Merck Manual

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Aortic Branch Aneurysms

By

Mark A. Farber

, MD, FACS, University of North Carolina;


Federico E Parodi

, MD, University of North Carolina School of Medicine

Last full review/revision Nov 2020| Content last modified Nov 2020
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Aneurysms may occur in any major aortic branch; such aneurysms are much less common than abdominal or thoracic aortic aneurysms. Symptoms vary depending on the location and artery affected but may include pain in areas where the aneurysm compresses nearby structures. Diagnosis is made by ultrasonography or CT angiography. Treatment is endovascular stent grafting or surgery.

Risk factors for aneurysms of aortic branch arteries include atherosclerosis, hypertension, cigarette smoking, and older age. Localized infection can cause mycotic aneurysms.

Subclavian artery aneurysms are sometimes associated with cervical ribs or thoracic outlet compression syndrome.

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, portal hypertension, multiple pregnancies, penetrating or blunt abdominal trauma, pancreatitis, 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.

Superior mesenteric artery aneurysms occur equally in men and women. Causes include fibromuscular dysplasia, cystic medial necrosis, and trauma.

Symptoms and Signs

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

  • Ultrasonography, CT scan, or other axial imaging study

With the routine availability of axial diagnostic imaging, many aneurysms are now 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

  • 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 should be operated on electively because of the high risk of rupture.

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