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What is Phlegm-Mist Affecting the Orifices of the Heart?

An Examination of a TCM Perspective on Causes of Stroke

essay by Subhuti Dharmananda, Ph.D., Director, Institute for Traditional Medicine, Portland, Oregon

There is a concept in Chinese medicine depicting a phlegm disorder primarily affecting brain functions. The terminology of "phlegm misting the orifices of the heart" (tanmi xinqiao) is frequently used for this concept. Most Chinese texts simply list the symptoms and signs pointing to this diagnosis, rather than elucidating what the condition is. An exposition of this diagnostic category may benefit the development of Chinese medical practice.

The condition is sometimes described as phlegm entering the heart, or as phlegm entering the heart meridian (or "channel"). In another article (Drawing a Concept: Jingluo), the original description of meridians in the Chinese medical system is shown to be related to blood vessels. We know this, in part, because virtually all mentions of the flow of qi in the ancient texts are actually about the combined flow of "qi and blood." It is easy to become confused about the Chinese view of human physiology when modern writers describe meridians as pathways existing solely for the flow of qi, to be distinguished from blood vessels for the flow of blood, which is not consistent with the prior 2,000 years of Chinese literature. The fact that the meridian maps do not correspond with blood vessels merely indicates that what was eventually mapped for purposes of describing acupuncture therapies failed to follow precisely the underlying traditional conceptual framework.

Classical Chinese depiction of the heart       Modern depiction of the heart
Two representations of the heart: the classical Chinese representation (left) and the modern medical representation (right).

Early Chinese doctors had the opportunity to see the internal organs, particularly as a result of war injuries. The heart is a distinctive organ that has several large vessels protruding (e.g., aorta and pulmonary artery), and these could easily be understood as "orifices of the heart." Further, the flow of blood upward to the brain was readily displayed when injuries to the neck (including decapitation) occurred. So, it was clear that there was a strong blood flow from the heart to the brain. Again, this would be interpreted as flow of qi and blood through the large vessels linking the heart and brain. Since the heart, as a yin organ (zang), was deemed to be "solid"(one of the yin organs, the zang) rather than "hollow" (as with the yang organs, the fu), it would be a natural assumption that the phlegm accumulated in the heart channels. Such accumulation was not restricted to the heart meridian as described today (traversing the arm) but, rather, to the actual arteries of the heart.

Phlegm mist is a concept that can be traced back at least to the Song Dynasty. By that time, Chinese doctors were distinguishing "substantial" phlegm (such as sputum, which is described as "condensed pathological fluid") and "insubstantial phlegm" or "hidden phlegm" (such as the mist of the heart orifices; a "thin pathological fluid"). The substantial phlegm would mainly accumulate in the lungs and stomach, while the insubstantial phlegm would accumulate in the meridians, distributing to various parts of the body, such as the heart orifices and the brain (e.g., causing dizziness or loss of consciousness), the lymph nodes (causing nodules and swellings), and the limbs (e.g., causing numbness). The two types of phlegm were thought to have the same origin and the same fundamental nature, but would permeate different parts of the body (the thick sputum could not penetrate the meridians, but the insubstantial phlegm could). Further, insubstantial phlegm could combine with other pathological influences to yield phlegm-fire, wind-phlegm, and phlegm-turbidity. According to the doctrine that evolved, the phlegm mist could cause the other pathological factors-such as fire, wind, or damp-to produce more severe symptoms. Further, its material nature would capture the more ethereal forces of fire or wind to make the disease persist; similarly, the phlegm-mist could blend with damp to yield turbidity that obscures the clear flow of qi and yang to the brain, interfering with normal mental and sensory functions though not completely blocking the circulation to the brain.

Diseases and symptoms attributed to phlegm mist affecting the heart orifices include dizziness, loss of consciousness (coma), hemiplegia (stroke), mania (emotional outbursts, disturbed speech), convulsions (especially epilepsy), sudden sensory loss (deafness, blurred vision, loss of taste and smell, inability to speak), lockjaw, and stiff tongue. Diseases currently treated in China by herbs that resolve phlegm-mist affecting the heart orifices (see Table), also include manic-depressive disorder and senile dementia (Alzheimer's disease).

Table 1: Herbs that are commonly used in formulas to clear phlegm mist and open the orifices

Herb Main Actions Comments
opens orifices, expels phlegm and turbidity, replenishes intelligence This is the most commonly-used Chinese herb (of plant origin) for treatment of mental disorders. It was listed in the Shennong Bencao Jing as a superior herb.
tiannanxing, dannanxing
relieves convulsions, resolves phlegm mist, disperses accumulations Arisaema is described as having the power to vaporize phlegm accumulations; it is mainly used when treating phlegm obstruction of the orifices. Bile processed arisaema is used for phlegm-mist associated with a fire syndrome.
zhuru, zhuli, tianzhuhuang
removes heat, transforms phlegm, calms fright Bamboo shaving, leaves, juice, or dried secretion are all used to treat irritability, fidgets, and convulsions. They are particularly favored in treatment of children's disorders.
opens orifices, moves qi, clears vision Borneol is usually used as an adjunct ingredient in formulas for resolving phlegm that causes brain disorders; it is often combined with musk and/or acorus to open orifices.
regulates flow of qi, dissolves qi stagnation, disperses stagnant blood Curcuma is best known for its ability to vitalize circulation of qi and blood, but it enters into several formulas for brain disorders because it is useful in treating phlegm accumulation disorders, especially when there is a heat syndrome.
opens orifices Musk, with its penetrating aroma and stimulating quality, is mostly used for severe cases of brain disorder, especially when the person is losing consciousness or suffering from delirium.
Ox gallstone
opens orifices, transforms phlegm, clears heat, removes toxin, calms fright Ox gallstone is utilized to correct gallbladder disorders that result in hot phlegm moving upward to cloud the consciousness. A mixture of bile acids and minerals is used today to make synthetic oxstone.
harmonizes stomach, dries dampness, removes phlegm, disperses accumulation Pinellia is the most commonly-used phlegm-resolving herb in Chinese medicine and it enters into formulas for treating brain and mind disorders that involve phlegm accumulation due to stomach/spleen weakness.
resolves phlegm Platycodon is thought to direct the action of other herbs to the upper body, making it useful in treating brain disorders; in addition, it helps to resolve phlegm accumulation
stabilizes the heart and calm the mind Polygala is often used as an adjunct to acorus for resolving phlegm that obstructs the orifices of the heart. In addition, it is used as a sedative, often along with zizyphus.
calms wind, resolves phlegm, disperses accumulation A fungus infecting the silkworm is the active component, as with cordyceps. It is especially used for wind-phlegm disorder, with tonic paralysis or convulsion.

It is tempting to try and correlate the traditional Chinese concept of phlegm-mist with a substance or condition defined by modern medicine so that the Chinese diagnostic category could be explained in terms of our current knowledge of physiology. Attempts to find correlations between modern medical knowledge and other traditional Chinese concepts, such as qi, blood, and even the organ functions, are often unsatisfactory. However, we may be able to link some of the TCM concepts to modern interpretations. Thus, for example, the condition of atherosclerosis, where plaques that include fatty materials (e.g., cholesterol and lipoproteins) coat the arteries, might be one case of phlegm-mist affecting the orifices; certainly, stroke is frequently associated with this type of blockage of the carotid arteries. The accumulation of amyloid plaques in the brain of persons with Alzheimer's disease might also correspond, to some extent, to phlegm mist. Disorders of the thick fluid in the ear drum, which might be depicted as a phlegm-type disorder (e.g., phlegm-turbidity), can yield dizziness. The formation of blood clots in the arteries or veins, while seeming to fit the category of blood stasis, may be an example of phlegm accumulation, in the sense that phlegm is a sticky substance and the clot forms by the coagulation of various blood components (such as fibrin and platelets) into a spongy mass. By contrast, extensive bruising, where clotted blood resides outside the vessels and forms a firm mass, more clearly fits the blood stasis description.

The ancient doctors saw phlegm-mist primarily involved with sudden and dramatic change: the person would faint, go into a convulsion, or suddenly erupt with crazy behavior. For example, as described in the Advanced Textbook of Traditional Chinese Medicine and Pharmacology: "voracious eating, overdrinking alcohol, and emotional irritation combine to cause food retention in the stomach, which causes stomach qi to disturb upward, blocking the clear cavity and thus resulting in loss of consciousness." The idea was that a substantial amount of phlegm would suddenly rush to the heart. Then, when the phlegm blockage cleared, the person would return to normal, though in some cases, there could be persisting symptoms (e.g., hemiplegia). The condition being described parallels what happens when a blood clot forms in the arteries supplying the heart or brain, causing the person to collapse. If the clot clears out quickly enough (spontaneously or with medical intervention), the person recovers; if not, there may be persisting symptoms or the person may die.

This connection between the traditional concept of phlegm blockage and the modern understanding of formation of obstructive blood clots in the vessels is well illustrated in the presentation by Wang Yongyan and his colleagues describing their work with stroke patients, presented at a 1987 TCM conference in Shanghai. They differentiated the disease conditions of 158 patients who suffered from "upward disturbances of wind-phlegm and accumulation of phlegm-heat." Using the TCM criteria, they divided these cases into: 120 of "channel stroke" (phlegm blocking the heart orifices); 32 cases of fu-organ stroke (e.g., phlegm originating from the stomach or gallbladder); and 6 cases of zang-organ stroke (e.g., phlegm blocking the heart). Turning to Western medical diagnosis for these same patients yielded: 145 cases of thrombosis of the carotid artery system; 8 cases of thrombosis of the vertebro-basilar system; and 5 cases of embolism. The treatment administered to the patients was based on expelling phlegm and purging the intestines, using a formula that included bile-treated arisaema, rhubarb, and trichosanthes seed (which has a laxative effect due to the thick seed oils; this herb also phlegm-resolving). After a few days of this purging therapy (generally less than two weeks), the focus of treatment shifted to "clearing heat, expelling phlegm, vitalizing blood, and invigorating the channels." Liquid bamboo sap (zhuli) was used as an essential ingredient in most of the cases.


To treat patients who remained unconscious for a long time (more than a few minutes), Chinese physicians would administer aromatic formulas in an attempt to get the vapors to break up the blockage. These are usually rich in borneol and musk (see appendix for further descriptions of the ingredients). The formula might be forced into the stomach, so that it could potentially have a greater effect, compared to merely placing some of the fragrant substance in the nostrils (some coma patients retain a swallowing reflex making oral administration easier). In modern China, the formulations are given by intravenous drip (e.g., Qingkailing injection or Xingnaojing injection). The same highly aromatic agents are also given to those who are not in a coma, such as persons suffering from frequent convulsions or other phlegm-mist disorders.

Pills made with ingredients listed in Table 1 were among the important formulas of the Hejiju Fang (ca. 1110) of the Song Dynasty. A typical example, a pill still used in recent times (though finally taken off the international market due to concerns about toxic substances and endangered species among its 30 ingredients), is Niuhuang Qingxin Wan (Ox Gallstone Cleanse the Heart Pill). Key ingredients for eliminating phlegm obstruction in this formula are ox gallstone, borneol, musk, platycodon, and curcuma. According to Commonly Used Chinese Herbal Formulas with Illustrations, the formula is said to calm a person who is suffering from fright, and is prescribed for mental-distress conditions including panic, amnesia, absent-mindedness, mental uneasiness, horror, sorrow, irritability, perversities, anger, hysteria, madness, mental disorders, and spiritual miasma, especially in those who also experience physical manifestations such as loss of ability to control the limbs, difficulty in speech, distorted mouth and stiff tongue, heart palpitations, visual disturbances, or rigidity of neck and back.

During the Jin-Yuan reform period (1127-1368), Zhu Danxi wrote about the phlegm-mist disorder. He gave an example, recorded in Danxi Zhifa Xinyao, where fright is the initiating cause: "Because of fright, the spirit leaves its abode, and, when its abode is left vacant, phlegm may enter. Occupying this abode, phlegm repulses the spirit. Thus, it is impossible for the spirit to return." The abode spoken of here is the heart orifices, the resting place of shen, the spirit. This description follows an ancient concept that the spirit takes its rest in the heart, but is not confined there: it may wander, and then return. This wandering gives us the experiences of imagination and brilliant ideas, dreams, spiritual experiences, and visions. The spirit returns to the heart for its rest. However, if the orifices are filled with phlegm mist, the spirit cannot return (also, if the heart yin and blood is deficient, the heart is not providing a comfortable resting place, and the spirit becomes disturbed). Excessive wandering of the spirit, especially without rest, leads to bizarre and unrealistic thoughts and speech, nightmares, emotional disturbance, and other undesirable conditions.

Another reason that the phlegm can fill this abode (aside from the spirit being absent) is because the abode is not already rich in qi and blood. Hence, an underlying deficiency syndrome greatly increases the chance of having a phlegm obstruction. Still, the accumulation of phlegm is a type of excess. Describing the problem of coma, Clinical Manual of Chinese Herbal Medicine and Acupuncture says that this condition "often presents with an excess syndrome marked by obstruction of phlegm and heat, the principle is to clear heat, resolve phlegm, and promote mental resuscitation." According to this text, commonly used herbs in the treatment of obstruction syndromes include: acorus, curcuma, polygala, and bamboo silica (tianzhuhuang); to further resolve excessive phlegm, bile processed arisaema, pinellia, and bamboo sap (liquid; zhuli) are added.

As to the origins of the phlegm mist, the starting point is understood to be the generation of pathological phlegm (excess phlegm-fluid) which can be the result of external influences (six exogenous pathogenic factors), internal influences (abnormal emotional activities), and/or behavior (especially irregular diet, but also overeating rich foods and/or drinking excess alcohol). For phlegm mist to affect the heart orifices, which are at the top of the internal organs, it must rise upward, and that occurs through certain mechanisms such as uprising qi from the stomach; uprising damp-heat from the gallbladder (often due to persistent qi stagnation of the liver and rising liver yang); excessive "steaming" of water by kidney yang (due to kidney yin deficiency); and heart fire. Perhaps the most serious of the phlegm-mist syndromes is from a fire disorder (tanhuo raoxin). It is described in Chinese Herbal Therapies Formulas and Strategies this way: "The vigorous blazing heat scorches the fluids and causes them to congeal into phlegm. Heat and phlegm accentuate each other and completely veil the orifices of the heart, further disturbing the spirit and impairing the consciousness."

Persons with phlegm-mist syndrome need not have obvious phlegm excess, such as coughing up sputum, runny nose, obesity, or phlegm-nodules, but the problems of substantial phlegm and insubstantial phlegm may go together. Usually, the patient suffering from phlegm-mist will display some signs of phlegm, such as slippery and smooth tongue coating or slippery pulse. In the ancient Chinese texts, there are stories about treating patients with phlegm-mist disorder using herbs that induce vomiting: discharge of copious amounts of mucous fluid from the stomach occurs, followed by alleviation of the symptoms.

Several ingredients used in the traditional formulas for phlegm-mist disorders are problematic for Western practitioners, aside from the banned ingredients cinnabar (a mercury compound) and realgar (an arsenic compound) that are used as sedatives and detoxicants. For example, neither ox gallstone nor musk are readily available, and sometimes the dosage of borneol used in Chinese formulas can be risky (it acts as a heart stimulant in high doses). But, other ingredients are considered acceptable and the most commonly used ones are the pair of acorus and polygala, usually combined with herbs that are considered heart sedatives, and the pair of bamboo with arisaema, often with herbs that resolve phlegm-damp. A good example of the former is Anshen Dingzhi Wan, which is comprised of acorus, polygala, dragon teeth, fu-shen, ginseng, hoelen; an example of the latter is Ditan Tang, which is comprised of bamboo, arisaema, pinellia, citrus, chih-shih, hoelen, ginseng, acorus, and licorice. Note that both formulas include ginseng, hoelen, and acorus, where ginseng and hoelen tonify the spleen (to help prevent phlegm-fluid accumulation) and calm the heart (fu-shen is a type of hoelen with greater calming qualities), and acorus is used to clear phlegm mist from the orifices.

The role of the stronger medicinal agents (musk, ox gallstone, borneol) for opening the orifices is described in the Advanced Textbook of Traditional Chinese Medicine and Pharmacology:

Herbs that open the obstructed heart orifice and restore consciousness are known as herbs for promoting resuscitation, or analeptics [agents that strongly stimulate the central nervous system]. These herbs are acrid, aromatic, and dispersive. They mainly enter the heart meridian and restore consciousness in comatose patients. They are applied for loss of consciousness in febrile diseases, apoplexy, epilepsy, and syncope due to heat attacking the pericardium or phlegm and turbidity obstructing the heart orifice. The heart orifice obstruction syndrome can be of either the hot or cold type. Those cases of the heat type are due to obstruction by pathogenic heat, exhibiting fever, flushed face, convulsion, deep red tongue with yellow coating and rapid pulse. Here analeptic herbs are combined with those that purge heat and toxins, cool the blood and eliminate wind, thus resuscitating with cool herbs [e.g., rhino horn, raw rehmannia, moutan, coptis, gardenia]. Cases of the cold type are usually due to obstruction by pathogenic cold or phlegm-turbidity, manifested as bodily coldness, cyanosis, or rattling in the throat due to phlegm, pale tongue with white coating and slow pulse. For such cases, analeptic drugs are used together with drugs that eliminate cold and activate qi, thus resuscitating with warm herbs [e.g., aconite, cinnamon bark, dry ginger]. Analeptics are mostly used for emergency cases. As they have a powerful dispersive action and likely cause damage to the primordial qi, they should not be taken for a long time.

The text then notes that the action of acorus is not as strong as that of musk and borneol, but it resolves phlegm and damp and is indicated for phlegm-damp obstructing the heart and for those cases due to dampness retained in the center (i.e., stomach/spleen). In traditional texts, the phlegm-mist herbs, such as acorus, are specifically indicated for loss of consciousness (e.g., having a stroke) with stiff tongue (a frequent result of brain damage due to stroke).

The idea of phlegm-mist has evolved over time, and this entity is now included as a diagnostic category for certain chronic ailments that do not necessarily have sudden onset, as occurs with some cases of depression, deterioration of memory, or gradual onset of a seizure disorder, as well as for the prolonged period of post-stroke syndrome. In such cases, milder agents (other than the highly aromatic musk and borneol) are relied upon. As an example, Clinic of Traditional Chinese Medicine recommends a formula for treating a syndrome of "depressive psychosis" marked by conditions such as emotional depression, apathy, dementia, muttering to oneself, frequent outbursts of crying or laughing for no apparent reason, and low desire for food; the formula is comprised of acorus, polygala, arisaema, curcuma, pinellia, citrus, chih-shih, cyperus, hoelen, licorice. In the book Traditional Chinese Treatment for Senile Diseases, a similar formula is suggested for cases of senile dementia with depression and other symptoms such as those just mentioned, with the herbs chih-shih and licorice removed and replaced by gardenia. These formulas are modifications of the traditional Shunqi Daotan Tang (Smooth the Qi and Purge the Phlegm Decoction).

For the long-term therapy of patients suffering from phlegm-mist disorder, dietary adjustments are considered very important. Fried foods, heavily salted foods, and foods that are difficult to digest are eliminated to avoid the problem of producing pathological phlegm. Herbs that promote digestion are also potentially of value, including shen-chu, raphanus, and crataegus. If constipation is present, this disorder is to be addressed because it contributes to abdominal stagnation and the increased possibility of upward flow of qi and fluid to affect the heart and its orifices. Rhubarb is the primary ingredient in formulas for alleviating constipation, and it is typically combined with chih-shih to aid the downward flow.

APPENDIX: Herbs in the Materia Medica Section Devoted to Opening the Orifices

In the book Ten Lectures on the Use of Medicinals from the Personal Experience of Jao Shude, three key herbs from the Materia Medica section devoted to opening the heart orifices are described in detail. The book's presentation of these herbs for phlegm-mist obstructing the orifices is relayed here:

Musk: acrid in flavor and warm in nature, musk opens the orifices of the heart, frees the channels and network vessels [jingluo, may correspond to arteries and veins], frees the twelve channels above and below, and penetrates inward to the bone and marrow and outward to the skin and hair. As an aromatic, mobile, and penetrating substance, it opens the gates (i.e., frees the jaws) and disinhibits orifices. For coma and clenched jaw that result from wind strike, heat entering the pericardium, or phlegm confounding the orifices of the heart, this medicinal opens the orifices of the heart and arouses the heart spirit.

Borneol: acrid and bitter in flavor and slightly cold in nature, borneol is aromatic, penetrating, and mobile; there is nowhere it does not reach. It dissipates depressed fire and frees all the orifices, clears the heart and arouses the brain, and dispels eye redness and nebulous eye screens. For all symptoms such as coma, hoisted eyes [eyes open and turned upward], convulsions, and loss of speech that results from wind-phlegm harassing the upper body or phlegm-heat confounding the heart, acute childhood fright wind due to febrile disease, epilepsy, or sudden collapse from wind stroke, use borneol to open the orifices of the heart and clear heart heat and to arouse the brain and quiet the spirit.

Acorus: acrid in flavor and warm in nature, opens and frees the orifices of the heart, diffuses qi, and eliminates phlegm, sharpens hearing and vision, and enhances the voice. For heat entering the pericardium or phlegm confounding the orifices of the heart that result in coma, clouding, inability to speak, and in severe cases, convulsions, acorus is frequently used to open and free the orifices of the heart, diffuse qi, and eliminate phlegm, thereby arousing the brain and clearing the spirit. When phlegm turbidity and qi depression affect the heart spirit and result in palpitations, forgetfulness, fright and fear, and disquieted essence-spirit, which in severe cases can manifest as epilepsy or mania and withdrawal, acorus is used to diffuse qi and eliminate phlegm and to open the orifices of the heart in order to quiet the heart spirit.

Musk, which is obtained from the musk deer, a rare and endangered species, is now replaced in China by synthetic muscone, the primary active component. Borneol is considered potentially unsafe, particularly by the California Bureau of Foods and Drugs; the amount should be limited to about 2% of a prescription to maintain its concentration consistent with that in simple extracts of borneol-containing herbs (such as cardamom). Acorus is commonly derived from two species: Acorus gramineus, which is considered a safe herb, and the stronger Acorus calamus, for which some health warnings have been issued (mainly due to a single laboratory study conducted over 30 years ago, indicating a carcinogenic potential). Ox gallstone (not mentioned in the Jao Shude book) is a rare and expensive agent that is sometimes replaced by manufactured compounds using bile salts; due to inconsistencies in production of this artificial form, it is not used outside of China.

December 2004

APPENDIX: Cause of Stroke As Understood by Modern TCM

In their article Progress of Research on Ischemic Stroke Treated with Chinese Medicine (Journal of Traditional Chinese Medicine, 1992), Chen Keji and Song Jun present a diagram (reproduced below) summarizing the primary causes of stroke (apoplexy) as understood in the TCM view. Chen Keji is a professor at Beijing's Xiyuan Hospital. He is also an academician of the Chinese Academy of Sciences, World Health Organization consultant on traditional medicine, and President of the Chinese Association of Integrative Medicine. He was one of the chief researchers involved in the studies of the widely-used formula Coronary Heart No. II, and the first clinician to apply ligustrazine (the main active ingredient of the herb chuanxiong) in treating acute ischemic stroke, having studied its pharmacology in relation to anti-platelet activity and thromboxane inhibition. He directed the project of sorting out original medical archives preserved in the imperial palace of the Qing Dynasty and published the findings in the book Medical Prescriptions Written for Cixi and Guangxu with Commentary. He is editor in Chief of the Chinese Journal of Integrated Traditional and Western Medicine; Song Jun is a member of the China Academy of Traditional Chinese Medicine and an editorial board member for this journal.

Diagram of the factors causing ischemic stroke

Diagram of the factors causing ischemic stroke

In this diagram, the causative factors are first subdivided into three categories: those that cause accumulation and blockage in the channels; genetic influences; and factors that lead to deficient nourishment, referring mainly to qi, yin, and blood deficiency. The first category is further subdivided into fatigue and worry and dietary imbalance; the third category is also further subdivided into decrepitude, dissatisfaction, and deficiency of qi. Genetics (inherent defect), which is under-represented in standard TCM, is not expanded upon in this TCM-based diagram, but will be elaborated below, along with discussion of the other factors.

The uppermost entry in the diagram is the influence of fatigue and worry. Here, fatigue refers not to the symptom but to the actions that lead to fatigue, such as overwork, insufficient sleep, and sweating too much (such as from working in hot conditions). These actions, as well as worrying a lot, are said to consume the heart yin, causing imbalances that ultimately affect the circulation (including damage to the fluids that yield a phlegm-mist). The next entry involves improper diet, focusing on its contribution to phlegm accumulation. Overeating or eating difficult to digest foods (including foods that are too fatty, too cold, or too high in sugar) can cause one to feel tired after a meal, a sign that the food is improper and that the digestive process ultimately will be incomplete, leading to production of pathogenic phlegm (with repeated improper eating, the stomach and spleen are weakened, thus leading to further problems with digestion of foods). The combination of overeating and overdrinking, referring to drinking too much alcohol, contributes to "phlegm misting the heart orifices," which is considered a major contributor to blockage of the vessels to the brain.

In addition, inherent defect is mentioned, but the diagram provided by Chen is incomplete. Inherent defects may be of several types and are understood now to be based on genetics or traced to injuries that might occur during early development (or from diseases during childhood). For example, there can be a defect in the blood vessels themselves, leading to easy blockage or to an aneurism; there can be defects in the digestive system or the metabolism of food components, leading to production of the phlegm mist even in the absence of overeating or excess alcohol consumption; or, there may be defects in the heart or in the blood constituents that lead to easy clotting of the blood. These defects are difficult to eliminate; their impact may be exacerbated by the other factors depicted in the diagram or minimized by healthful practices.

"Decrepitude" refers to the deterioration that is seen with aging. This is expressed as decline of kidney essence; it is a natural process, but it can be accelerated by a variety of factors, especially emotional distress ("psychic trauma"), which causes imbalances leading to circulatory disturbance. Decrepitude also involves a decline in the overall activity of the body, so that it suffers from sluggish circulation that results from lack of exercise; this problem especially occurs when the joints become stiff, the legs become weak, or the heart muscle loses its strength.

Dissatisfaction is a gnawing, ongoing psychological state that may be based partly on one's circumstances and partly on one's approach to dealing with difficult circumstances. This irritating condition involves stagnation of the liver qi circulation, which generates heat in the liver and damages the liver yin (over time, this will contribute to the decline of heart yin, a disorder that was mentioned in relation to worry and overwork). Liver qi stagnation can be exacerbated by highly distressing events, leading to a severe disturbance in the circulation of qi and blood. Thus, one may suffer a stroke following an outburst of anger or other emotion, because of the underlying disturbance that already exists due to persistent dissatisfaction.

Finally, a deficiency of qi is an important contributor to susceptibility to disease and damage to the organs and other body parts. As implied in the chart, external pathogenic factors, such as wind, heat, and damp, are able to penetrate the channels and cause pathological conditions if the channels are relatively empty of their vital qi and blood (by contrast, when the vessels are full of healthy qi and blood, external environmental changes are unlikely to "enter" and cause disturbances). Similarly, viruses and other pathogens can affect the person who has qi deficiency because of the lack of sufficient defensive qi. Ultimately, the environmental influences and/or pathogens will result in circulatory changes, including sudden blockage.

This variety of potential adverse influences comes together in two calamitous outcomes: the channels become blocked by phlegm mist and blood stasis, while the lack of adequate circulation of qi allows these blocking accumulations to impede the circulation and cause a stroke. While any one of the listed factors alone may not cause a catastrophic event, the combination of two or more, particularly the combination of a deficiency (e.g., qi or heart yin) and an accumulation-blockage (e.g., phlegm mist or blood stasis) will likely result in a stroke or heart attack