Part nine hypertension - Sino_western_Joint TCM Prevention Diseases Chinese Medicine

Part nine hypertension

Hypertension is one of the greatest health problems facing industrialized nations and continues to be a major contributing factor in the development of, and death from CAD, stroke, heart failure, and renal failure. Because uncomplicated hyper-tension is an asymptomatic condition, many people are un-aware that they have it. Campaigns by national medical orga-nizations have raised public awareness, and the mass screening of patients has resulted in an increased recognition of the prob-lem so that now only an estimated 30 % of patients with hyper-tension are unaware of their diagnosis. This has contributed to significant decreases in the rates of death from stroke and coro-nary artery disease (CAD). Nonetheless, and only 50 % of pa-tients with hypertension are on therapy, and only 30% have their blood pressure controlled to ideal levels. Because of the asymptomatic nature of this disease (at least until complica-tions develop) and the frequent side effects associated with treatment, initiation of medical therapy and continued compli-ance with a treatment regimen is an ongoing challenge.

As currently defined, systemic hypertension is present in an adult (age18) if the systolic blood pressure is greater than or equal to 140mm Hg or the diastolic blood pressure is greater than or equal to 90 mm Hg. According to this definition, an estimated 50 million adult Americans have hypertension. This is a somewhat arbitrary definition in that it is not derived from any pathophysiologic data but, rather, from an analysis of the range of pressures in the population and the risks of associated morbidity and mortality. Nonetheless, the current definitions make clinical sense because the longterm risk of cardiovascular morbidity and mortality clearly rises in direct relation to in-creases in systemic blood pressure.

Hypertension can be further classified into various stages reflecting mild, moderate, or severe elevations in blood pres-sure (Table 13). When there is a discrepancy between the classification of the systolic and diastolic blood pressures, the higher category should be used to classify the patient's hyper-tension. The diagnosis of hypertension is generally not based on a single elevated blood pressure measurement; rather, it re-flects a pattern of elevated blood pressure, with abnormally high values obtained on at least three separate occasions. The normal blood pressure in children and pregnant women is slightly lower, although care must be taken in making the for-mal diagnosis of hypertension in children and adolescents be-cause the blood pressure frequently normalizes in adulthood.

TABLE 13 Classification of Blood Pressure in Adults

Classification

Systolic BP(mmHg)

Diastolic BP(mmHg)*

Normal

High-normal

Hypertensive
Stage 1
Stage 2
Stage 3

£¼ 130

130 -- 139

140--159
160--179
¡Ý 180

and

or

or
or
or

£¼ 35

85--89

90--99
100--109
¡Ý110

* BP= blood pressure (in mm Hg), lmmHg=0.133kPa

The incidence of hypertension increases with age and is more common in African-Americans than in whites. It is more common in younger men than in women, although this differ-ence does not exist after the age of 55 and is reversed after the age of 75. Despite advances in the treatment of hypertension, much is still unknown regarding the etiology of the disease. In 90% to 95 % of patients, no identifiable cause of the hyperten-sion is found and the patients are said to have primary or essen-tial hypertension. Familial patterns of primary hypertension are common and suggest that genetic factors are important. However, environmental factors, such as obesity, alcohol con-sumption, sedentary lifestyle, and salt intake, likely play a role. Proposed pathophysiologic mechanisms include excessive renal sodium retention, overactivity of the sympathetic nervous system reninangiotensin excess, hyperinsulinemia, and alter-ations in vascular endothelium. This last mechanism may re-sult from a decrease in endothelium-derived vasorelaxing sub-stances (e. g. nitric oxide) or an increase in endothelium-de-rived constricting factors (e. g. , endothelin). Several of these factors may be present in a given individual and may mediate the hypertensive response through alterations in eirculating blood volume, constriction of vascular smooth muscle, and/or vascular hypertrophy. In approximately 5% of hypertensive patients, the elevated blood pressure is the direct result of an-other disorder (Table 14).

TABLE 14 Secondary Causes of Hypertension

Renal

Renal parenchymal disease (glomerulonephritis, polycystic disease, diabetic

nephropathy)

Renovascular disease (renal artery stenosis, fibromuscular dysplasia, vasculi-

tis)

Endocrine

Hypo-or hyperthyrodisim

Hyperparathyroidism

Adrenocorticoid excess (Cushing's syndrome, primary aldosteronism)

Pheochromocytoma

Exogenous hormones (oral contraceptives, estrogen replacement)

Neurologic Disorders

Brain tumors, sleep apnea, spinal cord injuries, lead poisoning, porphyria

Stress-Induced

Pain, anxiety, hypoglycemia, alcohol withdrawal, postoperative

Toxic/Pharmacologic

Alcohol and drug use, NSAIDs*, ephedrine, corticosteroids, monoamine

oxidase inhitibitors

Miscellaneous

Aortic coarctation

Carcinoid syndrome

Pregnancy

* NSAIDs:nonsteroidal anti inflammatory drugs

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