An aortic aneurysm is a dangerous bulge that develops in the wall of the aorta, the body’s largest blood vessel. This condition often grows silently without symptoms, but if left undetected and untreated, it can lead to life-threatening internal bleeding.
Understanding Aortic Aneurysm
The aorta is the main artery in your body, shaped like a curved candy cane. It carries oxygen-rich blood from your heart to all other parts of your body, including your brain, muscles, and organs. The aorta has thick walls designed to withstand the normal pressure of blood pumping through it.[1]
An aortic aneurysm occurs when a section of the aorta’s wall becomes weakened and begins to bulge outward, similar to a balloon. This bulging happens because the pressure of blood flowing through the artery pushes against the weakened area. The medical definition describes an aortic aneurysm as an enlargement of the aorta to greater than one and a half times its normal size.[5]
There are two main types of aortic aneurysms, classified by their location in the body. An abdominal aortic aneurysm, often abbreviated as AAA, develops in the portion of the aorta that runs through the belly area. This type is the most common form of aortic aneurysm. A thoracic aortic aneurysm, abbreviated as TAA, occurs in the section of the aorta that passes through the chest cavity. Some individuals may have both types present at the same time.[1]
The real danger of an aortic aneurysm lies in two serious complications. The aneurysm can rupture, meaning it bursts completely and causes severe internal bleeding. It can also dissect, which means the force of blood pumping splits the layers of the artery wall, allowing blood to leak between them. Both situations are medical emergencies that can be fatal without immediate treatment.[3]
How Common Are Aortic Aneurysms
Aortic aneurysms are found in approximately five to ten people out of every 100,000 individuals. Abdominal aortic aneurysms occur much more frequently than thoracic aneurysms. This difference may exist because the wall of the thoracic aorta is thicker and stronger than the wall of the abdominal portion.[4]
Every year in the United States, about 200,000 people receive a diagnosis of abdominal aortic aneurysm. A ruptured AAA ranks as the 15th leading cause of death in the country, and the 10th leading cause of death specifically in men older than 55 years.[6]
Abdominal aortic aneurysms are four to six times more common in men than in women. Among men aged 55 to 64, only about one percent are affected. However, the likelihood of developing an AAA increases significantly with age, rising by up to four percent with every decade of life. The condition becomes more common as people grow older.[4]
Thoracic aortic aneurysms affect men and women equally, and they also become more common with increasing age. Abdominal aortic aneurysms are more common among White people than among Black people.[3]
In 2019, aortic aneurysms or aortic dissections caused approximately 9,904 deaths in the United States. About 59 percent of these deaths occurred among men. According to global data through 2019, the worldwide prevalence of abdominal aortic aneurysm was about 0.9 percent in people under age 79, and it is approximately four times higher in men than in women at any age. Death occurs in about 55 to 64 percent of people experiencing rupture of an AAA.[3][5]
Causes of Aortic Aneurysm
The exact causes of aortic aneurysms are often unknown, but medical problems, genetic conditions, and trauma can damage or weaken the walls of the aorta. Several factors are known to contribute to the development of these dangerous bulges.[2]
Atherosclerosis, which is the hardening and narrowing of the arteries, is a major cause. This condition involves the buildup of plaque inside artery walls. Abdominal aortic aneurysms are usually caused by atherosclerosis, though infection or injury can also lead to their formation. Thoracic aortic aneurysms are usually caused by high blood pressure or sudden injury.[3][4]
Inflammation of the arteries can damage the aortic wall and create weak spots. Inherited conditions, especially those affecting connective tissue, play an important role in some cases. People with Marfan syndrome, Ehlers-Danlos syndrome, or Loeys-Dietz syndrome have a higher risk of developing thoracic aortic aneurysms because these genetic disorders affect the strength and structure of connective tissues throughout the body, including in blood vessel walls.[3][4]
Physical injury to the aorta, such as from a car crash or fall, can create damage that later develops into an aneurysm. Untreated infections, including syphilis and salmonella, can also weaken the aortic wall and contribute to aneurysm formation.[4]
Risk Factors
Understanding who is at higher risk for developing an aortic aneurysm can help with early detection and prevention. Both family history and lifestyle choices play significant roles in determining risk.[4]
Smoking is the most important behavioral risk factor for aortic aneurysm. A history of smoking accounts for about 75 percent of all abdominal aortic aneurysms. The toxic chemicals in tobacco products damage blood vessel walls and increase the likelihood that an aneurysm will develop and grow. Quitting smoking is crucial for anyone at risk.[3]
Age is a major factor, with risk increasing significantly after age 65. Men and individuals assigned male at birth face higher risk than women. Family history matters greatly—if you have a first-degree relative such as a mother, father, brother, or sister who has been diagnosed with an aortic aneurysm, you are 12 times more likely to develop one yourself. About 15 to 25 percent of people who need treatment for an AAA have an immediate family member with the same type of aneurysm. Aneurysms often run in families.[6][9]
High blood pressure, also called hypertension, puts extra force on artery walls and increases the chance that a weak spot will bulge out. High cholesterol levels contribute to atherosclerosis, which damages artery walls. Having coronary artery disease or peripheral artery disease also raises risk.[4][7]
People born with a bicuspid aortic valve, a heart valve defect, are at increased risk. Individuals with chronic obstructive pulmonary disease, or COPD, face higher risk as well. Heavy alcohol consumption and obesity contribute to conditions that damage blood vessels and increase aneurysm risk.[7][9]
Symptoms
Most people with an aortic aneurysm do not experience any symptoms, which is why this condition is sometimes called “the silent killer.” An aneurysm often doesn’t cause symptoms until it ruptures or grows quite large. Many aneurysms are discovered by accident during imaging tests performed for unrelated medical reasons.[4][9]
As an aortic aneurysm grows larger, some individuals begin to notice warning signs. For an abdominal aortic aneurysm, symptoms may include a throbbing or deep pain in the back or side, pain in the buttocks, groin, or legs, or a pulsing feeling in the abdomen. Some people notice a feeling of fullness in the stomach even after eating a small meal. A healthcare provider might detect a large throbbing mass in the abdomen during a physical examination, or hear an unusual sound when listening to the abdomen with a stethoscope.[3][7]
Thoracic aortic aneurysms that grow large enough to cause symptoms may produce sharp, sudden pain in the chest or upper back. Individuals might experience shortness of breath, difficulty breathing, or trouble swallowing. Coughing, possibly coughing up blood, hoarseness, and wheezing can occur. Swelling in the arms, neck, or head may develop if the aneurysm presses on nearby structures.[3][4]
When an aneurysm ruptures, symptoms come on suddenly and are severe. These emergency symptoms include sudden, intense pain in the chest, neck, back, or abdomen. The pain is often described as ripping, stabbing, or tearing in nature. Other signs of rupture include pale or sweaty skin, a very faint pulse, fast heartbeat, dizziness or lightheadedness, rapid heart rate, numbness or tingling in the arms or legs, and nausea or vomiting. Some people lose consciousness. These symptoms require immediate emergency care—call 911 or go straight to an emergency department without delay.[4][7]
Prevention
While you cannot always prevent an aortic aneurysm from developing, especially if you have genetic risk factors, you can take important steps to reduce your risk and slow the growth of an existing aneurysm. Heart-healthy lifestyle changes can help prevent aortic aneurysms from forming or from growing larger.[2]
The single most important prevention step is to quit smoking if you currently smoke. Smoking is the strongest modifiable risk factor for aortic aneurysm. When you stop smoking, the risk of rupture drops, especially in women. There are many resources available to help you quit, including medications and counseling options. The National Cancer Institute’s Smoking Quitline at 1-877-448-7848 offers free help and support.[3][11]
Controlling high blood pressure is critical. If you have been prescribed blood pressure medication, take it exactly as instructed by your doctor. The extra force of high blood pressure pushes against aneurysm walls and can cause the bulge to expand. Managing blood pressure helps slow aneurysm growth and reduces rupture risk.[11]
Eating a heart-healthy diet supports overall cardiovascular health. Focus on reducing the amount of sodium and cholesterol you consume. Eat lean meats, plenty of fruits and vegetables, and whole grains. Limit foods that come in jars, cans, or bags, as these tend to be high in salt. Try to keep your daily sodium intake below 2,300 milligrams by reading food labels. Many products now offer low-salt versions.[11]
Maintaining a healthy weight and staying physically active benefit your blood vessels. Talk to your doctor about what level of physical activity is appropriate for you. Studies show that moderate physical activity does not raise the risk of rupture or growth of an aneurysm and can have health benefits. However, you should avoid heavy weightlifting and intense straining, as these can cause sudden increases in blood pressure. Activities like brisk walking or biking for at least 30 minutes on most days of the week are usually beneficial.[11]
Managing stress helps control blood pressure. Keep alcohol intake moderate—at most one to two drinks per day. If you have high cholesterol, work with your doctor to lower it through diet, exercise, and medication if needed.[11]
Screening is an important prevention tool for those at high risk. The U.S. Preventive Services Task Force recommends that men aged 65 to 75 years old who have ever smoked should have a one-time screening using abdominal ultrasound, even if they have no symptoms. For men in this age group who have never smoked, the need for screening depends on other risk factors such as family history. If you have a first-degree relative with an aortic aneurysm, talk to your doctor about screening regardless of your age. Women who have never smoked generally do not need screening, but those with a smoking history or family history of aneurysm should discuss screening with their healthcare provider.[3][12]
How Aortic Aneurysms Develop
The development of an aortic aneurysm involves complex changes in the structure and function of the artery wall. Understanding what happens inside the blood vessel helps explain why aneurysms are so dangerous.[5]
The aorta normally has thick, strong walls made up of three layers. These layers contain elastic fibers and smooth muscle that allow the artery to expand and contract with each heartbeat while maintaining its structural integrity. When the aorta is healthy, it can easily withstand the normal pressure of blood pumping through it.[2]
An aortic aneurysm begins when something damages or weakens a section of the aortic wall. This initial injury might come from years of high blood pressure pounding against the artery wall, from inflammatory processes that break down the wall’s structural proteins, from genetic conditions that produce defective connective tissue, or from direct physical trauma. Once this weak spot forms, the normal pressure of blood flow begins to push outward against it.[2]
The weakened section of the artery wall cannot resist the blood pressure as effectively as healthy tissue. Over time, this area starts to bulge outward like a balloon being inflated. The process involves a cascade of inflammation and breakdown of extracellular matrix proteins—the structural proteins that normally hold the artery wall together. Enzymes called proteinases break down these proteins, further weakening the wall.[5]
As the aneurysm grows larger, the wall becomes stretched thinner. This increases the tension on the wall, making it even more likely to continue expanding. The larger an aneurysm becomes, the faster it tends to grow and the higher the risk of rupture. This is because the physical stress on the wall increases with the size of the bulge, following principles of physics related to pressure and curved surfaces.[5]
Inside the aneurysm, blood flow becomes turbulent rather than smooth. This turbulence can cause blood clots or debris to form within the bulge. These clots can break off and travel downstream, blocking blood flow to other parts of the body. If clots travel to the legs, they can cause severe pain or even limb loss if blood flow is cut off for too long.[6]
A tear in the inner layer of the aortic wall creates a condition called aortic dissection. When this happens, blood gets forced between the layers of the artery wall, separating them. The buildup of blood between the layers causes narrowing of the true channel where blood should flow, resulting in decreased blood flow to organs. The separation also weakens the artery further, which can cause the aneurysm to enlarge more rapidly and rupture.[3]
When an aneurysm ruptures, it bursts completely. Blood pours out of the torn artery and into the body cavity—either the chest or abdomen depending on the aneurysm’s location. The body loses large amounts of blood very quickly, leading to shock, a life-threatening condition where organs do not receive enough blood and oxygen. Without immediate surgical intervention, rupture is usually fatal.[2]
