Where is the aorta located? What is aortic dissection?

Author: Guo Wei, Chief Physician, PLA General Hospital (301 Hospital)

Vice Chairman of the Vascular Surgery Committee of the Chinese Medical Doctor Association

Reviewer: Liu Changwei, Chief Physician, Peking Union Medical College Hospital

There are no blood vessels in the human body except in the hair and nails, but there are blood vessels everywhere else in the human body. You can imagine that the blood vessels in the human body are very long.

Blood vessels are channels for transporting blood, and are divided into arteries and veins. The heart pumps blood out like a pump. The blood flowing out of the heart is arterial blood, which is supplied to the limbs and organs; the blood flowing back to the heart from the distal end is called venous blood.

These blood vessels vary in thickness and length, and the thickest and most important one is the aorta.

1.Where is the aorta located?

The projection of the aorta on the body surface is relatively backward, like a question mark.

The aorta that goes upward from the heart is called the ascending aorta. It crosses a bend called the aortic arch. There are branches on the aortic arch that supply blood to the brain and upper limbs. The aorta that goes downward is called the descending aorta, which is in the chest and abdominal cavity.

Figure 1 Original copyright image, no permission to reprint

The aorta is very important in the human body because the blood flow to the internal organs is diverted through the aorta. It is a main artery, so it is called the aorta.

The arteries branching out from the aorta are called branch arteries. Some branches supply the heart, some branches supply the brain, some branches supply the upper limbs, some branches supply the lungs, some branches supply the kidneys, intestines, pancreas, lower limbs, and so on.

If there is a problem with the aorta, it may cause damage and ischemia to many branch blood vessels. The ischemia of branch blood vessels may cause problems with one or several organs, which can be fatal.

2. What is aortic dissection?

Aortic dissection is a disease that occurs in the aorta.

The aorta is a tubular structure like a paper tube. The blood vessel wall is divided into three layers: the intima, the middle layer, and the outer layer. These three layers are tightly combined and intact. When the blood vessel wall is torn into two layers, it is called aortic dissection.

Figure 2 Original copyright image, no permission to reprint

The blood vessel wall has a three-layer structure, and dissection occurs more often between the middle layer and the outer layer. The outer part of the middle layer, that is, the elastic layer, is torn.

3. What factors may be related to aortic dissection?

The blood vessel wall is originally very intact. If blood wants to flow into the blood vessel wall, there must first be a crack on the side of the blood vessel close to the intima. Why does the crack appear?

It is not very clear at the moment. Some are caused by arteriosclerosis, some are related to inflammation, some are related to developmental abnormalities, some are related to trauma, and some have no cause.

After the blood vessel wall has cracks, blood needs pressure to flow in. Without blood pressure, there is no impact force. If there is no blood pressure, but the blood can still flow, it means that the blood vessel is not tough enough. Tough blood vessels cannot be torn far, while weak blood vessels can be torn very far.

The vast majority of patients with aortic dissection have hypertension, and the average age is around 50 years old.

4. What does it feel like to have an aortic dissection?

It is a feeling of near death, with an almost unbearable pain in the back. The blood vessels are torn in half, which is more severe than any abdominal pain or heart pain. It feels like a knife piercing the flesh, like the feeling of tearing clothes. If you are lucky enough to survive, this feeling is unforgettable.

If the tear is on the waist, when you tear it upwards, you will feel the pain rushing up; if the tear is in the upper part of the aorta, when you tear it downwards, you will feel the pain rushing down, and your blood pressure will generally be very high after the pain.

More than 90% of patients will experience unbearable pain and paleness. Some people do not experience severe pain, such as patients with Marfan syndrome or those who take hormones for a long time. Their blood vessel walls are in poor condition, so when they are torn, they do not need much force. For about 10% of patients, the pain may not be so obvious.

Patients with aortic dissection are usually sent to the emergency room due to severe chest or abdominal pain, and enhanced CT scan can be used to determine whether it is aortic dissection.

When diagnosed with dissection, controlling blood pressure is the first priority. If blood pressure is not well controlled, the prognosis is very poor. Heart rate must also be controlled.

Once a blood vessel is torn, the only way to replace the damaged blood vessel is through surgery. Now there is a minimally invasive method, minimally invasive endovascular treatment can solve the problem of dissection. Whether it is open surgery or minimally invasive endovascular treatment, the operation is difficult.