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Atherosclerosis
Atherosclerosis, the most common cause of heart disease, is the
progressive thickening and hardening of the walls of medium-sized and
large arteries as a result of inflammation and fat deposits on their
inner lining. The process starts early in life and is strongly governed
by someone’s genes and body weight.
The arteries are blood vessels that carry blood from the heart to
all parts of the body. They are made up of several layers of tissue
that are normally soft and pliable. The layers must be able to expand
and contract as blood passes through them.
Arteries often become leathery and inflexible, making it harder for
blood to flow freely. This general hardening of arteries is called
arteriosclerosis, and it can be caused by many factors including
ageing, high blood pressure, and certain diseases such as diabetes.
If blood flow is constricted in an artery leading to the heart, a
heart attack may occur. If constricted in an artery leading away from
the heart, the brain may not get the blood and oxygen it needs,
resulting in a stroke.
Atherosclerosis can occur anywhere in the body. It can affect
arteries of the neck, kidneys, thighs, and arms. In such cases, the
interruption of blood flow can produce any of a variety of medical
conditions, such as kidney failure, high blood pressure or gangrene
(death of tissue).
Atherosclerosis can occur anywhere in the body. It can affect arteries of the neck, kidneys, thighs, and arms.
Atherosclerosis, a form of arteriosclerosis, refers to the
progressive narrowing, or complete obstruction, of an artery caused by
a process of fat deposition and inflammation. This can lead to a number
of cardiovascular (heart and blood vessel) problems.
There are many risk factors, which include:
- Heredity
- Diabetes mellitus
- Obesity
- High blood cholesterol
- High triglycerides
- High blood pressure
- Physical inactivity
- Cigarette/tobacco smoking
The symptoms of atherosclerosis vary depending on which arteries are
affected. If it occurs in the arteries of the heart, a person may
experience arm, neck or chest pain, heart attack, or sudden death. If
it occurs in the brain, a person may experience sudden dizziness, loss
of speech, loss of vision or stroke. In arteries of the leg,
atherosclerosis can lead to muscle cramps or pain when exercising.
Diagnosis
A doctor may suspect atherosclerosis based on the above symptoms,
and can confirm the diagnosis with any one of a number of tests. For
example, an electrocardiogram measures electrical activity of the
heart. An abnormal flow of blood to the heart can change this activity.
Electrocardiograms are sometimes performed while a patient is taking
part in vigorous activity, such as riding a stationary bicycle. Such
tests are known as stress tests.
An echocardiogram uses sound waves to produce a pattern (an echo) as
they pass through the heart. Blockages in arteries can sometimes be
detected by this method.
Coronary angiography is the most accurate way to diagnose
atherosclerosis. In this procedure, a catheter is inserted into a blood
vessel in the patient's arm. A catheter is a long, narrow tube that can
be pushed through the vein into the patient's heart, allowing a dye to
be pumped through the catheter into the heart. Then, X-ray pictures are
taken of the heart. The dye makes it possible to see whether or not
there are obstructions in blood vessels in the heart.
The first line of treatment is a change in lifestyle. Patients can
reduce their intake of fatty foods, quit smoking, lose weight, and
become more physically active. Fish oil supplements can also be taken.
For more serious forms of atherosclerosis, other treatments may be
necessary. These include the use of drugs and various forms of
surgery.
Several classes of drugs are used with atherosclerosis, such as the
statin and fibrate groups, designed to lower cholesterol or
triglycerides. Aspirin may also be recommended because it thins the
blood.
One form of surgery used to treat atherosclerosis is angioplasty. A
catheter tipped with a balloon is inserted into a blood vessel in the
patient's thigh or arm, and directed into the artery where the
obstruction exists. At that point, the balloon is inflated, allowing
blood flow to resume. . The balloon is then deflated and removed from
the artery.
Vascular stenting, is often performed at the same time as an
angioplasty if the arteries are severely affected (very narrow or
completely blocked). Stenting involves a little wire mesh being
permanently inserted into the artery and inflated to re-establish blood
flow. Some stents have drugs in them that diffuse out into the blood
stream and prevent the narrowing of the arteries recurring at that
particular site.
If lifestyle and drugs are insufficient, and angioplasty not an
option, heart bypass surgery may be required (where the obstruction is
literally bypassed by a new blood vessel). Bypass surgery is completely
successful in about 70 percent of all cases and partially successful in
another 20 percent.
Our research looks at how certain diseases or conditions predispose
people to developing atherosclerosis. We are particularly interested in
diabetes, metabolic syndrome, pre-diabetes and obesity, all of which
relate to fats in the blood and in the body.
We know that obesity may cause some of the very early changes in blood
vessel dynamics that can lead to atherosclerosis. We also know that it
promotes the changes in metabolism that lead to diabetes. By measuring
the pliability of arteries, and the speed at which blood travels
through them, we can gain an understanding of how inflammation and
narrowing of the arteries evolve over time.
We are investigating different types of obesity through clinical
trials. One group of participants are morbidly obese (between
100-150 kg) and they are losing weight. Another group has a specific
genetic syndrome, known as Prader-Willi Syndrome.
Our clinical trials involve measuring the flexibility of arteries using
ultrasound performed at the wrist and the neck. We also use ultrasound
to measure the speed at which the pulse wave travels down an artery.
This is performed non-invasively.
News
Clues to how diet might affect the immune system
02 Dec 2006
Garvan scientists are proposing that dietary fats can affect how well our immune system works and have discovered that one of the earliest steps in immune system activation relies on a molecule that binds fats.
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