Dissection aortique

What is the aorta?

The aorta is the largest blood vessel in the body. It is an artery and carries blood from the heart and descends through the chest and the tummy (abdominal aorta).

The part of the aorta that connects with the heart is called the aortic root. The aorta then goes up towards the head (ascending aorta) but then loops (aortic arch) and heads down towards the abdomen (descending aorta).

Many arteries come off the aorta to supply blood to all parts of the body. At about the level of the hips, the aorta divides into two arteries, one going to each leg.

The aorta

© By Edorado (Own work based on: Arterial System en.svg, Coronary arteries.svg) via Wikimedia Commons

An aortic dissection occurs in a weakened area of the wall of the aorta. An aortic dissection is a serious condition of sudden onset in which the inner layer of the aorta tears. Blood then surges through the tear, causing the inner and middle layers of the aorta to separate (dissect).

Aortic wall layers

© Image: patient information from the International Registry of Acute Aortic Dissection

Aortic dissections are divided into two groups, depending on which part of the aorta is affected:

Type A aortic dissection

Type A. This involves a tear in the part of the aorta where it exits the heart or a tear in the upper aorta (ascending aorta). The tear may extend into the descending aorta and may extend into the tummy (abdomen).

Type B aortic dissection

Type B. This involves a tear in the lower aorta only (descending aorta). The tear may also extend into the abdomen but any tear that involves the ascending aorta is called a type A aortic dissection.

Aortic dissection may cause:

• Sévère douleur thoracique.

• Essoufflement.

The symptoms may be very similar to those of a heart attack.

• The chest pain starts suddenly and is often described as a tearing, ripping or shearing feeling.

• The pain often spreads to the neck or down the back.

• Aortic dissection may also cause loss of consciousness or symptoms similar to a stroke.

• There will often be changes in blood pressure and heart rate, with an increased heart rate and low blood pressure.

These may be, for example:

• Loss of vision.

• Weakness of your legs.

• Weakness of one side of your body.

Certain conditions make a tear in the wall of the aorta more likely.

• Hypertension artérielle over a long period of time may weaken the wall of the aorta, making it more likely to tear.

• People who already have an enlarged aorta (anévrisme aortique) are also at increased risk of aortic dissection.

• Some people are born with a condition that causes a weakened wall of the aorta, such as connective tissue disorders. These conditions are uncommon and include Syndrome de Marfan, bicuspid aortic valve and syndrome d'Ehlers-Danlos.

• There is an increased risk of aortic dissection with regular cocaine or amphetamine use and with any extremely strenuous exercise such as weightlifting.

• A severe injury to the chest may also cause aortic dissection.

• Sténose aortique, previous cardiac surgery, having a history of aortic diseases in your family and smoking can also increase the risk.

Initial investigations to diagnose aortic dissection and rule out a heart attack may include:

• Analyses de sang.

• Un tracé cardiaque (électrocardiogramme, ou ECG).

• A chest X-ray.

• An ultrasound scan of your heart (echocardiogram, or echo). Either transthoracic or transoesophageal echocardiography may be used.

• A computed tomography (CT) scan ou un examen d'imagerie par résonance magnétique (IRM).

An aortic dissection is an emergency and needs immediate treatment. Immediate treatment often involves surgery to repair the damaged aorta.

However, medicines such as beta blockers and nitroprusside may be used before surgery to reduce your heart rate and lower your blood pressure. Using these medicines can help to prevent the aortic dissection from becoming worse and so make surgery more likely to be successful. Surgery for type A aortic dissection may also include replacing the aortic valve of the heart at the same time if this is affected.

After the initial treatment, you may need to take medicine to lower your blood pressure. It is likely that you will remain on this medicine to control your blood pressure for the rest of your life. You may also need regular checks with a specialist doctor, including CT or MRI scans, to monitor the aorta in case any further problems occur.

• An aortic dissection may cause death due to severe internal bleeding.

• Death may also occur as a result of damage to an organ (for example, lésion rénale aiguë), or as a result of a AVC or damage to the aortic valve of your heart.

• Blood may also rupture into the lining around your heart (pericardium) to cause severe pressure on your heart (this is called cardiac tamponade).

How common is aortic dissection?

Aortic dissection is relatively uncommon. The condition most frequently occurs in people in their 50s and 60s and is rare in people under 40 years of age. Aortic dissection is more common in men but is still very rare: only about 30 people per million will have one, in a year.

Quel est le pronostic ?

Aortic dissection is often fatal if the blood-filled channel within the wall of the aorta ruptures through to the outside aortic wall (this is called aortic rupture). However, early diagnosis and treatment of aortic dissection can greatly improve survival.

Can aortic dissection be prevented?

The most effective ways to prevent aortic dissection are to take regular medicine to control blood pressure if you are found to have high blood pressure. You can also reduce your risk by reducing the risk of damage to your heart and arteries. This can be achieved by eating a healthy diet, taking regular exercise, keeping to an ideal body weight and avoiding smoking.