hypertension

High blood pressure; transitory or sustained elevation of systemic arterial blood pressure to a level likely to induce cardiovascular damage or other adverse consequences. H. has been arbitrarily defined as a systolic blood pressure above 140 mm Hg or a diastolic blood pressure above 90 mm Hg. Consequences of uncontrolled h. include retinal vascular damage (Keith-Wagener-Barker changes), cerebrovascular disease and stroke, left ventricular hypertrophy and failure, myocardial infarction, dissecting aneurysm, and renovascular disease. An underlying disorder ( e.g., renal disease, Cushing syndrome, pheochromocytoma) is identified in fewer than 10% of all cases of h.. The remainder, traditionally labeled “essential” h., probably arise from a variety of disturbances in normal pressure-regulating mechanisms (which involve baroreceptors, autonomic influences on the rate and force of cardiac contraction and vascular tone, renal retention of salt and water, formation of angiotensin II under the influence of renin and angiotensin-converting enzyme, and other factors known and unknown), and most are probably genetically conditioned. SYN: hyperpiesis, hyperpiesia. [hyper- + L. tensio, tension] Because of its wide prevalence and its impact on cardiovascular health, h. is a major cause of disease and death in industrialized societies. It is estimated that 50–70 million Americans, including about 50% of all people over age 60, have h., but that only about one-third of these are aware of their condition and are under appropriate treatment. H. causes 35,000 deaths annually in the U.S., and is a contributing factor in a further 180,000 deaths. It is associated with a 3-fold increase in the risk of heart attack and a 7- to 10-fold increase in the risk of stroke. The prevalence of h. and the incidence of nonfatal and fatal consequences are substantially higher in African-Americans. Although people with extremely high diastolic pressure may experience headache, dizziness, and even encephalopathy, uncomplicated h. seldom causes symptoms. Hence the diagnosis of h. is usually made by screening apparently healthy persons or those under treatment for another condition. Risk factors for h. include a family history of h., African-American race, advancing age, the postmenopausal state, excessive dietary sodium, obesity, excessive use of alcohol, sedentary lifestyle, and chronic emotional stress. Treatment options include lifestyle changes (maintenance of healthful weight; at least 30 minutes of aerobic exercise several days a week; limitation of sodium intake to 2.4 g daily and of ethanol to 1 oz daily; consumption of adequate potassium, calcium, and magnesium; and avoidance of excessive emotional stress) and a broad range of drugs, including diuretics, beta-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, α₁-adrenergic antagonists, centrally acting alpha-agonists, and others. In recent decades, early detection and aggressive treatment of h. have reduced associated morbidity and mortality. Current practice standards call for still more diligent management, including prevention through avoidance of known risk factors, particularly in persons with a family history of h., and control of cofactors known to increase the risk of cardiovascular damage in persons with h. (smoking, hypercholesterolemia, diabetes mellitus). Some studies suggest that the goal of treatment should be a diastolic blood pressure of 80 or lower.

- accelerated h. h. advancing rapidly with increasing blood pressure and associated with acute and rapidly worsening signs and symptoms.

- adrenal h. h. due to an adrenal medullary pheochromocytoma or to hyperactivity or functioning tumor of the adrenal cortex.

- benign h. h. that runs a relatively long and symptomless course.

- borderline h. by consensus, that blood pressure zone between highest acceptable “normal” blood pressure and hypertensive blood pressure. The Framingham Heart Study defines this as pressures between 140 and 160 mm Hg systolic and 90 and 95 mm Hg diastolic.

- episodic h. h. manifest intermittently, triggered by anxiety or emotional factors. SYN: paroxysmal h..

- essential h. h. without known cause. SYN: idiopathic h., primary h..

- gestational h. h. during pregnancy in a previously normotensive woman or aggravation of h. during pregnancy in a hypertensive woman. SYN: pregnancy-induced h..

- Goldblatt h. increased blood pressure following obstruction of blood flow to one kidney.

- idiopathic h. SYN: essential h..

- labile h. frequently changing levels of elevated blood pressure.

- malignant h. severe h. that runs a rapid course, causing necrosis of arteriolar walls in kidney, retina, etc.; hemorrhages occur, and death most frequently is caused by uremia or rupture of a cerebral vessel.

- pale h. h. with pallor of the skin, a severe form with pronounced constriction of peripheral vessels.

- paroxysmal h. SYN: episodic h..

- portal h. h. in the portal system as seen in cirrhosis of the liver and other conditions causing obstruction to the portal vein.

- postpartum h. increased blood pressure immediately following the completion of labor.

- pregnancy-induced h. SYN: gestational h..

- primary h. SYN: essential h..

- pulmonary h. h. in the pulmonary circuit; may be primary, or secondary to pulmonary or cardiac disease, e.g., fibrosis of the lung or mitral stenosis.

- renal h. h. secondary to renal disease.

- renovascular h. h. produced by renal arterial obstruction.

- secondary h. arterial h. produced by a known cause, e.g., hyperthyroidism, kidney disease, etc., in contrast to primary h. that is of unknown cause.

- systemic venous h. increased pressure in the veins ultimately leading to the right atrium nearly always due to disease of the right heart or pericardium but occasionally due to blockade of one or both venae cavae.

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hy·per·ten·sion 'hī-pər-.ten-chən n

1) abnormally high arterial blood pressure that is usu. indicated by an adult systolic blood pressure of 140 mm Hg or greater or a diastolic blood pressure of 90 mm Hg or greater, is chiefly of unknown cause but may be attributable to a preexisting condition (as a renal or endocrine disorder), that typically results in a thickening and inelasticity of arterial walls and hypertrophy of the left heart ventricle, and that is a risk factor for various pathological conditions or events (as heart attack, heart failure, stroke, end-stage renal disease, or retinal hemorrhage) see essential hypertension, secondary hypertension, white coat hypertension

2) a systemic condition resulting from hypertension that is either symptomless or is accompanied esp. by dizziness, palpitations, fainting, or headache

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n.

high blood pressure, i.e. elevation of the arterial blood pressure above the normal range expected in a particular age group. Hypertension may be of unknown cause (essential hypertension or hyperpiesia). It may also result from kidney disease, including narrowing (stenosis) of the renal artery (renal hypertension), endocrine diseases (such as Cushing's disease or phaeochromocytoma) or disease of the arteries (such as coarctation of the aorta), when it is known as secondary or symptomatic hypertension.

Complications that may arise from hypertension include atherosclerosis, heart failure, cerebral haemorrhage, and kidney failure, but treatment may prevent their development. Hypertension is symptomless until the symptoms of its complications develop. Some cases of hypertension may be cured by eradicating the cause. Most cases, however, depend upon long-term drug therapy to lower the blood pressure and maintain it within the normal range. The drugs used include thiazide diuretic, beta blocker, ACE inhibitor, calcium antagonist, and alpha blocker. Combinations of drugs may be needed to obtain optimum control. See also portal hypertension, pulmonary hypertension.

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hy·per·ten·sion (hi″pər-tenґshən) [hyper- + tension] high arterial blood pressure; various criteria for its threshold have been suggested, ranging from 140 mm Hg systolic and 90 mm Hg diastolic to as high as 200 mm Hg systolic and 110 mm Hg diastolic. Hypertension may have no known cause (essential or idiopathic h.) or be associated with other primary diseases (secondary h.).