|
|
|
Introduction
High blood pressure is frequently referred to as the"silent killer". Although elevated blood pressure causes no symptoms in most people it directly kills 35,000 to 40,000 Americans a year and is a major factor in the 400,000 plus deaths each year from heart attacks, congestive heart failure, and stroke. An estimated 50 million Americans (25% of all adults) have high blood pressure. Two-thirds of the population will experience at least mild high blood pressure before the age of 65. Although the majority have mild hypertension, even this condition requires medical attention. Only 20% of American adults have their blood pressure under control. About one-third of patients with high blood pressure are overweight. Anyone who is overweight has a risk for hypertension that is 50% higher than people with normal weight. Proper detection and treatment of high blood pressure can improve quality of health and delay or prevent many premature deaths in people having hypertension. Blood pressure is produced by the pumping heart. Most people are familiar with two separate numbers used in measuring blood pressure. In laymen's terms these numbers are referred to as the"top" and "bottom" numbers. Medically speaking blood pressure has a systolic (top number ) measurement and a diastolic (bottom number) measurement. Systolic pressure is the blood pressure created while the heart is contracting (systole). Diastolic pressure is the blood pressure measured when the heart is not contracting (diastole). Blood pressure measurements reflect the pressure within the artery being measured. Pressure may be different in different arteries of the body. The artery traditionally used for blood pressure measurement is the brachial artery in the arm. Blood pressure does not fall to zero in the arteries when the heart is not contracting due to several factors. The main reason is due to elastic stretch of the arteries. During systole arteries expand slightly (much like a balloon inflates as you blow into it). As the arteries relax (slightly deflate) they continue to propel blood forward just as a deflating balloon releases air in a continuous manner. During diastole the aortic valve closes preventing the flow of blood back into the heart. The heart beats again to repeat this cycle. Steady delivery of blood to body organs is extremely important. Optimal
blood pressure is less than 120/80 mm Hg (systolic/diastolic).
Normal pressure is below 140/90. A person is considered to
have hypertension (high blood pressure) if their blood pressure
is above 140/90. Any blood pressure above normal should be
attended to with appropriate treatments.
Hypertension
is divided into four stages: mild (greater than 140/90 but
less than 160/100); moderate (less than 180/110); severe (less
than 210/120); very severe (greater than 210/120). When the
systolic and diastolic numbers are in different categories
the measurement in the higher category should be used to determine
the severity of hypertension. For example, if systolic pressure
is 165 (moderate) and diastolic is 92 (mild), the patient
would still be diagnosed with moderate hypertension.
A child's blood pressure is normally much lower than an adult's. Children are at risk for hypertension if blood pressure is greater than:
High blood pressure is a very important risk factor for heart disease (coronary artery disease). There are other major risk factors as well including family history, smoking, diabetes, and high cholesterol. The effects of these risk factors are additive. A person with all of these risk factors, including high blood pressure, is more likely to develop heart disease than another person with the same blood pressure but no other risk factors. The important point to remember is high blood pressure is not the only risk factor for heart disease and stroke. How a person's blood pressure is treated may depend on other factors in addition to the blood pressure number. The National Heart Blood and Lung institute has recognized the influence of other risk factors in addition to high blood pressure. High blood pressure is now categorized by risk groups A, B, and C. For example, group A has no risk factors for heart disease or other medical problems; people in this risk group who have mild hypertension would use diet and exercise to try to reduce their blood pressure. Mild hypertension in group C, which covers major risk factors for heart disease, however, would probably require medication. Blood pressure varies the same way throughout a given day. It is usually highest at work and then drops a bit at home. Pressure is lowest during sleep but suddenly increases at waking. What
Causes High Blood Pressure?
In over 90% of patients with high blood pressure the physician cannot find a specific cause. This is called essential, or primary, hypertension. Several genetic factors regulating important physiologic processes may interact with environmental influences to produce essential high blood pressure. Current studies are examining genes that affect a group of hormones known as the angiotensin-renin system, which influences all aspects of blood pressure control, including blood vessel contraction, salt and water balance. Studies suggest that some people with essential hypertension may inherit abnormalities of the sympathetic nervous system, which controls heart rate, blood pressure, and the diameter of the blood vessels. Increased insulin resistance and low levels of a naturally occurring vasodilator (nitric oxide) are also suspected of playing a role in hypertension.
Secondary HypertensionSecondary
hypertension (less than 10% of people with high blood pressure)
has identifiable causes, which are usually treatable or reversible.
Medical conditions and medications may contribute to secondary
hypertension. Medical conditions include:
Certain prescription and over-the-counter drugs can cause temporary high blood pressure. Medications contributing to secondary hypertension include:
SaltDiets high in salt may speed up hypertension in people as they age. There have been conflicting view in the medical community on how much a high salt diet contributes to hypertension. Between 30 - 50% of people with high blood pressure are salt-sensitive; that is they are particularly vulnerable to the effects of salt on blood pressure. People who are most likely to be very salt-sensitive are overweight, older, and African American. High salt diets in such people can also harm the kidney and brain, even independently of high blood pressure. Alcohol An estimated 10% of hypertension cases are caused by excessive alcoholic intake. An analysis of a major study found that those who drank more than three alcoholic drinks a day had higher blood pressure than those who didn't, with heavier drinkers having higher pressure. People who were binge-drinkers had higher blood pressure than people who drank regularly. On the other hand, mild to moderate drinking (one to two drinks a day) seems to have certain benefits, including raising HDL cholesterol levels (high levels of HDL cholesterol are considered good, whereas high levels of LDL cholesterol are considered bad) and reduced risk of heart disease. Other Causes of Secondary High Blood Pressure Temporary high blood pressure can result from stress, exercise, and long-term consumption of large amounts of licorice. Exposure to even low lead levels also appears to cause hypertension in adults.
Risk Factors-Who Gets High Blood Pressure? Age and WeightAn
estimated 50 million Americans (25% of all adults) have high
blood pressure. Two-thirds of Americans will experience at
least mild high blood pressure before the age of 65. Although
the majority have mild hypertension, even this condition requires
medical attention. Only 20% of American adults have their
blood pressure under control. About one-third of patients
with high blood pressure are overweight. Anyone who is overweight
has a risk for hypertension that is 50% more than people with
normal weight. In fact, the increase in blood pressure as
one ages may be due primarily to weight gain. (This is true
particularly in America; in other cultures old age does not
necessarily coincide with weight gain--or high blood pressure.)
Children and adolescents who are obese and babies who are
underweight at birth are at greater risk for high blood pressure
when they reach adulthood.
Gender and EthnicityWomen
under 60 are 50% to 75% less likely to have hypertension than
men of the same age. Between ages 50 and 60, 40% of white
men and 30% of white women have high blood pressure. In African
Americans of the same age groups over half of men and slightly
less than half of women have hypertension. After age 60, half
of white men and women have high blood pressure, but the rate
in African Americans is 60% in men and leaps to 80% in women.
Both whites and African Americans in the Southeast have a
higher incidence of hypertension and stroke than people living
in other parts of the country. African Americans tend to have
a greater sensitivity to salt than others, although researchers
have not found that this trait fully explains the higher incidence
for hypertension. The combination of high blood pressure and
insulin resistance (type II diabetes)is more common in African
Americans, Hispanics, and Pima Indians than in whites. It
should be noted that a recent study of African villagers whose
diets were high in fish had only a 3% rate of high blood pressure.
Genetic FactorsSome
experts believe that essential hypertension may be inherited
in 30% to 60% of cases, although several genes, not just one,
are probably involved. It is difficult to differentiate between
genetic and environmental influences, even in studies of identical
twins.
Cholesterol and StressAbout
40% of people with high blood pressure also have high cholesterol
levels, although any causal relationship remains unclear.
Stress may play a role in this association; in one study people
with high cholesterol levels experienced a steep increase
in high blood pressure when given a mental stress test; those
with normal cholesterol levels had only a modest increase.
When the high-risk group lowered their cholesterol intake,
their blood pressure dropped to normal levels during stressful
situations. This finding should encourage physicians to test
for heart disease risks, particularly unhealthy cholesterol
levels, in people with so-called white-coat hypertension--a
phenomenon that causes high blood pressure in the physician's
office despite normal blood pressure at home.
Emotional DisordersA
number of studies have linked chronic stress, depression,
and anxiety with high blood pressure in both men and women.
People who are anxious or depressed may have over twice the
risk for high blood pressure than those without these problems.
It is not clear whether these mood disorders contribute to
high blood pressure due to some physiologic effect on blood
vessels or if they may lead to behaviors, such as weight gain
or alcohol abuse, which are also risk factors for hypertension.
Stress caused by discrimination may play a role in the high
rate of hypertension in African Americans; in one study, those
who experienced discrimination but did not report it suffered
higher blood pressure than those who challenged it. Anger
does not appear to predict high blood pressure.
Other FactorsPeople
who experience sleep apnea, a disorder in which breathing
halts briefly but repeatedly during sleep, also have a higher
incidence for hypertension. Many experts believe that a causal
relationship exists between the sleep disorder and high blood
pressure. Seasonal changes may influence variations in blood
pressure, with hypertension increasing during cold months
and declining during the summer. This seasonal effect is particularly
high in smokers. While cold may narrow blood vessels, another
study showed that lack of light was associated with higher
blood pressure. A recent study reported that people with normal
resting blood pressure that increases to abnormally high levels
during treadmill exercises may be at risk for essential hypertension.
Oral contraceptives, even low doses, may increase the risk
for high blood pressure in African American women.
How Serious Is High Blood Pressure? High
blood pressure killed over 35,000 Americans in 1992 and was
a major contributor to deaths from stroke, heart attack, and
heart failure. The death rate from hypertension declined by
8.6% between 1982 and 1992. However, it is still particularly
deadly in African Americans; an estimated 30% of deaths in
men and 20% of deaths per year in women who are African Americans
are attributed to hypertension.
Damage to Other OrgansHypertension
can cause certain organs to deteriorate over time. People
who do not control their blood pressure die earlier than people
who control their blood pressure. High blood pressure contributes
to 75% of all strokes and heart attacks. Compared with normal
individuals, hypertensive people can have as high as ten times
the risk of stroke and five times the risk of a heart attack
depending on the severity of the hypertension. The risk for
developing congestive heart failure is also significantly
higher with high blood pressure. People whose high blood pressure
has caused left ventricular hypertrophy (a thickening of the
muscles on the left side of the heart causing enlargement)
remain at risk for strokes, heart attacks, sudden death, and
heart failure even after their blood pressure is under medical
control. High blood pressure causes 30% of all cases of kidney
failure that require dialysis and transplant operations. This
rate is second only to diabetes. African Americans with high
blood pressure are at even higher risk for kidney failure
than people in other population groups with hypertension.
Sexual DysfunctionSome
form of sexual dysfunction occurs in 17% of hypertensive men.
It is often caused by medications that treat high blood pressure,
but there are indications that the disorder itself may impair
sexual function. Impotence related to hypertension is treatable.
A study found that women with high blood pressure, regardless
of medications, found it difficult to achieve sexual satisfaction
and had impaired vaginal lubrication.
Mental DeteriorationHigh
blood pressure may accelerate age-related shrinkage of the
brain. Chronic high blood pressure is associated with mental
deterioration, especially short-term memory and attention.
A study has found that middle-age people with high systolic
blood pressure are at higher risk for poor mental function
in later life; the higher the blood pressure the greater the
risk. Increased blood pressure in elderly men is also associated
with a higher risk for Alzheimer's and dementia.
Pregnancy and PreeclampsiaSevere,
sudden high blood pressure in pregnant women caused by a condition
called preeclampsia can be very serious for both mother and
child. It occurs in up to 10% of all pregnancies, usually
in the third trimester (last three months) of a first pregnancy,
and resolves after delivery. Symptoms and signs of preeclampsia
include protein in the urine and swollen ankles. The reduced
supply of blood to the placenta can cause low birth weight
and eye or brain damage in the fetus. Severe cases of preeclampsia
can cause kidney damage, convulsion and coma in the mother
and can be lethal to both mother and child.
Hypertension
has been called the "silent killer", because it usually produces
no symptoms. It is important for anyone with risk factors
to have their blood pressure checked regularly and to make
appropriate lifestyle changes. Following these recommendations
is important for individuals who have overall high-normal
blood pressure, mild or above systolic pressure with normal
diastolic, family histories of hypertension, are overweight,
or are over forty years old.
Untreated hypertension increases slowly over the years. In
rare cases (fewer than one percent of hypertensive patients),
the blood pressure rises quickly (with diastolic pressure
usually rising to 130 or higher), resulting in malignant or
accelerated hypertension. This is a lifethreatening condition
and must be treated immediately.
Symptoms
may include:
Hypertensive individuals should call a physician immediately if these symptoms appear. How is High Blood Pressure Diagnosed? Medical HistoryIf hypertension is suspected, the physician should obtain the following information:
Physical ExaminationAlmost
all physical exams include blood pressure measurement. An inflatable
cuff is placed around the arm, and the person taking the blood
pressure listens with a stethoscope over the artery. If high
blood pressure is present or suspected, the physician or health
professional should take two or more measurements separated
by two minutes with the patient sitting or lying down, as well
as one taken after the patient has been standing for two minutes.
Patients should not smoke or drink caffeinated beverages within
30 minutes of the measurement.
Although this test has been used for nearly 100 years, inaccurate results can occur in certain situations. A person who has recently exercised or a heavy smoker who has not smoked for awhile can have a temporarily low pressure reading. Temporary high pressure can result from an arm cuff that is too small, talking during the test, or from having recently eaten foods that raise blood pressure. Anxiety can cause a person's blood pressure to be elevated in the doctor's office while it is normal at home. This is known as "White Coat Hypertension". Home monitoring is important to avoid unnecessary treatment in patients whose pressure returns to normal after leaving the doctor's office. Some people initially suspected of only having "White Coat Hypertension" develop true hypertension. Persons with very severe high blood pressure or those exhibiting any evidence of organ damage due to hypertension should consider drug therapy immediately. An individual with mild to moderate hypertension found during a first examination and who has no evident organ damage should be retested at least twice over several weeks. An average of all the measurements will be considered in the diagnosis of hypertension. People with normal blood pressure should be rechecked every two years and those with high normal pressure one year after. Anyone whose blood pressure is above high normal should be evaluated as soon as possible for organ damage and possible medications to reduce the pressure. Laboratory TestsIf
a physical examination indicates hypertension, additional laboratory
tests may determine whether it is secondary hypertension (high
blood pressure caused by another disorder) or essential hypertension
(no other disorder is present). The physician might also order
tests to uncover organ damage due to hypertension. These tests
include a complete blood count, urinalysis, and measurements
of potassium, blood urea nitrogen, fasting blood glucose, serum
cholesterol, and serum uric acid. An electrocardiogram (ECG)
may also be performed.
Home TestsMany home tests are available for checking blood pressure between doctor visits. Manual cuffs and stethoscopes are fairly accurate, but they require practice to use, and the cuff must be the right size (one size does not fit all). Devices that use a digital readout and a cuff that can be electronically inflated and deflated are as accurate as a stethoscope. A physician may fit a patient with a portable unit that records blood pressure during a full day's activity. This test, known as ambulatory monitoring, is particularly useful for those who experience wide blood pressure swings, including white-coat hypertension, or show resistance to drug therapy. Some physicians feel that such monitoring is not worth the expense and that electronic home tests that print out a record for the doctor are more cost effective and very reliable. Devices that take the pressure from the finger can be very inaccurate. Life Style Changes (no medication)
ExerciseEven
moderately intense physical activity can reduce blood pressure.
An additional benefit of exercise is weight loss, which is
a key factor in reducing blood pressure. Studies have shown
that regular activity, particularly aerobic exercises, helps
to reduce mild to moderate hypertension. In one study African-American
men with severe hypertension who engaged in moderately intense
aerobic exercise using a stationary bike three times a week
not only reduced their diastolic pressure but also reduced
left ventricle hypertrophy after about four months. One study
showed that even exercise that does not result in weight loss
or have any aerobic benefits still significantly reduces blood
pressure in postmenopausal women. As little as 35 minutes
of walking three times a week can help lower blood pressure,
but 20 to 30 minutes of daily brisk walking or other aerobic
exercise is more likely to help.
Intensive aerobic exercises, such as running or biking, may lead to so-called athlete's heart, which, like hypertrophy caused by high blood pressure, is muscular enlargement of the heart. Unlike the disease-caused condition, however, this muscular enlargement is not associated with heart problems and regresses when training stops. Isometric workouts, such as snow shoveling or weight lifting, tend to stress the heart and raise blood pressure for a brief period. Such intense isometrics can cause cardiac death, and one major study found that sedentary people who throw themselves into a grueling workout increase the risk of heart attack by 107 times. Two small studies found that people with very mild hypertension who exercised with a hand-grip device for a few weeks achieved lower blood pressure, which increased after the subjects stopped exercising. In all cases, but particularly before strenuous exercise, it is very important to warm up in order to ease the increase in blood pressure. No person with high blood pressure should start an exercise program without consulting a physician. Before exercising, no one with hypertension should drink caffeinated beverages, which increase heart rate, the workload of the heart, and blood pressure during physical activity. Certain antihypertensive medications can interfere with exercise capacity. Diuretics decrease body fluid and may result in fluid imbalances, particularly in hot weather. It is important to boost potassium intake if this type of drug is being taken. Beta blockers inhibit adrenaline and may cause fatigue and loss of endurance during exercise. ACE inhibitors and calcium channel blockers are the best drugs for active individuals. However, patients who must take drugs that interfere somewhat with exercise capability should still adhere to an exercise program and consult a physician on how best to balance medications with exercise.
Stress Reduction and Psychologic TherapyEmotional
factors or psychologic stress are possible precursors to hypertension.
A recent study found that 73% of patients with mild to moderate
hypertension who had cognitive-behavioral therapy were able
to reduce their medication after 6 weeks; after 12 months,
55% required no medication. In another study, a technique
called transcendental meditation (TM), a simple relaxation
method that involves silent repetition of a single sound was
shown to be effective in reducing blood pressure .
What Are the Drug Treatments for High Blood Pressure?
Side Effects of Hypertension Treatment One of the most difficult issues that hypertensive patients face, particularly those with primary hypertension, is that the treatment may make them feel worse than the disease, which is almost always symptomless. Patients face a lifelong prospect of taking drugs with unpleasant side effects, reducing their salt intake, exercising, and watching their diet. Many drugs that treat high blood pressure impair sexual function, for example, although this is immediately reversible once the drug is stopped. Whatever the difficulties, compliance with a drug and lifestyle program is worth the effort and the cost. Other Sources of Information About High Blood Pressure?
Doctors Corner INternet Group, Inc. 1997-2004 Statement |