Author/Hu Mengmeng
Clinical Medical College, Chengdu University of Traditional Chinese Medicine
Class of 2022, Nine-Year Program in Traditional Chinese Medicine, Li Sichu Class
Abstract For a long time, the heart ‘pump’ theory has been the mainstream view of the cardiovascular system, yet it still presents contradictions. The emergence of the heart ‘wave’ theory provides a new perspective for studying the relationship between the cardiovascular system and the organs. In Traditional Chinese Medicine (TCM), the generation of ‘pulse’ is closely related to the heart’s role in blood vessels, and the xian mai (string pulse) is a common and important pulse manifestation in daily life. Therefore, this article reflects on the relationship between heart vascular function and xian mai based on the heart ‘wave’ theory, rethinking the generation of xian mai as a result of qi stagnation, deepening the understanding of xian mai and pulse diagnosis.
Keywords pump theory, wave theory, pulse wave, heart, string pulse
“The subtlety lies in the pulse, which must not be overlooked.” (Suwen, Discussion on the Subtlety of Pulse) Pulse diagnosis is an important part of TCM diagnosis. Currently, pulse diagnosis often employs the method of palpating the cun kou (cun position pulse), where the physician uses the index, middle, and ring fingers to feel the pulsation at the radial artery of the patient’s wrists. The generation of pulse and the pathological implications of pulse changes have been a focus of research for physicians throughout history.
For a long time, the heart ‘pump’ theory has dominated the medical field, but practitioners have gradually discovered its shortcomings. The advent of the heart ‘wave’ theory offers a new perspective for understanding the heart’s function and the generation of pulse. Among the various pulse manifestations in TCM, xian mai is a common and significant pulse, thus the author will reconsider the generation and pathological implications of xian mai from the perspective of the heart ‘wave’ theory.
1
Heart ‘Wave’ Theory
In mainstream Western medical views, the heart is regarded as a ‘pump’ for blood transport, facilitating the entry and exit of blood through its contraction and relaxation. However, the heart ‘pump’ theory presents inherent contradictions: the heart pumps blood intermittently, while blood originates from the heart, suggesting that blood flow should also exhibit periodicity. Yet, the ‘pump’ theory analyzes blood flow as a continuous and stable stream, contradicting the periodic nature of the heart’s pumping action, creating a conflict between the periodicity of heartbeats and the continuity of blood flow. With advancements in science and technology, human research has become increasingly refined, and the development of disciplines such as hemorheology and fluid mechanics has promoted the study of the cardiovascular system. The heart ‘wave’ theory integrates medicine with biomechanics and other disciplines, proposing that the heart’s role is not merely that of a muscular mechanical pump, but rather as a pulse wave generator, producing a series of sequential energy-carrying pulse waves, enabling continuous circulation of blood within the body.
1.1 Concept and Characteristics of Pulse Waves
Pulse waves are generated by the heart’s contractions, which not only propel blood flow, facilitating the delivery of components within the blood to various parts of the body, but also propagate through the blood vessels, enabling the vessels to undergo contraction and relaxation, further promoting blood flow within the vessels. Modern researchers have combined pulse waves with TCM pulse diagnosis, hoping to utilize modern technology and machinery to detect pulse waves, forming objective data that aids clinical practitioners in diagnosis and self-monitoring for patients.
1.2 Blood-Vessel Coupling System
Blood flows within the vessels, where both are mutually constraining and interdependent. Pulse waves cannot simply be understood as compressible pressure longitudinal waves in fluid blood, nor can they be merely seen as transverse waves of expansion and contraction propagating along solid vessels; rather, they are complex waves that involve fluid-solid coupling and longitudinal-transverse wave coupling. From a fixed point on the vessel, pulse waves create longitudinal pressure waves that cause the soft, elastic vessels to contract and relax, compressing the blood within the vessels. Coupled with the presence of venous valves and gravity, blood flows in a specific direction. Throughout the entire vessel, pulse waves propagate along the vessel, generating transverse displacement waves, unifying the entire vascular system with the heart, allowing for orderly blood flow within the vessels.
1.3 TCM Understanding of the Cardiovascular System
The Suwen states: “The heart is… its fullness resides in the blood vessels.” The heart governs blood, and the fullness of blood is one of the conditions for pulse generation, indicating a close relationship between pulse generation and the heart. “Stagnation of the nutritive qi leads to no escape; this is called pulse.” (Lingshu, Decision on Qi) TCM posits that the pulse contains not only blood but also ‘qi’; with the propulsion of ‘qi’, blood can flow within the vessels, generating a strong pulse. Yuan Liang and others have analyzed the scientific connotation of pulse theory from a philosophical perspective, suggesting that pulse diagnosis encompasses not only anatomical information but also information on the functional structure of qi transformation, proposing the principle of ‘pulse qi transformation structure’. The presence of ‘qi’ is analogous to the energy carried by pulse waves, whether kinetic or potential.
‘Qi’ is related not only to the heart but also to the liver. The liver governs the smooth flow and upward movement of qi, regulating its circulation. If qi stagnates, blood will also stagnate; if qi cannot circulate normally, blood flow will slow or even come to a standstill, leading to increased pressure in the blood vessels where blood accumulates. Therefore, during liver disease, blood circulation is also affected. Xian mai corresponds to the liver and is the primary pulse for liver diseases. When liver disease occurs, blood stagnation increases pressure on the vessel walls, making the pulse more pronounced upon palpation. Simultaneously, if blood circulation is obstructed and the vessels are inadequately nourished, they will gradually harden and lose elasticity, presenting a stiff sensation akin to pressing on a guitar string. This is characteristic of xian mai.
2
Xian Mai and Heart ‘Wave’ Theory
The heart ‘pump’ theory overlooks the active role of blood vessels in blood flow; the vessel walls merely passively endure the impact of blood. When blood is ejected, the heart seems to have no further connection with other organs until the next pumping action, which does not align with TCM’s holistic view. Under this theory, the TCM concept of ‘qi’ is limited to the kinetic energy produced during the heart’s pumping. Thus, both blood and ‘qi’ are propelled by the heart to the cun kou, and pulse theory can only reflect the functional state of the heart, which contradicts TCM pulse diagnosis theory. Therefore, the author believes that the heart ‘wave’ theory can more reasonably explain the generation of xian mai.
2.1 Xian Mai as the Primary Pulse of Spring, Corresponding to the Liver
Xian mai is commonly used to diagnose pain, liver, and gallbladder diseases, and is a frequently encountered pulse in clinical practice. TCM holds that xian mai corresponds to the liver, which governs the smooth flow of qi. If the flow of qi is disrupted, blood circulation is affected, leading to a lack of nourishment in the pulse pathway, resulting in a tense pulse. Therefore, the typical pulse manifestation during liver disease is xian mai. Xian mai belongs to wood, which governs upward movement. In spring, the yang energy rises, and the pulse tends to float outward, while the weather has not yet fully warmed, causing the pulse pathway to appear somewhat constricted; thus, the primary pulse of spring is xian mai. Li Wen and others have compiled and summarized the descriptions of xian mai from 60 ancient and modern pulse theory texts and diagnostic works, referencing the International Standard for Chinese Medicine Terminology in Chinese and English, and combining professional knowledge and clinical practice, suggesting that the definition of xian mai is “straight and long, like pressing a guitar string.”
2.2 The Connection Between Xian Mai and Heart ‘Wave’ Theory
The heart ‘wave’ theory posits that most of the energy from the heart’s contractions is transmitted to the blood vessels to generate pulsations, allowing the vessels to promote blood circulation through contraction and relaxation. This aligns more closely with the TCM view that the heart governs blood vessels and better explains the relationship between the movement of qi and blood.
2.2.1 Formation of Xian Mai from a TCM Perspective
The basic mechanism for the generation of xian mai is qi stagnation. When qi flows, blood flows; if the liver’s ability to regulate qi is impaired, or if other organs fail to regulate qi, or due to other reasons, blockage occurs in the pulse pathway, leading to qi stagnation. This prevents the normal distribution and circulation of qi, blood, and body fluids, resulting in a lack of nourishment in the pulse pathway, which gradually hardens and fails to contract and relax properly to promote blood circulation. Blood stagnation impacts the vessel walls, leading to a strong or even hard sensation upon palpation. Additionally, since ‘qi’ is yang and active, when qi stagnation occurs, the movement of blood tends to be more vigorous.
2.2.2 Mechanism of Xian Mai from the Perspective of Heart ‘Wave’ Theory
The strong pulse and hard pulse pathway of xian mai may be related to arterial stiffness, increased blood flow resistance, and decreased vascular elasticity. Increased blood flow resistance slows blood flow, increasing pressure on the vessel walls, resulting in a stronger pulse sensation, akin to pressing a guitar string. Poor vascular elasticity makes it difficult for the vessels to fluctuate, leading to a stiff pulse manifestation. As vessels harden and elasticity decreases, the resistance to pulse wave transmission diminishes, increasing the transmission speed, thus producing a strong pulse.
2.3 Modern Common Pathological Implications of Xian Mai
The heart ‘wave’ theory emphasizes the role of blood vessels in blood circulation, promoting research on cardiovascular diseases. Considering the heart ‘wave’ theory, xian mai is often associated with vascular sclerosis. Arterial sclerosis refers to the reduced expandability of arteries, and the degree of arterial sclerosis can typically be reflected by measuring parameters such as pulse wave velocity, pulse pressure difference, and the amplitude of forward and reflected waves. Arterial elasticity can be assessed through arterial expandability and elastic modulus. Many factors influence pulse wave conduction speed, including age, vessel wall thickness, blood flow resistance, vessel diameter, blood pressure, blood viscosity, and blood flow velocity. From a physiological perspective, age, blood pressure, and gender significantly affect pulse wave velocity. Elderly individuals experience a decline in essence and blood, leading to inadequate nourishment of the vessels, decreased elasticity, and gradual hardening. The vessel walls struggle to contract, reducing the pressure exerted on blood, resulting in decreased blood flow velocity and increased pressure on the vessel walls, leading to hypertension. As blood pressure rises, the areas of the vessel walls that bear pressure shift from the highly elastic elastic fibers to the harder collagen tissue, causing an increase in pulse wave velocity, elevated systolic pressure, decreased diastolic pressure, and increased pulse pressure. Therefore, xian mai has become one of the common pulse manifestations in the elderly.
2.3.1 Coronary Artery Atherosclerosis
Zhang Hui and others explored the syndrome elements of 680 patients with coronary heart disease through factor analysis, finding that the most frequently observed pulse manifestation was xian mai, accounting for 50.74%. Patients with coronary heart disease often have arterial sclerosis or concurrent hypertension, leading to increased vascular tension, reduced compliance, and increased peripheral resistance, resulting in increased tension and decreased elasticity of the vessel walls, hence the presence of xian mai.
2.3.2 Left Ventricular Hypertrophy
Increased stiffness of large arteries raises systolic pressure and pulse pressure, leading to increased load on the left ventricle. Persistent hypertension can exacerbate arterial stiffness, creating a vicious cycle that worsens arterial damage and leads to cardiac hypertrophy, which can also present as xian mai.
2.3.3 Liver Cirrhosis
Xian mai corresponds to the liver, which is yin in nature but utilizes yang, governing smooth flow and blood storage. Liver qi stagnation disrupts smooth flow, leading to an imbalance of yin and yang, preventing normal circulation of blood and qi, which can stagnate and lead to liver cirrhosis. Poor blood flow results in a lack of nourishment in the pulse pathway, leading to decreased elasticity, manifesting as xian mai.
3
Conclusion
The introduction of the heart ‘wave’ theory provides new insights for studying TCM pulse diagnosis. Although the heart ‘wave’ theory still has unresolved aspects, continuous technological advancements will deepen our understanding of human physiology and further progress in medicine. From the perspective of the heart ‘wave’ theory, it aligns more closely with TCM’s holistic thinking. The generation of xian mai should not be limited to the liver and blood; the heart ‘wave’ theory indicates that various parts of the body influence blood circulation, leading to the pulse manifestation at the cun kou encompassing a wealth of information. The convergence of multiple results into a single expression is complex, posing a significant challenge for precise judgment by practitioners, while also presenting a substantial difficulty in the objective quantification of pulse data.
References
1 Sun Qingwei, Wang Chunmei, Gao Yanhua, et al. Medical Physiology [M]. Beijing: China Medical Science and Technology Press, 2000
2 Zhu Siming. Medical Physiology [M]. Beijing: Beijing Science Press, 2002
3 HALL J E. Guyton and Hall Textbook of Medical Physiology [M]. Philadelphia: Elsevier, 2016
4 BARRETT K E, BARMAN S M, BROOKS H L, et al. Ganong’s Review of Medical Physiology [M]. 26th ed. New York: McGraw-Hill Education, 2019
5 Wang Hui, Wang Lili, Miao Fuxing, et al. On the Heart Function ‘Pump’ Theory and ‘Wave’ Theory [J]. Explosion and Shock, 2020, 40(11): 4-13
6 Miao Fuxing, Wang Hui, Wang Lili, et al. Relationship Between Blood-Vessel Coupling Characteristics and Pulse Wave Propagation Characteristics [J]. Explosion and Shock, 2020, 40(04): 4-13
7 Yuan Liang, Wang Zhaoyang. Analysis of the Principle of Pulse Qi Transformation Structure [J]. Chinese Journal of Traditional Chinese Medicine, 2015, 30(8): 2765-2768
8 Huang Lanying, Chen Jing. Progress in Research on TCM Pulse Diagnosis [J]. Chinese Journal of Traditional Chinese Medicine Information, 2018, 25(03): 132-135
9 Li Wen, Liu Congying, Liang Jinbing, et al. Analysis of the Definition, Clinical Main Diseases, and Treatments of TCM Pulse Manifestations and Modern Research [C]. Proceedings of the 8th National Academic Conference on Diagnosis of the Chinese Association of Integrative Medicine. Shanghai University of Traditional Chinese Medicine, 2014: 7
10 Li Zhenji. International Standard for Chinese Medicine Terminology in Chinese and English [M]. Beijing: People’s Health Publishing House, 2008
11 Yan Haixia. Analysis and Classification of Common TCM Pulse Characteristics Based on Hemodynamic Principles and Methods [D]. Shanghai: Shanghai University of Traditional Chinese Medicine, 2010
12 Wang Xixie. Research on the Application Value of Pulse Wave Velocity in TCM Organ and Meridian Identification [D]. Beijing University of Chinese Medicine, 2014
13 Zhang Wei. Correlation Study of Pulse Manifestations and Radial Artery Hemodynamic Parameters in Patients with Qi Deficiency and Blood Stasis Type Coronary Heart Disease [D]. Shandong University of Traditional Chinese Medicine, 2021
14 Wang Jiankang, Zhong Guanghui, Xu Cheng, et al. Zhang Zhongjing on the Main Diseases of Xian Mai and Pulse Theory Effects [J]. TCM Research, 2023, 36(01): 5-8
▲Swipe to view
Editor/Meng Meng
WeChat ID:
Cheng TCM Debate Editorial Committee
Compiled and Edited by:
Cheng TCM Debate Editorial Committee
Reviewed and Proofread by: Tang Yue
Media Editor: Cheng Yushu
[Copyright Statement] Copyright belongs to “Traditional Chinese Medicine and Dialectics”. The WeChat account “Traditional Chinese Medicine and Dialectics” is for learning and communication purposes only. Reproduction requires citation of the source. If there are any improper uses, please feel free to contact us.
Light Up In View