  • The whole body more humid than common, unless antagonised by the parts about the liver. 
"When the temperament is both hotter and drier, the pulse is large, hard, and quick and dense; and the respirations large, quick, and dense. And of all others such persons have the most hair upon the breast aud pnecordia; they are prone to action, given to anger, fierce and tyrannical in their dispositions; for they are both passionate and implacable.

"But, if humidity prevails with heat, such persons are less covered with hair than the afore-mentioned; they are prompt to action, their disposition is not tierce, but only prone to anger; their pulse is large, soft, quick, and dense. 

"But when the temperament is more humid and cold than common, the pulse is soft, the disposition spiritless, timid and sluggish; they have no hair on the breast, and neither indulge in lasting resentment, nor are prone to anger. 

"A cold and dry heart renders the pulse harder and small. Of all others, such persons are least given to anger, but when provoked they retain their resentment. They are also particularly distinguished by having no hair on the breast.

Okay, so the modern reader might read all that and think: what a bunch of bull. What does hair on the chest have anything to do with the heart.  However, when we consider what the ancients thought of the heart, it all makes sense.  Francis Adams, who translated the works of Aeginenta in the 19th century, clarifies what Aegineta wrote.  Adams said:
In the ancient system of physiology, the heart was considered as the seat of the Vital powers, its office being the preservation of the innate heat of the body.
The philosopher, Aristotle, had pointed out the connexion between heat and vitality, and had taught that the heart, as being the centre of heat, is the prime organ in the animal frame. Hence, as his commentator, Averrhoes, remarks, it is the primum movens et ultimum moriens (the first mover and the last dying).
Galen, however, maintained with Hippocrates, that the animal frame is a circle, having neither beginning nor end, and that, consequently, it has no prime organ. He taught that the brain does not, properly speaking, derive its powers from the heart, nor the heart from the brain; but that these organs are mutually dependent upon one another, the heart being in'" 'debted to the brain for supplying the parts concerned in respiration with muscular energy, and the brain being indebted to the heart for its vital heat, without which it could not continue to be the vehicle of sensibility and motion.
We have mentioned in the preceding Section, that the ancient physiologists looked upon respiration as being a process similar to combustion. The heart, then, was supposed to convey heat to all parts of the body, by means of the animal spirits incorporated with the blood in the arteries.
Respecting the contents of the arteries, two hypotheses divided the ancient schools of medicine. The first was that of the celebrated Erasistratus, who maintained, that the arteries do not contain a fluid, but merely certain airs or vapours. The other hypothesis was that of Galen, who keenly attacked this, as he did most of the tenets of Erasistratus, and endeavoured to prove, by experiment, observation, and reasoning, that the contents of the arteries is blood, mixed, indeed, with a certain proportion of heat and airs, but in every respect a fluid, little different from that contained in the veins.
It was also part of his system, that the right cavity of the heart attracts blood from the liver, and conveys it to the left, from which it is diffused all over the body by the arteries. He taught that, at every systole of the arteries, a certain portion of their contents is discharged at their extremities, namely, by the exhalents and secretory vessels; and that at every diastole a corresponding supply is attracted from the heart. He decidedly inculcates, in opposition to Asclepiades, that it is the expansion or diastole of the artery which occasions the influx of the blood, and not the influx of the blood which occasions the expansion of the artery; or, in other words, that the systole is the function of the heart, and the diastole its return to its natural state.
Though he demonstrated the anastomosis of arteries and veins, he nowhere hints his belief, that the contents of the former pass into the latter, to be conveyed back to the heart, and from it to be again diffused over the body. In a word, his system appears to have been nearly, or altogether, the same as that which was afterwards taught by the unfortunate Servetus.
It is clear, therefore, that Galen had made a very near ap proach to the Harveian theory of the circulation; indeed, Harvey himself candidly admits this. It will be perceived, from what' "' we have stated, that the grand point of difference between Galen and Harvey, and that upon which the theory of the latter mainly rests, is the question whether or not at every systole of the left ventricle more blood be thrown out than is expended on exhalation, secretion, and nutrition. Upon this point Galen held the negative, Harvey, as we all know, the affirmative.\
With regard to the passages collected by the ingenious M. Dutens and others, from the works of Hippocrates, Plato, Nemesius, Pollux, and Theodoret, to prove that the ancients were acquainted with the circulation of the blood, as taught by Harvey, we shall only remark, that, after having attentively considered them, we cannot but draw the conclusion, that some of these authors must have had, at least, an obscure idea of this doctrine, although, in general, these passages may be understood to refer merely to the lesser circulation and the movement of the blood from the centre to the extremities, as maintained by Galen.
The last of these writers, whose minute acquaintance with the earlier works on medicine entitles his opinion to every consideration, after a searching investigation into the state of anatomical knowledge in the days of Hippocrates and his immediate successors, comes to the conclusion, that the germ of the theory of the circulation is, beyond doubt, to be found in the Hippocratic treatises.
In 1553, Michael Servetus (1509?-1553) was the first to accurately describe the circulation of the blood through the body, although he was burned at the stake for opposing accepted opinion.  His pupil was William Harvey (1578-1657), and because he was the first to publish evidence that blood circulates, he is given credit by history.

However, Harvey openly acknowledged that he was not the first to conclude that blood circulates, even going as far to say that the ancients knew of it, or, if not, were very close to knowing it.

Still, Galen described the blood as ebbing to and fro, from the heart to the liver and back to the heart, for example.  This was a common belief until Harvey proved, without a doubt, that the blood did circulate.

Further reading:
  1. Aegineta, Paulus, "The Seven Books of Paulus Aegineta," translated by Francis Adams, volume I, 1834, London, Snydenham Society, pages 94-96
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