Hypertension

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Hypertension (HTN or HT), also known as high blood pressure or arterial hypertension, is a chronic medical condition in which the blood pressure in the arteries is elevated. Blood pressure is expressed by two measurements, the systolic and diastolic pressures, which are the maximum and minimum pressures, respectively, in the arterial system. The systolic pressure occurs when the left ventricle is most contracted; the diastolic pressure occurs when the left ventricle is most relaxed prior to the next contraction. Normal blood pressure at rest is within the range of 100–140 mmHg systolic (top reading) and 60–90 mmHg diastolic (bottom reading). Hypertension is present if it is persistently at or above 140/90 millimeters mercury (mmHg) for adults; different criteria apply to children.[1]

Hypertension usually does not cause symptoms, but it is a major risk factor for hypertensive heart disease, coronary artery disease,[2] stroke, aneurysms of the arteries (e.g. aortic aneurysm), peripheral artery disease, and chronic kidney disease.

Hypertension is classified as either primary (essential) hypertension or secondary hypertension; about 90–95% of cases are categorized as primary hypertension which means high blood pressure with no obvious underlying medical cause.[3] The remaining 5–10% of cases categorized as secondary hypertension is caused by identifiable conditions such as kidney disease, narrowing of the aorta or kidney arteries, or endocrine disorders such as excess aldosterone or excess cortisol.

Dietary and lifestyle changes can improve blood pressure control and decrease the risk of health complications, although treatment with medication is still often necessary in people for whom lifestyle changes are not enough or not effective. The treatment of moderately high arterial blood pressure (defined as >160/100 mmHg) with medications is associated with an improved [6]

Signs and symptoms

Hypertension is rarely accompanied by any symptoms, and its identification is usually through [8]

On [7]

Secondary hypertension

Some additional signs and symptoms may suggest [10]

Hypertensive crisis

Severely elevated blood pressure (equal to or greater than a systolic 180 or diastolic of 110—sometimes termed malignant or accelerated hypertension) is referred to as a “hypertensive crisis“, as blood pressure at this level confers a high risk of complications. People with blood pressures in this range may have no symptoms, but are more likely to report headaches (22% of cases)[12]

A “hypertensive emergency”, previously “malignant hypertension”, is diagnosed when there is evidence of direct damage to one or more organs as a result of severely elevated blood pressure greater than 180 systolic or 120 diastolic.[12]

Pregnancy

Hypertension occurs in approximately 8–10% of pregnancies.[15]

Children

[17]

Cause

Primary hypertension

Primary (essential) hypertension is the most common form of hypertension, accounting for 90–95% of all cases of hypertension.[30]

Recent studies have also implicated events in early life (for example [32]

Secondary hypertension

Secondary hypertension results from an identifiable cause. Kidney disease is the most common secondary cause of hypertension.[34]

Pathophysiology

Determinants of mean arterial pressure

Illustration depicting the effects of high blood pressure

In most people with established diastolic dysfunction.

[43]

Many mechanisms have been proposed to account for the rise in peripheral resistance in hypertension. Most evidence implicates either disturbances in the kidneys’ salt and water handling (particularly abnormalities in the intrarenal [48]

Diagnosis

Typical tests performed
System Tests
Kidney creatinine
Endocrine Serum TSH
Metabolic triglycerides
Other chest radiograph
Sources: Harrison’s principles of internal medicine[54]

Hypertension is diagnosed on the basis of a persistent high blood pressure. Traditionally, the [59]

Once the diagnosis of hypertension has been made, physicians will attempt to identify the underlying cause based on risk factors and other symptoms, if present. Secondary hypertension is more common in preadolescent children, with most cases caused by kidney disease. Primary or essential hypertension is more common in adolescents and has multiple risk factors, including obesity and a family history of hypertension.[60] Laboratory tests can also be performed to identify possible causes of secondary hypertension, and to determine whether hypertension has caused damage to the heart, eyes, and kidneys. Additional tests for diabetes and high cholesterol levels are usually performed because these conditions are additional risk factors for the development of heart disease and may require treatment.[3]

Serum [10]

Adults

Classification (JNC7)[61] Systolic pressure Diastolic pressure
mmHg kPa mmHg kPa
Normal 90–119 12–15.9 60–79 8.0–10.5
High normal[62] or prehypertension 120–139 16.0–18.5 80–89 10.7–11.9
Stage 1 hypertension 140–159 18.7–21.2 90–99 12.0–13.2
Stage 2 hypertension ≥160 ≥21.3 ≥100 ≥13.3
Isolated systolic
hypertension
≥140 ≥18.7 <90 <12.0

In people aged 18 years or older hypertension is defined as a systolic and/or a diastolic blood pressure measurement consistently higher than an accepted normal value (currently 139 mmHg systolic, 89 mmHg diastolic: see table —Classification (JNC7)). Lower thresholds are used (135 mmHg systolic or 85 mmHg diastolic) if measurements are derived from 24-hour ambulatory or home monitoring.[61]

Children

Hypertension in [17]

Hypertension defined as elevated blood pressure over several visits affects 1% to 5% of children and adolescents and is associated with long term risks of ill-health.[65]

The value of routine screening for hypertension in children over the age of 3 years is debated.[70]

Prevention

Much of the disease burden of high blood pressure is experienced by people who are not labelled as hypertensive.[71] for the primary prevention of hypertension:

  • maintain normal body weight for adults (e.g. body mass index 20–25 kg/m2)
  • reduce dietary sodium intake to <100 mmol/ day (<6 g of sodium chloride or <2.4 g of sodium per day)
  • engage in regular aerobic physical activity such as brisk walking (≥30 min per day, most days of the week)
  • limit alcohol consumption to no more than 3 units/day in men and no more than 2 units/day in women
  • consume a diet rich in fruit and vegetables (e.g. at least five portions per day);

Effective lifestyle modification may lower blood pressure as much as an individual antihypertensive drug. Combinations of two or more lifestyle modifications can achieve even better results.[64]

Management

Lifestyle modifications

The first line of treatment for hypertension is identical to the recommended preventive lifestyle changes[62] If hypertension is high enough to justify immediate use of medications, lifestyle changes are still recommended in conjunction with medication.

Dietary change, such as a [78]

Some programs aimed to reduce psychological stress such as [81]

Several exercise regimes—including isometric resistance exercise, aerobic exercise, resistance exercise, and device-guided breathing—may be useful in reducing blood pressure.[80]

Medications

Several classes of medications, collectively referred to as [62]

If treatment with medication is initiated the Joint National Committee on High Blood Pressure (JNC-7)[89]

The best first line medication is disputed.[94]

Medication combinations

The majority of people require more than one medication to control their hypertension. In those with a systolic blood pressure greater than 160 mmHg or a diastolic blood pressure greater than 100 mmHg the American Heart Association recommends starting both a thiazide and an ACEI, ARB or CCB.[74]

Unacceptable combinations are non-dihydropyridine calcium blockers (such as verapamil or diltiazem) and beta-blockers, dual renin–angiotensin system blockade (e.g. angiotensin converting enzyme inhibitor + angiotensin receptor blocker), renin–angiotensin system blockers and beta-blockers, beta-blockers and centrally acting medications.[96]

Elderly

Treating moderate to severe hypertension decreases death rates and cardiovascular [92]

There are no randomized clinical trials addressing the goal blood pressure of hypertensives over 79 years old. A recent review concluded that antihypertensive treatment reduced cardiovascular deaths and disease, but did not significantly reduce total death rates.[101]

Resistant hypertension

Resistant hypertension is defined as hypertension that remains above goal blood pressure in spite of using, at once, three antihypertensive medications belonging to different drug classes. Guidelines for treating resistant hypertension have been published in the UK[105]

Epidemiology

[106]

  no data
  <110
  110-220
  220-330
  330-440
  440-550
  550-660
  660-770
  770-880
  880-990
  990-1100
  1100-1600
  >1600

As of 2000, nearly one billion people or ~26% of the adult population of the world had hypertension.[62]

In 1995 it was estimated that 43 million people in the United States had hypertension or were taking antihypertensive medication, almost 24% of the adult United States population.[3]

Children

Rates of high blood pressure in children and adolescents have increased in the last 20 years in the United States.[115]

Prognosis

Diagram illustrating the main complications of persistent high blood pressure

Hypertension is the most important [61]

History

Image of veins from Harvey’s Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus

Modern understanding of the cardiovascular system began with the work of physician [120]

Historically the treatment for what was called the “hard pulse disease” consisted in reducing the quantity of blood by renin inhibitors were developed as antihypertensive agents.

Society and culture

Awareness

Graph showing, prevalence of awareness, treatment and control of hypertension compared between the four studies of NHANES[110]

[128]

Economics

High blood pressure is the most common chronic medical problem prompting visits to primary health care providers in USA. The American Heart Association estimated the direct and indirect costs of high blood pressure in 2010 as $76.6 billion.[131]

Live heart strong

Research

Selective [134] but supported continuing research activity in this field.

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Further reading

  • James, Paul A.; Oparil, Suzanne; Carter, Barry L.; Cushman, William C.; Dennison-Himmelfarb, Cheryl; Handler, Joel; Lackland, Daniel T.; Lefevre, Michael L.; MacKenzie, Thomas D.; Ogedegbe, Olugbenga; Smith, Sidney C.; Svetkey, Laura P.; Taler, Sandra J.; Townsend, Raymond R.; Wright, Jackson T.; Narva, Andrew S.; Ortiz, Eduardo (18 December 2013). “2014 Evidence-Based Guideline for the Management of High Blood Pressure in Adults”. JAMA 311 (5): 507–20. doi:10.1001/jama.2013.284427. PMID 24352797. 

External links

This article uses material from the Wikipedia article Hypertension, which is released under the Creative Commons Attribution-Share-Alike License 3.0.

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