Arterial aneurysm

Dr Jason Toniolo

An aneurysm is a localised enlargement or bulging of an artery due to a weakness in the artery wall.

If untreated, aneurysms can rupture, leading to life-threatening bleeding. While brain aneurysms are common, this article focuses on aneurysms occurring elsewhere in the body. Vascular surgeons treat all aneurysms except for those found within the heart or the brain (which are treated by cardiothoracic surgeons or neurosurgeons / neuro-interventional radiologists)

Where Arterial Aneurysms Can Occur

Aneurysms can develop in several vital arteries in the body, including:

Abdominal Aortic Aneurysms (AAA): The most common type, occurring in the lower part of the aorta, typically below the arteries that supply the kidney, before the aorta divides into arteries that supply each leg with blood.
Thoracic Aortic Aneurysms (TAA): These form in the upper part of the aorta, with the aorta attached to the heart
Peripheral Arterial Aneurysms: These can occur in arteries in the arms, legs, or groin, including:
Iliac artery (in the pelvis) – most common, often found with abdominal aortic aneurysms
Popliteal artery (behind the knee)
Femoral artery (in the thigh)

Visceral aneurysms

Splenic artery (supplying the spleen)
Renal artery aneurysm
Mesenteric aneurysms (supplying the intestines or liver)

What Size Criteria Are Used to Decide on Intervention?

The decision to intervene surgically is based on the size of the aneurysm and the risk of rupture. Standard size criteria include:

Abdominal Aortic Aneurysm (AAA): Intervention is undertaken when the aneurysm reaches a diameter of 5.5 cm in men and 5.0 cm in women. Aneurysms smaller than this are monitored periodically for growth and not repaired until they are large enough, as the risk of surgery outweighs the risk of death from rupture
Thoracic Aortic Aneurysm (TAA): Surgery is often considered when the aneurysm exceeds 6.0 cm. However, surgery may be performed at smaller diameters (around 4.5 cm) for patients with certain genetic conditions like Marfan syndrome.
Peripheral Aneurysms: Intervention is advised :
Popliteal aneurysms exceed 2.0 cm, or if they are causing issues with blockages below the popliteal aneurysm
Femoral aneurysms reach approximately 3.0 cm or are symptomatic.
Iliac aneurysms grow to 3.5-4.0 cm.

What symptoms can aneurysms cause?

Aneurysms are often asymptomatic until they grow large or rupture, but when symptoms do occur, they vary depending on the aneurysm’s location:

Abdominal Aortic Aneurysm (AAA):
A pulsating feeling near the navel
Deep, constant pain in the abdomen or back
Sudden, severe pain indicates rupture, which can lead to rapid death if not treated immediately.
Thoracic Aortic Aneurysm (TAA):
Chest or back pain
Shortness of breath, cough, or difficulty swallowing (due to pressure on nearby organs)
Hoarseness due to pressure on the vocal cords
Pain with swallowing, with some aneurysms pushing on the oesophagus – this is very rare (dysphagia lusoria)
Peripheral Aneurysms:
Popliteal or femoral aneurysms: A pulsatile mass behind the knee or in the groin, leg pain, or symptoms of reduced blood flow (such as coldness or numbness), sudden onset of pain from the aneurysm blocking blood supply due to clot formation
Iliac artery aneurysm: Lower back pain or a pulsatile mass in the pelvis. Rupture may cause severe abdominal pain.
Splenic artery aneurysm: Often asymptomatic but can cause left upper abdominal pain. Rupture leads to sharp pain and internal bleeding

What are the risk factors, and how can their progression be modified?

Risk factors for aneurysms include:

Age: The risk of aneurysm increases with age.
Smoking: One of the most significant modifiable risk factors. Smoking weakens the arterial wall and accelerates aneurysm growth.
Hypertension: High blood pressure contributes to the formation and expansion of aneurysms.
Atherosclerosis: Plaque build-up in the arteries can weaken the arterial wall.
Family History: A genetic predisposition to aneurysms increases risk, particularly in first-degree relatives.
Genetic Conditions: Disorders like Marfan syndrome or Ehlers-Danlos syndrome increase the risk of aortic aneurysms.

Modifying progression:

Lifestyle modifications, such as quitting smoking, managing blood pressure and cholesterol, and maintaining a healthy weight, are advantageous for slowing aneurysm growth. Patients with aneurysms should be regularly monitored with imaging, and any rapid growth requires prompt medical attention. Studies are being conducted using doxycycline and metformin to reduce aneurysm growth, but this is not yet prescribed or common practice among vascular surgeons at this stage.

treatment options

How Can Aneurysms Be Treated?

Treatment options vary depending on the size, location, and growth rate of the aneurysm:

Monitoring:

Keeping an eye on the size of an aneurysm is essential. All aneurysms will grow, but some may not become large enough to be a problem until you are over 100! You will need someone to monitor its size and growth trajectory. Medicine can help modify risk factors for aneurysm progression.

Surgical Intervention:

Open surgical repair: Removing the weakened section of the artery and replacing it with a graft (fabric) is the traditional method for treating large or symptomatic aneurysms.
Endovascular repair (EVAR or TEVAR): A less invasive approach is inserting a stent graft through the arteries to reinforce the weakened area. This method is commonly used for AAA and TAA but may also be used for other peripheral aneurysms, depending on location and anatomy.
Coiling or embolisation): This is used to block blood flow towards or within an aneurysm, removing the pressurise within the wall and eliminating the risk of rupture. Not all aneurysms can be blocked, which may lead to organ or limb ischaemia. Coiling is reserved for specific aneurysm locations, such as splenic artery aneurysms and some mesenteric aneurysms.

The choice between open and endovascular repair depends on the patient’s health, the aneurysm’s location and size, and the risks associated with surgery.

The most common discussion to be had involves deciding whether an abdominal aortic aneurysm should be fixed with open surgical repair (big cut) or minimally invasive stent grafting (keyhole surgery).

Deciding on minimally invasive (EVAR) versus open surgical repair

Pro of minimally invasive

Lower risk of death and major complications in the short-term
Faster recovery, with minimal pain and suffering

Cons of minimally invasive

The repair is not as durable. It may begin to leak around the stent graft fabric, or other small vessels that attach to the aorta can deliver blood under low pressure into the aneurysm. Growth in the following 5-10 years may eventually need further minimally invasive surgeries to resolve the leak.
Because of the risk of a leak in the years to come, it needs a lifetime of ongoing surveillance with ultrasound, usually once yearly

Pro of open surgical repair

The repair is far more durable, likely to last > 20 years, and unlikely to cause further issues when the initial surgery has been recovered from
Requires minimal follow-up surveillance in the years following surgery

Cons of open surgical repair

There is a much higher risk of complications, including death, bowel resection or stoma formation, kidney failure, respiratory failure, heart attack, impotence, and return to the operating theatre for emergent surgery.
Requires prolonged recovery, often one week in the hospital and six months until energy levels return to normal