What is Abdominal Aortic Aneurysm?
An arterial aneurysm is a condition where a part of an artery expands to at least 1.5 times its normal size. A specific type, called an abdominal aortic aneurysm, is a dangerous condition where the abdominal aorta, the largest artery in the abdomen, unusually expands. The severity of this condition is such that it requires constant monitoring or medical treatment, depending on how big the aneurysm has become and the symptoms associated with it. This condition can be discovered either by chance, or at the time when the artery ruptures, which can be a life-threatening situation.
What Causes Abdominal Aortic Aneurysm?
Factors that increase the chances of getting an abdominal aortic aneurysm include a condition that hardens the arteries (the most common cause), smoking, being older, being male, being White, having a family member who had an abdominal aortic aneurysm, high blood pressure, high cholesterol, and a history of aortic dissection. Other causes can include a condition that breaks down the middle layer of the artery walls, syphilis, HIV, and diseases that impact your body’s connective tissues, like certain syndromes.
Interestingly, being non-White and having diabetes can actually reduce the risk of getting an abdominal aortic aneurysm.
An aneurysm can enlarge in a steady way. It can stay the same size for a while before it starts enlarging faster. Smaller aneurysms (about 1 to 2 inches) grow by roughly 1/10 of an inch per year, while bigger ones (over 2 inches) grow by roughly 1/8 to 1/5 of an inch per year.
Pressure on the artery wall changes depending on the size of the aneurysm. Bigger aneurysms put more stress on the artery walls, so they have a higher chance of bursting. High blood pressure also increases this risk.
Risk Factors and Frequency for Abdominal Aortic Aneurysm
Abdominal aortic aneurysms are a medical condition that are found in 0.5% to 3% of cases, based on autopsy studies. They become more common after the age of 60, most commonly occurring in the 70s and 80s. This condition is most frequently seen in white men, and is less common in Asian, African American, and Hispanic individuals. Research shows a rate of 1.4% in people aged between 50 and 84, which is about 1.1 million cases.
Due to more use of ultrasound, abdominal aortic aneurysms are often diagnosed. These are more often seen in smokers and older white males. Autopsy studies might not fully represent the number of cases, but a study in Malmo, Sweden, showed a rate of 4.3% in men and 2.1% in women based on ultrasound detection.
Signs and Symptoms of Abdominal Aortic Aneurysm
An abdominal aortic aneurysm is often discovered accidentally during medical check-ups for other unrelated health problems. Most of the time, people with this condition experience no symptoms. However, an observable sign might be a pulsating lump in the abdomen that doesn’t hurt when touched.
If the aneurysm grows bigger, it can cause discomfort in the abdomen, side, or back. It may also push against neighboring organs, resulting in digestive or kidney-related symptoms.
A ruptured abdominal aortic aneurysm is a medical emergency and can be deadly. The way a patient presents with a ruptured aneurysm can range from being hardly noticeable to extremely obvious. If this happens, the individual may exhibit widespread abdominal pain and bloating, often going into shock. In many cases, people with a ruptured aneurysm might not even make it to the hospital.
Other signs of a ruptured abdominal aortic aneurysm could include tenderness over the site of the aneurysm or indications of blood clotting. If the aneurysm bursts into neighboring organs or blood vessels, it could cause symptoms such as intestinal bleeding or heart congestion due to blood flow disruptions.
Another part of the examination process might involve looking for other related aneurysms, with iliac artery aneurysm being the most common. About 5% of patients might also present with peripheral aneurysms, with the most common subtype being in the popliteal artery, which runs behind the knee joint.
Testing for Abdominal Aortic Aneurysm
The identification of an abdominal aortic aneurysm, a condition where the large blood vessel that supplies blood to the abdomen, pelvis, and legs becomes enlarged, is usually accomplished with an ultrasound. However, a detailed scan called a computed tomography (CT) is essential to establish the exact location and size, as well as how it may be impacting nearby vessels. CT scan is particularly recommended if the patient is showing symptoms of the condition.
Ultrasounds are excellent for regular checks but may not be as precise for aneurysms located higher in the body due to interference from air within the lungs and gut. Keep in mind that CT scans do involve radiation exposure and the use of a contrast agent, a substance that makes certain areas show up better on the scan.
If the patient is allergic to the contrast agent, magnetic resonance angiography, a type of MRI scan, can be used instead. This process does not need radiation. This imaging technique provides detailed information about the blood vessels and, importantly, doesn’t require the use of ionizing radiation.
Most of these aneurysms occur below the kidney arteries and may be localized (saccular) or surrounding the entire aorta (fusiform). Over 90% of these aneurysms are fusiform. An inflammatory abdominal aortic aneurysm is marked by severe inflammation, a thickened covering, and it tends to stick to nearby structures.
In the interest of heart health, an echocardiogram is recommended, as numerous individuals with this condition may also have related heart disease. To supplement these imaging tests, normal blood tests, including cross-matching for surgical preparation, are recommended. For people with other health conditions such as diabetes, lung disease, or heart disease, it is a good idea to receive assessments from a relevant specialist before deciding on surgery.
Treatment Options for Abdominal Aortic Aneurysm
Treatment for abdominal aortic aneurysms, which are internal lumps that happen in your biggest blood vessel, is generally advised when they get to be 5.5 cm or larger in men, or if they grow by more than half a centimeter in half a year, or if they cause any symptoms. According to the European Society for Vascular Surgery (ESVS), surgery should be considered if the aneurysm triggers symptoms, grows larger than 4 cm or increases in size by more than 1 cm per year. For women, it is proposed to consider surgery if the aneurysm is larger than 5 cm.
The primary option for dealing with these aneurysms has traditionally been surgery, with a choice of approaches through the belly. However, a newer method involving inserting a stent (a tube) through an artery in the thigh is now commonly used, especially for older patients or those who carry a higher risk. This is the recommended approach if the patient is not fit for open surgery, owing to heart problems or other illnesses.
In situations where the aneurysm ruptures, treatment becomes an emergency. An endovascular approach (where the body’s blood vessels are used for access) yields better results compared to open surgery, but regardless, the condition can still be lethal.
Studies suggest that the long-term results of endovascular therapy and open surgery are comparable. In terms of medication, blood pressure drugs, such as beta-blockers, play a key part in managing this condition over time. Monitoring in intensive care is required for one to two days following open surgery, which typically involves a large cut along the middle of the belly.
If an aneurysm isn’t large enough to justify surgery, patients will still need to have a scan every six months to a year to check that it’s not getting bigger. Endovascular surgery isn’t always an option, and it’s usually not considered if the starting point of the aorta is too short. Despite this, endovascular repair is increasingly used for more complex cases, with certain benefits, including fewer complications.
The success of endovascular procedures over the long term is dependent on the choice of stent and its durability. Types of endovascular repair that use windows (fenestrations) or branches in the stent are often considered together in studies, even though they might act differently. The main consideration in choosing the stent is the surgeon’s preference.
Due to the potential for complications, high risk patients and those who have certain characteristics of their aneurysms will be particularly considered for fenestrated repair, which uses a stent with windows. This kind of treatment has specifically shown advantages for abdominal aortic aneurysms next to the kidney.
The Society for Vascular Surgery (SVS) published updated guidelines in 2020 which recommend regular checks for patients with aneurysms between 4 cm and 5 cm. For aneurysms that aren’t at risk to rupture, the guidelines recommend endovascular repair. Other guidelines include only performing endovascular procedures in hospitals that do at least ten a year and have less than a two percent rate of needing to switch to open repair.
Emergency treatment is preferred at centers that can start an intervention in less than 90 minutes. Conditions related to leaking, enlarging aneurisms should be treated. The guidelines also recommend not giving antibiotics routinely before certain procedures unless the patient’s immune system is compromised. Duplex ultrasonography should be used to monitor patients after endovascular surgery, and a heart rhythm check is recommended before any aneurysm repair surgery.
If a patient had a drug-releasing stent put in recently, it is advised to wait at least six months before carrying out open aneurysm surgery, or to consider endovascular surgery while the patient is still on drugs to prevent blood clotting. Furthermore, blood should only be given during the surgery if the patient’s hemoglobin level drops below 7 g/dL. The guidelines recommend considering surgery for aneurysms larger than 5.5 cm in diameter in patients who are at low risk. Finally, the guidelines advise that open surgery should be performed under general anesthesia.
What else can Abdominal Aortic Aneurysm be?
When trying to diagnose an abdominal aortic aneurysm, doctors could also consider other health issues that might cause similar symptoms. These might include:
- Blocked blood flow to the intestines (also known as mesenteric ischemia)
- Stomach or duodenal ulcers (peptic ulcer disease)
- Inflammation of small pouches in the digestive system (diverticulitis)
- Urinary tract infection that has reached the kidneys (pyelonephritis)
- A heart attack (myocardial infarction)
- Pain from a kidney stone blocking the urinary tract (ureteric colic)
These conditions have similar symptoms to an abdominal aortic aneurysm, so it’s important for doctors to distinguish between them for an accurate diagnosis.
What to expect with Abdominal Aortic Aneurysm
If an abdominal aortic aneurysm, a ballooning in a part of the aorta in your belly, bursts, the situation can become very dangerous. Over half of patients in this predicament don’t make it to the emergency room alive, and those that do often suffer from very severe health conditions. Factors that tend to increase the chances of dying from this include having a heart attack before surgery, being over 80 years old, being a woman, losing a lot of blood, and needing ongoing blood transfusions.
The most critical factor that determines whether a patient will survive an exploded aneurysm is the ability to quickly stop the bleeding from the tear in the aorta. For patients who have scheduled surgery before the aneurysm bursts, the prognosis, or predicted outcome, is generally good. However, their long-term survival is tied to other existing health problems like chronic lung diseases, heart diseases, and diseases affecting the blood vessels in the limbs. Around 70% of people live for at least 5 years after their aneurysm is repaired.
Possible Complications When Diagnosed with Abdominal Aortic Aneurysm
There are several complications that can arise from an abdominal aortic aneurysm. Some of these are pretty severe and can have a significant impact on a person’s health.
- Bleeding
- Reduced blood flow to limbs (limb ischemia)
- Delayed rupture due to leakage in the aneurysm (endoleak)
- Increased pressure in the abdomen (abdominal compartment syndrome)
- A type of heart attack (myocardial infarction)
- Pneumonia
- Infection of the graft used in surgery
- Reduced blood flow to the colon (colon ischemia)
- Kidney failure
- Blockage in the intestine (bowel obstruction)
- Blue toe syndrome, condition causing the toes to turn blue
- Amputation
- Impotence
- Formation of a fluid-filled swelling in the lymph nodes (lymphocele)
- And, in severe cases, death
Recovery from Abdominal Aortic Aneurysm
Once the surgical procedure is completed, it’s crucial for the patient to quit smoking, eat healthily, and maintain an appropriate weight. Depending on their particular situation, they may need physical or occupational therapy. It’s also recommended that a follow-up CT scan be done five years after the operation in order to check for possible late dilation (expansion) of the aorta or pseudoaneurysm (false aneurysm).
Preventing Abdominal Aortic Aneurysm
Many people living with abdominal aortic aneurysms can actually lead healthy lives without any symptoms. Choosing to have surgery requires careful thought and discussion. A key part of this decision involves considering the risk of the aneurysm bursting versus the potential risks and benefits of the surgery itself.
While the size of the aneurysm and how fast it’s growing are important factors, every decision about treatment should be personalized. It’s crucial that doctors clearly explain all surgical risks, so patients can make choices based on a full understanding of their situation.
