High Blood Pressure (hypertension)
When someone has high blood pressure, or hypertension,
the force of blood against his or her artery walls is
too strong. High blood pressure can damage the arteries,
heart, and kidneys, and lead to heart disease and stroke.
Blood pressure readings consist of an upper number
and a lower number (such as 120 over 90 or 120/90).
Blood pressure readings are measured in units called
millimeters of mercury (mm Hg).
A person has high blood pressure (hypertension) when
either or both of the following are present:
- The top number (systolic) is 140 mm Hg or higher.
- The bottom number (diastolic) is 90 mm Hg or higher.
People are considered
prehypertensive if their blood pressure
readings are 120 to 139 mm Hg systolic over 80 to 89
mm Hg diastolic.
Normal blood pressure
is 119 mm Hg systolic over 79 mm Hg diastolic or below.
Systolic blood pressure
refers to the pressure of blood in the artery when the
heart contracts. It is the top (and higher) number in
a blood pressure reading.
Diastolic blood pressure
refers to the pressure of blood in the artery when the
heart relaxes between beats. It is the bottom (and lower)
number in a blood pressure reading.
For example, if a person's systolic pressure is 120
millimeters of mercury (mm Hg) and the diastolic pressure
is 80 mm Hg, blood pressure is recorded as 120/80 and
read as "120 over 80."
People with some medical conditions may have a different
target blood pressure. For example, the goal for people
with diabetes is less than 130 over 80.
Over time, high blood pressure can damage the inner
lining of the blood vessels, making it easier for cholesterol
and other substances to build up. This process is called
atherosclerosis. High blood pressure also increases
the workload on the heart, especially the left ventricle,
which may become thick and stiff. This can affect the
heart's pumping ability and may lead to heart failure.
Untreated high blood pressure increases the risk of
coronary artery disease and other heart problems, aneurysms,
stroke, kidney problems, and eye problems.
High blood pressure can be treated effectively with
lifestyle changes and medications that can reduce the
risk of complications.
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Atherosclerosis
Atherosclerosis, sometimes called “hardening
of the arteries,” occurs when fat (cholesterol)
and calcium build up in the inner lining of the arteries,
forming a substance called plaque. Over time, the fat
and calcium buildup narrows the artery and blocks blood
flow through it.
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Stroke
A stroke occurs when a blood vessel (artery) that supplies
blood to the brain bursts or is blocked by a blood clot.
Within minutes, the nerve cells in that area of the
brain become damaged and die, and as a result, the part
of the body controlled by the damaged section of the
brain cannot function properly.
A stroke can be caused by:
- Blockage of a blood vessel that supplies blood
to the brain. The blockage may be a blood clot that
forms inside the blood vessel (thrombus) or an object
(such as an air bubble or piece of tissue) that moves
through the blood from another part of the body (embolus).
- Sudden bleeding from a blood vessel that supplies
blood to the brain. This is most often caused by the
rupture of a weakened area in a blood vessel (aneurysm).
- A sudden drop in blood pressure, which reduces
blood flow to the brain. Low blood pressure can result
from a heart attack, a large loss of blood, or a severe
infection.
- High blood pressure, which can damage the delicate
lining of blood vessels. Once damaged, fat and calcium
can easily build up along the artery walls, forming
a plaque. The blood vessel becomes narrowed and stiff
(atherosclerosis), and blood flow is reduced.
Symptoms of a stroke tend to appear suddenly and may
include:
- Numbness, weakness, or lack of movement (paralysis)
in the face, an arm, or a leg, especially on only
one side of the body
- Trouble seeing in one or both eyes
- Confusion and difficulty speaking
- Dizziness and a loss of balance or coordination
- Vomiting
- A sudden, severe headache
The effects of a stroke may be mild or severe and temporary
or permanent, depending on which brain cells are damaged,
how much of the brain is involved, and how quickly the
blood supply is restored to the area. A stroke can affect
speech, movement, behavior, and thought processes. When
severe, it can cause paralysis, coma, and death.
A person having symptoms of a stroke needs
immediate medical attention.
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* Text Resources: The Mayo Clinic Staff
