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:  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:  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.