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Abdominal aortic aneurysm

Overview

Illustration of abdominal aortic aneurysm

1. Aorta
2. Heart
3. Aortic aneurysm
4. Normal aorta leading to heart
5. Kidney Type the text here

 

Repair of the abdominal aortic aneurysm is a surgical procedure that is usually carried out when it is felt that there is an unacceptably high risk of the abdominal aorta rupturing (splitting). This is a life-threatening emergency.

The abdominal aorta

The abdominal aorta runs down the centre of the abdomen, and it is one of the largest arteries in the body. The role of the abdominal aorta is to take blood from the heart and distribute it, via a network of branching blood vessels, to all of the body’s organs.

What is an aneurysm?

An aneurysm is a bulge in a blood vessel that is caused by a weakness in the blood vessel wall. As the blood runs through the weakened blood vessel, the pressure of the blood causes the blood vessel to bulge outwards like a balloon.

In many cases, the exact cause of an aneurysm is often unclear, but known risk factors include:

  • smoking,
  • high blood pressure (hypertension), and
  • having a family history of aneurysms.

A healthy abdominal aorta has a diameter of 2-3cm (one inch). If an aneurysm develops, the diameter of the aorta may increase. The increase in diameter weakens the walls of the aorta, increasing the risk of the aorta rupturing (splitting).

A ruptured aortic aneurysm can cause massive internal bleeding and requires prompt emergency treatment to prevent death. It is estimated that 80% of people with a ruptured aneurysm will die, and that many of these will die before being able to reach a hospital. Even with emergency treatment, the outlook is poor and 50% of people will die despite the best efforts of surgeons.

When should surgery be carried out?

Due to the risk, it is usually recommended that surgery should be used to repair the aneurysm:

  • if the aneurysm grows to (or beyond) a diameter of 5.5cm (2.1 inches),
  • if the aneurysm grows by more than 0.6-0.8cm (0.25-0.3 inches) a year, and/or
  • if you have a family history of ruptured aneurysm.

An abdominal aortic aneurysm is usually repaired using a technique called grafting. This involves removing the section of the aorta that contains the aneurysm and replacing it with a piece of synthetic tubing which is known as a graft.

 

Why it is necessary

Abdominal aortic aneurysm repair is necessary if it is thought that the risk of the aneurysm rupturing is significant.

Identifying risk

Aortic aneurysms tend to be more common among older people who are 65 years of age, or over. It is estimated that between 1.3- 8.9% of older men, and 1-2.2% of older women have an aortic aneurysm.

As unruptured aneurysms do not usually cause symptoms, it is difficult for researchers to arrive at a more precise estimate. Aneurysms that do not cause symptoms are known as asymptomatic aneurysms.

Many asymptomatic aneurysms are diagnosed during a routine physical examination when the GP notices a vibrating sensation in your abdomen, which is caused by the blood pushing against a weak spot in the aortic wall.

Alternatively, an aortic aneurysm can be detected during diagnostic tests, such as ultrasound, or X-ray examinations, that are carried out to diagnose unrelated conditions.

Assessing the risk

Surgery to repair an aneurysm is recommended when it is thought that the risk of the aneurysm rupturing is high enough to outweigh the possible risks associated with having surgery.

The assessment is usually based on five factors:

  • the size of the aneurysm,
  • how quickly the aneurysm is growing,
  • your sex - for reasons that are unclear, the risk of an aneurysm rupturing is four times higher in women,
  • whether you have a first-degree relative who has had a ruptured aneurysm, and
  • whether you have high levels of a chemical called MMP-9 in your blood - which can be caused by extensive weakening of the aortic wall.

Usually, the recommended treatment options are:

  • if the size of the aneurysm is less than 5cm, a policy of watchful waiting is recommended (see the alternatives section for more information about this),
  • if the size of the aneurysm is between 5 - 5.5cm (1.9- 2.1 inches), and you have one of the risk factors mentioned above, such as high levels of MMP-9, or you are female, preventative surgery is recommended, and
  • if the aneurysm is larger than 5.5cm (2.1 inches), surgery is recommended, regardless of whether you have any associated risk factors.

Ruptured aneurysm

In cases of ruptured aortic aneurysm, immediate emergency surgery is required to repair the aneurysm and prevent massive blood loss occurring.

If your aortic aneurysm ruptures you will experience a sudden and severe pain in the middle, or side, of your abdomen. In men, the pain can also radiate down into the scrotum (the pouch of skin that contains the testicles).

Other symptoms include:

  • dizziness,
  • sweaty and clammy skin,
  • rapid hear beat (tachycardia),
  • shortness of breath,
  • feeling faint, and
  • loss of consciousness.

If you suspect that you, or someone you know, may have developed a ruptured aortic aneurysm, you should dial 999 immediately to request an ambulance.

Preparation

A couple of weeks before having an abdominal aortic aneurysm repair, you will usually be asked to attend a pre-operative assessment clinic to meet your surgeon and the other members of your surgical team. They will take your medical history and carry out a physical examination.

You should bring with you details of any medication that you are taking, including over-the-counter (OTC) medication, because this information may be important in planning your surgery.

Preliminary tests

The surgical team will carry out a number of tests to make sure that you are healthy enough to have an anaesthetic and surgery.

These tests may include:

  • blood tests,
  • urine tests,
  • an electrocardiogram (ECG) - a test that assesses how healthy your heart is by measuring its electrical activity, and
  • a lung function test - a test that uses a machine to measure how much air you can breathe in and out in order to provide information about how well your lungs are working.

The surgical team will give you advice about what you can do to prepare for surgery, and they will also ask you about your home circumstances so that your discharge from hospital can be planned. If you live alone, have a carer, or you feel that you need extra support, you should tell the surgical team so that any help or support can be arranged before you go into hospital.

Stop smoking

If you are a smoker, you are strongly advised to stop smoking as soon as you are told that surgery is required.

Research has found that people who stop smoking for at least two months before having surgery are four times less likely to experience complications following surgery compared with those who smoke.

How it is performed

Your treatment plan

There are two ways that aortic aneurysm repair can be carried out:

  • open repair - where an incision is made in your abdomen, and
  • endovascular aneurysm repair (EVAR) - where the aneurysm is repaired by passing instruments through one of your veins.

The two techniques are discussed in more detail below.

Open repair

During open surgery, the surgeon will make an incision in your abdomen in order to gain access to the abdominal aorta.

The weakened section of the aorta will be opened, before being patched with a tube of synthetic material, known as a graft. The graft should help to strengthen the walls of your aorta, preventing it from rupturing (splitting).

After the graft is in place, the aorta will be closed and the incision in your abdomen will be sealed with dissolvable stitches, or surgical clips.

Endovascular aneurysm repair (EVAR)

During endovascular aneurysm repair (EVAR), the surgeon will cover a small metal tube, known as a stent with the graft, which is known as a stent-graft.

The stent-graft will be attached to a thin tube called a catheter. The catheter will be inserted into one of the arteries in your groin, before being moved up to the site of the aneurysm.

The stent-graft will be attached to the inside of your aorta with pins, which will strengthen the walls of the aorta. The catheter will then be removed.

Open or endovascular repair?

Each surgical technique has its own set of advantages and disadvantages.

Endovascular surgery has a quicker recovery time than open surgery because it is non-invasive, which means that it does not involve making major incisions (cuts) into the body.

Studies have found that endovascular repair carries a lower risk of the graft failing in the first 30 days after surgery, which would result in a ruptured aneurysm and death.

It is estimated that 2% of people who are treated with endovascular repair will die during the first 30 days after surgery compared with 5-7% of people who are have an open repair.

In terms of medium- to long-term effectiveness, there seems to be no significant difference between either technique. However, endoscopic repair does carry a higher risk of complications than open repair, such as the stent-graft malfunctioning, which would require further surgery to correct.

The obvious disadvantage with open surgery is that because a major incision (cut) in your abdomen is required, it could take you several months for you to recover from the operation.  Also, while the risks of complications are lower with an open repair compared with an endovascular repair, if complications do develop, they tend to be more serious.

You may be able to choose which technique you would prefer to have, although this is not possible in all circumstances.

For example, open repair is not usually recommended for people who are in a poor state of health due to other health conditions because the effects of the surgery could be too much for their body to cope with. Endovascular repair may not be possible if you have narrowed arteries.

Before deciding on a type of surgery, you should discuss the risks and benefits of each treatment option with your surgical team.

Recovery

After you have had an aortic aneurysm repair, you will be taken to the intensive care unit (ICU), or the high dependency unit (HDU), so that your condition can be closely monitored.

Once you are stable, you will be returned to the surgical ward so that any lines and tubes that have been inserted can be removed. You will usually be free of these by about five days after an open repair and 1-2 days after endovascular repair.

Pain relief

If you were treated with open repair, you will have an incision (cut) in your abdomen, which is likely to be uncomfortable at first. However, any discomfort should settle fairly quickly over the first few days after surgery, but you may get twinges and aches for between 3-4 weeks.

You will be prescribed painkillers. While you are in hospital, these will usually be given by injection via an epidural tube in your back, or by a machine that you control yourself by pressing a button.

Moving about will not cause any damage to the graft, or to your wound, and will help your recovery.

If you have had endovascular repair, you are likely to experience less discomfort, although the incisions (cuts) that were made in the arteries in your legs may be sore for the first few days.

Going home

If you were treated with open repair, you will probably have to stay in hospital until the stitches have dissolved, or it is safe to remove the surgical clips, which can take between 7-10 days.

It will usually take several months to make a full recover from the operation. You will be given an exercise plan that is based on regular, light exercise which is combined with periods of rest. This should help to speed your recovery time.

If you were treated with endovascular repair, you should be able to leave hospital within 3-4 days after the surgery has been completed. Most people will make a full recovery within two weeks.

Working and driving

You can drive as soon as you can perform an emergency stop safely. This is often a week after endovascular repair and 3-4 weeks after open repair. However, if you are in doubt, you should check with your GP.

How long it will be before you are able to safely return to work will depend on the type of surgery that you had and the type of job that you do. Most people who are treated with endovascular repair can return to work within a month after having surgery. Those who are treated with open repair may need to wait 6-12 weeks before returning to work. Your GP will be able to advise you further.

Scarring

If you have had open surgery, you will have a scar where the surgeon makes an incision (cut) in your abdomen. This will be red at first but will gradually fade.

You do not have to take any special precautions to prevent the scar becoming infected beyond normal washing with mild soap and water when you have a bath or shower.

However, you should protect your scar from exposure to sunlight during the first year after having surgery because the scar will become darker if it is exposed to the sun.

If you were treated with endovascular repair, you will have a number of small puncture wounds in your groin that will soon fade.