The main causes of aortic aneurysm

An aortic aneurysm develops when the wall of your aorta—the large artery that carries blood from your heart to the rest of your body—weakens and bulges outward. The most common cause is high blood pressure, which puts constant strain on the artery wall over years or decades. Smoking is the second leading cause; it damages the elastic fibers in the aorta and accelerates weakening. Together, high blood pressure and smoking account for the majority of cases.

Age plays a significant role as well. The aorta naturally loses elasticity as you grow older, making aneurysms far more common in people over 65. Men are diagnosed with aortic aneurysms much more often than women, though the reasons are not fully understood—it may relate to differences in how blood pressure affects the sexes, or to higher smoking rates historically among men.

Beyond these primary causes, several other conditions can weaken the aortic wall. Atherosclerosis (buildup of plaque inside arteries) damages the inner lining and reduces the aorta's ability to handle pressure. Chronic obstructive pulmonary disease (COPD) is associated with aortic aneurysms, possibly because it causes inflammation throughout the body. Untreated syphilis can scar the aortic wall, though this is now rare in developed countries because of antibiotics.

Key Takeaways

  • High blood pressure is the leading cause of aortic aneurysm, followed closely by smoking, and both damage the aorta over many years.
  • Age and male sex are strong risk factors; most aortic aneurysms occur in men over 65.
  • Atherosclerosis, COPD, and certain genetic conditions can also weaken the aortic wall and increase aneurysm risk.
  • Some people inherit a genetic predisposition to aortic aneurysm through conditions like Marfan syndrome or bicuspid aortic valve.

Genetic conditions that affect aortic strength

Some people are born with conditions that make their aortic wall weaker or more prone to aneurysm. Marfan syndrome, an inherited disorder of connective tissue, weakens the elastic fibers that give the aorta its flexibility. People with Marfan syndrome can develop aortic aneurysms at a younger age than those without the condition, sometimes in their 30s or 40s. Screening and early treatment are important for this group.

Ehlers-Danlos syndrome, another connective tissue disorder, also increases aortic aneurysm risk. Bicuspid aortic valve—being born with two valve leaflets instead of three—is associated with aortic aneurysm, particularly in the ascending aorta (the part closest to the heart). A family history of aortic aneurysm itself is a risk factor; if a close relative had one, your risk is higher than average.

Inflammation and infection as causes

Inflammation inside the aorta can weaken its wall over time. Takayasu arteritis and giant cell arteritis are inflammatory conditions that specifically target large arteries, including the aorta. These autoimmune diseases cause the immune system to attack the artery wall, leading to scarring and weakening. Giant cell arteritis typically affects people over 50 and can develop relatively quickly.

Infection of the aorta itself, called aortitis, is uncommon but serious. Bacterial infections can reach the aorta through the bloodstream or from nearby infected tissue. Tuberculosis and syphilis historically caused aortic infections; today in developed countries, other bacteria are more common. Infection-related aortic aneurysms can develop and enlarge rapidly, making prompt treatment critical.

How high blood pressure damages the aorta

High blood pressure forces the aortic wall to work harder with each heartbeat. Over years, this constant pressure causes the muscle layer of the aorta to thicken and the elastic fibers to fray and break down. The wall becomes less able to stretch and recoil smoothly, and weak spots can form where the pressure is greatest.

The damage is often silent—you may have high blood pressure for decades without symptoms, while the aorta is gradually weakening. This is why controlling blood pressure is one of the most important ways to prevent aortic aneurysm. People with uncontrolled high blood pressure are at much higher risk than those whose blood pressure is managed with medication.

Smoking and other lifestyle factors

Smoking damages the aorta in multiple ways. Tobacco smoke contains chemicals that weaken the elastic fibers in the arterial wall and trigger inflammation. Smokers develop aortic aneurysms at younger ages than non-smokers, and the aneurysms tend to grow faster. Former smokers retain some increased risk, but quitting stops further damage and slows growth.

Excessive alcohol use may increase aortic aneurysm risk, though the evidence is less clear than for smoking and high blood pressure. Cocaine use has been linked to aortic aneurysm, particularly in younger people. Obesity and lack of physical activity are associated with high blood pressure and atherosclerosis, both of which increase aneurysm risk indirectly.

Atherosclerosis and arterial disease

Atherosclerosis—the buildup of fatty deposits (plaque) inside arteries—damages the inner lining of the aorta. This damage triggers inflammation and weakens the wall's ability to maintain its structure. People with high cholesterol, diabetes, or a history of heart disease or stroke are at higher risk for both atherosclerosis and aortic aneurysm.

The relationship between atherosclerosis and aneurysm is complex. Plaque buildup narrows arteries, but it also damages the wall in ways that can lead to aneurysm formation. Managing cholesterol, blood sugar, and blood pressure together addresses multiple causes of aortic damage.

Trauma and surgical injury

A severe injury to the chest can damage the aortic wall, sometimes immediately and sometimes years later. Motor vehicle accidents and falls from height are common causes of traumatic aortic injury. In some cases, the damage heals with scar tissue that is weaker than the original wall, creating a site where an aneurysm can develop.

Aortic surgery itself carries a small risk of aneurysm formation at the surgical site. This can occur months or years after the original procedure. People who have had aortic surgery are monitored with imaging to watch for this complication.

Frequently Asked Questions

Can you feel an aortic aneurysm developing?

Most aortic aneurysms cause no symptoms and are found by chance on imaging done for another reason. You cannot feel the bulging aorta itself. Symptoms only appear if the aneurysm ruptures or if it presses on nearby structures like nerves or the esophagus, which is uncommon.

Is aortic aneurysm hereditary?

Some genetic conditions like Marfan syndrome and Ehlers-Danlos syndrome increase aneurysm risk and run in families. A family history of aortic aneurysm itself also raises your risk. However, most aortic aneurysms are caused by high blood pressure and smoking, not genetics alone.

Can you reverse aortic aneurysm damage?

Once the aortic wall has weakened and an aneurysm has formed, the damage cannot be reversed. However, controlling blood pressure, quitting smoking, and managing other risk factors can slow the growth of an existing aneurysm and prevent new ones from forming.

Does exercise cause aortic aneurysm?

Regular moderate exercise does not cause aortic aneurysm and may help prevent it by lowering blood pressure and improving overall cardiovascular health. However, people with known aortic aneurysm should discuss exercise limits with their doctor, as intense exertion can temporarily raise blood pressure.

Are women less likely to get aortic aneurysm?

Yes, aortic aneurysm is diagnosed in men roughly five to ten times more often than in women. The reasons are not completely clear, but may involve differences in how blood pressure affects the sexes and historical differences in smoking rates. Women with risk factors like high blood pressure or smoking should not assume they are protected.