An aortic dissection is a rare, but potentially life-threatening condition that occurs when a tear occurs in the inner layer of the aorta, the tunica intima that allows blood to pass into the middle layer of the aorta, the tunica media (see more information on the aorta here). This creates a new passage through which blood flows and is known as the false lumen. The creation of this passage can block the passage of blood to important blood vessels mean that important organs no longer have a blood supply.
What problems do aortic dissections cause?
The problems caused by aortic dissection are due to the extent of the tear in the tunica intima and the size of the false lumen. As blood is directed away from the true lumen, blood vessels can become occluded; this can affect the limbs, brain, bowel and kidneys.
The tear can extend through the aortic valve allowing blood to flow back into the heart as it relaxes after each heartbeat, a condition called aortic regurgitation. The dissection can burst into the sac in which the heart is contained causing a life threatening condition called cardiac tamponade.
Who does aortic dissection affect?
Aortic dissection is a rare condition affecting approximately 3-4 people per 100000 per year. It affects people aged 60-70 years old with men 3 times more liklely to be affected than women.
What are the symptoms of aortic dissection?
- Sudden and severe chest pain classically described as tearing or ripping that radiates through to the back
- Sudden loss of consciousness
- Symptoms of stroke due to occlusion of the arteries supplying the brain such as: weakness on one side, difficulty speaking, visual disturbance, altered sensation
The presence of any of these symptoms should prompt urgent presentation to an emergency department
What are the risk factors for aortic dissection?
Modifiable risk factors include:
- High blood pressure
- High cholesterol
- The use of stimulant recreational drugs e.g. cocaine or amphetamines
Various genetic disorders affecting the connective tissues lead to weakness in structural tissues throughout the body increase the risk of suffering an aortic dissection. These include:
- Marfan syndrome
- Loeys-Dietz syndrome
- Ehlers-Danlos syndrome
- Turner syndrome
An important group of people who have an increased risk of dissection include people with hereditary vascular disorders, particularly people with bicuspid aortic valve (see more information on bicuspid aortic valve here) and aortic coarctation.
Some rare inflammatory disorders can affect the lining of the vessels including:
- Giant-cell arteritis
- Takayasu arteritis
- Bechet disease
Untreated infections such as syphilis and tuberculosis can lead to weakness in the wall of the aorta and lead to an increased risk of aortic dissection.
How do doctors classify aortic dissection?
Doctors classify aortic dissection based on where they occur in the aorta. This is an important distinction because it determines not only the likely outcome of the condition but also who it is managed. The Stanford Classification system separates aortic dissection into 2 types: type A and type B dissections.
Standford classification system:
Type A – all dissections that involve the ascending aorta
Type B – all dissections that do not involve the ascending aorta
How is aortic dissection diagnosed?
On presenting to the emergency department the doctor will take a history and perform a physical examination. Various imaging studies are necessary to diagnose and guide the management of the aortic dissection these tests include:
- Chest x-ray
- CT aortagram
- Transthoracic echocardiogram
- Magnetic resonance angiogram
How is aortic dissection treated?
Type A dissections are managed surgically. The surgery involves opening the chest and removing as much of the aorta that is affected by the dissection as possible, this is then replaced using a synthetic graft which a plumbed in to all the major blood vessels supplied by the aorta. If the aortic valve has been involved this will be replaced at the time of the surgery. Depending on the extent of the dissection flap, collapsible wire mesh tube (stent) may be sited to help close off the false lumen in the aorta further away from the heart.
Type B dissections can be managed with medications or with stents depending on the presence of complications and the appearance on the imaging studies.
Goldfinger JZ, Halperin JL, Marin ML, Stewart AS, Eagle KA, Fuster V. Thoracic Aortic Aneurysm and Dissection. Journal of the American College of Cardiology. 2014;64(16):1725-39.
Nienaber CA, Clough RE. Management of acute aortic dissection. The Lancet. 2015; 385(9970):800-11.