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High
blood pressure (hypertension) killed 42,565 Americans in 1997 and
contributed to the deaths of about 210,000. Blood pressure
readings indicate the values for two pressures. The higher (systolic)
number represents the pressure while the heart is beating. The lower
(diastolic) number represents the pressure when the heart is resting
between beats. Systolic pressure is always stated first and the
diastolic pressure second.
A
normal reading for adults is a blood pressure of less than 140 over
90 (millimeters of mercury or mm Hg). A blood pressure reading
equal to or greater than 140 (systolic) over 90(diastolic)
is considered elevated or high. High blood pressure, or
hypertension, affects as many as 50 million Americans.
Causes
Approximately 90 - 95% of all hypertension is essential
hypertension, meaning the cause is unknown. Family history
(genetics), obesity, lack of fitness, poor nutrition, and stress may
contribute to essential hypertension. Genetic factors appear to play
a major role in essential hypertension.
Secondary hypertension is due to an underlying disease process.
Kidney disease is
the most common cause of secondary hypertension such as renal
artery stenosis (narrowing of the arteries which supply the kidneys
with blood). Other medical conditions that contribute to secondary
hypertension are sleep apnea, pregnancy, cirrhosis of the liver, and
Cushing's disease.
Risk Factors
Approximately one-third of all patients with high
blood pressure are overweight. Even being moderately obese doubles
the risk of hypertension compared to non-obese individuals.
Ethnicity also plays a role. African Americans are more likely to
have high blood pressure than Caucasians.
Until age 55 men have a greater risk of high blood pressure than
women. After the age of 55 male and female risks are similar and at
age 75 and older, women are at higher risk of developing high blood
pressure.
Recent genetic research supports the importance of family history
(genetics) in hypertension development. The Howard Hughes Medical
Institute’s research teams have recently identified genes involved
in hypertension and many other illnesses. One of the key objectives
of modern cardiovascular research is elucidating the genetic causes
of hypertension. Knowing the genes responsible for this condition is
an important prerequisite for the development of therapies
addressing the root causes of the disease. Recent research indicates
that frequently several genes act together to cause high blood
pressure.
Drugs (including certain
diet drugs, antihistamines, and anti-inflammatories) may cause
secondary hypertension. And one’s state of mind can produce powerful
effects on the body. Stress can be a powerful risk factor for
hypertension.
Symptoms
High
blood pressure usually has no symptoms.
Its called the "silent
killer."
Diagnosis
The diagnosis of
hypertension is made by taking the blood pressure on several
different occasions and determining if it is consistently elevated.
If an initial blood pressure reading is high, waiting and
relaxing 5 minutes between 3 readings will help determine if the
blood pressure is elevated or if it is temporarily elevated i.e. as
a result of stress or anxiety. If a blood pressure reading taken
in the office setting is elevated but taken in a relaxed environment
it is normal, this is called white coat hypertension.
If
hypertension is suspected your doctor will ask for: a detailed
medical history, your personal risk factors of heart disease and
stroke, medications you’re taking, symptoms of secondary
hypertension, such as headache, excessive sweating, muscle cramps or
weakness, heart palpitations, excessive urination, and possible
emotional or environmental factors that could affect your blood
pressure.
An
exercise stress test could be important for those with borderline
hypertension.
Treatment
The latest guidelines from the Joint National
Committee on Detection, Evaluation, and Treatment of High Blood
Pressure (JNC) recommend that patients first try getting blood
pressure under control by losing weight, getting more exercise, and
reducing intake of sodium and alcohol. If, after three to six
months, your condition doesn't improve, the JNC recommends drug
therapy. Diuretics and beta blockers are the first options.
Dozens of antihypertensive drugs are available. They usually fall
into the following categories:
(1)
diuretics, which cause the body to excrete water and salt
(2)
ACE inhibitors, which reduce the production of angiotensin, a
chemical that causes arteries to constrict
(3)
beta-blockers, which block the effects of adrenaline, thus
easing the heart's pumping action and widening blood vessels
(4)
vasodilators, which expand blood vessels
(5) calcium-channel blockers, which help decrease the
contractions of the heart and widen blood vessels
Diuretics act by flushing excess water and sodium from the
body. The increase in urine reduces the amount of fluid in the
bloodstream, and results in less pressure on the artery walls.
Blood pressure then drops and the heart doesn’t have to work as
hard.
Types of diuretics include potassium-sparing diuretics, such as
Aldactone (spironolactone): thiazides, such as Diuril
(chlorothiazide) and Esidrex (hydrochlorothiazide); and loop
diuretics, such as Lasix (furosemide)
Beta blockers reduce the heart rate and the heart's output of blood.
Beta blockers include Lopressor (metoprolol), Inderal
(propranolol), and Tenormin (atenolol).
Vasodilators cause blood vessel wall muscles to relax, resulting in
the vessel dilating or widening.
(ACE) inhibitors reduce the body's production of angiotensin, a
chemical that causes arteries to constrict and narrow. As the blood
vessels relax, blood pressure goes down. ACE inhibitors include
Zestril (lisinopril),Altace (ramipril), and Capoten (captopril).
Calcium channel blockers act by dilating the arteries,
reducing resistance to blood flow, and reducing the heart rate.
Calcium antagonists is another name for these drugs. Some calcium
channel blockers are Isoptin (verapamil), Procardia (nifedipine),
and Cardiazem (diltiazem).
Medications chart
Prognosis
Consequences
of
untreated Hypertension
Prevention
Physical inactivity is a risk
factor for heart disease. A sedentary or inactive lifestyle also
contributes to obesity, a risk factor for both high blood pressure
and heart disease. Regular exercise helps control weight and lower
blood pressure.
Statistics show
that many people who have high blood pressure are also overweight.
If you’ve gained weight over the years, cut down on calories and
select foods low in salt and sodium. And if you drink alcoholic
beverages, be sure to practice moderation.
For
more information on Hypertension refer to the web sites below.
National Heart, Lung, and Blood
Institute:
Understanding high blood pressure
The Franklin
Institute Online:
Understanding
hypertension with interactive programs.
PharmInfoNet:
Hypertension Information center.
Hypertensionmeds.com:
Locate
information on hypertension medications by brand or generic
name.
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