Aneurysms

Aneurysms:

Definition:

An aneurysm is a localized, permanent dilatation of an artery greater than 1.5 times its normal diameter. Aneurysms occur all over the body and in any vessels, including the aort

a, and the iliac, femoral, popliteal, subclavian, axillary and carotid arteries.

Classification of aneurysms:

Aneurysms can be grouped according to their:

A.    Wall:

1)    True aneurysm: containing all 3 layers of an arterial wall (intima, media, and adventitia)

2)    False aneurysms: having a single layer of fibrous tissue as the wall of the sac

B.     Morphology (shape):

1)    Fusiform: when involving the total circumference of the artery.

2)    Saccular: when arising from a distinct portion of the wall

3)    Dissecting:

C.     Etiology:

1)    Atherosclerotic

2)    Mycotic (infectious due to bacteria rather than fungi)

3)    Collagen vascular disease

4)    Traumatic

Clinical features:

Aneurysms may be asymptomatic and discovered accidentally on routine examination as in most cases of abdominal aortic aneurysms.

Symptoms tend to arise from:

1-    Aneurysm expansion and pressure on nearby structures like nerves, veins, arteries, bone, skin,…etc

2-    Aneurysm thrombosis leading to ischemia of the organ or tissue supplied by that artery e.g. thrombosis of a splenic aneurysm may lead to splenic infarction. Thrombosis of a popletial aneurysm may lead to gangrene in the foot.

3-     Aneurysm embolization: the sac of the aneurysm usually contains thrombi, which if embolize will lodge in distal arteries and lead to ischemia, e.g. blue toe syndrome due to abdominal or thoracic aortic aneurysm emboliztion.

Note: blue toe syndrome is gangrene of one or both big toes due to multiple embolizations from an aortic aneurysm (thoracic or abdominal)

4-    Aneurysm rupture: leading to internal or external bleeding depending on the artery involved and the site of rupture. E.g. ruptured abdominal aortic aneurysm leads to a usually fatal retroperitoneal or intraperitoneal hemorrhage.

Investigations:

      1)    Duplex ultrasound

      2)    Angiography

      3)    CT and CT angiography

      4)    MRI and MRA

Treatment:

Depending on the involved artery, presentation and patients general condition, aneurysms can be treated by one of the following methods:

1-    Aneurysm excision with graft interposition (treatment of choice) as in most cases of true major artery aneuryms. E.g. aortic aneurysms, popliteal artery aneurysm, subclavian artery aneurysm,…etc

2-    Aneurysm repair: excision of the sac with repair of the artery as in most cases of false aneurysm repair. E.g. traumatic false aneurysm of descending thoracic aorta, femoral artery, popliteal artery,…etc

3-    Aneurysm excision with resection of supplying tissue. E.g. excision of a splenic artery aneurysm with splenectomy, excision of a renal artery aneurysm with partial or total nephrectomy.

4-    Aneurysm excision without arterial reconstruction proving that the blood supply to the distal tissue is unaffected. E.g. excision of a radial artery aneurysm in the presence of a normal and functioning ulnar artery.

5-    Endovascular aneurysmal  repair