Aortic aneurysm Health Dictionary

A localised swelling or dilatation of an artery (see ARTERIES) due to weakening of its wall. The most common sites are the AORTA, the arteries of the legs, the carotids and the subclavian arteries. The aorta is the largest artery in the body and an aneurysm may develop anywhere in it. A dissecting aneurysm usually occurs in the ?rst part of the aorta: it is the result of degeneration in the vessel’s muscular coat leading to a tear in the lining; blood then enters the wall and tracks along (dissects) the muscular coat. The aneurysm may rupture or compress the blood vessels originating from the aorta: the outcome is an INFARCTION in the organs supplied by the affected vessel(s). Aneurysms may also form in the arteries at the base of the brain, usually due to an inherited defect of the arterial wall.

Aneurysms generally arise in the elderly, with men affected more commonly than women. The most common cause is degenerative atheromatous disease, but other rarer causes include trauma, inherited conditions such as MARFAN’S SYNDROME, or acquired conditions such as SYPHILIS or POLYARTERITIS NODOSA. Once formed, the pressure of the circulating blood within the aneurysm causes it to increase in size. At ?rst, there may be no symptoms or signs, but as the aneurysm enlarges it becomes detectable as a swelling which pulsates with each heartbeat. It may also cause pain due to pressure on local nerves or bones. Rupture of the aneurysm may occur at any time, but is much more likely when the aneurysm is large. Rupture is usually a surgical emergency, because the bleeding is arterial and therefore considerable amounts of blood may be lost very rapidly, leading to collapse, shock and even death. Rupture of an aneurysm in the circle of Willis causes subarachnoid haemorrhage, a life-threatening event. Rupture of an aneurysm in the abdominal aorta is also life-threatening.

Treatment Treatment is usually surgical. Once an aneurysm has formed, the tendency is for it to enlarge progressively regardless of any medical therapy. The surgery is often demanding and is therefore usually undertaken only when the aneurysm is large and the risk of rupture is therefore increased. The patient’s general ?tness for surgery is also an important consideration. The surgery usually involves either bypassing or replacing the affected part of the artery using a conduit made either of vein or of a man-made ?bre which has been woven or knitted into a tube. Routine X-ray scanning of the abdominal aorta is a valuable preventive procedure, enabling ‘cold’ surgery to be performed on identi?ed aneurysms.... aneurysm

Narrowing of the AORTIC VALVE in the HEART which obstructs the ?ow of blood through it, with serious effects on the heart and the circulation. The muscle in the left ventricle works harder to compensate for the obstruction and thickens as a result. Stenosis is usually caused by the deposition of calcium on the valve and is commonly associated with ATHEROMA. Untreated, the condition leads to heart failure, but nowadays the stenosis can be treated surgically.... aortic stenosis

See also REGURGITATION. This is the back ?ow of blood through the AORTIC VALVE of the HEART into the left ventricle, caused by an incompetent valve. The failure to close may be caused by a congenital defect or by damage from disease. The defect may be cured by surgical replacement of the damaged valve with an arti?cial valve. (See HEART, DISEASES OF.)... aortic incompetence

The valve that controls the ?ow of blood from the AORTA to the left ventricle of the HEART.... aortic valve

An abnormal swelling that occurs at the junction of arteries supplying the brain. Berry aneurysms, which are usually due to a congenital weakness, can sometimes rupture, resulting in a subarachnoid haemorrhage.

(See also aneurysm.)... berry aneurysm

An abnormal communication between an artery and a vein. It is usually the result of an injury, such as a stab or a gunshot wound, which involves both a neighbouring artery and vein.... arterio-venous aneurysm

The condition in which a group of arteries become abnormally dilated and tortuous.... cirsoid aneurysm

that part of the aorta that extends from the ascending aorta, upward over the heart and then backward and down as far as the fourth thoracic vertebra. *Stretch receptors in its outer wall monitor blood pressure and form part of the system maintaining this at a constant level.... aortic arch

a surgical technique used to replace a diseased length of aorta, most often the abdominal aorta. It usually involves inserting into the aorta a flexible tube of artificial material, which functions as a substitute for the diseased section.... aortic replacement

a direct communication between an artery and vein, without an intervening capillary bed. It can occur as a congenital abnormality or it may be acquired following injury or surgery. It may affect the limbs, lungs, or viscera and may be single or multiple. If the connection is large, the short-circuiting of blood may produce heart failure. Large isolated arteriovenous aneurysms may be closed surgically.... arteriovenous aneurysm

(EVAR) a recently developed technique that involves the insertion of a covered metal *stent into an *aneurysm. The stent lines the aneurysm and thereby excludes it from the circulation, preventing further expansion and rupture. The delivery system containing the stents is introduced through the common femoral artery. *Fluoroscopy provides real-time imaging to guide placement of the stents and ensure they are in the correct anatomical position.... endovascular aneurysm repair

(TAVI) replacement of the aortic valve in patients with *aortic stenosis using a catheter-delivered prosthesis rather than open heart surgery. Usually the catheter is passed via the femoral artery, but sometimes it can be passed via the subclavian artery or through the wall of the left ventricle via a localized *thoracotomy.... transcatheter aortic valve implantation

a leak of the aortic valve resulting in reflux of blood from the aorta into the left ventricle during diastole. Aortic regurgitation is most commonly due to degenerative ‘wear and tear’ of the aortic valve. Other causes include dilatation of the aortic root with secondary dilatation of the aortic valve, scarring of the aortic valve as a result of previous acute rheumatic fever, or destruction of the valve by infection (see endocarditis). Mild cases are symptom-free, but patients more severely affected develop breathlessness, angina pectoris, and enlargement of the heart; all have a diastolic murmur. A badly affected valve may be replaced surgically with a prosthesis.... aortic regurgitation