- What is Hypertension?
- Types of Hypertension
- Diagnosing Hypertension
- Impact of Hypertension on African-American health
- Complications of Hypertension
- Living with Hypertension
- Current Hypertension Treatment guidelines
- Treatment options
- The Ten Commandments for Hypertensive patients
WHAT
IS HYPERTENSION?
This condition is also commonly referred to as "high blood pressure"
and it occurs when the pressure of blood flowing through the
body's arteries exceeds certain arbitrarily determined numbers.
Certain basic laws of physics govern the circulation of blood
around the body. The heart is essentially a pump, which is not
much different from the pump that causes water to flow through
the pipes that make up the plumbing in our homes. The blood
vessels represent the plumbing and serve to circulate blood
in much the same way that water "circulates" around our homes.
The pump generates a pressure, which then forces the blood through
the circulation. For the blood to continue to flow through in
one direction, the pressure of blood leaving the pump (i.e. heart) must be
significantly higher than the pressure of blood returning to
it. In physics this difference in pressure is called a gradient.
The pressure itself is the result of an inter-play between the
force generated by the pumping action of the heart and the resistance
to the flow of blood offered by the walls of the blood vessels.
When the heart contracts, thus forcing blood into the vessels,
the amount of pressure that is generated will depend on how
much the vessels are able to widen to accommodate the blood
expelled from the heart. If the vessels are unable to widen
significantly, resistance to the flow of blood is high and the
pressure is correspondingly high. However, if the amount of
blood expelled from the heart is smaller than usual, or it is
expelled very slowly, the blood vessels are much better able
to channel that flow without a dramatic increase in pressure,
even if it's walls are not able to distend as fully as they
normally do. This very fascinating inter-play is what determines
blood pressure, and it is therefore not surprising that blood
pressure tends to vary depending on what is occurring in the
circulation when it is taken. Although the pressure in blood
vessels tends to vary somewhat depending on when it is taken,
overall the body tries to keep it within a fairly narrow range.
This is because extremes of blood pressure in either direction
tend to damage vital organs in the body. The pioneering efforts
of some doctors and scientists in the last couple of centuries
has led to the ability to measure blood pressure, and therefore
to correlate different levels of blood pressure with observed
adverse events. It was noted quite early in the evolution of
its measurement that it had two components. A system of recording
blood pressure was devised that reflects these components. The
first component is measurable shortly after the heart empties
blood into the arteries and is called the systolic blood pressure,
and it is followed shortly after by a second component, which
coincides with changes in the size of the blood vessels. This
second component is called diastolic blood pressure because
it is measured during a period of heart muscle relaxation, in
between contractions, that is known as diastole. By convention,
both numbers are written down together, one on top of the other.
The top number is always the systolic blood pressure. Based
on adverse event correlation studies previously referred to,
a blood pressure greater than 140/90 was consistently associated
with a higher and rising incidence of damage to body organs.
For this reason, this pressure was, somewhat arbitrarily, designated
the upper limit of normal for blood pressure. While it remains
an acceptable guideline for most people, it is now quite clear
that for certain high-risk individuals such as diabetic patients,
a lower level of blood pressure may be associated with fewer
complications .
TYPES
OF HYPERTENSION
There are several different ways of classifying hypertension,
with some schemes being more complicated than others. For the
purpose of this article, simply dividing it into two large groups
should suffice. The first group is referred to as having primary
or essential hypertension. The hallmark of this group is that
the cause of their hypertension is obscure. They tend to have
a strong family history of the disease, making it probable that
genetic factors are involved. In these patients, the disease
tends to become manifest sometime during middle age and to generally
respond to treatment quite well. Other factors that are thought
to contribute to the development of this form of hypertension
include obesity, salt and alcohol intake, stress and a lack
of exercise. Secondary hypertension refers to disease that is
clearly attributable to readily identifiable dysfunction of
one or more organs. There is a fairly long list of causes including
kidney, adrenal, cardiac, hormonal and metabolic disease but
an exhaustive list is beyond the scope of this article. The
disease tends to manifest much earlier in life and to follow
a more aggressive course. Treatment is much more difficult and
sometimes requires surgical intervention. However, treatable
causes may be completely cured by appropriate therapy unlike
essential hypertension, which usually requires life-long treatment.
DIAGNOSING
HYPERTENSION
As previously mentioned, population studies over time have established
generally accepted norms for normal blood pressure. However
these numbers were adopted somewhat arbitrarily, and it has
become quite clear that other co-existing illnesses may necessitate
different standards for control. Hypertension is remarkable
in the fact that it is essentially a disease without symptoms
in the vast majority of cases. The most effective way to diagnose
it is by periodically having your blood pressure checked. When
symptoms are present they usually reflect severe disease with
target organ dysfunction, or in the case of secondary hypertension,
may be the result of symptoms referable to the cause of the
hypertension. Some symptoms of severe disease include headaches,
blurring of vision, shortness of breath, dizziness, palpitations,
chest pain and poor exercise tolerance. Symptoms due to secondary
causes are variable and are determined by the specific organ
involved. Recently, there has been considerable interest in
hooking patients up to a portable device that takes the blood
pressure at frequent intervals during a period of several hours
to many days. This more intense monitoring of blood pressure
is presumed to be more effective at identifying patients with
abnormal blood pressure because it can document increased pressure
in patients whose blood pressure is normal during a portion
of the day. Such patients may have their pressure checked at
a time when it is normal even though it remains elevated for
the greater part of a twenty four-hour period.
IMPACT
OF HYPERTENSION ON AFRICAN AMERICAN HEALTH
Hypertension has been described as the most important public health problem
in the United States of America. In large population screening studies
involving predominantly white people, close to 50% of screened people
without symptoms had blood pressures greater than 140/90. An astonishing
one in five people had pressures greater than 160/95. All told,
over sixty million Americans have high blood pressure and more than a
third are completely unaware of it! All available data suggests that
the numbers are much worse for African Americans, particularly black males.
One indication of the magnitude of the problem is the epidemic of kidney
failure that is sweeping through black communities in urban America. While
diabetes is a major cause of the kidney failure in these communities, the
problem is undoubtedly exacerbated by untreated hypertension.
African Americans also have disproportionately high levels of sudden death,
stroke, and congestive heart failure, all of which are traceable to high
blood pressure.
COMPLICATIONS
OF HYPERTENSION
Hypertension
is considered such a silent and deadly killer because the first
indication of the disease is often a devastating and irreversible
complication. Complications affect virtually all organs and
are related to damage to blood vessels supplying these organs
caused by prolonged abnormally high pressure. The following
represents a non exhaustive summary of specific hypertension
related complications;
Stroke
This is probably the most devastating complication of hypertension.
It frequently occurs completely without warning and may be the
result of either a blood clot or a rupture of a blood vessel
with bleeding into the substance of the brain. Occasionally
there are warning signs such as blurred vision, headache, nausea
and vomiting. Unfortunately, even when warning signs occur,
patients who have not been conditioned to view these symptoms
as indicative of an impending "brain attack" usually ignore
them! Strokes frequently result in paralysis with prolonged or
irreversible disability, or death.
Kidney
Failure
Damage to the kidneys' blood vessels leads to progressive
decline in the function of these organs, culminating in the
inability to effectively filter the body's waste. Chronic renal
failure is irreversible and eventually requires that a machine
take over the excretory functions of the kidney. Once dialysis
is initiated, it leads to other problems, which shorten the
life expectancy of the patient.
Heart
Disease
Hypertension is probably the single most important
predisposing factor to heart disease. The range of heart problems
caused or exacerbated by high blood pressure includes congestive
heart failure, heart attacks, irregular heartbeats, and sudden
death.
Peripheral
Vascular Disease
Damage to blood vessels supplying the
arms and legs leads to poor circulation which manifests as severe
and prolonged pain in the affected extremities, as well as diminished
exercise tolerance. In many cases the extremity is eventually
lost to gangrene and the doctor has no choice but to have it
amputated. Diabetes, high cholesterol, and smoking worsen these
circulatory problems.
LIVING
WITH HYPERTENSION
A few common
sense life style adjustments can go a long way in mitigating
the worst consequences of hypertension;
Diet
A low salt, low saturated fat diet is strongly recommended for
patients with high blood pressure. Some researchers believe
that abnormalities of salt metabolism underlie essential hypertension.
While this has not been found to be universally true, there
is clear experimental evidence to support the notion that a
sub-set of patients has difficulties with salt metabolism. Keeping
the cholesterol and saturated fat levels low is important because
high levels of both substances exacerbate the damage that hypertension
causes to the walls of blood vessels.
Obesity
Obese patients tend to have higher blood pressures than their
non-obese peers do. They also have greater difficulty controlling
their hypertension with medication. When some patients lose
weight their blood pressure becomes better controlled on the
same medication regimen they were taking prior to losing weight.
Exercise
Regular exercise improves blood pressure control. The exercise
regimen does not have to be extremely taxing to have a beneficial
impact. Vigorous walking several times a week may be all that
is required.
Stress
Stress clearly worsens blood pressure control. A stressful work
or home environment may make it difficult to control blood pressure.
Stress reduction techniques such as biofeedback may augment
medication in the control of blood pressure.
Alcoholism
and Substance Abuse
Alcohol and illegal substances such
as cocaine raise blood pressure and may make it difficult to
control blood pressure.
Medications
A variety of medications when taken by susceptible individuals
can raise blood pressure and make control difficult. Such medications
include oral contraceptives, steroids, decongestants and appetite
suppressants.
Co-existing
Medical Conditions
Obstructive sleep apnea raises blood
pressure and is an excellent example of a co-existing medical
condition that can either unmask hypertension or make known
high blood pressure more difficult to treat.
CURRENT
HYPERTENSION TREATMENT GUIDELINES
In November of 1997, the Joint National Committee on Prevention,
Detection, Evaluation, and Treatment of High Blood Pressure
issued its sixth report which recommended that hypertension
be staged as follows;
Stage 1: Systolic Blood Pressure of 140-159
mmHg or Diastolic Blood Pressure of 90-99 mmHg.
Stage 2: Systolic
Blood Pressure of 160-179 mmHg or Diastolic BP of 100-109 mmHg.
Stage 3: Systolic Blood Pressure of 180 mmHg or greater or Diastolic
BP of 110 mmHg or greater.
The report also recommended placing
patients into one of three different risk groups based on a
number of life-style and other risk factors for heart disease.
The specified risk factors include smoking, elevated cholesterol,
diabetes mellitus, age greater than sixty years for either sex,
and family history of heart disease in men younger than age
fifty five or women younger than age sixty five. The idea is
to use a combination of staging and grouping to assess risk
and thereby make appropriate treatment decisions for individual
patients.
Risk Group A: No other risk factors for heart disease
and no evidence of organ damage from Hypertension.
Risk Group
B: A minimum of one additional risk factor not including diabetes
mellitus.
Risk Group C: Patients with diabetes, target organ
damage from hypertension, heart disease, with or without other
risk factors for heart disease.
The practical effect of assessment
that combines staging and grouping is to enable earlier and
more aggressive treatment of patients with apparently mild elevation
of their blood pressures who are never-the-less at great risk
for complications due to the nature of their life-style or the
presence of co-existing illnesses.
TREATMENT
OPTIONS
As previously alluded to, a healthy life-style including a sensible
diet, moderate exercise, and the avoidance of alcohol and illegal
drugs, is an essential adjunct to medication in the treatment
of hypertension. The considerable sums of money that have been
invested in research into the treatment of this condition has
produced several classes of chemicals that have proven useful
in lowering blood pressure. Because of the likely multi-factorial
causes of elevated BP, and the presence of genetic influences,
some forms of treatment are more effective in particular genetic
groups, or for hypertension due to specific causes. A comprehensive
discussion of the different classes of anti-hypertensive medications
is beyond the scope of this article. However, since the article
is directed to African-American populations, it is necessary
to comment on classes of pharmaceuticals that are either particularly
effective at lowering blood pressure in blacks, or have been
found to be relatively less effective when compared to their
effect on whites;
More Effective in Blacks. Studies have shown that blood
pressure medications that work by inducing the body to excrete
salt and water appear to be disproportionately effective in
black patients. While the reason for this is not entirely clear,
some researchers believe that it may be due to genetically influenced
abnormalities in the body's' handling of salt. It is however
very difficult to isolate any one abnormality because cultural
factors concerning the intake of salt, as well as other issues
likely also contribute to the observed differences. What is
clear however, is that some black patients whose blood pressure
has been hard to control have achieved significantly better
control once a "water pill", known medically as a diuretic,
has been added. If you are on blood pressure medications and
your control has been poor, you need to ask your doctor whether
your regimen includes a diuretic. If you are not on one, he
may want to consider adding it provided that there are no contraindications.
Less Effective in Blacks. The class of medications called
Beta Blockers is less effective for BP control in blacks when
compared with whites. Once again, the reasons for this observed
difference are not clear but there has been speculation, partially
supported by research findings, that it is related to differences
in the nature of key hormones and chemicals involved in the
regulation of blood pressure. Beta blockers have several other
beneficial effects on the heart that, in the absence of contraindications,
they are frequently prescribed for their other benefits, and
a diuretic or other blood pressure lowering medication is added
to the regimen to ensure adequate blood pressure control.
Other Considerations. Although several different classes
of anti-hypertensive medications are now available, physicians
have to consider many factors before deciding which class of
medications to prescribe for a particular individual. Some of
these factors include coexisting medical conditions, possible
side effects, age, and affordability issues. Thus, it is very
important that, as a patient, you discuss with your doctor,
all your medical problems, medications, and socio-economic issues
that could potentially affect your compliance with the prescribed
regimen. Some medications are particularly suitable for patients
with particular combinations of health problems. A good example
of this would be a patient with diabetes and high blood pressure.
There is abundant experimental and clinical evidence of the
protective effect on the kidneys, of a class of medications
called ACE Inhibitors, in this setting. Unless there are other
contra-indications, a drug from this class should be prescribed
to all such patients. One must also be mindful of potentially
dangerous side effects of some of the medications. For example,
Beta Blockers can be dangerous for patients with asthma, circulatory
problems affecting the limbs, and diabetes mellitus. The bottom
line is that, as a patient, you have a responsibility to stay
as informed as possible about your condition. You can do this
by asking lots of questions, and taking every opportunity you
can find to read up about your condition.
BHO
TEN COMMANDMENTS FOR HYPERTENSIVE PATIENTS
- Thou shall maintain a healthy weight.
- Thou shall not smoke.
- Thou shall limit your alcohol consumption to no more than
one to two drinks a day.
- Thou shall be physically active (at least thirty minutes of
moderate physical activity 3-4 times a Week.
- Thou shall have your blood pressure checked at least once
every six months.
- Thou shall make life style changes to minimize stress.
- Thou shall limit your salt intake to no more than 4-6 grams
a day(1-1 ½ teaspoons of table salt Per day).
- Thou shall eat a healthy diet consisting of fruits, vegetables,
and limited amounts of saturated fat.
- Thou shall take your medications religiously.
- Thou shall make a commitment to learn as much as possible
about your illness.
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