Abdominal Aortic Aneurysm

What is an abdominal aortic aneurysm?

While it is normal for blood vessels like the aorta to widen as we age, when it widens too far, or balloons out, it’s called an aneurysm. The wall of the artery within an aneurysm becomes weaker than the wall of a normal part of the artery. This makes it susceptible to rupturing or tearing, which can lead to serious internal bleeding.

Aortic aneurysms are classified by their location and characteristics. Aneurysms that occur in the portion of the aorta that comes out of the heart and travels through the chest cavity (thorax) are called thoracic aortic aneu­­rysms.

Aneurysms that occur in the part of the aorta that lies in the abdomen are abdominal aortic aneurysms (AAA). About 3% of people between ages 65 and 80 have an AAA.

Symptoms of aortic aneurysms

​​Aortic aneurysms usually don’t cause any symptoms. They are typically diagnosed by abdominal imaging, either done for routine screening or for another condition. Aortic aneurysm screening is often done using ultrasound. A doctor may also be able to feel a pulsating mass in the abdomen. If there are symptoms, they may be back pain, abdominal pain, flank pain, leg pain, or weakness.

Screening and Early Detection

Given that most abdominal aortic aneurysms (AAAs) do not cause symptoms, screening plays a crucial role in early detection and prevention of rupture. The U.S. Preventive Services Task Force recommends a one-time screening ultrasound for AAA in men aged 65 to 75 who have ever smoked. This non-invasive test can effectively identify AAAs before they become dangerous.

While AAAs are often asymptomatic, some individuals may experience symptoms as the aneurysm enlarges. These can include:

- A pulsating feeling in the abdomen
- Deep, constant pain in the abdomen or side of the abdomen
- Back pain

It's important to note that these symptoms can be caused by other conditions and do not necessarily indicate an AAA. However, if you experience any of these symptoms, especially if you're in a high-risk group, it's crucial to consult your healthcare provider promptly.

Complications

A complication of AAAs is when there is a partial tear, called a dissection, in the vessel wall.  The blood separates the inner wall from the outer wall and can push its way down (or back up) the entire length of the vessel in a matter of seconds.

In rare cases, this can lead to disruptions in blood flow to vital organs in the abdomen or chest cavity. This can cause trouble breathing, chest pain, weight loss, blood in the urine, or bloody bowel movements. Aortic dissection almost al­ways occurs in people who have chronic high blood pressure.

The most feared complication is rupture of an AAA, where blood spills into the abdominal cavity.  When an aortic aneurysm ruptures, it can cause severe stabbing pain, followed by a loss of consciousness. About 80% of people who have ruptured aneurysms die, half of them before reaching the hospital.

Causes

Aortic aneurysms usually form at a spot on the artery wall weakened by atherosclerosis (plaque buildup) and long-time high blood pressure. Being male is also a risk factor for developing an aneurysm.

One of the biggest risk factors is smoking. It is such a big risk factor that it’s recommended that men between the ages of 65 and 75 who have ever smoked get screened for an AAA with an abdominal ultrasound.

There is also a genetic component to aneurysms, as they are far more common in people whose close relatives have had one. A small number of people have an inherited connective tissue disorder called Marfan syndrome, which increases their risk of developing aneurysms (even if they do not have atherosclerosis).

Other risk factors include:

• Advanced age
• Arterial aneurysms located elsewhere in the body
• History of aortic surgery or aortic instrumentation.
• Infections like advanced syphilis can also damage the aorta, leading to an aneurysm, though this more commonly happens in the thoracic aorta.

Risk factors for a rupture include rapidly growing aneurysm, very large aneurysm (typically > 5.5cm), and having any symptoms.

Aortic aneurysm treatment options

Since most people don’t have symptoms and the AAA is found through routine screening, or accidentally, there is usually time to figure out the best solution. Your doctor will refer you to a vascular surgeon.

Aneurysms that are under a certain size and stable over time do not need to be repaired unless they are causing symptoms.

Those that are causing symptoms, very large, or rapidly growing are at increased risk of rupture and may need to be repaired. It can either be done through an endovascular approach or open surgery. Endovascular is less invasive, but not everyone can have it, so it’s decided on a case-by-case basis.

If you have a known AAA and suddenly experience abdominal pain, back pain, flank pain, or any of the other symptoms described above, go to an ER. An aortic aneurysm may rupture at any time and cause life-threatening blood loss. The ER team will order imaging to assess the size and location of the aneurysm and consult a vascular surgeon to plan the intervention.