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|Topic: The Cardiology of Arabian Medicine|
Joined: 12 October 2005
Location: United States
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| Topic: The Cardiology of Arabian Medicine
Posted: 08 September 2006 at 9:49pm
Medieval Arabian or Islamic medicine offers a very colorful and varied picture. In addition to tribal traditions of the Arabian peninsula, there were influences from Syria, Mesopotamia, Persia and India. The unparalleled expansion of Islam created within a century an empire that extended from Spain to India. Contact with the West, and especially with Hellenism was inevitable, and eventually led to an active movement of translation, sponsored by the khalifs and wealthy patrons, in which major works of Greek philosophy, science and medicine were translated into Arabic. Of all the Greek doctors, Galen was for the Arabs by far the most significant, and Hippocratic tradition only followed in his shadow. From Galen came the teleological thinking that sought to recognize and explain each organ and each natural process in terms of its purpose, and to Galen can be traced back that rationalism that has left its impress on most Arabic writings. This is not to say that the Arabs were uncritical; there were indeed some cases in which individual doctrines of Galen were questioned, but the general Galenical system was usually accepted as perfect and final. This system was based largely on "The Four Humours Theory". According to this theory, the body has four cardinal fluids or "humours": blood, phlegm, chole (yellow bile) and melanchole (black bile). The variant mixtures of these humours in different persons determined their' 'temperaments', their physical and mental qualities and their disposition. The ideal person had the ideally proportioned mixture of the four; a predominance of one produced a person who was sanguine, phlegmatic, choleric, or melancholic. Each of theses temperaments had specific characteristics. Health required f an equilibrium between the four humours (eucrasia) and it was the, physician's task to restore this equilibrium whenever it was disturbed by disease (dyscrasia). There was even considered to be some son of analogy, and probably interrelation, between the four humours of man (the microcosm) and the four elements of the universe (the macrocosm): fire, water, earth and air, as formulated by Empedocles. In addition to the humours, Galen also believed in what he called the "pneuma"- a material but very subtle component carried by the blood and responsible for guiding many body processes.
This, in brief, is the basic, general doctrine underlying Galen's physiology. Galen's anatomy was largely based on the dissection of lower animals, particularly the African monkey, form which he made inferences concerning human anatomy. He described the valves of the heart, and observed the structural differences between veins ad arteries. One of his most important demonstrations was that the arteries carry blood, not air, as had been taught for 400 years. Galen did not discover that the blood circulates. According to his view, the most important organ in the vascular system was the liver, where blood was formed from the chyle of absorbed food, and where the veins originated. Blood vessels carried the blood out to the periphery of the body where it was transformed into flesh. He accounted for the large amount of blood in the aorta by suggesting a passage from the right to the left ventricle of the heart through minute invisible pores in the septum that separates them. The two ventricles pulsate in unison, but the left one does so more strongly because it contains a greater amount of blood, "animal spirit" and "innate heat". The right ventricle contains only blood, and only in a small amount. The function of the heart consists in the fact that it is the storehouse and source of the "innate heat" by which life is maintained, but it was not realized that it was a mechanical pump. The movement of the blood and the pneuma in the two vessel systems is unidirectional, centrifugal and tidal.
Such was the theory of the structure and function of the cardiovascular system that dominated medieval Arabian cardiology. To understand it we must free ourselves completely from what is taught today. It was the natural corollary of the teleological rationalism and schematization that characterized the theology and scholasticism of the Middle Ages. By modern empirical standards it was a real straitjacket for medical thought. Rigid and artificial as it was, it did not however prevent the keen observers of Arabian medicine form recording some of the most interesting clinical reports. Consider for example this case history from Rhazes' "continens":
"I was consulted by a man who complained of palpitation of his heart within his chest. When I laid my hand on his left mamma, I felt a pulsation of his aorta so violent as 1 had never observed before. When he stretched out his left arm to show me his basilic vein, the pulsation of his brachial artery was equally violent, so that it was visible, the flesh being raised and sinking in a regular fluctuation. He informed me that he had been bled from his basilic vein without any useful result. His condition as regards the pulse is the same as in asthmatic patients who have an emphysematous distention of the chest, which is not able to inhale the breath sufficiently".
This case of Rhazes is quoted very often; Meyerhof believes it was a case of aortic regurgitation; the late Prof. Kamel Hussein considers also the possibility of a traumatic aneurysm or arteriovenous fistula with a water-hammer pulse. Avicenna, the other great name of Arabic medicine, devotes an entire chapter in his encyclopedic "Canon of Medicine" to a description of the pulse and its clinical significance. Rate, rhythm, volume, force, tension -are all dealt with at length, and a wide range of arrhythmia's is described in detail, including premature beats, pulsus bigeminus, dicrotism, paroxysmal tachycardia and atrial fibrillation. It is really Interesting how Avicenna could squeeze all this information about the pulse in twenty lines of rhyme in his famous "Poem of Medicine", in which the entire "Canon of Medicine" was summarised in just over a thousand lines as an aid to his pupils.
It was however, a later Arab physician who made the real breakthrough in the concepts of medieval cardiology. This was Ibn-an-Nafis, who practiced and taught medicine in Damascus and Cairo and died in 1288. Ibn-Al-Nafis wrote several commentaries on Hippocrates, but he is chiefly known for his " Al-Mujiz", an epitome of Avicenna's "Canon" which was widely known as a practical handbook. He also commented on Avicenna in a larger work, and here he mentions how the blood in the right ventricle is refined so that it was prepared and ready to be mixed with the air:
"When the blood has been refined in this ventricle, it must reach the left ventricle where the pneuma (ar-ruh) is formed. But between these two ventricles there is no passage because the substance of the heart is here compact (musmat). In it there is neither a visible passage, as some suppose, nor an invisible passage which would serve to carry the blood through, as Galen thought, because the pores (masamm) of the heart are closely placed here and its substance is firm. Thus this blood, when it has been refined, must certainly reach the lungs by the arterial vein, so that it can spread out in their substance and mix with the air, so that its finest constituents can be clarified, and so that it can then reach the venous artery, and from there the left ventricle".
In these words Ibn-an-Nafis described for the first time the pulmonary circulation. Several Western historians of medicine believe that he gained his knowledge not on the basis of systematic physiological research but by plain logical deduction derived from knowledge about the impenetrability of the septum. They base their argument on the fact that dissection of human cadavers was forbidden on religious grounds. However, there is ample evidence to suggest that Ibn-an- Nafis did practice dissection secretly. In this respect, it is noteworthy that he was also the first to point out that the nutrition of the heart was derived, not from the blood in its cavities, but throuspecial blood vessels penetrating its muscle wall, i.e. the coronary vessels.
Unfortunately, Ibn-an-Nafis's discoveries received little attention in the Islamic World. Almost three centuries later, the Spaniard Michael Servetus published his book "Christianismi restitutio" in 1553, in which he gives a presentation of the pulmonary circulation which resembles Ibn-an-Nafis' so strongly that one can hardly reject a direct influence. Following on Servetus, Giovanni de Valverde and Realdo Colombo, both in the middle of the sixteenth century, described the " lung circulation similarly, and after another eighty years the Englishman William Harvey succeeded in 1628 in proving that the blood flows in a complete circle. But in his account too, one problem remained unexplained, namely, the transfer of the blood from the arteries into the veins. It was the microscope that first allowed Mar- cello Malpighi in 1661 to see the capillaries in the lungs and in the bladder of the frog. Only in this way was the last gap closed, so that the circulation of the blood was proved to be uninterrupted.
Considering therapy, this was again dictated by the four humours theory. Since disease was the result of a disturbance of their balance, treatment consisted in an attempt to restore this balance by applying measures and using drugs possessing the opposite effect. Restoration of health could often be achieved simply by a change of life style, or by due observance of the air conditions and the change of the seasons, so that instead of unclear and misty air the patient is advised to breathe clear air that purifies his pneuma. Arab doctors were aware of the double-edged nature of drugs, and always preferred the use of dietetics whenever possible. Drugs were differentiated into simple and compound. The materia medica of the Arabs was largely derived from Dioscorides, but original contributions were made by Ibn-al-Baytar. Texts on Materia Medica described the medicines found in their raw state in the mineral, vegetable and animal kingdoms, their treatment and everything relating to the preparation and preservation of the drugs. The indications and dosage schedules were also treated with great care. Fundamental concepts such as "potentiation", were discovered, and more pleasant forms of administration such as pastes, powders, sherbets (sorbets) and gilded pastilles for masking bad-tasting medicines were elaborated. Some present-day medicinal herbs such as ginger, gentian and rhubarb can be traced right back to medieval Arabian pharmacology. The same may be said of metal preparations, e.g. mercury, white lead, quicklime, copper salts and many other agents for internal and external use. Venesection was practiced very freely, almost for the treatment of every ailment. It was an elaborate and sophisticated procedure. Surgery did not, however . receive much attention from medieval doctors, and was always considered inferior to internal medicine. Abul-Qassim az-Zahrawi was an exception, he was undoubtedly the greatest surgeon of Islam. He wrote a separate treatise on surgery in which he described and illustrated about 200 surgical instruments, many of which were of his own invention. He removed foreign bodies from the gullet and ear , extracted barbed arrows stuck in the throat or below the eye, cut for stones in the baldder and urethra describing for the first time the lithotomy position, performed tracheotomy, devised various obstetric dilators and forceps, and was a pioneer in oral and dental surgery.
More could be said of other aspects of Arabian medicine, including for example its insistence on high ethical standards, and its concern for the poor as evidenced by the widespread establishment of first- class hospitals for the free admission of patients, but space and time will not allow. I hope my sketchy outline has served as a preliminary introduction.
A feeling of discouragement when you slip up is a sure sign that you put your faith in deeds. -Ibn 'Ata'llah
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