Alternative names: High blood pressure
Hypertension is a very common condition in which the force of blood on the walls of the arteries is too high, resulting in a dramatically increased risk of developing serious conditions such as heart attack, stroke, or kidney damage. Because of its potential seriousness, doctors and hospitals regularly check blood pressure even when the patient's problem appears unrelated.
Blood pressure is measured with a blood pressure cuff (sphygmomanometer) and recorded as two numbers that represent systolic (peak pressure, when the heart beats, shown first or top) and diastolic (base pressure, when the heart relaxes, shown second or bottom). Either or both numbers can be elevated. When the first number is the only one elevated the condition is called Isolated Systolic Hypertension (ISH); when the lower number is elevated it is called Diastolic Hypertension.
Optimal blood pressure is below 120⁄80mm Hg. When a person has readings that are regularly above 140⁄90, she/he is considered to have high blood pressure. In the past, many physicians relied on diastolic blood pressure to diagnose hypertension. Recent research, however, has found that diastolic blood pressure rises until about age 55 and then declines, while systolic blood pressure increases steadily with age.
Systolic hypertension (ISH) is a major threat to health, especially for older people. Many older Americans suffer from ISH, defined as a systolic reading at or above 140mm Hg and diastolic reading under 90mm Hg. In fact, for older Americans, ISH is the most common form of high blood pressure: 65% of all hypertensives older than age 60 have ISH. Unfortunately, many older Americans do not have their blood pressure under control.
For many years we were taught that diastolic blood pressure counts more. That may be true for younger people but we now know that, as people get older, systolic blood pressure becomes more important. If you are middle aged or older, systolic blood pressure is a better blood pressure indicator than diastolic of your risk of heart disease and stroke, which are the first- and third-leading causes of death among Americans. High blood pressures can lead to other conditions, such as congestive heart failure, kidney damage, dementia and blindness. While it cannot be cured, systolic hypertension can be treated and its complications prevented.
Diastolic Hypertension occurs when the lower number is sustained at levels greater than 90mm Hg.
Primary (essential) hypertension
In many cases, hypertension occurs without any symptoms whatsoever, and has no known cause. These patients are classified as having "essential" hypertension. While heredity is a predisposing factor, the exact mechanism is unclear. Environmental factors (e.g. dietary sodium, obesity, stress) seem to act only in genetically susceptible persons.
Only about 5% of people have a cause for their elevated blood pressure (such as pre-existing kidney disease) that can be reversed and this places them in the category of "secondary" hypertension. This condition is associated with kidney disease (e.g. chronic glomerulonephritis or pyelonephritis, polycystic renal disease, collagen disease of the kidney, obstructive uropathy) or pheochromocytoma, Cushing's syndrome, primary aldosteronism, hyperthyroidism, myxedema, coarctation of the aorta, or renovascular disease. It may also be associated with the use of excessive alcohol, oral contraceptives, sympathomimetics, corticosteroids, cocaine, or licorice root.
Although current guidelines for the management of high blood pressure (BP) rest almost completely on the measurement of systolic (top) and diastolic (bottom) blood pressure, a new study has found that something known as the "pulse pressure" may actually be a better predictor of heart disease risk. The pulse pressure is the difference between the systolic and diastolic pressures. For example someone with a blood pressure of 120⁄80 has a pulse pressure of 40.
This study was a meta-analysis combining the results of several studies, including nearly 8,000 elderly patients. A 10mm Hg increase in pulse pressure was found to increase the risk of major cardiovascular complications and mortality by nearly 20%. The authors contend that this association of pulse pressure to risk of heart disease helps to explain the apparent elevations in risk associated with low diastolic pressure. The authors of the study note that some high blood pressure medications may actually increase the pulse pressure. For example, if someone has an elevated BP of 150⁄95 (pulse pressure = 55) and medication brings it down to 140⁄80 (pulse pressure = 60), then according to this study's findings, this person may actually be at GREATER risk of heart disease than before.
With each heartbeat, two chambers (ventricles) contract in order to push blood to the lungs and through the arteries. As blood flows through the arteries, three main factors affect the pressure on their walls:
Resistance: Anything that is working against the blood flowing through your arteries.
Over time, high blood pressure will damage the walls of the arteries: the walls may become weak and form an enlargement called an aneurysm, or the wall may burst and bleed into the surrounding tissue. In addition, small tears in the artery walls may attract cholesterol, fat and calcium from the blood to form a build-up called a plaque. As a plaque enlarges, blood flow through the artery decreases; if a plaque ruptures, a clot may form at the site of the rupture and further reduce – or even stop – blood flow.
This then creates a vicious cycle: Damage to arteries raises blood pressure even more as the heart beats more forcefully to push blood through damaged arteries, causing more damage.
Primary hypertension is usually without symptoms until complications develop in target organs (e.g. left sided heart failure, atherosclerotic heart disease, cerebrovascular insufficiency with or without stroke, renal failure). Dizziness, flushed face, headache, fatigue, epistaxis (nasal bleeding), and nervousness are not caused by uncomplicated hypertension.
To find out if you have ISH – or any type of high blood pressure – see your doctor and have your blood pressure checked regularly. Everyone – including children – should have their blood pressure measured every time they see a doctor. Special attention should be paid when there is a family history of hypertension requiring at least annual measurements beginning at age 20.
Recent work possibly explains the cause of 30-40% of essential hypertension. Parathyroid Hypertensive Factor (PHF) is a hormone produced by the parathyroid gland. When elevated, it can cause any increase in blood pressure. PHF levels can be tested, and elevated levels could serve to predict salt sensitivity, and calcium treatment responsiveness. Meridian Valley Laboratory in Seattle, Washington is one lab that does this test.
At least two BP determinations should be taken on each of 3 days before a patient is diagnosed as hypertensive. More BP determinations are desirable for patients in the low hypertension range and especially for patients with fluctuating BP. Normal BP is much lower for infants and children. Sporadic higher levels in patients who have been resting for greater than 5 minutes suggest an unusual lability of BP that may precede sustained hypertension. For example, office or white coat hypertension refers to BP that is consistently elevated in the physician's office but normal when measured at home or by ambulatory BP monitoring.
Primary hypertension has no cure, but treatment can modify its course. It is estimated that only 24% of hypertensive patients in the USA have their BP controlled to less than 140⁄90mm Hg, and 30% are unaware that they have hypertension.
No one need put his or her health at risk from uncontrolled hypertension, but treatment for hypertension must begin early to prevent organ damage – whatever the patient's age. Treatment options for ISH are the same as for other types of high blood pressure, in which both systolic and diastolic pressures are high. Except in patients over 65 years of age, the goal of therapy should be to reduce blood pressure to less than 135⁄80mm Hg or as near to this level as tolerable. Measuring BP at home is generally a good idea with adequate training and equipment.
You should try to achieve normal pressure through lifestyle and diet changes such as extra rest, moderate weight reduction, reduced salt (NaCl) intake, dietary potassium (K) supplementation, exercising and selected nutrient supplementation as a first attempt in an effort to avoid medications. Meditation and other therapies (e.g. biofeedback) have also been found to be effective.
Dietary restrictions can help control diabetes mellitus, obesity, and blood lipid abnormalities. In cases of low grade hypertension, weight reduction to ideal levels, modest dietary sodium restriction to less than 2gm per day, and alcohol consumption to less than 1oz per day may make drug therapy unnecessary. An exercise habit should be started, and smoking stopped.
Lifestyle modifications alone are sometimes not as effective as conventional antihypertensive drug therapy. Patients with uncomplicated hypertension need not restrict their activities as long as their BP is controlled.
There are no early pathologic changes that occur in primary hypertension. Ultimately, hardening of the arteries develops, where it is particularly apparent in the kidney (nephrosclerosis). Left sided heart muscle enlargement and, eventually, dilation develop gradually. Coronary, cerebral, aortic, renal, and peripheral atherosclerosis are more common and more severe in hypertensives because hypertension accelerates the thickening of artery walls. Hypertension is a more important risk factor for stroke than for atherosclerotic heart disease.
An untreated or poorly-treated hypertensive patient is at great risk of disabling or fatal left-sided heart failure, heart attack, stroke (cerebral hemorrhage or infarction), severe circulatory problems, or kidney failure at an early age.
Hypertension is the most important risk factor for stroke and one of three risk factors (along with cigarette smoking and hypercholesterolemia) predisposing to coronary atherosclerosis. The higher the BP and the more severe the changes in the retina, the worse the prognosis. Effective medical control of hypertension will prevent or forestall most complications and will prolong life in patients with ISH or diastolic hypertension.
Peaks of fluctuating hypertension can be as strong a risk factor for cardiovascular disease as established (sustained) hypertension. Coronary artery disease is the most common cause of death among treated hypertensive patients. Systolic BP is a more important predictor of fatal and nonfatal cardiovascular events than diastolic BP. In a follow-up of men screened for the Multiple Risk Factor Intervention Trial, overall mortality was related to systolic BP, regardless of diastolic BP.
Some patients may notice a "swishing" noise in either ear with each heartbeat. This sound may occur as blood flows past a blockage in a carotid artery.
It is a common misconception that nosebleeds are often caused by high blood pressure. Though a high intracapillary pressure may slightly increase risk, it is not a significant cause.
High blood pressure can affect the vessels in the eyes; some blood vessels can narrow and thicken / harden (arteriosclerosis). There will be flame-shaped hemorrhages and macular swelling (edema). This edema may cause distorted or decreased vision and is a condition known as hypertensive retinopathy.
High blood pressure (usually extremely high) can cause damage to the brain, with associated dizziness.
Heredity is a predisposing factor, but the exact mechanism is unclear. Environmental factors such as dietary sodium, obesity and stress seem to act only in genetically susceptible persons.
One study found that high dose fish oil can produce a small but significant reduction in blood pressure in men with essential hypertension. [NEJM, April 20, 1989;320: pp.1037-1043.]
An Alabama researcher found that lack of enough sunshine exposure may increase risk of hypertension in blacks and other dark-skinned people. Those with greater amounts of pigment in the skin require six times the amount of ultraviolet B (UVB) light to produce the same amount of vitamin D3 found in lighter-skinned people.
As IgAN progresses, it is common for patients to develop high blood pressure. It is very important to treat hypertension by whatever means are necessary, because hypertension itself greatly increases the risk of progressing to end-stage renal disease.
Hypertension occurs more often in black adults (32%) than in white (23%) or Mexican American (23%) adults, and morbidity and mortality are greater amongst blacks.
Hypertension is prevalent in patients with OSA, and it has been shown that treating OSA can modestly lower blood pressure.
OSA and other forms of Sleep-Disordered Breathing can cause temporary elevations in blood pressure as well as lowered blood-oxygen levels; it may also cause elevated blood pressure during daytime and, eventually, sustained high blood pressure.
Statistics now show that the wide use of the Pill has given rise to health hazards such as breast cancer, high blood pressure and cardiovascular disease on a scale previously unknown in medicine.
University of Michigan researchers in Beijing, China found during a two-year study that extreme air pollution adversely affects blood pressure (hypertension) and insulin resistance.
Caffeine raises the production of the adrenal hormone cortisol, a stress hormone. Cortisol causes the blood vessels to constrict and the heart to pump harder, which leads to high blood pressure. Studies have shown that coffee seems to worsen the symptoms of persons with high blood pressure, and can nullify the effect of high blood pressure medications, making expensive drugs useless.
A study of 9,600 Americans found that those who ate plenty of legumes had lower blood pressure and were less likely to be diagnosed with high blood pressure. [Archives of Internal Medicine 2001;161: pp.2573-8].
Malignant hypertension and renovascular hypertension are more common in people who smoke. Approximately 15% of hypertension is attributable to smoking. Smoking interferes with the metabolism of multiple anti-hypertensive medications, neutralizing their effectiveness.
Researchers estimate that 26% of Americans with normal blood pressure and about 58% of those with high blood pressure may be salt sensitive. [Feb. 16, 2001 supplemental issue of Hypertension]
Those with high blood pressure should have a yearly eye examination.
High blood pressure is the main risk factor for having a stroke and those with hypertension are 8 times more likely to suffer from stroke than those with normal blood pressure. Long-term high blood pressure narrows and weakens blood vessels, including those in the brain, making it easier for them to rupture or become blocked.
Hypertrophic cardiomyopathy is usually a hereditary disorder, although incidence of this form of cardiomyopathy may also be higher in people with hypertension. [Hypertension 1994;24(5): pp.585-90]
In a study of 32 patients whose diets were changed to include 62% of calories from raw foods, their mean diastolic pressure reduction was 17mm Hg. This study was conducted over a period of 6 months. Of these patients, 28 were also overweight. [South Med J 1985 Jul;78(7): pp.841-4]
A study of 9,600 Americans found that those who ate plenty of legumes had lower blood pressure and were less likely to be diagnosed with high blood pressure. [Archives of Internal Medicine 2001;161: pp.2573-8].
Fruit and vegetable consumption (a minimum of five portions daily) was associated with modest reductions of systolic and diastolic blood pressures in a controlled study of 690 healthy people ages 25-64. [Lancet May 28, 2002]
If you have high blood pressure, reducing the level of salt in your diet will reduce your blood pressure. In some people with mild high blood pressure this could free them from blood-pressure-lowering medications entirely. In people with marked high blood pressure, it should mean that a reduction in medications is possible. If you are taking medication for high blood pressure, particularly diuretics, let your doctor know that you are reducing your salt intake.
Salt restriction is recommended for those individuals with hypertension who are "salt-sensitive" or are prone to retaining sodium, gaining weight, and developing a rise in blood pressure as a result of a high-salt diet. Those who are "salt-resistant", on the other hand, do not experience change in weight or blood pressure on either high- or low-salt diets. For the salt-sensitive population, extreme amounts of salt restriction are not needed for improvement of blood pressure. Several studies have shown that diets containing 1600 to 2300mg of sodium per day are associated with average reductions in systolic pressure of -9 to -15mm Hg and in diastolic pressure of -7 to -16mm Hg in salt-sensitive individuals. Thus, salt restriction in this range is recommended in the dietary management of most individuals with hypertension.
Fasting is a way to correct high blood pressure without drugs. Fasting will normalize blood pressure in the vast majority of cases; the blood pressure will remain low after the fast if a person follows a health-supporting diet and lifestyle.
Study after study has shown that the more plant-based a person's diet, the lower their risk of having high blood pressure. The Adventist 2 Study – a major study of 89,000 Californians – found that those who ate meat only once a week had a 23% lower rate of high blood pressure; those who excluded all meat except fish from their diets had a 38% lower rate; vegetarians a more than 50% lower rate, and vegans a 75% lower rate.
It has long been known that the prevalence of hypertension among vegetarians is about one-third to one-half that of non-vegetarians [1-3]. A study of Caucasian Seventh-day Adventists found hypertension in 22% of omnivores, but only 7% of vegetarians. Among African Americans, the prevalence was 44% of omnivores and 18% of vegetarians . Adopting a vegetarian diet significantly lowers blood pressure in both normal and hypertensive individuals [4-8].
Caffeine raises the production of the adrenal hormone cortisol, which causes the blood vessels to constrict and the heart to pump harder, which leads to high blood pressure. Studies have shown that coffee seems to worsen the symptoms of persons with high blood pressure, and can nullify the effect of high blood pressure medications, making expensive drugs useless.
An increased risk of developing hypertension was associated with drinking five or more cups of coffee per day in a large study of white, male, former medical students followed for an average of 33 years. [Arch Intern Med 2002;162(6): pp.657-62]
The relationship between dietary fats and blood pressure has not been definitively answered. However, evidence suggests that the multiple components of the "Mediterranean diet", i.e. low saturated fatty acids (SFAs), high monounsaturated fatty acids (MUFAs), and carbohydrate, fiber, and micronutrient content have favorable blood pressure effects, and therefore that this diet is desirable for health. Dietary MUFAs may have a greater protective effect than initially realized.
While bromelain is considered to have very low toxicity, caution is advised when treating individuals with hypertension. One report has indicated that those with pre-existing hypertension might experience tachycardia following high doses of bromelain. [Hawaii Med J 1978;37: pp.143-6]
In January, 2014 the Journal of Investigative Dermatology reported that just 20-30 minutes of exposure to sunlight lowers blood pressure by about 5 points for half an hour. The researchers, from University of Edinburgh and the University of Southampton, suggested that sunlight increases levels of nitric oxide, a chemical linked to blood flow.
Magnesium has a mild effect on lowering blood pressure and so is used to treat and prevent hypertension and its effects. In a double-blind, placebo-controlled trial, it was demonstrated that oral magnesium resulted in a significant dose-dependent reduction of systolic and diastolic blood pressure. A mean reduction of 6mm Hg in diastolic pressure in patients with hypertension results in approximately 10% lower risk of coronary artery disease, and a 40% reduction in risk of strokes.
The relaxation and exercise components of yoga have a major role to play in the treatment and prevention of high blood pressure. A combination of biofeedback and yogic breathing and relaxation techniques has been found to lower blood pressure and reduce the need for high blood pressure medication.
Out of 20 patients with high blood pressure who practiced biofeedback and yoga techniques, 5 were able to stop their blood pressure medication completely, 5 were able to reduce significantly the amount of medication they were taking, and another 4 experienced lower blood pressure at the end of a 3 month study.
Researchers at the University of Miami School of Medicine found that massage is helpful in decreasing blood pressure in those with hypertension.
Regular and substantial consumption of green tea may provide protective effect against hypertension.
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