a sac formed by the localized dilatation of the wall of an artery, a vein, or the heart.
Classification of aneurysms. All three tunica layers are involved in true aneurysms (fusiform and saccular). In false aneurysms, blood escapes between tunica layers and they separate. If the separation continues, a clot may form, resulting in a dissecting aneurysm. From Copstead and Banasik, 2000.
aneurys´mal. The chief signs of an arterial
aneurysm are the formation of a pulsating tumor, and often a bruit (aneurysmal bruit) heard over the swelling. Sometimes there are symptoms from pressure on contiguous parts.
The most common site for an arterial aneurysm is the abdominal aorta. A true
aneurysm results from formation of a sac by the arterial wall with at least one unbroken layer. It is most often associated with atherosclerosis
. A false
aneurysm usually is caused by trauma. In this case, the wall of the blood vessel is ruptured and blood escapes into surrounding tissues and forms a clot. Because of pressure within the clot arising from the heart's contractions, the clot often pulsates against the examiner's hand as does a true aneurysm.
Although atherosclerosis is responsible for most arterial aneurysms, any injury to the middle or muscular layer of the arterial wall (tunica media)
can predispose the vessel to stretching of the inner and outer layers of the artery and the formation of a sac. Other diseases that can lead to an aneurysm include syphilis, cystic medionecrosis, certain nonspecific inflammations, and congenital defects in the artery.
It is possible for a person to be unaware of a small aneurysm for years. About 80 per cent of all abdominal aneurysms are palpable and may be noticed on a routine physical examination. One should be particularly alert to the possibility of an aneurysm in persons with a history of cardiovascular disease, hypertension, or peripheral vascular disease.
Aneurysms tend to increase in size, presenting a problem of increasing pressure against adjacent tissues and organs and a danger of rupture. When an aneurysm ruptures, a critical situation ensues. The patient with a ruptured aortic aneurysm exhibits severe pain and blood loss, leading to shock. A ruptured cerebral aneurysm produces neurologic symptoms and can resemble the clinical picture of stroke syndrome
Treatment of aneurysm depends on the vessel involved, size of the aneurysm, and general health status of the patient.
an aneurysm arising in a large artery, most commonly the abdominal aorta, as a result of weakening of the wall in severe atherosclerosis; called also atherosclerotic 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.
bacterial aneurysm an infected aneurysm caused by bacteria.
) 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 cerebral aneurysm
cardiac aneurysm thinning and dilatation of a portion of the wall of the left ventricle, usually a consequence of myocardial infarction.
dilatation and tortuous lengthening of part of an artery; called also racemose aneurysm
one in which some of the layers of the wall of the vessel are ruptured and some merely dilated; called also mixed 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 (see aortic dissection
) but can also occur in other large arteries. See illustration.
one in which the entire wall is injured and the blood is contained by the surrounding tissues, with eventual formation of a sac communicating with the artery (or heart). See illustration.
fusiform aneurysm a spindle-shaped aneurysm; see illustration.
infected aneurysm one produced by growth of microorganisms (bacteria or fungi) in the vessel wall, or infection arising within a preexisting arteriosclerotic aneurysm.
mycotic aneurysm an infected aneurysm caused by fungi.
saccular aneurysm (sacculated aneurysm) a saclike aneurysm; see illustration.
false aneurysm (def. 1).
varicose aneurysm one formed by rupture of an aneurysm into a vein.
aneurysm, aneurism (an'yu-rizm) [Gr. aneurysma, a widening]
Localized abnormal dilatation of a blood vessel, usually an artery, due to a congenital defect or weakness in the wall of the vessel. As aneurysms dilate, they become more and more vulnerable to rupture. aneurysmal
As people age, the combined effects of high blood pressure and atherosclerotic weakening of arteries produce most aneurysms in the aorta. Congenital malformations of arteries in the circle of Willis are relatively common causes of aneurysms in the brain. Aneurysms in the chest or peripheral arteries are sometimes caused by blunt trauma or by bacterial or mycotic infection.
abdominal aortic aneurysm Abbreviation: AAA
A localized dilatation (saccular, fusiform, or dissecting) of the wall of the abdominal aorta. It is generally found to involve the renal arteries and frequently the iliac arteries. Occasionally the dilatation can extend upward through the diaphragm.
The patient is usually asymptomatic, and diagnosis is made accidentally during a routine physical examination or abdominal x-ray or during screening of the elderly hypertensive male. Serial ultrasounds confirm the diagnosis and determine the size, shape, and location of the aneurysm. Small, asymptomatic aneurysms may be followed over time, rather than repaired (see below). Computed tomography, magnetic resonance imaging, or aortography may assist in confirming the diagnosis and the condition of proximal and distal vessels.
Symptoms, when present, include generalized abdominal pain, low back pain unaffected by movement, and sensations of gastric or abdominal fullness. Sudden severe lumbar or abdominal pain radiating to the flank and groin, esp. if associated with tachycardia and hypotension, may indicate enlargement or imminent rupture. Signs can include a pulsating mass in the periumbilical area and a systolic bruit over the aorta.
Untreated abdominal aortic aneurysms gradually enlarge and in some instances rupture. The likelihood of rupture increases for aneurysms that are larger than 5.5 cm. Surgical repair is recommended for all aneurysms larger than 6 cm. If an aneurysm is tender and known to be enlarging rapidly (no matter what its size), surgery is strongly recommended. Surgical therapy consists of replacing the aneurysmal segment with a synthetic fabric (Dacron) graft. Immediate surgery is indicated for a ruptured aortic abdominal aneurysm. An alternative treatment to traditional laparotomy is to insert a bypass graft percutaneously into the aorta.
In acute dissection of an abdominal aortic aneurysm, oxygenation, blood pressure and cardiac rhythm are closely monitored, and a pulmonary artery line may be inserted to monitor hemodynamics. The patient is observed for signs of rupture, which may be fatal. He will require an intravenous line via a large-bore catheter, a urinary catheter, and an arterial line and pulmonary artery catheter to monitor fluid and hemodynamic balance. Additionally, cardiac monitor electrodes will be placed, and a nasogastric tube inserted.
Prescribed medications are administered to manage contributory factors such as hypertension and hypercholesterolemia; a beta-adrenergic blocking agent may be prescribed to reduce the risk of expansion and rupture. The patient is instructed in their use and taught about adverse effects that should be reported. In acute aortic rupture, admission to the intensive care unit is arranged, a blood sample is obtained for typing and cross-matching, and a large-bore (14G) venous catheter is inserted to facilitate blood replacement. The patient is prepared for and informed about elective surgery if indicated or emergency surgery if rupture occurs. The patient will require an intravenous line via a large-bore catheter, a urinary catheter, and an arterial line and pulmonary artery catheter to monitor fluid and hemodynamic balance. Additionally, cardiac monitor electrodes will be placed, and a nasogastric tube inserted. During surgery the patient will be intubated and mechanically ventilated, and such therapies will most likely still be in place postoperatively in the ICU.
Desired outcomes include the patient's ability to express anxiety, use support systems, and perform stress reduction techniques that assist with coping; demonstrated abatement of physical signs of anxiety; avoidance of activities that increase the risk of rupture; understanding of and cooperation with the prescribed treatment regimen; ability to identify indications of rupture and to institute emergency measures; maintenance of normal fluid and blood volume in acute situations; and recovery from elective or emergency surgery with no complications. Generally post-operative patients are assisted to ambulate by the second day after surgery. Pain management and psychological support are extremely important during the acute postoperative period.
Because of the relatively high incidence of AAA in men over age 60 (esp. smokers or men with intermittent claudication) and patients with myesthenia gravis, screening for AAA is recommended for these people.
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
An aneurysm of congenital or traumatic origin in which an artery and vein become connected. Symptoms may include pain, expansive pulsation, and bruits or, occasionally, high-output heart failure.
Aneurysm due to degeneration or weakening of the arterial wall caused by atherosclerosis.
Bérard's aneurysm See: Bérard's aneurysm
A small saccular congenital aneurysm of a cerebral vessel. It communicates with the vessel by a small opening. Rupture of this type of aneurysm may cause subarachnoid hemorrhage, a devastating form of stroke.
Aneurysm of a blood vessel in the brain.
Charcot-Bouchard aneurysm See: Charcot-Bouchard aneurysm
A dilatation of a network of vessels commonly occurring on the scalp. The mass may form a pulsating subcutaneous tumor. Synonym: racemose aneurysm
Aneurysm in which some of the layers of the vessel are ruptured and others dilated.
Aneurysm in which the blood makes its way between the layers of a blood vessel wall, separating them; a result of necrosis of the medial portion of the arterial wall. See: aortic aneurysm for illus.
Aneurysm in which all the walls of a blood vessel dilate more or less equally, creating a tubular swelling. See: aortic aneurysm for illus.
Aneurysm due to bacterial infection.
racemose aneurysmCirsoid aneurysm.
Aneurysm in which there is weakness on one side of the vessel; usually due to trauma. It is attached to the artery by a narrow neck. See: aortic aneurysm for illus.
Aneurysm forming a blood-filled sac between an artery and a vein.
Localized expansion and weakening of the wall of a vein.
a sac formed by the localized dilatation of the wall of an artery, vein or the heart.
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.
one arising as a result of weakening of the tunica media in severe atherosclerosis.
an infected aneurysm caused by bacteria.
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
thinning and dilatation of a portion of the wall of the left ventricle, usually a consequence of myocardial infarction.
dilatation and tortuous lengthening of part of an artery.
one in which some of the layers of the wall of the vessel are ruptured and some merely dilated. Called also mixed aneurysm.
observed sporadically in the aorta and pulmonary artery.
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.
a spindle-shaped 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.
may result from the lodgement of pulmonary emboli; rupture and pulmonary hemorrhage are potential sequelae.
an infected aneurysm caused by fungi.
a saclike aneurysm.
one formed by rupture of an aneurysm into a vein. See also aneurysmal varix