Aortic Aneurysm
An aortic aneurysm is an abnormal bulging or widening of the aorta—the largest artery in the body that carries oxygenated blood from the heart to the rest of the body. An aneurysm occurs when a weakened area of the aortic wall balloons outward, creating a permanent dilation typically defined as 50% larger than the normal vessel diameter. Aortic aneurysms can occur in the chest (thoracic aortic aneurysm) or abdomen (abdominal aortic aneurysm), with the latter being more common. While many aneurysms grow slowly and cause no symptoms, they carry a serious risk of rupture, which is often fatal, making detection and monitoring critical.
What is it?
The aorta originates from the left ventricle of the heart and extends through the chest and abdomen, supplying blood to all major organs and tissues. It is divided into several segments: the ascending aorta (from the heart to the aortic arch), aortic arch (curving portion giving off branches to the head and arms), descending thoracic aorta (through the chest), and abdominal aorta (below the diaphragm). An aortic aneurysm develops when the structural integrity of the aortic wall deteriorates, leading to progressive dilation. The wall weakening involves degradation of elastin and collagen fibers, inflammation, and sometimes atherosclerotic changes. Most aneurysms are fusiform (circumferential widening) though some are saccular (localized outpouching).
Aortic aneurysms are classified by location: abdominal aortic aneurysms (AAA) are most common, typically occurring below the renal arteries and affecting 4-8% of older men; thoracic aortic aneurysms (TAA) occur in the chest and are subdivided into ascending aortic aneurysms (often associated with connective tissue disorders or bicuspid aortic valve), aortic arch aneurysms, and descending thoracic aortic aneurysms; and thoracoabdominal aneurysms involve both chest and abdominal segments. Risk factors vary by location but include age, male gender, smoking (strongest modifiable risk factor for AAA), hypertension (particularly important for TAA), atherosclerosis, family history, genetic conditions such as Marfan syndrome, Ehlers-Danlos syndrome, Loeys-Dietz syndrome, and bicuspid aortic valve (for TAA), chronic obstructive pulmonary disease, high cholesterol, and previous aortic dissection. The size threshold for intervention also varies by location—AAA typically requires treatment at 5.5 cm, while ascending thoracic aneurysms often warrant surgery at 5.0-5.5 cm depending on risk factors.
Important to Know
Most aortic aneurysms are asymptomatic and discovered incidentally on imaging. When symptoms occur, they depend on location: abdominal aneurysms may cause pulsating sensation near the navel, deep abdominal or back pain, or a pulsating mass; thoracic aneurysms may cause chest or back pain, cough, hoarseness (from compression of recurrent laryngeal nerve), difficulty swallowing, or shortness of breath. Symptoms of rupture—a life-threatening emergency with mortality exceeding 80%—include sudden severe chest, back, or abdominal pain, signs of shock, rapid heart rate, low blood pressure, and loss of consciousness. Diagnosis varies by location: abdominal ultrasound for AAA screening and surveillance; CT angiography (CTA) for detailed assessment of any aortic aneurysm, providing size, location, and anatomical details; transthoracic or transesophageal echocardiography for ascending aortic aneurysms; and MRI angiography as an alternative to CTA. Management depends on aneurysm size, location, growth rate, and patient factors. Small aneurysms undergo surveillance with serial imaging every 6-12 months. Risk factor modification is crucial for all patients including smoking cessation, blood pressure control (beta-blockers often preferred for TAA), statin therapy, and managing other cardiovascular risks. Elective repair is recommended when aneurysms reach size thresholds that indicate high rupture risk, are growing rapidly (more than 0.5 cm/year for AAA), or cause symptoms. Repair options include open surgical repair (replacing aneurysmal segment with synthetic graft) and endovascular repair (inserting stent-graft through catheters), with choice depending on aneurysm location, anatomy, and patient factors. Screening recommendations include one-time ultrasound for men aged 65-75 who have ever smoked, which significantly reduces AAA-related mortality. For patients with genetic conditions predisposing to aneurysms, more aggressive surveillance and earlier intervention are warranted. Prognosis varies widely—small, stable aneurysms can be managed safely with surveillance, while large or ruptured aneurysms carry significant mortality risk. Elective repair has much better outcomes than emergency surgery for rupture, underscoring the importance of screening, surveillance, and timely intervention.