A Review on the Hypotheses about Arterial Hypertension from the Viewpoint of Traditional Persian Medicine

Hypertension is one of the most common chronic diseases in recent decades worldwide. It has been distinguished as the main risk factor of coronary artery disease, aortic dissection, heart failure, renal failure, cerebrovascular diseases, and death. In recent years, the global attention has been paid to complementary medicine to preventive, diagnostic and treatment strategies for hypertension, in previous studies, the history of hypertension from the viewpoint of traditional Persian medicine have been reviewed and several hypotheses raised. In this article, we present the concept of an Iranian physician namely Ali ibn Sahl Rabban al-Tabari on hypertension, which has not been considered properly until now. He defined a state called "Hayajan al-dam" that has clinical manifestations similar to hypertension, although these are not the same, also, we reviewed the viewpoint of other Persian medicine scholars namely Rhazes, Haly Abbas, Akhawayni and Avicenna for this topic.

However, many patients are unresponsive to standard treatment [5], also, drug therapy is long term, costly and may cause side effects [2,6], therefore, a large number of patients not taking proper treatment as prescribed [7], some patients use complementary and alternative therapies for the management of HTN [2,5]. Traditional Persian medicine (TPM) with a long history is one of the ancient medicine which is widely used today [6], several studies have been reviewed the history of HTN from GMJ [11]. In the Persian literature, there is evidence that he performed human dissection first-hand and descried the embryology and anatomy of the brain, nerves, heart, and liver [11]. Rhazes was the student of Tabari [11]. Tabari is the author of "Firdous al-Hikmat fi al-Tibb" (Paradise of Wisdom), this book was an essential medical encyclopedia for his time [12], which written in Arabic and mainly influenced by Greek, Syrian, Persian, and Indian sources [11,13] and is one of the oldest medical texts in the Islamic world [12,13]. This book is mainly devoted to anatomy and principles of medicine (temperaments, humors, general aspects of health), pharmacy, also, symptoms, signs, and treatment of diseases of the special organs is discussed in detail [12][13][14]. Furthermore, Tabari considered examination of pulse and urine and dental medicine, therefore "Firdous al-Hikmat fi al-Tibb" is a practical and technical book in medicine [13,14].

Clinical Description of "Hayajan al-Dam"
In "Firdous al-Hikmat," Tabari explained that any direct or indirect change in the quantity/ quality of each one of humors in the body's systems could cause disease [14]. He described a condition due to change in "Dam" humor and named it"Hayajan al-Dam" (blood excitement), according to Tabari, this disorder can manifest itself with symptoms including the presence of red face, feeling hot in the body, Imtila (fullness) in the vessels, feeling sweetness in the mouth and oversleeping (a lot of sleep) [14]. Imtila in the vessels is considered as one of the symptoms of "Hayajan al-Dam," in this condition, quantity/quality of intravascular fluid changed beyond vessels' capacity and increased total amount of blood volume [14][15][16][17][18]. The general symptoms of Imtila such as; heaviness in the head and headache, sluggish body movement, redness of the body, warmness of the body on touch, prominent, distended and tense veins, loss of appetite, blurred vision, yawing and drowsiness, difficulty concentration, dense and colored (turbid) urine, epistaxis, skin tension, Furthermore, increased vascular tension can lead to rupture and present with hemorrhage and sudden death [15][16][17][18]. According to historical medical manuscripts, clinical manifestations of"Hayajan al-Dam" have also been defined later by other TPM scientists such as Rhazes [15], Akhawayni [6], Haly Abbas [17] and Avicenna [18], under the topic of Imtila, in the TPM textbooks, Imtila means accumulation of matter and humors in vessels and organs, it is divided into "imitial bi-hasabi-l-aw'iyah" (quantitative change of blood composition, which causes the fullness of the canals and vessels of the body) and "imtila GMJ.2020;9:e1065 www.gmj.ir bi-hasabi-l-qowwah" (qualitative change of blood composition) [15][16][17][18]. Comparison of clinical manifestations of "Hayajan al-Dam" and HTN is shown in Table-1.

Suggested Treatment
From the perspective of TPM, although there are common therapeutic plans for treatment of diseases, each method in each is exclusive [18]. Lifestyle modification, oral drugs, and phlebotomy or getting massage is suggested for treating this condition [14]. Tabari recommended the use of Ziziphus jujube (Annab) can lead to alleviation of blood excitement [14], other TPM scholars pointed out the jujube can relieve the excitement of the blood [16][17][18]. Furthermore, Tabari recommended the Annab for treatment of the digestive disorder, headache, lung disease, and types of fevers [14].

Discussion
In this article, we explained the concept of "Hayajan al-Dam" according to Tabari's opinion and evaluated it from the viewpoint of other TPM scholars, based on our findings; there are similarities between the "Hayajan al-Dam" and "imtila bi-hasabi-l-aw'iyah" [14][15][16][17][18]. It is clear that in TPM approach, pathophysiology and recommended treatments for any disease were based on humoral theories which cannot be easily compared by the cur-rent concept of medicine. Reviewing the main textbooks of TPM, indicate that there is no specific disease, which be considered exactly equivalent of HTN in the conventional medicine [14][15][16][17][18] [8]. Shamshad Ahmad considered that those symptoms have been described by Rhazes for imtila bihasabi-l-aw'iyah are similar to clinical features of HTN [9]. TPM scientists were familiar with other medical traditions like Unani medicine and had used their theories. Therefore, the history of HTN in other traditional medicine has also been reviewed [9,10]. Although some authors use the term "Zaghtuddam Qawi" to describe HTN in Unani medicine, this term has not been considered in the classical Unani literature; it is believed that most of HTN manifestations were matched with imtila bi-hasabi-l-aw'iyah in those literature [9,10]. An accurate reviewing of main textbooks of TPM clarified that types of imtila like imtila bi-hasabi-l-aw'iyah is a general condition and did not considered as a distinct disease in special organ diseases, in fact, it is a condition can affect various parts of the human body then specific symptoms of the distinct disease be revealed, in those textbooks, Imtila is considered as a predisposing and precipitating factor for other specific diseases

Conclusion
It seems that arterial HTN is not equivalent of a specific disease in TPM; however, it may be considered as a complication of other diseases like cardiac and renal diseases, arterial diseases, and blood flow disorders. In previous studies, several hypotheses have been made to achieve the etiology of HTN in TPM sources, most of them presume that clinical features of HTN are as the same as imtila bihasabi-l-aw'iyah, also other diseases are also proposed such as black bile dominance, vascular wall dry dystemperament, cardiac hot dystemperament and damages of other body organs like liver, kidney, and nervous system, finally, based on the basics of TPM, we cannot confirm these results, we strongly recommend doing more clinical and experimental studies to achieve better clinical outcomes.