Renovascular Hypertension
What is it?
Hypertension is another name for high blood
pressure. Renovascular hypertension is a
form of what is called secondary hypertension,
which is hypertension caused by another condition
in the body. In this case, the high blood
pressure is caused by the hardening and narrowing
of the renal artery, which carries blood to the
kidneys. Narrowing of the renal artery is called
renal artery stenosis.
Who gets it?
Renovascular hypertension occurs more often in
white men and blacks of both sexes. It
occurs in approximately 6 out of 100,000 people.
Age of onset depends upon the cause of damage to
the kidney blood vessels. It often occurs in
men over the age of 45 with atherosclerosis, and
in women under the age of 45 with fibromuscular
dysplasia. Around 10% of children with
fibromuscular dysplasia also develop renovascular
hypertension. Smoking, eating a diet high in
salt, obesity, high levels of stress, frequent
exposure to heavy metals, and a family history of
hypertension increase a personŐs risks of
developing this condition.
What causes it?
There are several conditions that can cause a
blockage in the renal artery. These include
atherosclerosis, which causes plaque deposits to
collect in the renal artery, and fibromuscular
dysplasia, in which cells from the artery wall
overgrow and narrow the artery. Narrowing of
the renal artery can also be caused by compression
from an injury or tumor, or by blood clots.
A renal artery that becomes narrow due to a
blockage reduces blood flow to the kidney.
In response, the kidney produces a protein called
renin. When renin is released into the
bloodstream, it ends up being converted into an
enzyme that makes the body retain sodium (salt)
and constricts the arterioles, which causes the
symptoms of renovascular hypertension.
What are the symptoms?
The main symptom of renovascular hypertension
is high blood pressure. Blood pressure is recorded
in two values. The top number, called the
systolic, is taken when the heart contracts.
It is considered normal when it is below 130.
The bottom number, the diastolic blood pressure,
reflects the pressure in blood vessels when the
heart is at rest. It should be below 90, but
in people with renovascular hypertension, the
diastolic pressure is often higher than 104.
Other symptoms depend upon the severity and cause
of the disease, and can include headache, fatigue,
nausea and vomiting, chest pain, vision problems,
confusion, anxiety, excessive perspiration, and
pale or reddened skin. However, many people will
have no symptoms at all. When renovascular
hypertension is caused by a blood clot in a renal
artery, the patient will usually have a sudden
pain in the side and bloody urine.
Renovascular hypertension can lead to many serious
complications, including hypertensive heart
disease, stroke, blindness, myocardial infarction,
congestive heart failure, blood vessel damage,
kidney damage, and kidney failure.
How is it diagnosed?
Over time, people with renovascular
hypertension will have a pattern of severely high
blood pressure that is difficult to control. A
doctor may suspect renovascular hypertension if it
begins when the patient is at an advanced age, if
it is difficult to control, or if controlling a
new onset of hypertension requires multiple
medications. Upon a physical examination, the
doctor may be able to place a stethoscope on the
abdomen and hear the sound of blood rushing
through a narrowing in the artery supplying the
kidney. This sound is called a bruit.
Tests used to diagnose atherosclerosis or renal
stenosis include renal ultrasound, which uses
sound waves to produce an image of the kidneys;
renal angiography, in which a dye is injected into
the renal artery so that a narrowing of the artery
shows up on x-ray; and intravenous urography, in
which a dye is injected into the kidney, x-rays
are taken, and the kidneys are compared.
Tests can also be performed to measure levels of
renin production.
What is the treatment?
The goal of treatment for renovascular
hypertension is to control the high blood
pressure. Your doctor may first recommend
some lifestyle changes that may be aggravating
your hypertension. For example, you may need
to lose weight, get more exercise, or change your
diet so it is lower in fat and salt. If you
smoke or drink alcohol frequently you should stop
because both can cause serious complications for
someone with renovascular hypertension.
Frequently used medications include diuretics,
which help the kidneys eliminate salt and water;
potassium supplements, because diuretics cause a
loss of potassium; beta blockers, which stop the
nervous system from raising blood pressure during
stress; and calcium channel blockers and
angiotensin-converting enzyme inhibitors, both of
which lower blood pressure by dilating the
arteries. Drugs such as diazoxide or
nitroprusside are given in hypertensive
emergencies where the blood pressure must be
lowered quickly. Treatment is extremely
individual and your doctor may need to try several
different medications before finding the one that
is right for you. Your doctor will want to
monitor your blood pressure and medications
frequently. Renovascular hypertension does not
always respond well to anti-hypertensive drugs.
In these cases, the narrowed artery to the kidney
can be dilated with a balloon catheter. A
balloon catheter is a long, thin tube with a small
balloon at the end. After the catheter is
inserted into the kidney, the balloon is inflated
to open the narrowed artery. This procedure
is often effective for patients with fibromuscular
dysplasia. Surgery may also be
performed to repair or bypass the narrowed part of
the artery supplying the kidney. If the
kidney has been severely damaged, it may need to
be removed.
Self-care tips
You can reduce your risk of atherosclerosis,
which causes renal artery stenosis, by eating a
diet low in fats and salts, maintaining a healthy
weight, and getting plenty of exercise.
However, doctors do not know how to prevent
fibromuscular dysplasia.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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