Aortic branch aneurysms are bulges (dilations) in the wall of the major arteries that come directly off of the aorta.
The aorta is the largest artery of the body. It receives oxygen-rich blood from the heart and distributes it to the body through smaller arteries that branch off of it. Aneurysms may occur in any major branch of the aorta. Such aneurysms are much less common than abdominal aortic aneurysms or thoracic aortic aneurysms.
Risk factors for aneurysms include
Infection in tissues near an artery can cause an infected aneurysm (mycotic aneurysm). Autoimmune diseases can cause inflammation in different arteries, leading to weakening of the arterial wall, and formation of aneurysms (inflammatory aneurysm).
Where Do Aortic Aneurysms Occur?
Aneurysms can develop anywhere along the aorta. Most develop in the abdominal aorta. The rest develop in the thoracic aorta, most commonly in the ascending aorta.
Subclavian artery aneurysms
Aneurysms in the subclavian artery (located in the upper part of the chest under the collarbone) sometimes occur in people with an extra rib located in the neck area (cervical rib) or thoracic outlet syndrome.
Aneurysms in the arteries of the abdominal organs
Aneurysms in the arteries that deliver blood to the digestive tract (splanchnic arteries) are uncommon. However, aneurysms may occur in arteries that supply blood to other organs, including the
- Spleen (splenic artery, about 60% )
- Liver (hepatic artery 20%)
- Intestine (superior mesenteric artery 5.5%)
- Kidneys (renal arteries)
Splenic artery aneurysms occur in more women than men. Causes include abnormal growth of muscle in the artery's wall (fibromuscular dysplasia), high blood pressure in the blood vessels connected to the liver (portal hypertension), multiple pregnancies (such as with twins or triplets), penetrating abdominal injury (stab wound) or blunt abdominal trauma (such as from a motor vehicle crash), inflammation of the pancreas (pancreatitis), and infection.
Hepatic artery aneurysms occur in more men than women. They may result from previous abdominal injury, use of illicit intravenous drug (such as heroin), damage to the wall of the artery, or inflammation of tissues around the artery.
Superior mesenteric artery aneurysms are relatively uncommon among aneurysms in the arteries that go to the abdominal organs. They may result from infections, atherosclerosis, and other disorders that weaken the arterial wall.
Renal artery aneurysms may dissect (the layers of the artery separate) or rupture, causing sudden blockage (occlusion) of blood flow to the kidneys and kidney failure.
Symptoms of aortic branch aneurysms vary depending on the organ that is deprived of blood. Regardless of location, infected or inflammatory aneurysms may cause pain in the area near the affected artery and symptoms of infection such as fever, weight loss, and a general feeling of illness. Furthermore, rupture of any type of aneurysm can cause rapid blood loss, pain at the site of the aneurysm, low blood pressure, and even death.
Subclavian aneurysms can cause shoulder or arm pain, a pulsating sensation, blood clots or swelling in nearby veins (due to pressure on the veins), transient ischemic attacks, stroke, or hoarseness or impaired nerve function (due to compression of the recurrent laryngeal nerve or brachial plexus).
Most aneurysms in the abdominal aortic branches do not cause any symptoms unless they rupture. Rarely, people with splenic artery aneurysms will have abdominal pain, nausea, and vomiting. People with hepatic artery aneurysms will have abdominal pain or yellowing of the skin (jaundice) if the aneurysm compresses the tubes that transport bile from the gallbladder to the intestine (the biliary tract). People with superior mesenteric artery aneurysms will have abdominal pain and bloody diarrhea (ischemic colitis), and people with renal artery aneurysms will have high blood pressure, abdominal or flank pain, or blood in the urine.
- Ultrasonography or computed tomography (CT)
Sometimes aneurysms that are not causing symptoms are discovered when an x-ray or another imaging test is done for another reason. However, most aortic branch aneurysms are not diagnosed before they rupture.
- Surgical repair of the aneurysm
- Often endovascular stent graft repair
Treatment is surgical repair of the aneurysm in which an artificial artery made of synthetic material (graft) is placed inside the aneurysm. The old arterial wall (aneurysm) is wrapped around the new graft.
Often, doctors do endovascular stent graft repair, which does not require surgery on the abdomen. To do an endovascular stent graft repair, doctors thread a long, thin wire through the large artery in the groin (femoral artery) and up to the aneurysm. Then they slide the stent graft, which is a thin tube like a collapsible straw, over the wire and inside the aneurysm. Then the stent graft is opened, forming a stable channel for blood flow.
The decision to repair aneurysms that are not causing symptoms is based on the risk of rupture, extent and location of the aneurysm, and the risks caused by other conditions the person may have. For splanchnic aneurysms, risk of rupture and death is high, particularly for women of childbearing age and for people with hepatic aneurysms, so aneurysms in these people are usually repaired even if they are not causing symptoms.
Surgery for subclavian artery aneurysms may involve removal of a cervical rib (if present) from the upper chest before repair and replacement.
Treatment of infected (mycotic) aneurysms is antibiotic therapy appropriate for the specific infectious organism. Generally, these aneurysms must also be surgically repaired once the infection has been treated.
© 2020 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Merck Manual Disclaimer