4,500-Year Voyage: From Pulse Tension To Hypertension (1)
The Blood Pressure and I
Only recently during the 1950s, did physicians become aware of the clinical importance of high blood pressure (BP)? The critical relationship between high blood pressure and mortality caused by strokes, heart attacks, congestive heart failure, and vascular disease is now well understood.
I came in contact with hypertension probably earlier than many of my colleagues. During my last year of high school in Doha, I was staying awake late at night, studying very hard, aiming to maintain the top rank in my graduating class. I remember I hung a small poster I wrote in my room quoting an Arabic poetry verse that could be translated as follows: “He, who seeks glory, accepts nights of sleep deprivation”. But for me, sleep deprivation resulted in recurrent headaches. I was certainly not glorified, but rather horrified then.
I consulted a Palestinian physician, a general practitioner (G.P.), in Rumailah hospital, Dr. AboAlroub, (the literary meaning in Arabic Abo: Father, Alroub: buttermilk. He was not the father of hypertension for sure). He was my friend and I used to visit him socially and ask him about the study of medicine. During that time, because I was planning to be a physician, I wanted to join the “club” early. Therefore, I created friendship and maintained good relations with several physicians in Rumailah hospital. Dr. Aboalroub told me that I had hypertension “due to the stress of studying hard.” He put me on diuretic tablets daily, probably hydrochlorothiazide.
Fig. 1: Chinese feeling the Pulse23.
I returned to him two months later unable to study well with fatigue, palpitation, dizziness, severe weakness and muscular pain, especially of the legs. My BP was low but my blood test revealed a very low potassium level. He told me to stop the diuretic because it was the cause of the problem, drink a lot of orange juice, and sent me home. That GP probably did not know that very low potassium level required emergency admission and intravenous potassium therapy. Obviously, I survived. A few days later, all the above symptoms resolved and my BP returned to normal.
Hypertension is still a frustrating problem for both patients and physicians in our region.
I have seen over the last couple of decades many hypertensive patients not taking their drugs, thinking that they were “cured” because they felt fine. It is difficult to convince some patients that this deadly disease could be silent. One patient told me once: “You doctors are not logical, how could I be sick when I feel perfectly well”.
Unlike epilepsy, tuberculosis or malaria which were known in our region for centuries and described in both Arabic literature and Arabic medical books, hypertension which is probably as old as mankind was not known or mentioned in the old Arabic books. Measuring BP requires instrumentation that was not available in ancient times. Hence, I became interested in finding out when and how this devastating disease was discovered.
First came the pulse
The Arab physicians during the 9th century A.D. did not know blood pressure as we understand it today, as reflected by their books such as Al Razi’s encyclopedic medical book Al-Hawi fit tib1, but they probably intuitively assessed the force of blood flow subjectively by pulse palpation. They knew the pulse very well because it was known by the Greeks, Egyptians and the Chinese before them. The Egyptians knew that blood flowed through the body. The ancients did not know the concept of blood pressure as we know it today but the character and the force of the pulse could have given them a feeling of the pressure and the blood flow. Not so ancient, but relatively recently, William Osler at 1892 mentioned in his discussion on chronic Bright disease “increased pulse tension” rather than hypertension2.
The Chinese were probably the first to recognize the pulse around 2500 BC (Fig. 1). The Yellow Emperor’s Classic of Internal Medicine, Nei Ching, contain references to the pulse3. The Chinese gained so much experience by feeling the arterial pulses that they were able to associate the bad effect of salt on the arteries. The Nei Ching noted, “If too much salt is used for food, the pulse hardens”.
“Ancient Egyptians knew the origin of the pulse and the pumping function of the heart”5. The Egyptians were the first to suggest that “air and blood enter the heart, and the heart distributes them to the rest of the body”.
The pulse was mentioned by the Egyptians in the Edwin Smith Papyrus, 1600 BC (Fig.2), The Therapeutic Papyrus Of Thebes, 1552 BC, and Ebers Papyrus, 1550 BC7.
The Edwin Smith papyrus has the following observations on the pulse and its relationship to the heartbeat:
"... examining is like one counting a certain quantity with a bushel, or counting something with the fingers ... like measuring the ailment of a man in order to know the action of the heart. There are canals in it [the heart] to every member. Now if the priests of Sekhmet or any physician put his hands or his fingers upon the head, upon the two hands, ... upon the two feet, the measures to the heart ... because its pulsation is in every member ... Measure ... his heart in order to recognize the indications which have arisen therein; meaning ... in order to know what is befalling therein".
Fig. 2 Counting the pulse as described hieroglypohic characters in Smith Papyrus. Symbol on the right represent seeding being emptied for container8.
The Therapeutic Papyrus of Thebes 1552 BC stated:
“If the physician places his finger on the head, neck, arms, hand, feet or body, everywhere he will find the heart, for the heart leads to every member and speaks in the vessels of every member”.
The description in Ebers Papyrus is as follows:
“To know the movements of the heart and to know the heart ... From the heart arise the vessels which go to the whole body ... if the physician lay his finger on the head, on the neck, on the hand, on the epigastrium, on the arm or the leg, everywhere the motion of the heart touches him, coursing through the vessels to all the members ... When the heart is diseased its work is imperfectly performed; the vessels proceeding from the heart become inactive so that you cannot feel them ...If the heart trembles, has little power and sinks, the disease is advancing”.
“If you examine a man for illness in hiscardia, and if he suffers from pain in his arms, in his breast, and in one side of his cardia, it is death threatening him.
The Greeks thought that the pulse was due to air which filled the arteries. Erasistratus advanced the belief that the ‘pneuma’ in the arteries was derived from respiration. But Galen thought that the arteries are the solid body and the pulse was that “peculiar action initiated of the heart”. He described the main characteristics of the pulse: speed, size, strength, quality and tension.
Arab medicine reached its highest level between the 8th and the 13th century when Baghdad was the scientific capital of the world. The Arab and Muslim physicians based much of their theoretical information and clinical practice in relation to the heart and the pulse mainly on the Greek medicine.
Arab physicians took full advantage of their position in history, acquiring knowledge from Chinese, Greek and Indian writings, free from the influence of the magic of the dark ages. They translated the available knowledge of other civilizations before them and preserved it. They added their own observations and wisdom and passed their contribution to the world civilization that followed.
The first physician who wrote about the pulse in Arabic was Abu Zakariya Yuhanna Ibn Masawayh (777-857) a Christian, known in Latin literature as Mesue Senior. He learned anatomy by dissecting animals. He was a physician to the caliph in Baghdad and a hospital director. The Galenic pulse was modified and greatly improved by Al Razi (Rahazes 865-932)7.
Ibn Sina (Avicenna 980-1037A.D.) wrote in his book The Canon, a detailed description of the pulse, characteristics, and variation in health and disease. He was considered the successor of Galen, and he kept that position for 500 years. He devoted a large portion of his work to the study of the pulse. He described more than 50 identifiable pulses. Avicenna wrote in The Canon:
"The pulse is a movement in the heart and arteries . . . which takes the form of alternate expansion and contraction"7.
He also referred to the pulse in his Arabic poetry: “Differences in pulsation mean illness and causation”. The Arabs referred to Galen as “THE PHYSICIAN”. His teaching was highly respected. That was true from 8th to 13th century AD except for one Arab physician, Ibn Al-Nafis (1207-1288) the Arab father of circulation, dared to say that Galen was wrong on two accounts: the circulation and the nourishment of the heart muscles.
Ibn Al_Nafis wrote his finding in his manuscript of anatomy book(Sharh Altashrih) dated 1333. It was published only recently, 1988 in Cairo. Few years before its publication, I had to go to Welcom libraryof medicine in London to see a copy of the manuscript. It was well preserved as if it was written that day.I read the information related to the circulation while a librarian stood by watching me until I gave it back to him.The library provided me with a slide copy of that page (Fig 3)
Fig 3a: Ibn Alnafis manuscript first page. Fig 3b: Ibn Alnafis manuscript.
Ibn Al_Nafis did not accept Galen'sand Ibn Sina's concept (Fig.4) that "the right heart cavity is full of spirits....and the blood from the right cavity reaches the left cavity through pores acros the interventricular septum".
Ibn Al_Nafis opposed that concept, first on logical reasoning, "if the blood from the right ventricle goes directly to the left ventricle without modification, it will spoil the spirit. Then he addedAnatomy proved that they were wrong. There were no visible nor invisible holes in the interventricular septum”11.
He said that blood from right heart cavity goes to the lung through the Arterialized Vein (Pulmonary Artery). In the lungs, the blood divides into two: thin blood filters through pores of the arterialized vein (pulmonary Artery) and thick blood remains in the lung for its nutrition. The thin blood mixes with the air that comes from the trachea and enters the vein-like artery (pulmonary veins) through its wall. The thin blood mixed with air, reach the left heart cavity, the center where vital spirit form. The spirit moves from the left heart cavity to the aorta and the rest of the arteries to the tissues.
So Ibn Al-Nafis suggested that blood moves from Arteries to Veins across the wall inside the lungs, but his student, Ibn Al Quff, explained later in his bookkitab al-omda fi sina’at altib, i.e., basic works concerning the art of surgery12, and proposed the existence of capillaries. This was not actually confirmed until the era of the microscope when Malphighi saw the capillaries in 1661.
Ibn Al Nafis also said that the heart muscles
Fig 4: Galen’ physiology.
Ibn Al-Nafis also said that the heart muscles receive nourishment from the arteries [coronary arteries] that pass through it, not directly from the blood in the heart cavity as Galen claimed. He described his finding in his book Sharh Al Tashrih four hundred years before Harvey published “De Motu Cordis”. Ibn Al Nafis’ book was available for Harvey to see when he went to Italy to study in Padua University.
Ibn Al Nafis wrote more than twenty books, including Alshamil, a multivolume encyclopedia of medicine. He also wrote books on pediatrics and ophthalmology. He devoted one paper to the pulses.
Western writers admit that: ”The Arabic teaching on the pulse became standard reference works, many of which have survived into the present day”.
Until the death of Ibn Al Nafis in 1288, there was no mention of blood pressure or hypertension in the medical literature. A few centuries later, physiologists made the discovery.
The road to sphygmomanometer: see
4,500-Year Voyage: From Pulse Tension To Hypertension (2)