Abdominal aortic aneurysm

Causes of an AAA

It’s not known exactly what causes the aortic wall to weaken, although increasing age and being male are known to be the biggest risk factors.

There are other risk factors you can do something about, including smoking and having high blood pressure and cholesterol level.

Having a family history of aortic aneurysms also means that you have an increased risk of developing one yourself.

Causes of an abdominal aortic aneurysm

The aorta is the largest blood vessel in the body. It transports oxygen-rich blood away from the heart to the rest of the body.

An abdominal aortic aneurysm (AAA) occurs when part of the aorta wall becomes weakened and the large amount of blood that passes through it puts pressure on the weak spot, causing it to bulge outwards to form an aneurysm.

The abdominal aorta is usually around 2cm wide – about the width of a garden hosepipe – but can swell to over 5.5cm, which is what doctors classify as a large aneurysm.

Risk factors for an AAA

It’s not known exactly what causes the aortic wall to weaken, although increasing age and being male are known to be the biggest risk factors.

One study found that people aged over 75 are seven times more likely to be diagnosed with an AAA than people under 55 years old.

Men are around six times more likely to be diagnosed with an AAA than women.

However, there are other risk factors that you can do something about – described below – the most important of which is smoking.

Smoking

Research has found that smokers are seven times more likely to develop an AAA than people who have never smoked.

The more you smoke, the greater your risk of developing an AAA. People who regularly smoke more than 20 cigarettes a day may have more than 10 times the risk of non-smokers.

The risk may increase because tobacco smoke contains harmful substances that can damage and weaken the wall of the aorta.

Smoking is a major risk factor for aneurysms because it causes atherosclerosis (hardening of the arteries) and raises your blood pressure.

Tobacco smoke contains substances that can damage the walls of the arteries.

It is known that smokers are seven times more likely than non-smokers to develop an AAA.

The more you smoke, the greater your risk. People who regularly smoke more than 20 cigarettes a day may have more than 10 times the risk of non-smokers.

If you want to stop smoking, your GP will be able to refer you to an NHS Stop Smoking Service, which will give you dedicated help and advice about the best ways to quit.

You can also call or chat online with Quit Your Way Scotland. The specially trained helpline staff can offer you free expert advice and encouragement.

Read more about stopping smoking and nicotine replacement therapies (NRTs), which can make it easier to quit.

Atherosclerosis

Atherosclerosis is a potentially serious condition where arteries become clogged up by fatty deposits, such as cholesterol.

An AAA is thought to develop because these deposits (called plaques) cause the aorta to widen in an attempt to keep blood flowing through it. As it widens, it also gets weaker.

Smoking, eating a high-fat diet and high blood pressure all increase your risk of developing atherosclerosis.

High blood pressure

As well as contributing to atherosclerosis, high blood pressure (hypertension) can place increased pressure on the aorta’s wall.

Family history

Having a family history of AAAs means that you have an increased risk of developing one.

One study found that people who had a brother or sister with an AAA were eight times more likely to develop one than people whose siblings were unaffected.

This suggests that certain genes you inherit from your parents may make you more vulnerable to developing an AAA.

However, no specific genes have yet been identified.

Diagnosing an abdominal aortic aneurysm

Because an abdominal aortic aneurysm (AAA) usually causes no symptoms, it tends to be picked up either through a screening test or during a routine check-up, for instance if a doctor notices a pulsating sensation while examining your abdomen.

The screening test used is an ultrasound scan, which lets the size of your abdominal aorta be measured on a monitor. This is also the test your doctor will use to confirm the diagnosis if an AAA is suspected.

Screening

Read more about screening for an AAA.

All men in the UK aged 65 or over are offered an ultrasound scan to check for AAAs. Every man should receive an invitation in the year he turns 65.

For more information, visit our page on AAA screening.

Diagnosing an abdominal aortic aneurysm

An abdominal aortic aneurysm (AAA) usually causes no symptoms, so it tends to be diagnosed either through screening or during a routine physical examination, when a doctor notices a distinctive pulsating sensation in your abdomen.

The diagnosis can be confirmed with an ultrasound scan. This scan can also show the size of the aneurysm, which is an important factor in deciding on the right course of treatment.

If a large AAA is found before it ruptures, your doctor will usually advise treatment to prevent that from happening.

This is normally done through surgery, replacing the weakened part of the blood vessel with a piece of synthetic tubing.

If surgery isn't advisable for you, or if you choose not to have it, there are non-surgical steps that can lower the risk of the aneurysm rupturing.

These include medicines to bring down your cholesterol and blood pressure, and quitting smoking.

Your aneurysm's size will also be checked regularly with ultrasound scans.

Treating an abdominal aortic aneurysm

Treatment for an abdominal aortic aneurysm (AAA) depends on several things, including the size of the aneurysm, your age, and your general health.

Generally, if you have a large aneurysm (5.5cm or larger), you will be advised to have surgery, either to strengthen the swollen part of the aorta or to replace it with a piece of synthetic tubing.

This is because the risk of the aneurysm rupturing is usually greater than the risk involved in repairing it.

If you have a small (3.0 to 4.4cm) or medium (4.5 to 5.4cm) aneurysm, you will be offered regular scans to keep an eye on its size.

You will also be given advice on slowing its growth and lowering the risk of rupture, such as stopping smoking, and you may be given medicines to reduce your blood pressure and cholesterol level.

If you have a large AAA

If you are diagnosed with an AAA that is 5.5cm or larger, you will be referred to a vascular surgeon (a surgeon who specialises in diseases of the blood vessels), who may recommend an operation.

The surgeon will talk through treatment options with you, taking into account your general health and fitness, as well as the size of your aneurysm.

If it's decided that surgery isn't suitable for you, it's still possible to lower the risk of the aneurysm bursting, and you will have regular scans to check its size, in the same way people with small or medium aneurysms are followed up.

See below for more on treating small and medium aneurysms.

There are two surgical techniques used to treat a large aneurysm:

• endovascular surgery
• open surgery

Both techniques are equally effective at lowering the risk of the aneurysm bursting, but each has its own advantages and disadvantages.

Your surgeon will discuss with you which one suits you best.

Endovascular surgery

Endovascular surgery is a type of "keyhole" surgery in which the surgeon makes small cuts in your groin.

A small piece of tubing called a graft, made of metal mesh lined with fabric, is then guided up through the leg artery into the swollen part of the aorta, and sealed to the aorta's wall at both ends.

This reinforces the aorta and reduces the risk of it bursting.

This is the safer of the two types of surgery. Around 98 to 99% of patients make a full recovery, and the recovery time is shorter than with open surgery.

There are also fewer major complications, such as wound infection or deep vein thrombosis (DVT).

However, the way the graft is attached is not as secure as with open surgery. You'll need regular scans to make sure the graft hasn't slipped, and in some patients, the seal at each end of the graft starts to leak and needs to be resealed. Surgery would need to be repeated if either of these happens.

Open surgery

In open surgery, the surgeon cuts into your abdomen to reach the abdominal aorta and replaces the enlarged section with a graft.

This type of graft is a tube made of synthetic material.

Because the graft is stitched (sutured) into place by the surgeon, it's more likely to stay put, and will usually work well for the rest of your life.

The risk of graft related complications after surgery is lower than with endovascular surgery.

Open surgery isn't usually recommended for people in poor health, as it is a major operation. It carries slightly more risk than endovascular surgery, with 93 to 97% of patients making a full recovery.

The main risk with open surgery is death or heart attack, and recovery takes longer than with endovascular surgery.

There is also a greater risk of complications, such as wound infection, chest infection, and DVT.

If you have a small or medium AAA

If you are diagnosed with a small (3.0 to 4.4cm) or medium (4.5 to 5.4cm) aneurysm, you won't be referred to a vascular surgeon, since surgery is unlikely to benefit you at this stage.

You'll be invited back for regular scans to check whether the aneurysm is growing, once a year for a small aneurysm and every three months for a medium one.

You will also be given advice on preventing the aneurysm from getting bigger, including:

• stopping smoking
• eating a balanced diet
• keeping to a healthy weight
• taking regular exercise

If you smoke, the most important change you can make is to quit. Aneurysms have been shown to grow faster in smokers than in non-smokers.

Read more about stopping smoking and about nicotine replacement therapies (NRTs), which can make it easier to quit.

Your GP will receive your test results and may decide to adjust your current medication or start a new one, especially if you have:

• high blood pressure, which is usually treated with a medicine called an angiotensin-converting enzyme (ACE) inhibitor
• high cholesterol, which is usually treated with a medicine called a statin

Treating a ruptured AAA

Emergency treatment for a ruptured AAA follows the same principle as preventive treatment. Grafts are used to repair the ruptured aneurysm.

Whether open or endovascular surgery is used is decided case by case, by the surgeon carrying out the operation.

Prevention

The best way to prevent getting an aneurysm – or reduce the risk of an aneurysm growing bigger and possibly rupturing – is to avoid anything that could damage your blood vessels, such as:

• smoking
• eating a high-fat diet
• not exercising regularly
• being overweight or obese

Preventing an abdominal aortic aneurysm

The best way to prevent getting an aneurysm, or reduce the risk of an aneurysm growing bigger and possibly rupturing, is to avoid anything that could damage your blood vessels.

This includes:

• smoking
• eating a high-fat diet
• not exercising regularly
• being overweight or obese

If your GP finds out you have high blood pressure or a high cholesterol level, you may be prescribed medication for both. This will reduce the risk of developing an abdominal aortic aneurysm (AAA).

Diet

Eating a high-fat diet increases your risk of atherosclerosis.

It’s especially important to limit the amount of foods you eat that are high in saturated fat, such as biscuits, cakes, butter, sausages and bacon.

This is because eating too much saturated fat can lead to high cholesterol, which can build up in the artery walls.

Read more about high cholesterol. Find out more about healthy eating and how to reduce the amount of saturated fat you eat.

Exercise

Being active and doing regular exercise lowers blood pressure by keeping your heart and blood vessels in good condition.

Regular exercise can also help you lose weight, which will also help lower your blood pressure.

Adults should do at least 150 minutes (two hours and 30 minutes) of moderate-intensity aerobic activity every week.

Examples of moderate intensity activity include cycling or fast walking.

For it to count, the activity should make you feel warm and slightly out of breath. Someone who is overweight may only have to walk up a slope to get this feeling.

Physical activity can include anything from sport to walking and gardening.

Weight

Being overweight forces your heart to work harder to pump blood around your body. This can raise your blood pressure, which in turn puts pressure on your arteries.

Use a BMI healthy weight calculator to find out if you need to lose weight.

If you need to shed some weight, it’s worth remembering that losing just a few pounds will make a big difference to your blood pressure and overall health.

Get tips on losing weight safely

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