The aorta is the largest and most important blood vessel in the body. It exits straight from the heart’s left ventricle, branching into smaller arteries that carry oxygen-rich blood to every part of your body. The aorta is anatomically divided into five main segments — the aortic bulb, ascending aorta, aortic arch, thoracic (descending) aorta, and the abdominal aorta. Because the aorta is a continuous structure. this segmentation is mostly arbitrary, although there are minor differences between the segments, mostly when talking about their diameters and physical properties.
All segments of the aorta, except the abdominal, are anatomically located in the thorax (chest area). However, when talking about the thoracic aorta, we’ll primarily concentrate on the descending aorta.
What is a thoracic aortic aneurysm?
Any condition that affects the integrity of the thoracic aorta can lead to serious consequences. These conditions include genetic connective tissue diseases, infections, traumas, atherosclerotic diseases (which restrict blood flow due to plaque being formed inside the lumen of the aorta), dissections, and aneurysms.
The aortic wall can also be damaged even if the aorta isn’t dilated. If the inner layer is damaged, blood can flow between the layers, tearing them apart. This condition is known as an aortic dissection.
What are the types of thoracic aortic aneurysms?
The aortic wall consists of three layers — the smooth inner layer, elastic middle layer, and the outer layer, made of collagen and elastic tissue.
If the aneurysm is composed of all three layers of the aortic wall, that’s called a true aneurysm. A false aneurysm is when a collection of blood is formed between the middle and the outer layer of the aortic wall. Dissecting aneurysms can form as a result of dissection, where the blood runs both through the regular lumen and the so-called “false” lumen, created in the process of the inner wall injury.
Aneurysms can be fusiform, when the lumen is equally expanded, or saccular, where a ball-shaped sack is created on one side of the blood vessel.
Do I have a thoracic aortic aneurysm?
Thoracic aortic aneurysms are primarily caused by atherosclerosis, a condition in which plaque is building inside your arteries. The plaque is made of fat, cholesterol and calcium. It narrows the lumen of the blood vessel, so less blood flows through it, leading to a shortage of blood in your organs. It can also break off in a form of a blood clot, leading to further complications, such as a heart attack or stroke.
Atherosclerosis is a disease associated with high blood pressure, smoking, obesity, and a generally unhealthy lifestyle. It is important to mention that atherosclerosis is a process that starts at a very young age, so you can’t avoid it entirely, although you can minimize its effect it by maintaining a healthy diet with a reasonable amount of physical activities.
The symptoms of thoracic aortic aneurysm include:
- Chest pain that can radiate to the upper back
- Shortness of breath and coughing as a result of airway compression
- Coughing up blood
- Hoarseness in your voice
- Trouble swallowing as a result of a compression to the esophagus
How are thoracic aortic aneurysms diagnosed?
Imaging methods to diagnose aortic aneurysms consist of:
- A chest X-ray, in which the aorta can look suspiciously large. The trouble with this method is that you can’t make a difference between an aneurysm and potential other masses in that area.
- Transesophageal echocardiography (TEE), a relatively unpleasant procedure in which an ultrasound probe is placed in your esophagus. It monitors the heart and large blood vessels in real time, so it can be useful both in diagnostics and in operating rooms.
- CT scan, the most reliable method, because it’s quick, painless, and most importantly – other than the location and the size of the aneurysm, it can show if there are any other issues, as well as potential blood clots. Although it’s based on X-ray technology, the radiation should not scare you, because the benefits outweigh the risks.
- MRI angiography. Other than visualizing the structures, an MRI can help in heart function assessment as well as the evaluation of the arterial flow. Unfortunately, this procedure is still very expensive and it has limited use, both because of its duration and magnetic properties (patients with pacemakers and other electronic equipment aren’t allowed near the machine).
- Aortography, in which a contrast agent is injected via a catheter placed in the aorta. It once was superior to other methods when evaluating blood flow and anatomy, but today it has mostly been replaced by other imaging methods.
All of these methods are used both in diagnostics and in surgery planning.
How is a thoracic aortic aneurysm treated?
A patient diagnosed with an aortic aneurysm should be treated promptly to prevent further complications. If minor abnormalities exist but surgery is not yet necessary, regular checkups are recommended once or twice a year. Meanwhile, it is very important to regulate your blood pressure and cholesterol using beta blockers (Hemangeol, Inderal, Lopressor...) and statins (Lipitor, Mevacor, Lescol). You can prevent further complications by checking your blood pressure regularly, eating healthily and exercising frequently, while avoiding heavy lifting. Also, if you are a smoker, you should quit immediately.
If the aortic aneurysm has a diameter of over five centimeters (two inches), there is a growing risk of complications, of which aneurysm rupture and dissection are the most dangerous. Rupture is characterized by a sharp upper back pain radiating towards the belly or lower back, and it can imitate a heart attack.
Other signs of aneurysm rupture include:
- Trouble breathing
- Low blood pressure
- Loss of conscience
Classic open surgery is done in a way that removes the part of the aorta containing the aneurysm and substitutes it with a synthetic replacement. Newer surgical approach, called TEVAR (Thoracic endovascular aortic repair), involves a stent graft being placed inside the artery, specifically inside the aneurysm. A stent is a small tubular structure placed on the site of the aneurysm which keeps the blood vessels open. The stent strengthens the aneurysm wall and prevents rupture.
Because aortic aneurysms mostly don’t show any symptoms, it is strongly recommended to regularly check the condition of your heart and major blood vessels, especially if you belong to a high-risk population. If any problems are shown to exist, early diagnosis combined with a healthy lifestyle should be your first line of defense against the further growth of the aneurysm and its potential complications.