(See also Overview of Aortic Aneurysms Overview of Aortic Aneurysms Aneurysms are abnormal dilations of arteries caused by weakening of the arterial wall. Common causes include hypertension, atherosclerosis, infection, trauma, and hereditary or acquired connective... read more 
, Abdominal Aortic Aneurysms Abdominal Aortic Aneurysms (AAA) Abdominal aortic diameter ≥ 3 cm typically constitutes an abdominal aortic aneurysm. The cause is multifactorial, but atherosclerosis is often involved. Most aneurysms grow slowly (~10%/year)... read more 
, and Thoracic Aortic Aneurysms Thoracic Aortic Aneurysms A thoracic aortic diameter ≥ 50% larger than normal is considered an aneurysm (normal diameter varies by location). Most thoracic aortic aneurysms do not cause symptoms, although some patients... read more 
.)
Risk factors for aneurysms of aortic branch arteries include
Cigarette smoking
Older age
Localized infection can cause mycotic aneurysms.
Subclavian artery aneurysms sometimes occur in patients with cervical ribs or thoracic outlet compression syndrome Thoracic Outlet Compression Syndromes (TOS) Thoracic outlet compression syndromes are a group of poorly defined disorders characterized by pain and paresthesias in a hand, the neck, a shoulder, or an arm. They appear to involve compression... read more .
Aneurysms of the arteries of the splanchnic circulation are uncommon. About 60% occur in the splenic artery, 20% in the hepatic artery, 5.5% in the superior mesenteric artery.
Splenic artery aneurysms are more common in women than men (4:1). Causes include medial fibromuscular dysplasia Fibromuscular Dysplasia Fibromuscular dysplasia includes a heterogenous group of nonatherosclerotic, noninflammatory arterial changes, causing some degree of vascular stenosis, occlusion, or aneurysm. Fibromuscular... read more 
, portal hypertension Portal Hypertension Portal hypertension is elevated pressure in the portal vein. It is caused most often by cirrhosis (in North America), schistosomiasis (in endemic areas), or hepatic vascular abnormalities. Consequences... read more , multiple pregnancies, penetrating or blunt abdominal trauma, pancreatitis Overview of Pancreatitis Pancreatitis is classified as either acute or chronic. Acute pancreatitis is inflammation that resolves both clinically and histologically. Chronic pancreatitis is characterized by histologic... read more , and infection.
Hepatic artery aneurysms occur in more men than women (2:1). They may result from previous abdominal trauma, illicit IV drug use, medial degeneration of the arterial wall, or periarterial inflammation.
Renal artery aneurysms may dissect or rupture, causing acute occlusion Acute renal artery occlusion Renal artery stenosis is a decrease in blood flow through one or both of the main renal arteries or their branches. Renal artery occlusion is a complete blockage of blood flow through one or... read more 
.
Superior mesenteric artery aneurysms occur equally in men and women. Causes include fibromuscular dysplasia, cystic medial necrosis, and trauma.
Symptoms and Signs of Aortic Branch Aneurysms
Many aortic branch aneurysm are asymptomatic. Symptoms (when they occur) vary depending on the location and artery affected.
Subclavian aneurysms can cause local pain, a pulsating sensation, venous thrombosis or edema (due to compression of adjacent veins), distal ischemic symptoms, transient ischemic attacks, stroke, hoarseness (due to compression of the recurrent laryngeal nerve), or impaired motor and sensory function (due to compression of the brachial plexus).
Splenic artery aneurysm may cause left upper quadrant abdominal pain. Hepatic artery aneurysm may cause right upper quadrant pain and jaundice. Superior mesenteric aneurysms may cause generalized abdominal pain and ischemic colitis.
Regardless of location, mycotic or inflammatory aneurysms may cause local pain and sequelae of systemic infection (eg, fever, malaise, weight loss).
Diagnosis of Aortic Branch Aneurysms
Ultrasonography, CT scan, or other axial imaging study
With the routine availability of axial diagnostic imaging, many aneurysms are diagnosed before rupture. Calcified asymptomatic or occult aneurysms may be seen on x-rays or other imaging tests done for other reasons. Ultrasonography or CT is typically used to detect or confirm aortic branch aneurysms. Angiography is typically reserved for treatment or to evaluate distal organ perfusion.
Treatment of Aortic Branch Aneurysms
Open repair or sometimes endovascular stent grafting
Treatment is surgical removal and replacement with a graft. Endovascular repair is an option for some patients. The decision to repair asymptomatic aneurysms is based on risk of rupture, extent and location of the aneurysm, and perioperative risk.
Surgery for subclavian artery aneurysms may involve removal of a cervical rib (if present) before repair and replacement.
For splanchnic aneurysms, risk of rupture and death is as high as 10% and is particularly high for women of childbearing age and for patients with hepatic aneurysms (> 35%). Elective repair of splanchnic aneurysms is therefore indicated for
Aneurysms > 2 cm in diameter
Aneurysms in pregnant women or women of childbearing age
Symptomatic aneurysms in any age group
Hepatic aneurysms
For splenic aneurysms, repair may consist of ligation without arterial reconstruction or aneurysm exclusion and vascular reconstruction. Depending on location of the aneurysm, splenectomy may be necessary.
Treatment of mycotic aneurysms is aggressive antibiotic therapy directed at the specific pathogen. Generally, these aneurysms must also be surgically repaired.
Key Points
Aortic branch aneurysms are rarer than abdominal or thoracic aortic aneurysms.
Many are incidentally discovered and often asymptomatic.
When symptoms occur, they vary depending on the location and artery affected.
Diagnosis is often first suspected based on an incidental x-ray finding, and confirmed using ultrasonography and CT.
Treat with elective surgical repair and antibiotics in the case of mycotic aneurysms.
In general, indications for elective surgery are based on risk of rupture, extent and location of the aneurysm, and perioperative risk. Pregnant women or women of child-bearing age with splanchnic aneurysms and patient with hepatic aneurysms should be operated on electively because of the high risk of rupture.
