What Is Visceral Artery Aneurysm

Introduction

Aneurysm is defined as the expansion of blood vessels to the point where they look identical to a balloon, and this occurs as a result of the weakened walls of those blood vessels.

Visceral artery aneurysm (VAA) is a condition that occurs when the arteries supplying blood to the following visceral organs expand like a balloon due to the weakening of their walls. These organs are:

• Spleen
• Liver
• Intestines
• Kidneys 

Most cases of VAA involve the artery taking blood towards the spleen (splenic artery aneurysm). If the blood pressure increases, and pushes an increased volume of blood onto the walls of expanded arteries, the arteries may tear and burst open, resulting in internal bleeding, a condition also referred to as a haemorrhage.

VAA is not common and is mostly experienced without any symptoms (asymptomatic).¹ It is diagnosed by chance when the patient presents for some other condition and imaging tests are conducted. 

What are the types of visceral artery aneurysm?

There are two main types of visceral artery aneurysm: 

Pseudoaneurysm

This is also called a fake aneurysm and develops when there is a hole in the wall of your artery. Blood then seeps out of that hole and is collected around the artery. Clotting factors present in the blood build a weak wall around that “pool” of blood, resulting in a pseudoaneurysm. As the wall is weak, pseudoaneurysms are prone to rupturing.²

True aneurysm

This is when the artery wall is weak and bulges to form a balloon-like shape.

VAA is also classified on the basis of which organ it takes place at and is divided into the following categories:³

Splenic artery aneurysm

This is the most common form of VAA, as it happens in 60% of VAA cases. The risk of rupturing splenic artery aneurysm is typically low (2-3%), but this risk increases during pregnancy and after liver transplantation.

Hepatic artery aneurysm

This is the second most common type of VAA (20-50% of cases). The rupture rate is the highest in hepatic artery aneurysm, which covers about 80% of the cases.

Superior mesenteric artery aneurysm

These comprise about 6% of all forms of VAA. Pseudoaneurysms are more common than the true ones in this class of aneurysms, though. The mortality rate is high if an artery ruptures in this location, as it is about 30%.

Other less common types of visceral artery aneurysm are:

• Celiac artery aneurysm
• Mycotic aneurysm
• Spurious aneurysm 

What are the symptoms of visceral artery aneurysm?

VAA may be symptomatic or asymptomatic (no symptoms). Asymptomatic VAA is diagnosed by chance when imaging tests are conducted for a patient who visits the physician for some other condition.

Although most of the cases of VAA are asymptomatic, symptomatic VAA occurs when the artery has increased in size, squeezing your body organs. It is characterised by the following signs and symptoms: 

• Stomach pain
• Flank pain (pain on sides or lower back)
• Palpable mass in the abdomen

If the aneurysm ruptures, it may result in the following signs and symptoms:

• Anaemia (including shortness of breath and tiredness)
• Back pain
• Abdominal pain
• Vomiting blood
• Blood in stool²

What are the risk factors and causes of visceral artery aneurysm?

Risk factors are the elements that make a person vulnerable to a certain condition. You are more prone to develop visceral artery aneurysm in case of the presence of the following: 

• High blood pressure
• Diabetes
• High cholesterol level
• Smoking
• Family history of atherosclerosis (hardening of arteries)

Diseases or factors that weaken the artery wall can cause aneurysms and include the following:

• Atherosclerosis
• Connective tissue disorders (e.g. Marfan syndrome, Ehlers-Danlos syndrome, Fibromuscular Dysplasia)¹

Other causes of visceral artery aneurysm are: 

• Family history of relevant conditions (heart disease, high cholesterol, etc.)
• Gut surgery
• Trauma caused by  accidents or injury
• Other infections¹

What are the complications of visceral artery aneurysm?

Arteries, when they become inflated like a balloon, may tear and burst open. When they burst open, internal haemorrhage (bleeding) takes place, and it is a condition that can be life-threatening. The larger the swollen artery, the more likely it is to burst.

Although the chances of an artery rupturing due to aneurysm are quite low (2-3%), these chances increase if the individual has the following conditions: 

• After liver transplantation
• During pregnancy
• Portal hypertension

While death due to haemorrhage has a 10-25% risk of occurring, VAA in pregnant women results in maternal death in about 70% of the cases and foetal death in 90% of the cases - extremely high rates, therefore the relevant checks should be carried out prior to pregnancy to determine whether the chances of VAA occurrence are high or not.³

How is a visceral artery aneurysm diagnosed?

Your physician will carry out a standard physical examination and will then conduct the following imaging tests to determine whether you are at risk of or are suffering from VAA:

• Computerised tomography (CT scan)
• MRI
• Ultrasound

These tests help determine the size of the aneurysm, which is vital in directing the physician towards the most appropriate choice of treatment. Angiography is a minimally invasive diagnostic procedure in which your physician inserts a catheter (thin tube) into one of your blood vessels, and it then directs it towards your concerned visceral artery. They then introduce a contrast medium or dye, and X-ray images of that artery detect the dye and show any irregular regions that should be treated.

In the case of angiography, the treatment is typically done immediately by using the same catheter that is used to diagnose VAA during the same session.⁴

How is a visceral artery aneurysm treated?

The choice of treatment depends on multiple factors, such as the aneurysm size, severity, and location. The main objective of treatment is to prevent the arteries (blood vessels) from bursting. This may be done through a timely diagnosis.

If the aneurysm is small (smaller than 2 cm in diameter), your physician will do a routine monitoring of the aneurysm to keep its growth in check. The physician will also instruct you regarding lifestyle modifications that may prevent the aneurysm's growth, such as: 

• Maintaining blood pressure within healthy levels
• Control cholesterol level
• Quit smoking
• Maintain a healthy diet

In case of a large VAA (larger than 2 cm), the artery is fixed up before it bursts through the following processes:

• Surgical interventions
• Endovascular (within the blood vessel) procedures^{2, 4}

Surgical interventions

Surgical procedures require a large opening or cut near the site of the aneurysm, so the entire area of the aneurysm is exposed, therefore giving access to the surgeon. The surgeon then pulls out the affected section of the artery and either restores or or replaces it.⁵

Endovascular procedures

Endovascular procedures involve catheter-based embolisation and stent placement. These procedures involve the insertion of a catheter (thin tube) through a slit in the arm or groin, and the catheter is then directed towards the affected artery.⁶

Embolisation is carried out to plug or seal the aneurysm, and includes coil/plug embolization and liquid embolization. During coil embolization, the aneurysm is packed with a coil or a mechanical plug, while during liquid embolization, a liquid medium is used in order to plug the aneurysm. This liquid agent may be a non-toxic gel or glue.

A stent is a perforated metal tube that is covered with fabric before insertion into the affected artery (stenting). The stent provides perpetual support so the artery remains open.

How to prevent visceral artery aneurysm?

Although many cases of VAA cannot be prevented (such as aneurysm due to family history/genetic factors), managing the conditions that act as risk factors for VAAs can prevent the development of this disease. Atherosclerosis is one of the major causes of VAA, and it can be managed with the help of a healthier lifestyle. These lifestyle modifications include: 

• Regular exercise
• Managing cholesterol
• Controlling blood pressure
• Adopt a heart-supporting diet 
• Quit smoking
• Less alcohol consumption²

Summary

VAA is characterised by the bulging of an artery near the visceral organs due to its weakened walls. This bulge may rupture and result in internal bleeding, which may be fatal. VAA can potentially lead to an arterial rupture and even death if the diagnosis and treatment are not timely. Early diagnosis and treatment increase the odds of better health outcomes. Various risk factors include smoking, atherosclerosis, connective tissue disorders and high blood pressure. The causes of VAA include genetic factors, infection, trauma, and abdominal or intestinal surgery. Most of the cases are asymptomatic, while symptomatic VAA is characterised by abdominal pain, flank pain, and the presence of a pulsatile mass in the abdomen. Treatment can be carried out through lifestyle modifications and monitoring if the aneurysm is small. Large aneurysms require surgery or endovascular procedures.

FAQs

Are there any symptoms of visceral artery aneurysm?

In most cases, VAA is asymptomatic. However, when the size of the aneurysm increases, it starts pressing onto the surrounding organs and structures. This causes a variety of symptoms to appear, such as abdominal and/or flanking pain (pain on the sides and lower back). A pulsatile mass is also felt if someone suffers from symptomatic VAA.

What are the risks associated with an untreated visceral artery aneurysm?

The main complication or risk associated with an untreated VAA is the rupturing of an artery, resulting in internal bleeding (haemorrhage). This may be life-threatening, and therefore, timely diagnosis and treatment are crucial.

Is it possible to prevent visceral artery aneurysms?

While the genetic factors cannot be controlled, managing conditions such as high blood pressure (hypertension) and atherosclerosis (hardening of arteries) can reduce the possibility of developing VAAs.

Can visceral artery aneurysms be hereditary?

In some cases, yes. Genetic factors are one of the causes of VAAs. If you have a family history of VAA, it is important to convey this to a healthcare provider.

What is the prognosis after treatment for a visceral artery aneurysm?

The prognosis is good in case of timely diagnosis and prompt treatment. However, it is crucial for the patients to follow the instructions of their healthcare provider regarding the routine monitoring and management of the condition, including lifestyle modifications.

What are the treatment options for visceral artery aneurysms?

Treatment options may vary and depend on the size, location, and severity of the aneurysm, as well as the overall health of the patient. They can include watchful waiting, minimally invasive procedures like embolisation, or surgery, to repair or replace the affected artery.