[hyper- + tension]
ABBR: HTN In adults, a condition in which the blood pressure (BP) is higher than 140 mm Hg systolic or 90 mm Hg diastolic on three separate readings recorded several weeks apart. Hypertension is one of the major risk factors for coronary artery disease, heart failure, stroke, peripheral vascular disease, kidney failure, and retinopathy. It affects about 50 million people in the U.S. Considerable research has shown that controlling HTN increases longevity and helps prevent cardiovascular illnesses.
SYN: SEE: high blood pressure
SEE: blood pressure
All systems for categorizing high BP are somewhat arbitrary, but the current consensus is that normal BPs are less than 120 mm Hg systolic and 80 mm Hg diastolic, on average. Borderline high BPs (prehypertension) are between 120 and 139 mm Hg systolic and 80 to 89 mm Hg diastolic. Patients with BP readings between 140/90 and 160/100 mm Hg are said to have stage 1 (mild) HTN.
Stage 2 HTN is a pressure from 160/100 to 179/109 mm Hg. Stage 3 HTN begins at 180/110 mm Hg and has no upper limit. At each stage of HTN, from prehypertensive levels through the three stages of HTN, the risks of strokes, heart attacks, and kidney failure increase. SEE TABLE: Classification of Blood Pressure for Adults Age 18 and Older*
Hypertension in children has been defined as BP above the 95th percentile for age, height, and weight. As many as 28% of children have secondary HTN compared to 1% to 5% in adults.
Approx. one of every three American adults over age 18 is hypertensive. The prevalence of HTN increases with age. Hypertension is found more often in people born in the U.S. than in people who emigrate to it. It is higher in African-Americans than in other groups.
Hypertension results from many different conditions, some curable and others treatable. Curable forms of HTN (“secondary HTN”), which are relatively rare, may be caused by coarctation of the aorta, pheochromocytoma, renal artery stenosis, primary aldosteronism, and Cushing syndrome. Excess alcohol consumption (more than two drinks daily) is a common cause of high BP; abstinence or drinking in moderation effectively lowers BP in these cases. Aortic valve stenosis, pregnancy, obesity, and the use of certain drugs (such as cocaine, amphetamines, steroids, or erythropoietin) also may lead to HTN. Usually, however, the cause is unknown; then high BP is categorized as primary, essential, or idiopathic. Primary hypertension may result from the body's resistance to the action of insulin, hyperactivity of the sympathetic nervous system, hyperactivity of the renin-angiotensin-aldosterone system, or endothelial dysfunction.
SYMPTOMS AND SIGNS
Hypertension is usually a silent (asymptomatic) disease in the first few decades of its course. Because most patients are symptom free until complications arise, they may have difficulty taking seriously a condition from which they perceive no immediate danger. Occasionally, patients with HTN report headache. When complications result from high BP, patients mention symptoms referable to the affected organs.
If HTN is newly diagnosed, routine studies should be done on the patient to establish a baseline for treatment. In addition to a thorough patient history, assessment for risk factors, and physical examination, these studies include an electrocardiogram, urinalysis, serum potassium and calcium levels, blood urea nitrogen level, fasting glucose level, and cholesterol profile, including triglycerides. The Joint National Committee (JNC) on Prevention, Detection, Evaluation and Treatment of High Blood Pressure periodically issues recommendations regarding target blood pressures for patients, including those those with prior cardiovascular, diabetic, or renal disease. Because HTN has been identified as a growing concern among children, the JNC recommends regular BP checks beginning at age 3. Lifestyle modifications that lower BP include dietary sodium restriction to about 2 g/day, made possible by avoiding salted foods such as ham, potato chips, and processed foods and by not adding salt to food at the table; maintaining a healthy weight (a body mass index above 24.9 can elevate BP); eating lower-calorie foods; restricting total cholesterol and saturated fat intake; quitting smoking; limiting alcohol intake to about one drink daily; and participating in a program of regular exercise. When lifestyle modifications fail over the course of several months to control BP naturally, medications should be used. Drug therapy for stage 1 HTN includes low-dose thiazide diuretics for most patients, although angiotensin converting enzyme (ACE) inhibitors, beta blockers, calcium channel blockers, or a combination of these may be prescribed. If approx. 118 patients with stage 1 HTN are treated with antihypertensive drugs for 5 years, one patient will reduce his or her risk of adverse cardiovascular events, such as stroke or heart attack. For stage 2 HTN, two-drug combinations are prescribed for most patients, usually a thiazide-type diuretic along with a beta blocker, ACE inhibitors, angiotensin receptor blockers, alpha blockers, or centrally active alpha blocking agents. If a woman develops HTN during pregnancy, treatment should be with methyldopa, a beta blocker, or a vasodilator, as these drugs provide the least risk to the fetus. SEE TABLE: Methods to Reduce Blood Pressure without Medication; SEE: pregnancy-induced hypertension
BP should be checked at every health care visit, and patients should be informed of their BP reading and its meaning. Positive lifestyle changes should be encouraged. Adherence to medical regimens is also emphasized, and patients are advised to inform their health care providers of any side effects of therapy that they experience because these can often be managed with dosage adjustment or a change in medication. The technique of home BP monitoring is taught to receptive patients. Pressures should be measured and recorded for both arms unless there is a medical prohibition for one arm, indicating which arm was used for each reading.
Classification of Blood Pressure for Adults Age 18 and Older*
|Category||Systolic (mm Hg)||Diastolic (mm Hg)|
|Stage 2||160 or higher||or||100 or higher|
Methods to Reduce Blood Pressure without Medication
|Intervention||Approximate Decrease (in mm Hg)|
|Weight loss (20 lb)||5-10|
|Dietary approaches to stop hypertension (DASH) diet||8-14|
|Reducing sodium intake||2-8|
|Limiting alcohol intake to one or two drinks a day||2-4|
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