An aortic aneurysm is a bulge in the wall of the aorta, the large artery that carries blood from your heart to the rest of your body. When a section of the aortic wall weakens, the pressure of blood flowing through it forces that weak spot to balloon outward. Roughly 35 million people worldwide are living with an aortic aneurysm, and most have no idea because the condition rarely produces symptoms until it becomes dangerous.
Where Aortic Aneurysms Form
The aorta runs from your heart down through your chest and into your abdomen, and an aneurysm can develop anywhere along that path. The two main types are named for their location. Abdominal aortic aneurysms (AAAs) form in the lower portion of the aorta, most often in the section below the kidneys. These are far more common than their counterpart. Thoracic aortic aneurysms form in the chest, with about 60% involving the section closest to the heart (the ascending aorta or aortic root), 40% in the descending portion, and 10% in the aortic arch that curves between them. Some aneurysms span both regions.
Who Is Most at Risk
Men develop aortic aneurysms at roughly 3.7 times the rate women do. About 79% of all people living with an abdominal aortic aneurysm are male. Risk climbs with age, and abdominal aneurysms are most common in adults over 65.
Cigarette smoking is one of the strongest risk factors, particularly for abdominal aneurysms. Smoking doesn’t just make an aneurysm more likely to form; it also makes an existing one grow faster and more likely to rupture. High blood pressure is the leading risk factor for thoracic aneurysms and contributes to abdominal ones as well. Atherosclerosis, the buildup of fatty deposits in artery walls, weakens the aorta over time and is closely linked to aneurysm formation in the abdomen.
Genetics play a meaningful role. One in ten people with an abdominal aortic aneurysm has a family history of the condition, and if a parent or sibling has one, your own risk jumps to about 1 in 5. Thoracic aneurysms are especially tied to inherited connective tissue disorders like Marfan syndrome, Ehlers-Danlos syndrome, Loeys-Dietz syndrome, and Turner syndrome. A bicuspid aortic valve, a heart valve abnormality present from birth, also raises the risk for thoracic aneurysms.
Why Most Aneurysms Cause No Symptoms
Small and medium-sized aortic aneurysms typically produce no symptoms at all. They grow slowly over years, and many people only discover them incidentally during an imaging test done for another reason. This is what makes the condition dangerous: the first sign of a problem can be a life-threatening rupture.
As an aneurysm enlarges, it can begin pressing on nearby structures. Symptoms of a growing aneurysm depend on its location but may include pain in the chest, back, or abdomen, difficulty breathing, a feeling of fullness after small meals, painful swallowing, or swelling in the neck, face, or arms. These symptoms tend to develop gradually.
A ruptured aneurysm is an emergency. Symptoms come on suddenly: severe pain in the chest, abdomen, or back, dizziness or lightheadedness, and a rapid heart rate. Rupture carries a mortality rate exceeding 80% and causes an estimated 150,000 to 200,000 deaths worldwide each year.
Aneurysm vs. Dissection
These two conditions are related but mechanically different. An aneurysm is a balloon-like bulge where the entire weakened wall pushes outward. A dissection is a tear in the inner lining of the aorta that allows blood to force its way between the layers of the wall, creating a false channel. A dissection can occur in an aorta that already has an aneurysm, but it can also happen in an aorta of normal size. Both are medical emergencies when acute, but they require different approaches to treatment.
Screening Recommendations
Because most aneurysms are silent, screening can catch them before they become dangerous. The U.S. Preventive Services Task Force recommends a one-time ultrasound screening for men aged 65 to 75 who have ever smoked (defined as 100 or more cigarettes in a lifetime). For men in that age range who have never smoked, screening is offered selectively based on other risk factors like family history. There is currently no routine screening recommendation for women, though women with risk factors may benefit from a conversation with their doctor.
How Aneurysms Are Monitored
When an aneurysm is found but isn’t large enough to need repair, doctors track it with regular ultrasound imaging. The schedule depends on the size of the aneurysm. An aorta measuring between 2.5 and 3.0 cm (slightly wider than normal but not yet meeting the threshold for a true aneurysm) is rechecked after 10 years. Once an aneurysm reaches 3.0 to 3.9 cm, imaging is repeated every three years. At 4.0 to 4.9 cm, that interval tightens to once a year. And at 5.0 to 5.4 cm, you can expect imaging every six months, because the aneurysm is approaching the size where surgical repair is considered.
During the monitoring period, managing blood pressure, quitting smoking, and controlling cholesterol all help slow growth.
When Surgery Is Needed
Surgery is recommended when the risk of rupture outweighs the risk of the procedure. For abdominal aneurysms, repair has traditionally been considered at around 5.5 cm in diameter. For thoracic aneurysms, recent guidelines have lowered the threshold from 5.5 to 5.0 cm at experienced surgical centers, and even lower for people with genetic connective tissue disorders. These thresholds aren’t one-size-fits-all. Surgeons may adjust them based on your sex, height, body size, how fast the aneurysm is growing, and whether you have a genetic condition that makes the aortic wall more fragile.
What Surgical Repair Looks Like
There are two main approaches to repairing an aortic aneurysm. Open surgical repair involves making an incision in the chest or abdomen, clamping the aorta above and below the aneurysm, and replacing the damaged section with a synthetic graft. It’s a major operation with a longer recovery, but it tends to be durable over the long term. Younger patients with a long life expectancy and low surgical risk sometimes benefit more from open repair for that reason.
Endovascular aneurysm repair, or EVAR, is a minimally invasive alternative. Instead of opening the chest or abdomen, surgeons thread a compressed graft through small punctures in the arteries near the groin and guide it into position inside the aneurysm. Once deployed, the graft lines the weakened section and redirects blood flow through it, relieving pressure on the bulging wall. EVAR involves shorter operative time, fewer wound complications, and a shorter hospital stay compared to open surgery.
Not everyone is a candidate for EVAR. The anatomy of the aorta and surrounding arteries has to accommodate the graft, and the specific requirements vary by device. Women are disproportionately affected by this limitation: as many as 66% of women with infrarenal abdominal aneurysms don’t meet the anatomical criteria for standard endovascular repair. EVAR also requires follow-up imaging to ensure the graft stays sealed, since small leaks around the device can develop over time.