An aortic aneurysm is a localized bulge or swelling in the wall of the aorta. This large artery originates from the heart, extending through the chest and abdomen, and distributes blood throughout the body. It occurs when a weakened aortic wall segment expands under blood pressure, risking rupture or dissection.
Types of Aortic Aneurysms
Aortic aneurysms are primarily categorized by their location. Abdominal aortic aneurysms (AAA) occur in the abdominal aorta and are the most common type. These typically develop below the renal arteries, which supply blood to the kidneys.
Thoracic aortic aneurysms (TAA) form in the chest aorta. They include aneurysms of the aortic root, ascending aorta, aortic arch, and descending aorta. Less common than AAAs, TAAs also pose health risks.
Aneurysms are also described by their shape. Fusiform aneurysms are symmetrical, spindle-shaped bulges involving the entire circumference of the aortic wall. Saccular aneurysms are asymmetrical, blister-like outpouchings affecting only a localized portion of the aortic wall.
Causes and Risk Factors
The development of an aortic aneurysm is often linked to a weakening of the aortic wall. Atherosclerosis, the buildup of fatty plaques in arteries, is a common contributor, leading to hardening and narrowing of blood vessels. High blood pressure exerts increased force against the aortic walls, promoting weakening and expansion.
Smoking is a strong risk factor, especially for abdominal aortic aneurysms, and can accelerate their growth. Genetic predispositions also play a role; a family history of aortic aneurysms increases an individual’s susceptibility, with approximately one in five people having a first-degree relative affected by an abdominal aortic aneurysm.
Inherited conditions, such as Marfan syndrome, Ehlers-Danlos syndrome, and Loeys-Dietz syndrome, are associated with weakened connective tissues, including the aorta, making individuals more prone to aneurysm formation. A bicuspid aortic valve, where the heart’s aortic valve has two leaflets instead of the usual three, also elevates the risk. Less common causes include severe trauma and infections that can directly damage the aortic wall.
Symptoms and Diagnosis
Aortic aneurysms often develop silently, with no noticeable symptoms in their early stages. Many are discovered incidentally during medical imaging for unrelated health concerns. This asymptomatic nature highlights why regular check-ups are important for those with risk factors.
When symptoms do occur, they relate to the aneurysm’s size, location, or rapid expansion/leakage. An abdominal aortic aneurysm may cause a pulsating sensation in the abdomen or persistent pain in the abdomen or back, which can sometimes radiate to the buttocks and legs. For thoracic aortic aneurysms, individuals may experience chest or upper back pain, hoarseness, or difficulty swallowing due to pressure on surrounding structures.
Diagnosis relies on imaging tests to visualize the aorta. An abdominal ultrasound is often used for initial screening and to monitor abdominal aortic aneurysm size over time. If an aneurysm is suspected, a Computed Tomography (CT) scan provides more detailed cross-sectional images, revealing the aneurysm’s precise size, shape, and location. Magnetic Resonance Imaging (MRI) offers another detailed view of the aorta, using magnetic fields and radio waves. Echocardiography may be used to assess thoracic aneurysms.
Monitoring and Treatment
Management of an aortic aneurysm depends on its size, growth rate, and whether it is causing symptoms. For smaller aneurysms that are not rapidly enlarging, a strategy known as watchful waiting or active surveillance is used. This involves regular imaging tests, such as ultrasound, CT scans, or MRI, to monitor the aneurysm’s size. For instance, abdominal aortic aneurysms measuring between 3.0 and 3.4 centimeters might be monitored with an ultrasound every three years, while those 3.5 to 4.4 centimeters may require yearly surveillance.
Active treatment is considered for aneurysms that are larger, growing rapidly, or causing symptoms, as these factors increase the risk of rupture. Generally, intervention is recommended for abdominal aortic aneurysms reaching approximately 5.5 centimeters, though this can be individualized based on patient factors like age and overall health. Two primary surgical approaches are available.
Open surgical repair involves an incision to access the aorta, where the weakened segment is removed and replaced with a synthetic graft. This well-established procedure offers a durable repair.
Alternatively, endovascular aneurysm repair (EVAR for abdominal, TEVAR for thoracic) is a less invasive technique. It uses small punctures, often in the groin, to guide a catheter to the aneurysm site. A stent graft, a fabric tube supported by a metal mesh, is then deployed within the aorta to reinforce the weakened area and redirect blood flow, effectively excluding the aneurysm from circulation. While endovascular approaches offer benefits like shorter hospital stays and faster recovery, they often require ongoing surveillance due to potential for secondary interventions.