aortic aneurysm

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Aortic Aneurysm



An aneurysm is an abnormal bulging or swelling of a portion of a blood vessel. The aorta, which can develop these abnormal bulges, is the large blood vessel that carries oxygen-rich blood away from the heart to the rest of the body.


The aorta carries oxygen-rich blood to the body, and is therefore called an artery. Because the aorta is an artery, its walls are made of up three layers; a thin inner layer, a muscular middle layer (that gives the vessel its flexibility under pressure from the filling blood), and a fiber-like outer layer that gives the vessel strength to not burst when the heart pumps blood to the body.
Aortic aneurysms occur when a weakness develops in part of the wall of the aorta; three basic types are usually found. If all three layers of the vessel are affected and weakness develops along an extended area of the vessel, the weakened area will appear as a large, bulging region of blood vessel; this is called a fusiform aneurysm. If weakness develops between the inner and outer layers of the aortic wall, a bulge results as blood from the interior of the vessel is pushed around the damaged region in the wall and collects between these layers. This is called a dissecting aneurysm because one layer is "dissected" or separated from another. If damage occurs to only the middle (muscular) layer of the vessel, a sack-like bulge can form; therefore, this is a saccular aneurysm.

Causes and symptoms

Aortic aneurysms occur in different portions of the aorta, which begins in the chest (at the heart) and travels downward through the abdomen. Aneurysms found in the region of the aorta within the chest are called thoracic aortic aneurysms. Aneurysms that occur in the part of the aorta within the abdomen are called abdominal aortic aneurysms.
Thoracic aortic aneurysms do not usually produce any noticeable symptoms. However, as the aneurysm becomes larger, chest, shoulder, neck, lower back, or abdominal pain can result. Abdominal aortic aneurysms occur more often in men, and these aneurysms can cause pain in the lower back, hips, and abdomen. A painful abdominal aortic aneurysm usually means that the aneurysm could burst very soon.
Most abdominal aortic aneurysms are caused by atherosclerosis, a condition caused when fat (mostly cholesterol) carried in the blood builds up in the inner wall of the aorta. As more and more fat attaches to the aortic wall, the wall itself becomes abnormally weak and often results in an aneurysm or bulge.
Aortic aneurysms occur when a weakness develops in a part of the wall of the aorta. The aorta is the large blood vessel that carries oxygen-rich blood away from the heart to the rest of the body.
Aortic aneurysms occur when a weakness develops in a part of the wall of the aorta. The aorta is the large blood vessel that carries oxygen-rich blood away from the heart to the rest of the body.
(Illustration by Electronic Illustrators Group.)
Aortic aneurysms are also caused by a breakdown of the muscular middle layer of the artery wall, by high blood pressure, by direct injury to the chest, and although rare, by bacteria that can infect the aorta.


Silent, stable aneurysms are often detected when a person has an x ray as part of a routine examination or for other medical reasons. Otherwise, when chest, abdominal, or back pain is severe, aortic aneurysm is suspected and x-ray (radiographic) studies can confirm or rule out that condition.

Key terms

Atherosclerosis — The accumulation of fat on the inner wall of an artery. This fat is largely made up of cholesterol being carried in the blood.
Dacron — A synthetic polyester fiber used to surgically repair damaged sections of blood vessel walls.


Aortic aneurysms are potentially life-threatening conditions. Small aneurysms should be monitored for their rate of growth and large aneurysms require consideration for a surgical repair. The most common method of surgical repair is to cut out the bulging section of artery wall and sew a Dacron fiber material into its place in the vessel wall.


Only 1-2% of people die from having surgical repair of an aortic aneurysm. However, if the aneurysm is untreated and eventually ruptures, less than half of the people with ruptured aneurysms will survive. The challenge for the physician is to decide when or if to do the preventive surgery.


Aneuryms can develop in people with atherosclerosis. High blood pressure can also lead to this condition. Although no definite prevention exists, lifestyle and dietary changes that help lower blood pressure and the amount of fat in the blood stream may slow the development of aneurysms.



van der Vleit, J. Adam, and Albert P. M. Boll. "Abdominal Aortic Aneurysm." The Lancet 349 (March 22, 1997): 863.


American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300.
National Heart, Lung and Blood Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 251-1222.

a·or·tic an·eu·rysm

diffuse or circumscribed dilation of a portion of the aorta (for example, abdominal aortic aneurysm, aortic arch aneurysm).
See also: dissecting aneurysm.

aortic aneurysm

a localized dilation of the wall of the aorta caused by atherosclerosis, hypertension, connective tissue disease such as Marfan's, or less frequently, syphilis. The lesion may be a saccular distension or a fusiform or cylindrical swelling of a length of the vessel. Syphilitic aneurysms almost always occur in the thoracic aorta and usually involve the arch of the aorta. The more common atherosclerotic aneurysms are usually in the abdominal aorta below the renal arteries and above the bifurcation of the aorta. These lesions often contain atheromatous ulcers covered by thrombi that may discharge emboli, causing obstruction of smaller vessels. See also dissecting aneurysm.
enlarge picture
Ruptured abdominal aortic aneurysm

aortic aneurysm

A fusiform swelling of the aorta, which is linked to atherosclerosis, most (±75%) of which occur in the abdominal aorta.
Clinical findings
Most aortic aneurysms are asymptomatic and found incidentally during physical examination (PE); if pain is present, it is gnawing, relieved by positional changes and often pulsating in character.
PE, CT, US, MRI, digital subtraction angiography, aortic angiography.
Natural history
AAs enlarge with time; 15% to 20% rupture in 1 year if < 6 cm in diameter; 50% rupture if ≥ 6 cm.
Elective replacement of AA with synthetic vascular graft if > 4 cm and patient is stable; for large AAs, Creech’s intrasaccular approach, which places the graft inside of the aneurysm, is associated with the least morbidity.

aortic aneurysm

Cardiology A fusiform swelling of the aorta, which is linked to ASHD, ±75% of which occur in the abdominal aorta Clinical Most are asymptomatic and emerge as an incidental finding during physical examination–PE; if pain is present, it is gnawing, relieved by positional changes, and often pulsating in character Diagnosis PE, CT, US, MRI, digital subtraction angiography, aortic angiography Natural history AAs enlarge with time; 15% to 20% rupture in 1 yr if < 6 cm in diameter; 50% rupture if ≥ 6 cm Management Elective replacement of AA with synthetic vascular graft if > 4 cm and Pt is stable; for large AAs, Creech's intrasaccular approach, which places the graft inside of the aneurysm is associated with the least morbidity. See Aortic dissection.

a·or·tic an·eur·ysm

(AA) (ā-ōr'tik an'yūr-izm)
Diffuse or circumscribed dilation of a portion of the aorta.
See also: dissecting aneurysm
Synonym(s): antimycotic.
Enlarge picture

aortic aneurysm

An aneurysm affecting any part of the aorta from the aortic valve to the iliac arteries. The dilated artery is usually asymptomatic, detected as an incidental finding during imaging. See: illustration
See also: aneurysm

aortic aneurysm

A dangerous sac-like widening (dilation) of the wall of the AORTA. Aortic aneurysm was once most commonly caused by SYPHILIS but is now usually the result of degradation of the extracellular matrix proteins elastin and collagen by matrix metalloproteinases 2, 8 and 9 and by oxidative stress, chronic inflammation and genetic influences.

a·or·tic an·eur·ysm

(ā-ōr'tik an'yūr-izm)
Diffuse or circumscribed dilation of a portion of the aorta (e.g., abdominal aortic aneurysm, aortic arch aneurysm).


a sac formed by the localized dilatation of the wall of an artery, vein or the heart.

aortic aneurysm
see aortic aneurysm.
arteriovenous aneurysm
an abnormal communication between an artery and a vein in which the blood flows directly into a neighboring vein or is carried into the vein by a connecting sac.
atherosclerotic aneurysm
one arising as a result of weakening of the tunica media in severe atherosclerosis.
bacterial aneurysm
an infected aneurysm caused by bacteria.
berry aneurysm
a small saccular aneurysm of a cerebral artery, usually at the junction of vessels in the circle of Willis; such aneurysms frequently rupture, causing subarachnoid hemorrhage. Called also brain aneurysm.
cardiac aneurysm
thinning and dilatation of a portion of the wall of the left ventricle, usually a consequence of myocardial infarction.
cirsoid aneurysm
dilatation and tortuous lengthening of part of an artery.
compound aneurysm
one in which some of the layers of the wall of the vessel are ruptured and some merely dilated. Called also mixed aneurysm.
congenital aneurysm
observed sporadically in the aorta and pulmonary artery.
dissecting aneurysm
one resulting from hemorrhage that causes lengthwise splitting of the arterial wall, producing a tear in the inner wall (intima) and establishing communication with the lumen of the vessel; it usually affects the thoracic aorta. Seen most commonly in horses and caused by larvae of Strongylus vulgaris. See strongylosis. A specific disease of turkeys.
fusiform aneurysm
a spindle-shaped aneurysm.
infected aneurysm
one produced by growth of microorganisms (bacteria or fungi) in the vessel wall, or infection arising within a pre-existing arteriosclerotic aneurysm.
inherited aortic aneurysm
causes a high mortality rate in the affected cattle breed. The defect is in the abdominal aorta.
lung aneurysm
may result from the lodgement of pulmonary emboli; rupture and pulmonary hemorrhage are potential sequelae.
mixed aneurysm
compound aneurysm.
mycotic aneurysm
an infected aneurysm caused by fungi.
false aneurysm.
racemose aneurysm
cirsoid aneurysm.
sacculated aneurysm
a saclike aneurysm.
varicose aneurysm
one formed by rupture of an aneurysm into a vein. See also aneurysmal varix.
venous aneurysm
see venous dilatation.
verminous aneurysm


pertaining to or emanating from the aorta. See also aortic arch.

aortic aneurysm
occurs most often in dogs, where it is caused by Spirocerca lupi larvae, turkeys and primates, causing dyspnea, cyanosis and coughing. May be congenital affecting the aortic trunk and the arch sometimes associated with aneurysm of an aortic sinus. See also copper nutritional deficiency.
aortic aneurysm, inherited
see inherited aortic aneurysm.
aortic annulus fibrosus
the fibrous ring in the wall of the root of the aorta. In the bovine heart the ring carries the ossa cordis (see os2 cordis).
aortic base rupture
rupture of the vessel just above the semilunar valves.
aortic bodies
small neurovascular structures on either side of the aorta in the region of the aortic arch. The left body is located at the angle between the left subclavian artery and the aorta, and the right at the junction of the right subclavian and right common carotid arteries. They contain chemical receptors which send impulses through the afferent branches of the vagus nerve and are involved in regulating respiration so as to ensure an appropriate partial pressure of oxygen in the arterial blood.
aortic body tumors
single or multiple nodules within the pericardial sac near the base of the heart. Malignant tumors may invade the anterior mediastinum. Called also heart base tumor.
aortic bulb
the dilated part of the aorta at its origin, caused by the swellings of the aortic sinuses.
aortic coarctation
constriction of the aorta at the site of entry of the ductus arteriosus causing a syndrome similar to that of stenosis of the aortic valve.
aortic cystic medionecrosis
pools of ground substance within the elastic media of the aorta. May predispose to arterial aneurysm but this material is present in the aortas of normal horses.
aortic depressor nerve
pressure receptors in the aortic arch and thoracic aorta which assist in maintaining circulatory equilibrium by communicating pressure changes through the aortic depressor nerve, an afferent branch of the vagus nerve; stimulation causes heart slowing and vasodilation.
aortic dextraposition
the aorta receives blood from the right ventricle. There are a number of variations of the basic defect. The common one is the aorta overriding the septum, which is defective, so that the aorta receives blood from both ventricles. The clinical syndrome includes dyspnea and cyanosis from birth, usually with a loud systolic murmur. Affected animals are not viable.
aortic embolism
occurs in cats in association with feline cardiomyopathy and rarely in dogs. Acute pain with paresis to paralysis in the hindlegs, cold, cyanotic feet and no femoral pulse are signs of the condition.
aortic hiatus
an opening in the diaphragm through which the aorta, thoracic duct, the right and/or left azygos veins pass.
aortic-ilial embolism
see iliac artery thrombosis.
aortic mineralization
is one of the early lesions in poisoning by plants that induce mineralization of tissues, e.g. solanummalacoxylon. In combination with lesions in the myocardium causes a syndrome of congestive heart failure.
aortic nerve
see cardiac depressor nerve.
aortic palpation
the aorta is easily palpable per rectum in cattle and horses; valuable as a clinical sign only in cases of thrombosis at the bifurcation; incision at this point has been used as a means of euthanasia in an emergency.
aortic-pulmonary window
an anomaly of the aorta in which there is an opening between the ascending portion of the aorta and the pulmonary artery; clinical signs are similar to those of patent ductus arteriosus, but surgical correction is much more difficult.
aortic regurgitation
see valvular regurgitation.
aortic root
the part of the aorta attached to the atrioventricular fibrous rings and myocardium.
aortic rupture
1. in horses is caused by weakening of the wall of the aorta by migrating strongyle larvae. In cattle the cause may be onchocerciasis, in pigs experimental diets deficient in copper. Sudden death results from cardiac tamponade or dissecting aneurysm into the ventricular muscle.
2. sudden death in growing turkeys due to dissecting aneurysmal rupture of the aorta and death due to internal hemorrhage; the cause is unknown. Copper deficiency is suspected as a cause in several animal species.
aortic sac
the merged ventral aortae of the embryo which supplies blood to the aortic arches.
aortic septal defect
a congenital anomaly in which there is abnormal communication between the ascending aorta and the pulmonary artery just above the semilunar valves.
aortic sinus
the three pouch-like dilatations of the aortic bulb which carry the cusps of the aortic valve. The coronary arteries arise from the left caudal and the cranial sinuses.
aortic subvalvular stenosis
in dogs and pigs is possibly an inherited defect. Characterized by stenosis of the aorta just below the semilunar valves. In pigs, it causes congestive heart failure in the newborn, but in affected dogs severity increases with age so that clinical effects may not be apparent until the patients are older.
aortic thromboembolism
thrombosis is the usual forerunner of embolism, pieces of the thrombus breaking off the main mass and lodging in more distal parts of the vascular system. See also aortic embolism (above), verminous mesenteric arteritis, iliac artery thrombosis.
Enlarge picture
Aortic thromboembolism in a cat. By permission from Nelson RW, Couto CG, Small Animal Internal Medicine, Mosby, 2003
aortic valve
the valve at the entrance to the aorta from the left ventricle made up of three semilunar leaflets or valvulae.
aortic valve rupture
rupture of the medial cusp is recorded as a cause of sudden death in horses usually as a sequel to endocarditis.
aortic valvular disease
stenosis is rarely an acquired disorder, but may be an inherited defect in several species. In cats and rarely dogs, restrictive cardiomyopathy may be a cause of subvalvular aortic obstruction. Valvular incompetence may be congenital or acquired and results in diastolic overloading of the left ventricle with a characteristic water-hammer pulse and diastolic murmur. See also aortic stenosis, aortic subvalvular stenosis (above).
aortic vestibule
the cranial part of the left ventricular cavity leading to the root of the aorta in the avian heart.

Patient discussion about aortic aneurysm

Q. Is there a good screening test for aortic abdominal aneurysm? A friend of mine was diagnosed with an aortic abdominal aneurysm. I am afraid i might have this condition too. is there any screening test that is good for me?

A. Today there are "mobile" testing centers that charge to use ultrasound technology to detect such things as AAA. I would highly recommend it only because it can act as a preventative measure. I am 50 years old and just suffered a ruptured AAA that very nearly killed me. I was the fortunate one. This very possibly could have detected it before it actually ruptured. You may want to check in your local areas for these mobile testing centers.

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