Abdominal Aortic Aneurysm

Aneurysm is a ballooning of an artery due to weakening of the blood vessel walls. It may be an inherited disorder or may be due to atherosclerosis. The most common aneurysm is abdominal aortic aneurysm which occurs in the large artery that carries blood from the heart to the lower part of the body.

It is when the large blood vessel that supplies blood to the abdomen, pelvis and legs become abnormally large or balloons outward. AAA is much more common in men and risk increases with age. It needs a surgical therapy as it may prove to be life threatening.

An aortic aneurysm is so called as the aneurysm involves the aorta artery. The aorta is called the thoracic aorta as it leaves the heart through the chest and until it reaches the diaphragm. Then it is called the abdominal aorta after it has passed the diaphragm and continues down the abdomen. The abdominal aorta ends where it splits into two iliac arteries that go to the legs.

The most common pathologic condition associated with aortic aneurysm is atherosclerosis. Those in the abdominal aorta are almost always associated with atherosclerosis. Aortic aneurysms usually do not produce symptoms. However, as they expand, they may become painful. Compression or erosion of adjacent tissue by aneurysms also may cause symptoms. The formation of mural thrombi within the aneurysm may influence to peripheral embolization.

Occasionally, an aneurysm may leak leading to extravasations of blood into the vessel wall and the peri advential area and causing acute pain and local tenderness. This is usually an indication of rupture and represents a medical emergency.

More often, acute rupture occurs without any prior warning and this complication is always life-threatening. Male are often affected than the females.

Shape of aortic aneurysm – fusiform (spindle – shaped)

The exact cause of the degenerative disease is unknown. However, the risk factors include:

Emphysema (it is a chronic respiratory disease where there is over-inflation of the air-sacs (alveoli) in the lungs causing a decrease in lung function and often breathlessness.)
Genetic factors – there is a familial tendency to developing abdominal aortic aneurysms. Individuals with first degree relatives are at a higher risk than the common population. Such people can develop the aneurysm at an younger age and it can rupture than individuals without family history.
Post –trauma- due to any injury or trauma of the aorta.
Genetic disease – certain disorders of the connective tissues (tissues that make up the wall of aorta) such as Marfan syndrome and Ehlers – Danlos syndrome.
Arteritis – inflammation of blood vessels as occurs in Takayasu disease, giant cell arteritis and relapsing polychondritis.
High blood pressure
Cholesterol
Obesity
Smoking
Fungal infection or Mycotic infection
Other causes include cystic medical necrosis; diabetes mellitus etc.

The larger the aneurysm the more likely it is to rupture. When the aneurysm ruptures, it is a true medical emergency. Aortic dissection is caused when the innermost part of the artery ruptures and the blood leaks into the artery.

Symptoms

Most of the patients appear asymptomatic and is usually discovered during an abdominal ultrasound scan or CT scan. Both CT and MRI are useful in detecting and follow up of the aortic aneurysm.

They usually do not produce symptoms. However, as they expand they may become painful. Compression or erosion of adjacent tissue by aneurysms also may cause symptoms.

The formation of mural thrombi within the aneurysm may predispose to peripheral embolization. More often, acute rupture occurs without any prior warning and this complication is always life-threatening.

Abdominal mass
Abdominal rigidity
Pulsating sensation in the abdomen
Clammy skin
Pain in the abdomen or back and it may radiate to groin, buttocks or legs.
Rapid heart rate in a standing position

Tests of abdominal aortic aneurysm

Plain X-rays are not that useful in detecting the size and extent of the aneurysm.

Ultrasound is useful in determining the size of the aneurysm. But it can’t accurately measure the extent and not useful in case of a surgical plan.

CT scan is also a safe non-invasive method to determine the size and extent of the aneurysm. However, this method uses high doses of radiation and intravenous dye that can cause some kind of allergic reaction to the dye and irritant to the kidneys.

Therefore, for patients with kidney disease, Doctors usually recommend MRA (Magnetic resonance angiography), a study of the aorta and other arteries using MRI scanning.

Abdominal aortography remains the standard test in evaluating patients with aneurysm for surgery. It is the examination of the aorta using x-rays following the injection of a radiopaque substance.

But this procedure carries a small risk of complications, such as bleeding, allergic reactions and atheroembolism. This technique is useful in documenting the extent of the aneurysm, especially the upper and lower limits and the extent of associated atherosclerotic vascular disease. However, since the presence of mural clots may reduce the laminal size, aortography may underestimate the diameter of an aneurysm.

Aortogram - an image or set of the images of the aorta made after the injection of a radiopaque substance.

Glossary

Embolus - A mass, such as an air bubble, a detached blood clot, or a foreign body, that travels through the bloodstream and lodges so as to obstruct or occlude a blood vessel.
Embolization - The process by which a blood vessel or organ is obstructed by an embolus or other mass.
Occlusion is a term indicating that the state of something, which is normally open, is now totally closed.

In medicine, the term is often used to refer to blood vessels, arteries or veins which have become totally blocked to any blood flow. For issues of artery occlusion, See stenosis, atheroma, and coronary catheterization.

Takayasu disease or Takayasu arteritis is a chronic inflammation of the large blood vessel that distributes blood from the heart, called the aorta. It is most common in women (90%) of Asian descent. It usually begins between 10 and 30 years of age. The cause is unknown.

Takayasu disease has also been referred to as pulse less disease and aortic arch syndrome.

Relapsing polychondritis – an uncommon disorder of the cartilage that is characterized by inflammation of the cartilage tissues of the various parts of the body.
Cystic medical necrosis – a degenerative breakdown of collagen, elastin and smooth muscle contribute to weakening of the wall of the artery.
Marfan syndrome – a heritable disorder that affects the connective tissues. It affects many body systems including the eyes, skeleton, heart and blood vessels, nervous system, skin and lungs.
Ehlers- Danlos syndrome – a hereditary disorder that has clinical features such as looseness of joints, elasticity of skin, skin that can be easily scratched etc.
Clammy skin – smooth, moist and pale. It may be an emergency.

Emphysema (it is a chronic respiratory disease where there is over-inflation of the air-sacs (alveoli) in the lungs causing a decrease in lung function and often breathlessness.)

Genetic factors – there is a familial tendency to developing abdominal aortic aneurysms. Individuals with first degree relatives are at a higher risk than the common population. Such people can develop the aneurysm at an younger age and it can rupture than individuals without family history.

Post –trauma- due to any injury or trauma of the aorta.

Genetic disease – certain disorders of the connective tissues (tissues that make up the wall of aorta) such as Marfan syndrome and Ehlers – Danlos syndrome.

Arteritis – inflammation of blood vessels as occurs in Takayasu disease, giant cell arteritis and relapsing polychondritis.

High blood pressure

Cholesterol

Obesity

Smoking

Fungal infection or Mycotic infection

Other causes include cystic medical necrosis; diabetes mellitus etc.

Abdominal mass

Abdominal rigidity

Pulsating sensation in the abdomen

Clammy skin

Pain in the abdomen or back and it may radiate to groin, buttocks or legs.

Rapid heart rate in a standing position

Embolus - A mass, such as an air bubble, a detached blood clot, or a foreign body, that travels through the bloodstream and lodges so as to obstruct or occlude a blood vessel.

Embolization - The process by which a blood vessel or organ is obstructed by an embolus or other mass.

Occlusion is a term indicating that the state of something, which is normally open, is now totally closed.

Takayasu disease or Takayasu arteritis is a chronic inflammation of the large blood vessel that distributes blood from the heart, called the aorta. It is most common in women (90%) of Asian descent. It usually begins between 10 and 30 years of age. The cause is unknown.

Relapsing polychondritis – an uncommon disorder of the cartilage that is characterized by inflammation of the cartilage tissues of the various parts of the body.

Cystic medical necrosis – a degenerative breakdown of collagen, elastin and smooth muscle contribute to weakening of the wall of the artery.

Marfan syndrome – a heritable disorder that affects the connective tissues. It affects many body systems including the eyes, skeleton, heart and blood vessels, nervous system, skin and lungs.

Ehlers- Danlos syndrome – a hereditary disorder that has clinical features such as looseness of joints, elasticity of skin, skin that can be easily scratched etc.

Clammy skin – smooth, moist and pale. It may be an emergency.