Aortic Aneurysms

About

  • An aneurysm is the dilation of any artery by 50% more than its normal diameter. Aneurysms can affect any artery in the body.

    The aorta is the largest blood vessel in the body, and after leaving the heart, it curves around the chest (where it is called the thoracic aorta), before crossing into the abdomen (where it is called the abdominal aorta).

    Abdominal aortic aneurysms are the most common. There can also be aneurysms of the aorta in the chest, the large arteries in the pelvis that supply the legs (called iliac aneurysms), or the main artery of the leg behind the knee (popliteal aneurysms).

    Other aneurysms can affect the vessels that supply the kidneys (renal aneurysms) or intestines (mesenteric aneurysms).

  • ·Abdominal aortic aneurysms (called AAAs) affect 5% of men over the age of 65, and 5% more per decade of age after this.

    Thoracic aortic aneurysms are less common, impacting less than 1% of the population.

  • Common risk factors for aneurysms include:

    • Smoking

    • Age

    • Being male

    • Family history

    Less common risk factors include infection, genetic syndromes, and previous aortic damage (eg. from aortic dissections).

  • Aortic aneurysms result from plaque formation (called atherosclerosis) in the blood vessel called the aorta.

    Atherosclerosis occurs due to damage of the innermost layer of the artery.

    This damaged inner layer then allows inflammatory and cholesterol-carrying cells to get under this layer, which release factors that cause weakening of the arterial wall.

    Like a balloon, the artery can only get to a certain size before it is at risk of bursting (called a ruptured aneurysm). Thankfully, few people will ever have their aneurysms grow to this size.

    It is worth remembering that if you have developed an aneurysm, there is a chance you may have aneurysms elsewhere. For example, if you have an abdominal aortic aneurysm, you have a 10% chance each of having a thoracic aneurysm (the aorta in your chest) or a popliteal aneurysm (the popliteal artery behind your knee).

    Your vascular surgeon will perform tests to make sure you that don’t have aneurysms anywhere else.

  • Aortic aneurysms usually do not cause any symptoms.

    Uncommonly, they reach a size where the aortic wall becomes too weak, and the aneurysm ruptures. This causes abdominal and back pain.

    Aneurysm rupture is a medical emergency, as there is an extremely high death rate due to the extent and speed at which bleeding occurs.

    As such, aortic aneurysms are usually repaired before the point of rupture, called a prophylactic repair. Usually a repair is recommended on an abdominal aortic aneurysm that is 50mm to 55mm in size or 50mm to 60mm for a thoracic aneurysm.

  • Assessment begins with a thorough discussion about your medical history, followed by clinical examination.

    An ultrasound called an arterial duplex often follows, which is an excellent screening tool for abdominal aortic aneurysms. However, it may not pick up aneurysms elsewhere, and may miss some abdominal aneurysms.

    A CT scan with intravenous contrast is the most definitive test for imaging the aorta in the chest, abdomen and pelvis, and is often used to plan for surgery.

    Other ultrasound or CT scans may be used to exclude aneurysms elsewhere.

  • In NSW you may hold a ‘conditional’ license if you have an unrepaired aortic aneurysm (either thoracic or abdominal) that is under 55mm in diameter if due to atherosclerosis or bicuspid aortic valve (it may be <50mm if due to other causes).

    You may not drive if you have an unrepaired aortic aneurysm over 55mm diameter (or over 50mm in certain circumstances).

TREATMENT

How do you treat aortic aneurysms?

There are several treatment options for aortic aneurysms, depending on the site of the aneurysm.

An aneurysm indicates there is some disease in the arteries of the abdomen, which suggests there may be disease in the arteries that supply the heart, brain, abdominal organs or legs. As a result, if an aneurysm is diagnosed, it is recommended that risk factors for arterial disease are controlled (eg. by stopping smoking, and controlling high cholesterol or diabetes), and potentially starting medications to stop any arterial disease from developing or progressing. Managing these risk factors may also slow the growth of the aneurysm.

Treatment options include:

  • Surveillance – Most people do not need any intervention for their aneurysm, so they are usually monitored between three monthly and yearly, depending on their size, with a plan to intervene only if they reach the appropriate size.

  • Endovascular surgery – also called ‘keyhole surgery’, this involves an incision of around a centimetre in each groin. After a wire is passed across the aneurysm, a stent (a tubular metal frame covered in material) is used to divert blood flow through the stent, so the aneurysm no longer receives pressure that can cause rupture. This can be done under local anaesthetic, and is the method of choice in patients with ruptured aneurysms. Endovascular methods are used in over three-quarters of abdominal aortic aneurysm repairs in Australia.

  • Open surgery – before endovascular surgery, open surgery was the traditional way to manage aortic aneurysms. This involves an incision from the sternum to the pubic bone, where the bowel is moved out of the way, and the aorta clamped, the aneurysm opened, and a synthetic aorta is sewn in to replace the aneurysmal aorta. While this requires larger incisions and a longer hospital stay, it may be better in patients who are at very low risk of surgery.

We will discuss which treatment option may be most suitable for you, with consideration of your preferences and factors such as:

  • The size of the aneurysm

  • Which arteries are affected by the aneurysm

  • Your medical history

What are the risks of surgery?

Any operation requiring a general anaesthetic has risks such as stroke, heart attacks, respiratory failure, or death. As such, we avoid general anaesthetics in people who are at high risk of these complications.

The main risks of interventions for aneurysmal disease are listed below. These are often prevented by careful planning and treatment. While these can be life-threatening, they are actively watched for, and if they occur are immediately managed.

Main risks of endovascular surgery:

  • Bleeding or bruising

  • Reduction of blood supply to the pelvis or legs

  • Kidney damage

  • Need for a larger incision either in the groin or abdomen

  • Infection

Main risk of open surgery:

  • Bleeding or bruising

  • Kidney damage

  • Reduction of blood supply to the intestines, pelvis, legs or spinal cord

  • Nerve injury

  • Damage to the bowel

  • Infection

  • Hernias

Do I need to follow up with my Vascular Surgeon after the operation?

Dr Shiraev will want to see you after your operation, to make sure you have recovered well, your wounds are healing, and answer any questions you may have.

Unfortunately, ‘recurrence’ of aneurysmal disease (where the aneurysm returns) is not uncommon. This may be at the same site, or another artery in the body. This is due to the nature of the damage to the arteries, where the process of arterial damage from atherosclerosis has often been progressing for decades, and so may cause new arteries to enlarge, or cause the aneurysm that was originally treated to continue to grow. This is the case in less than 5% of people, and causes problems in even fewer than that.

As a result, people with aneurysmal disease benefit from monitoring, which will likely involve an annual checkup and ultrasound.

This advice is general, and is not intended to replace a formal clinical assessment and discussion with a health professional.