Aortic Dissection

What is an aortic dissection?

The aorta is the largest artery in the human body, arising directly from the heart. The aorta faces the pressure of the blood being pumped out of the heart from life to death. The wall of the aorta is designed in layers to give it the required strength and flexibility required for this. Sometimes, the innermost layer , called the intima, develops a tear and soplits from the layers below. In this situation, the blood is forced into the space formed between the layers and splits the layers apart. This is called a dissection.

Aortic dissection can occur from many causes. Some of these are present from birth, in the form of inherited defects in the development of the aorta, and some are due to other diseases affecting the aorta. There are many genetic or inheritable disorders that make the sufferer

This splitting or dissection can lead to many problems.

Firstly, as the wall of the aorta is weakened by the dissection , there can be bleeding in to the space around the aorta. Because of the large amount of blood flowing through the aorta , this can be life threatening and constitutes an emergency.

Secondly, this splitting can advance across the openings for the branches that come from the aorta. This causes blockage of blood supply to the affected branches. As the aorta supplies blood to almost all organs in the body, this can lead to life threatening situations. Blockage of the coronary arteries which supply blood to the heart can occur, and lead to a myocardial infarction , a heart attack. Blockage of supply to the brain can cause a stroke, brain attack. This situation can affect the kidneys, the intestines and the limbs and again be life threatening.

Sometimes though, the condition is slow to progress and causes a slow dilatation of the aorta over months and years, this leading to the formation of an aortic aneurysm.

What are the symptoms?

• Sudden chest / back or abdomen pain. This may feel like a tearing sensation. Typically it goes to the back.

• Fainting, collapse (loss of consciousness)

• Difficulty in breathing

• Stroke symptoms , like difficulty in speaking, seeing or weakness of one side of the body.

• Weak pulse in one arm or thigh compared with the other.

• Pain in the limbs, legs more often than arm

• Difficulty walking

• Leg paralysis

How do you diagnose an aortic dissection?

There may be a strong clinical suspicion of aortic dissection with typical features as mentioned. However, the confirmation is usually done by a CT scan with injection of a dye to see what is happening to the aorta. When the presentation is with pain, the possibilities of heart attack or a clot to the lungs also must be considered, so a " Triple Rule Out" CT is done to see the heart arteries (Coronary Arteries) , the lung arteries (Pulmonary Arteries) and the aorta itself. The picture below shows a typical aortic dissection.

The treatment of this condition depends on a few factors.

In case the part of the aorta coming out of the heart, the ascending aorta is involved, it is called a "Type A Dissection" and this is treated urgently by surgery to replace that part of the aorta. This is because the blood supply to the heart arises from this part and the blockage of the coronary arteries can cause death in a matter of minutes. A dissection that does not involve this part of the aorta, that is one which involves the descending aorta is called Type B . Type B may or may not be an emergency , but is usually treated by endovascular techniques , using devices similar to that used for aortic aneurysm treatment.

There are conditions which are acquired (not present from birth) and can increase the risk of aortic dissection.

• Uncontrolled high blood pressure (hypertension)

• Hardening of the arteries (atherosclerosis)

• Weakened and bulging artery (pre-existing aortic aneurysm)

• Inflammatory or infectious conditions. These may include giant cell arteritis, which is an inflammation of the arteries, and syphilis, a sexually transmitted infection.

• Cocaine use increases the blood pressure and so may cause dissection.

• Pregnancy. Infrequently, aortic dissections occur in otherwise healthy women during pregnancy.

• High-intensity weightlifting. This and other strenuous resistance training may increase the risk of aortic dissection by increasing blood pressure during the activity.

What can be done to decrease these risks?

People in the high risk group, with conditions listed above that they are born with, should be screened for aortic disease by an expert using multiple tools. For certain conditions, this means repeated ultrasound, echocardiography or CT scans to monitor the aorta.

Persons with family members who suffered from this condition must consult doctors to find out if they are vulnerable.

For others, the aim is to avoid high risk behaviour.

This would imply checking the blood pressure, and taking medication religiously if blood pressure is high. Drug and alcohol use increases risk of blood pressure related complications amongst many other diseases.