Hypertension

Latest updates: January 3, 2014

On December 18, 2013, the Eighth Joint National Committee (JNC 8) guidelines on the management of adult hypertension were published by The Journal of the American Medical Association (JAMA). Unlike the sweeping overhaul of the hypertension guidelines in 2004 by the JNC 7, the JNC 8 restricted its focus to first-line medications and treatment goals in various populations. Also unlike the JNC 7, these new guidelines are not endorsed by any federal agencies or professional societies, including the American College of Cardiology and the American Heart Association. An accompanying JAMA editorial states the following: 'The panel's report is now published in JAMA as a stand-alone document, and it remains unclear as to whether, or when, or by whom another consensus national hypertension guideline will again be formulated." However, a second JAMA editorial states the following regarding the panel's review process: 'Reading the critiques and responses, many readers will conclude that the panel was on solid ground in its interpretation of high-quality evidence about the limited but important set of questions that it chose to address.'

Summary of the JNC 8's recommendations:

• Target blood pressure for treatment of the elderly was raised to ≥150 mm Hg systolic or ≥90 mm Hg diastolic, and for patients with chronic kidney disease and with diabetes to ≥140 mm Hg systolic or ≥90 mm Hg diastolic. As well, the goal for treatment is no lower than these blood pressures
• First-line therapy for black patients includes calcium-channel blockers and thiazide-type diuretics. Other agents to consider in patients who are not black include angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs). Regardless of race, all patients with chronic kidney disease should receive either an ACE inhibitor or an ARB

Previous update: November 14, 2013

On November 12, 2013, the American College of Cardiology (ACC) and the American Heart Association (AHA) published four related guidelines on the prevention of atherosclerotic cardiovascular disease (ASCVD) events, with a focus on cholesterol, obesity, and lifestyle management tools.

The new AHA/ACC guideline on lifestyle management to reduce cardiovascular risk continues to recommend any medically recognized heart-healthy dietary program that emphasizes vegetables, fruits, and whole grains; that includes low-fat dairy products, poultry, fish, legumes, nontropical vegetable oils and nuts; and that limits sweets, sugar-sweetened beverages, and red meats. For lowering blood pressure, the strongest recommendation continues to be reducing sodium intake and following a DASH-type diet.

The 2013 ACC/AHA guideline on the assessment of cardiovascular risk introduces a new 10-year and lifetime cardiovascular risk assessment tool based on a pooled cohort to predict first ASVCD-related event in non-Hispanic men and women. Routine measurement of carotid intima-media thickness is not recommended as part of primary prevention.

Key points

• Hypertension is defined as blood pressure greater than 140/90 on two or more blood pressure readings taken at each of two or more visits after initial screening
• Stage 1 hypertension is defined as a systolic blood pressure of 140 to 159 mm Hg or a diastolic blood pressure of 90 to 99 mm Hg; stage 2 hypertension is defined as systolic blood pressure of 160 mm Hg or greater, or a diastolic blood pressure 100 mm Hg or greater
• Prehypertension is defined as systolic if the systolic blood pressure is between 120 and 139 mm Hg, and/or diastolic if the diastolic blood pressure is between 80 and 89 mm Hg in adults, or if either the systolic blood pressure or the diastolic blood pressure is between the 90th and the 95th percentile values in children
• Essential hypertension refers to the 90% of patients with hypertension with no identifiable secondary cause. There are no specific symptoms of raised blood pressure, only those attributable to damage to target organs
• Secondary hypertension has an identifiable cause, such as renal artery stenosis or pheochromocytoma, and is managed as part of the primary condition
• Hypertension in pregnancy, or preeclampsia, is managed as an obstetric urgency or emergency
• Hypertension is an important risk factor for cardiovascular disease and stroke. Treatment is effective in reducing the risk. In some patients, only changes in lifestyle are required
• Some patients can be adequately controlled on pharmacologic monotherapy, whereas other patients need additional agents, often in combination
• One of the most effective treatments for hypertension is lifestyle modification through diet and regular cardiovascular exercise
• Treatment should be started immediately if blood pressure is extremely high, if there is optic disk edema, or if there is evidence of rapidly progressive end-organ damage. Depending on the level of high blood pressure and the patient's condition, hypertension may require urgent and aggressive treatment in the following emergencies:
  • Accelerated or malignant hypertension
  • Hypertensive encephalopathy
  • Stroke
  • Subarachnoid hemorrhage
  • Unstable angina
  • Acute myocardial infarction
  • Heart failure
  • Aortic dissection

Background

Description

• Hypertension in adults is defined as a systolic blood pressure of at least 140 mm Hg and a diastolic blood pressure of at least 90 mm Hg
• Essential, idiopathic, or primary hypertension is the most common type and is seen in 90% of patients and is the focus of this monograph. Essential hypertension is an important risk factor for subsequent cardiovascular disease
• Uncomplicated essential hypertension usually is asymptomatic
• Isolated systolic blood pressure increases with age and is a major risk factor for coronary vascular disease, but only in patients aged older than 50 years. It can be caused by conditions that increase total peripheral resistance, such as rigidity of the aorta, or in conditions that increase cardiac output, such as hyperthyroidism, Paget's disease of the bone, arteriovenous fistula, and aortic regurgitation
• Adults whose blood pressure falls above the top normal level (either systolic or diastolic) but not in the hypertensive range are considered prehypertensive. These patients should be observed at least annually, and vigorous efforts should be made to address modifiable risk factors (eg, weight, sodium intake) if present
• Secondary hypertension has an identifiable cause, such as renal artery stenosis or pheochromocytoma, and is managed as part of the primary condition
• Hypertension in pregnancy, or preeclampsia, is managed as an obstetric urgency or emergency
• Preoperative hypertension is associated with significant risk for perioperative mortality and other complications, but the extent to which preoperative control may lower risk, and the duration of control necessary to achieve lower risk, are unknown
• Hypertension in children and adolescents appears to be increasing in the U.S. Approximately 5% of children and adolescents have essential hypertension. Blood pressure measurements should begin in children at 3 years of age. Hypertension in children is defined as a systolic blood pressure equal to or greater than the 95th percentile value for gender, age, and height. Those in the 90th percentile are considered prehypertensive. In adolescents, a blood pressure greater than 120/80 mm Hg should be considered prehypertensive

Epidemiology

Prevalence and frequency:

• Hypertension has a prevalence of approximately 25,000 cases per 100,000 of population
• In the U.S., more than 65 million adults are estimated to have hypertension

Demographics:

• Prevalence increases with age but occurs in up to 4% of young adults
• Prevalence is greater than 50% in people aged 60 years or older
• Secondary hypertension is more common in children, but approximately 5% of children and adolescents are believed to have essential hypertension
• In young and middle-aged people, hypertension is more common in men than in women
• Prevalence of hypertension increases more steeply with age in women than in men, and elderly women are at least as likely to be hypertensive as elderly men
• Hypertension is more common among black people than white people
• Rates of good blood pressure control in the U.S. are lowest among Mexican Americans and American Indians
• A family history of hypertension is associated with an increased risk of developing the disorder
• Prevalence of hypertension is greater in lower socioeconomic groups

Causes and risk factors

• Approximately 90% of cases of hypertension have no identifiable cause (primary or essential hypertension)

Common causes of secondary hypertension:

• Renal parenchymal disease is the most common cause of secondary hypertension and is responsible for up to 5% of cases. It includes hypertensive nephrosclerosis, diabetic nephropathy, polycystic kidney disease, and chronic glomerulonephritis. Renal parenchymal disease is suggested by elevated serum creatinine levels and abnormal urinalysis results
• Renovascular disease, especially in patients with hypertension of recent onset or with difficult-to-control hypertension and in patients who are smokers, have extensive vascular disease, or have hypertension accompanied by worsening renal function. Renovascular disease has an abrupt onset at less than 30 years of age or greater than 50 years of age. It causes severe hypertension, with a diastolic blood pressure greater than 115 mm Hg that may be refractory to medication. On physical examination, an abdominal bruit may be heard over renal arteries. Some of these patients may present with recurrent flash pulmonary edema
• Primary hyperaldosteronism accounts for up to 7% of cases. Patients are usually asymptomatic. Hyperaldosteronism is characterized by low serum potassium levels in the absence of diuretics and high serum aldosterone levels or high 24-hour urine aldosterone measurements without dietary sodium restriction. It is associated with suppressed plasma renin activity
• Pheochromocytoma, a tumor of catecholamine-secreting chromaffin cells, predominantly secretes norepinephrine. Its clinical features, the most common of which is hypertension, result from the raised catecholamine levels. Other features of pheochromocytomas include headache, palpitations, perspiration, pallor, and elevated plasma metanephrine levels
• Cushing syndrome is caused by excessive quantities of glucocorticoids, resulting either from excessive secretion by the adrenal cortex (endogenous) or from exogenous glucocorticoids. Features include truncal obesity, purple striae, and elevated urinary cortisol excretion
• A coarctation of the aorta is a constriction in the aorta, most frequently located just distally to the left subclavian artery at the junction of the ligamentum arteriosum. Features include delayed or absent femoral arterial pulses, decreased blood pressure in the lower extremities, interscapular murmur, and a reverse '3' sign on chest radiograph and rib notching from intercostal collaterals
• Elevated diastolic blood pressure may occur in patients with hypothyroidism; elevated systolic blood pressure may occur in patients with hyperthyroidism

The ABCDE mnemonic can be used to help remember potential causes of secondary hypertension:

• A: Accuracy of diagnosis; obstructive sleep apnea; aldosteronism, which may be more common than originally thought and may be present in 20% of patients with hypertension resistant to treatment
• B: Presence of renal artery bruits suggestive of renal artery stenosis, renovascular hypertension; bad kidneys (renal parenchymal disease)
• C: Excess catecholamines characterizing pheochromocytoma; coarctation of the aorta; Cushing syndrome
• D: Drugs (eg, oral contraceptives); diet (eg, excess sodium or licorice intake)
• E: Excess erythropoietin; endocrine disorders (eg, hyperthyroidism, preeclampsia)

Contributory or predisposing factors:

• Increasing age
• Obesity
• Physical inactivity
• Ethnicity
• Excessive alcohol consumption
• Smoking
• Diabetes mellitus

Screening

Summary approach

• Screening is the primary method of detecting hypertension
• All visits to a health care provider for whatever reason can be regarded as an opportunity to measure blood pressure

Population at risk

All patients, especially those with a family history of hypertension.

Screening modalities

• Periodic screening for hypertension is recommended for anyone aged 18 years or older. The optimal interval for blood pressure screening has not been determined and is left to clinical discretion
• Those with high to normal blood pressure (>130/80 mm Hg, but not fulfilling the criteria for hypertension) should have their blood pressure measured at least annually
• Although lipid levels do not affect blood pressure, guidelines recommend measuring lipid levels in hypertensive patients, because lipids can affect overall cardiovascular risk, which helps to determine the type of antihypertensive therapy

Primary prevention

Summary approach

• Because of the huge, overall community burden of hypertension, small individual advantages from primary prevention can translate into large population gains in morbidity and mortality rates and reduce treatment costs
• Lifestyle modifications for treating hypertension are also appropriate for prevention, and they can be introduced at low cost and with few health risks
• Measures for preventing hypertension are, therefore, important for everyone, but particularly for people at risk of developing hypertension, such as those with a positive family history

Population at risk

All patients, especially those with a family history of hypertension.

Preventive measures

Tobacco:

• Visits by smokers to health care providers are an opportunity to provide advice on the benefits of tobacco cessation
• Smoking cessation is important for all smokers but particularly for those at risk of hypertension or other cardiovascular disease
• Many smokers would like to quit but find it very difficult to do so
• Smokers attempting to quit require support, which may include prescription of nicotine replacement products, bupropion, or varenicline

Alcohol and drugs:

• Excessive alcohol consumption is associated with hypertension
• To reduce the risk of developing hypertension, alcohol consumption should be limited to the equivalent of 30 mL (in men) or 15 mL (in women) of ethanol per day
• Moderate alcohol consumption reduces the risk of cardiovascular disease, so there is no rationale for advising complete abstinence
• Some evidence suggests that the cardiovascular benefits of alcohol may be greater for red wine than for other alcoholic drinks, but the deleterious effects of chronic alcohol consumption in general on blood pressure are well documented

Diet:

• Obese or overweight people should be advised to lose weight
• Sodium intake should be limited to no more than 1500 mg per day
• Adequate potassium intake should be maintained, preferably from food sources such as fresh fruit and vegetables
• Although moderating intake of saturated fat has general benefits for cardiovascular health, it is unlikely to affect blood pressure

Physical activity:

• Physical activity should be encouraged in everyone
• Strenuous exercise is not necessary to reduce cardiovascular risk
• Approximately 30 to 45 minutes of brisk walking most days of the week is enough to have important benefits on the risk of blood pressure and other cardiovascular diseases
  • Exercise is considered adequate when one is short of breath, unable to complete a sentence, and sweating, if the patient is well-hydrated and the ambient temperature is warm enough
• Patients with a pre-existing cardiac disease should not undertake an exercise program without a proper medical assessment before initiation