Apr 012019
 

Today is the birthday (1578) of William Harvey an English physician who was the first known physician to describe completely, and in detail, the systemic circulation and properties of blood being pumped to the brain and body by the heart, though earlier writers, such as Realdo Colombo, Michael Servetus, and Jacques Dubois, had provided precursors of the theory. It is even more remarkable that he made all of his anatomical observations with no more than a hand-held magnifying glass for close analysis, so that much of his theory of circulation was based on reasoning. His initial conclusions were met with widespread criticism.

Harvey’s initial education was carried out in Folkestone, where he was born. He then entered the King’s School (Canterbury) where he stayed for five years. He then matriculated at Gonville and Caius College in Cambridge in 1593. Harvey graduated as a Bachelor of Arts from Caius in 1597. He then travelled through France and Germany to Italy, where he entered the University of Padua, in 1599. Harvey graduated as a doctor of medicine at the age of 24 from the University of Padua in 1602. After Padua, Harvey immediately returned to England where he obtained the degree of doctor of medicine from the University of Cambridge that same year, and became a fellow of Gonville and Caius College. Following this, Harvey established himself in London, joining the Royal College of Physicians on 5th October 1604. He joined Bart’s hospital and became Physician in Charge in 1609. He also acted as physician to James I and Charles I.

Harvey was a prominent sceptic regarding allegations of witchcraft. He was one of the examiners of four women from Lancashire accused of witchcraft in 1634, and as a consequence of his report, all of them were acquitted. Earlier, in 1632, while travelling with the King to Newmarket, he had been sent to investigate a woman accused of being a witch. Initially he told her that he was a wizard and had come to discuss the Craft with her, and asked whether she had a familiar. She put down a saucer of milk and called to a toad which came out and drank the milk. He then sent her out to fetch some ale, and killed the toad and dissected it, concluding that it was a perfectly ordinary animal and not supernatural in any way. When the woman returned she was naturally very angry and upset, but Harvey eventually silenced her by stating that he was the King’s Physician, sent to discover whether she were a witch, and if she were, to have her apprehended.

Harvey published Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus in 1628 in the city of Frankfurt (host to an annual book fair that Harvey knew would allow immediate dispersion of his work) The 72-page book contains his mature account of the circulation of the blood. Opening with a dedication to King Charles I, the quarto has 17 chapters which give a clear and connected account of the action of the heart and the consequent movement of the blood around the body in a circuit. Having only a tiny lens at his disposal, Harvey was not able to draw the adequate pictures that were attained through such microscopes as used by Robert Hooke and Antonie van Leeuwenhoek somewhat later. Thus, he had to resort to theory – and not practical evidence – in certain parts of his book. After the first chapter, which simply outlines past ideas and accepted rules regarding the heart and lungs, Harvey moves on to a fundamental premise of his treatise, stating that it was important to study the heart when it was active in order to truly comprehend its true movement; a task which he found of great difficulty.

His initial hypothesis that the heart is a pump led to a detailed analysis of the overall structure of the heart (studied with less hindrances in cold-blooded animals). After this, Harvey analyzes the arteries, showing how their pulsation depends upon the contraction of the left ventricle, while the contraction of the right ventricle propels its charge of blood into the pulmonary artery. He emphasizes the fact that these two ventricles move together almost simultaneously and not independently as had been thought previously by his predecessors. This discovery was made while observing the heart of such animals as the eel and several other types of fish.

The apex of Harvey’s work is probably the 8th chapter, in which he deals with the actual quantity of blood passing through the heart from the veins to the arteries. Coming into conflict with Galen’s accepted view of the liver as the origin of venous blood, Harvey estimated the capacity of the heart, how much blood is expelled through each pump of the heart, and the number of times the heart beats in a half an hour. All of these estimates were purposefully low, so that people could see the vast amount of blood Galen’s theory required the liver to produce. He estimated that the capacity of the heart was 1.5 imperial fluid ounces (43 ml), and that every time the heart pumps, ​1⁄8 of that blood is expelled. This led to Harvey’s estimate that about 1⁄6 imperial fluid ounce (4.7 ml) of blood went through the heart every time it pumped. The next estimate he used was that the heart beats 1,000 times every half an hour, which gave 10 pounds 6 ounces of blood in a half an hour, and when this number was multiplied by 48 half hours in a day he realized that the liver would have to produce 498 pounds of blood in a day, more than the weight of the whole body.

Having this simple but essential mathematical proportion at hand – which proved the overall impossibility of the role of the liver according to Galen – Harvey went on to prove how the blood circulated in a circle by means of countless experiments initially done on serpents and fish: tying their veins and arteries in separate periods of time, Harvey noticed the modifications which occurred. IF he tied the veins, the heart would become empty, while if he did the same to the arteries, the organ would swell up.

This process was later performed on the human body (in the image above): the physician tied a tight ligature on to the upper arm of a person. This would cut off blood flow from the arteries and the veins. When this was done, the arm below the ligature was cool and pale, while above the ligature it was warm and swollen. The ligature was loosened slightly, which allowed blood from the arteries to come into the arm, since arteries are deeper in the flesh than the veins. When this was done, the opposite effect was seen in the lower arm. It was now warm and swollen. The veins were also more visible, since now they were full of blood. Harvey then noticed little bumps in the veins, which he realized were the valves of the veins discovered by his teacher, Hieronymus Fabricius. Harvey tried to push blood in the vein down the arm, but to no avail. When he tried to push it up the arm, it moved quite easily. The same effect was seen in other veins of the body, except the veins in the neck. Those veins were different from the others – they did not allow blood to flow up, but only down. This led Harvey to believe that the veins allowed blood to flow to the heart, and the valves maintained the one way flow.

Contrary to a popular misconception, Harvey did not predict the existence of capillaries. His observations convinced him that direct connection between veins and arteries is unnecessary. He wrote “blood permeates the pores” in the flesh and it is “absorbed and imbibed from every part” by the veins.

Heart has to be the dish du jour.  I cook ox heart quite frequently when I can find it, usually in a simple stew spiced with cloves and allspice. It is not a popular meat in the US, but in most other countries where I have lived it is cheap and readily available. If you are cooking for guests who are unfamiliar with heart, it’s not a bad idea to cut it into bite sized chunks, discarding the valves and other gnarly bits that diners might be squeamish about. When I cook for myself alone I am not as fussy.

Heart is not the tenderest of muscle meats, but it is not the toughest either. When making a stew you should brown the meat and then simmer it in broth with the usual vegetables for about 2 hours.  The old fashioned way of cooking heart is to stuff it and roast it. That is the method my mum used, probably following Mrs Beeton.  Here’s her recipe.

TO DRESS A BULLOCK’S HEART.

INGREDIENTS.—1 heart, stuffing of veal forcemeat, No. 417.

Mode.—Put the heart into warm water to soak for 2 hours; then wipe it well with a cloth, and, after cutting off the lobes, stuff the inside with a highly-seasoned forcemeat (No. 417). Fasten it in, by means of a needle and coarse thread; tie the heart up in paper, and set it before a good fire, being very particular to keep it well basted, or it will eat dry, there being very little of its own fat. Two or three minutes before serving, remove the paper, baste well, and serve with good gravy and red-currant jelly or melted butter. If the heart is very large, it will require 2 hours, and, covered with a caul, may be baked as well as roasted.

Time.—Large heart, 2 hours. Average cost, 2s. 6d.

Sufficient for 6 or 8 persons.

Seasonable all the year.

Note.—This is an excellent family dish, is very savoury, and, though not seen at many good tables, may be recommended for its cheapness and economy.

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