Heart & Vascular Aortic dissection

Subject: Heart & Vascular Aortic dissection Sun Jan 02, 2011 7:50 pm

An aortic dissection is
a serious condition in which a tear develops in the inner layer of the
aorta, the large blood vessel branching off the heart. Blood surges
through this tear into the middle layer of the aorta, causing the inner
and middle layers to separate (dissect). If the blood-filled channel
ruptures through the outside aortic wall, aortic dissection is usually
fatal.

Aortic dissection, also called dissecting aneurysm, is relatively
uncommon. Anyone can develop the condition, but it most frequently
occurs in men between 60 and 70 years of age. Symptoms of aortic
dissection may mimic those of other diseases, often leading to delays in
diagnosis. However, when an aortic dissection is detected early and
treated promptly, your chance of survival greatly improves.

Symptoms

Aortic dissection symptoms may be similar to those of other heart
problems, such as a heart attack. Typical signs and symptoms include:

* Sudden severe chest or upper back pain, often described as a
tearing, ripping or shearing sensation, that radiates to the neck or
down the back
* Loss of consciousness (fainting)
* Shortness of breath
* Weakness or paralysis
* Stroke
* Sweating
* High blood pressure
* Different pulse rates in each arm

When to see a doctor
If you have signs or symptoms such as severe chest pain, fainting or
sudden onset of shortness of breath, contact your doctor or call for
emergency medical assistance. While experiencing such symptoms doesn't
always mean that you have a serious problem, it's best to get checked
out quickly. Early detection and treatment may help save your life.

Causes

An aortic dissection occurs in a weakened area of the aortic wall.
Chronic high blood pressure may stress the aortic tissue, making it more
susceptible to tearing. You can also inherit a condition associated
with a weakened and enlarged aorta, such as Marfan syndrome. Rarely,
aortic dissections may be caused by traumatic injury to the chest area,
such as during motor vehicle accidents.

Aortic dissections are divided into two groups depending on which part of the aorta is affected:

* Type A. This is the more common and dangerous type of aortic
dissection. It involves a tear in the ascending portion of the aorta
just where it exits the heart or a tear extending from the ascending
portion down to the descending portion of the aorta, which may extend
into the abdomen.
* Type B. This type involves a tear in the descending aorta only, which may also extend into the abdomen.

Risk factors

Risk factors for aortic dissection include:

* Uncontrolled high blood pressure (hypertension), found in at least two-thirds of all cases
* Hardening of the arteries (atherosclerosis)
* Weakened and bulging artery (pre-existing aortic aneurysm)
* An aortic valve defect (bicuspid aortic valve)
* Constriction of the aorta (aortic coarctation)

People with certain genetic diseases are more likely to have an aortic
dissection than are people in the general population. These include:

* Turner's syndrome. High blood pressure, heart problems and a
number of other health conditions may result from this disorder.
* Marfan syndrome. This is a condition in which connective tissue,
which supports various structures in the body, is weak. People with this
disorder often have a family history of aneurysms of the aorta and
other blood vessels. These weak blood vessels are prone to tears
(dissection) and rupture easily.
* Ehlers-Danlos syndrome. This group of connective tissue disorders
is characterized by skin that bruises or tears easily, loose joints and
fragile blood vessels.

Other potential risk factors include:

* Sex. Men have about double the incidence of aortic dissection.
* Age. The incidence of aortic dissection peaks in the 60s and 70s.
* Cocaine use. This drug has been implicated as a risk factor for
aortic dissection, most likely because it temporarily raises blood
pressure.
* Pregnancy. Infrequently, aortic dissections occur in otherwise healthy women during pregnancy.

Complications

An aortic dissection can lead to:

* Death, due to severe internal bleeding
* Organ damage, such as kidney failure or life-threatening damage to the intestines
* Stroke, possibly including paralysis
* Bleeding into the lining around the heart (pericardial sac)
* Aortic valve damage, such as causing the aortic valve to leak (aortic regurgitation)

Tests and diagnosis

Detecting an aortic dissection can be tricky because the symptoms are
similar to those of a variety of health problems. Doctors often suspect
an aortic dissection if the following signs and symptoms are present:

* Sudden tearing or ripping chest pain
* Widening of the aorta on chest X-ray
* Blood pressure difference between right and left arms

Although these signs and symptoms suggest aortic dissection,
more-sensitive imaging techniques are needed to establish the diagnosis.
The most frequently used imaging procedures include:

* Computerized tomography (CT) scan. CT scanning uses a machine that
generates X-rays to produce cross-sectional images of the body. In
order to diagnose an aortic dissection, a CT scan of the chest is taken.
A contrast liquid that contains iodine called contrast may be injected
into the blood during a CT scan. Contrast makes the heart, aorta and
other blood vessels more visible on the CT pictures.
* Magnetic resonance angiogram (MRA). A magnetic resonance imaging
(MRI) scan is a test that uses a magnetic field and pulses of radio wave
energy to make pictures of the body. MRA refers to the use of this
technique specifically to look at blood vessels. An MRA of the chest can
be used to diagnose aortic dissection.
* Transesophageal echocardiography (TEE). An echocardiogram is a
type of test that uses high-pitched sound waves to produce an image of
the heart. A TEE is a special type of echocardiogram in which an
ultrasound probe is inserted through the esophagus. Since the ultrasound
probe is placed close to the heart and the aorta, it provides a clearer
picture of your heart and its structures than would a regular
echocardiogram.
Treatments and drugs

An aortic dissection is a medical emergency requiring immediate
treatment. Therapy may include surgery or medications, depending on the
area of the aorta involved.

Type A aortic dissection
Type A aortic dissections are the more common and dangerous type of
aortic dissection. These dissections involve a tear in the ascending
portion of the aorta just where it exits the heart or a tear extending
from the ascending portion down to the descending portion of the aorta,
which may extend into the abdomen. Surgery is the preferred treatment
for type A aortic dissections.

During the surgical procedure, surgeons remove as much of the dissected
aorta as possible, block the entry of blood into the aortic wall and
reconstruct the aorta with a synthetic tube called a graft. Some people
with type A aortic dissection will need to have their aortic valve
replaced at the same time if there's valve leakage related to the
damaged aorta. If aortic valve replacement is required, the valve is
placed within the graft that is used to reconstruct the aorta.

Type B aortic dissection
This type of aortic dissection involves a tear in the descending aorta
only, which may also extend into the abdomen. People with type B aortic
dissection can be treated medically or with surgery. Surgical options
for type B aortic dissection are similar to the procedures used to
correct a type A aortic dissection. Sometimes stents — small wire mesh
tubes that act as a sort of scaffolding — may be placed in the aorta to
repair type B aortic dissections.

Medications for aortic dissection
Aortic dissections may be treated with medications, such as beta
blockers and sodium nitroprusside, to relieve the force of blood on the
aortic wall by reducing the heart rate and lowering blood pressure. With
reduced blood force, the aortic dissection is less likely to worsen.
These medications may be used to prepare a person for surgery. Most
people with type B dissections can be treated with medications alone.

After treatment many people with aortic dissections need to take blood
pressure lowering medication for the rest of their lives. In addition,
they'll often need follow-up CT or MRI scans every six to 12 months to
monitor their condition.
Prevention

The most important way to help prevent an aortic dissection is to keep
your blood pressure under control. Here are a few tips to reduce your
risk:

* Control your blood pressure. If you have high blood pressure, get a
home blood pressure measuring device to help you monitor and keep your
blood pressure well controlled.
* Don't smoke. Or, if you do, take steps to stop.
* Maintain an ideal weight. Follow a low-salt diet and exercise regularly.
* Watch your cholesterol. Keep your cholesterol levels within a range that is recommended by your doctor.
* Wear a seat belt. This reduces the risk of traumatic injury to your chest area.
* Keep your doctor well-informed. If you have a family history of aortic dissection, let your doctor know.

If you have a genetic condition that increases your risk of aortic
dissection, your doctor may recommend medications, even if your blood
pressure is normal. Talk to your doctor about which method or
combination of methods is best for you.

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