Aneurysm

Aneurysm: a sac formed by localized dilatation of an artery or vein

Thoracic aortic aneurysm:    In this disorder, the ascending, transverse, or descending part of the aorta widens abnormally.  A dissecting aneurysm indicates a hemorrhagic separation in the aortic wall, usually within the medial layer. A saccular aneurysm describes an outpouching of the arterial wall, with a narrow neck.  A fusiform aneurysm is a spindle shaped enlargement encompassing the entire aortic circumference.  Thoracic aortic aneurysms are most common in men between ages 50 and 70.  Some aneurysms progress to serious and eventually lethal complications.

Cause:  Usually this disorder occurs a s a consequence of atherosclerosis.  Other possible causes include infection of the aortic arch and descending segments, congenital defects, trauma, and syphilis.  Intimal tear in the ascending aorta as well as hypertension can initiate a dissecting aneurysm.

Symptoms:

Pain - In a dissecting aneurysm, pain usually occurs suddenly, with a tearing or ripping sensation in the thorax or anterior chest.  Pain may extend to the neck, shoulder, lower back, or abdomen but rarely reaches the jaw and arms.

Temporary loss of consciousness (syncope)
Pallor
Sweating
Shortness of breath
Tachycardia
Cyanosis
Leg weakness
Transient paralysis

Effects of saccular or fusiform aneurysms varies according to the aneurysm's size and location and degree of compression, distortion, or erosion of surrounding structures.

The patient may develop aortic valve insufficiency; diastolic murmur; substernal ache in his shoulders, lower back, or abdomen; marked respiratory distress, with dyspnea, brassy cough, or wheezing; hoarseness or loss of voice.

Treatment:

An extreme emergency: dissecting aortic aneurysm requires immediate attention.

To prevent further dissection, the doctor may order administration of antihypertensives, such as nitroprusside; negative inotropic agents that decrease contractile force, such as propranolol; oxygen for respiratory distress; narcotic for pain; I.V. fluids; and, if necessary, whole blood transfusions.

Depending on the extent of damage and the vessels involved, the patient may undergo vascular surgery.

Abdominal Aortic Aneurysm

Abdominal aortic aneurysm:  an abnormal dilation in the arterial wall, most commonly occurs in the aorta between the renal arteries and iliac branches.  More that 50% of all patients with untreated abdominal aneurysms die, primarily from aneurysmal rupture, within 2 years of diagnosis.  More than 85% die within 5 years

Causes:  Usually abdominal aortic aneurysm results from artherosclerosis.  Other possible causes include cystic medial necrosis, trauma, syphilis, and infection.

Symptoms:

When aneurysmal rupture isn't imminent, you may be able to see an asymptomatic pulsating mass in the periumbilical area.  Auscultation may reveal a systolic bruit over the aorta, and tenderness may be present on deep palpation.

Pressure on lumbar nerves may lead to lumbar pain that radiates to the flank and groin.

If the aneurysm ruptures into the peritoneal cavity, it causes severe, persistent abdominal and back pain, mimicking renal or ureteral colic.  The patient may hemorrhage; however, retroperitoneal bleeding may make such signs and symptoms as weakness, sweating, tachycardia, and hypotension appear rather subtle.

Treatment:

Usually, abdominal aneurysm requires resection of the aneurysm and replacement of the damaged aortic section with a Dacron graft.

If the aneurysm appears small and asymptomatic, the doctor may delay surgery.  However,  small aneurysms may rupture.  The patient must undergo regular physical examination and ultrasound checks to detect enlargement, which may forewarn rupture.

Femoral and Popliteal Aneurysms

Femoral and popliteal aneurysms:  Progressive atherosclerotic changes in the medial layer of the femoral and popliteal arteries may lead to aneurysm.  Aneurysmal formations may be fusiform (spindle -shaped) or saccular (pouchlike).  Fusiform aneurysms occur three times more frequently.

Femoral and popliteal aneurysm may occur as single or multiple segmental lesions, in many cases affecting both legs, and may accompany aneurysms in the abdominal aorta or iliac arteries.  Elective surgery before complications arise greatly improves prognosis.

Causes:  Femoral and popliteal aneurysms usually occur secondary to atherosclerosis, although in rare cases they may result from congenital weakness in the arterial wall. Other possible causes include blunt or penetrating trauma, bacterial infection, or peripheral vascular reconstructive surgery.

Symptoms:

Pain in the popliteal space.
Edema
Venous distention

Treatment:

Femoral and popliteal aneurysms requires surgical bypass and reconstruction of the artery, usually with an autogenous saphenous vein graft replacement.

Arterial occlusion that causes severe ischemia and gangrene may require leg amputation.

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