Thoracic Aortic Aneurysm - Causes, Symptoms, Diagnosis, and Treatment

What Is a Thoracic Aortic Aneurysm (TAA)?

An aneurysm is described as an abnormal bulge or ballooning within the wall of a blood vessel. A thoracic aortic aneurysm (TAA) is the widening or enlargement in the upper part of the aorta (the body’s largest blood vessel, which routes blood to the body from the heart). It is most often found in men, and the likelihood of developing it increases with age. It is a medical condition that progresses slowly. Only about five percent of the patients experience symptoms before an acute event occurs, and for the other 95 percent, the first symptom is often death.

What Is Aorta?

Aorta refers to the largest artery (blood vessel) in the body that starts at heart and carries blood from the heart to all body parts. The aorta is made of three parts, namely:

1. Ascending aorta (the first part).

2. Aortic arch (curved middle part).

3. Descending aorta (the last part, which moves downward).

What Are the Signs and Symptoms Associated With a Thoracic Aortic Aneurysm (TAA)?

A thoracic aortic aneurysm (TAA) does not elicit any signs and symptoms in most individuals. Symptoms are only seen when the aneurysm ruptures or expands. The signs and symptoms include:

• Hoarseness in voice.

• Dysphagia (difficulty in swallowing).

• Stridor (high-pitched breathing).

• Swelling in the neck.

• Pain in the chest or upper back.

• Nausea.

• Tachycardia (rapid heart rate).

• Dyspnea (shortness of breath).

• Chronic cough.

• Hypotension (low blood pressure).

What Are the Causes of a Thoracic Aortic Aneurysm (TAA)?

A thoracic aortic aneurysm can be caused due to several reasons, such as:

• Atherosclerosis - It is the primary cause of thoracic aortic aneurysm (TAA). It is described as the thickening and hardening of the arteries caused by the buildup of plaque within the inner lining of the artery. It occurs over time and starts at a relatively young age. Plaque is a waxy substance made of predominantly lipids. It is different from arteriosclerosis which involves only the hardening of the arteries. Risk factors for atherosclerosis include high cholesterol, high blood pressure, smoking, diabetes, obesity, physical inactivity, and a diet high in saturated fats.

• Marfan’s Syndrome - A genetic disorder that results in defective connective tissue affecting an individual’s skeleton, heart, blood vessels, eyes, and lungs.

• Loeys- Dietz - A familial connective tissue disorder characterized by the aorta’s enlargement. Individuals with Loeys-Dietz syndrome have aneurysms or dissections in arteries throughout the body and have arteries with abnormal twists and turns (arterial tortuosity).

• Bicuspid Aortic Valve (BAV) - A common congenital heart defect in which an individual has an aortic valve with two leaflets (cusps) instead of three. Thoracic aortic aneurysm (TAA) formation is the second most frequent consequence of the bicuspid aortic valve (BAV) after aortic valve dysfunction (stenosis or insufficiency).

What Are the Risk Factors Associated With a Thoracic Aortic Aneurysm (TAA)?

• Smoking.

• Hypertension (high blood pressure).

• Hypercholesterolemia (high levels of cholesterol in the blood).

• Obesity.

• Family history of peripheral vascular disease and cardiovascular disease.

How Does a Clinician Diagnose a Thoracic Aortic Aneurysm (TAA)?

A thoracic aortic aneurysm (TAA) is often not diagnosed until a rupture occurs. Several imaging tests can help a clinician diagnose a thoracic aortic aneurysm (TAA), such as:

• Chest Radiograph (X-Ray) - A chest X-ray is a diagnostic test that records images of the lungs, heart, and airways. It uses special beams of radiation, called the X-ray beam, to capture such images. It is the most widely used diagnostic procedure for acquiring and is a non-invasive and painless procedure that creates black-and-white images of the chest cavity.

• Computed Tomography Scan (CT-Scan) - A non-invasive diagnostic imaging technique that provides in-depth pictures of the heart and the structures that surround it, including blood vessels and valves. It gives more comprehensive scans when compared to those of traditional angiograms. Doctors may sometimes advise a ‘contrast cardiac CT scan (computed tomography), which involves injecting a special dye (also known as contrast) and helps amplify the images.

• Magnetic Resonance Imaging (MRI) or Cardiac Magnetic Resonance Imaging (MRI)- A comprehensive imaging test, MRI provides great details of the heart along with its associated structures. With the help of a giant magnet and computer, extensive images of the heart are created, which can help the clinician identify the severity and type of the heart disease.

• Echocardiogram - An echocardiogram is used to assess the heart along with its surrounding blood vessels. Also known as an echo scan, it is a type of cardiac ultrasound test in which a probe emits a higher frequency of sound waves. Echoes are created, and they bounce off from various body parts.

• Arteriogram - Also known as an Angiogram, it is a diagnostic test that uses X-rays and a special dye (contrast) to create images of the blood vessels to detect any blockages. This imaging test entails injecting contrast dye into a leg artery with a small, flexible tube. On the X-ray, the contrast dye makes the arteries and veins apparent.

How Is a Thoracic Aortic Aneurysm (TAA) Treated?

The treatment is tailored differently for every individual, and it depends on the location and size of the aneurysm along with the overall well-being of the individual. If there are no symptoms and the aneurysm is very small, the individual is regularly monitored with period imaging tests. The clinician may also prescribe the following medications:

• Statins (for example- Rosuvastatin) to lower cholesterol levels.

• Beta-blockers (for example- Metoprolol) for regulating blood pressure.

• Angiotensin II receptor blockers (for example-Losartan) when beta-blockers do not help regulate blood pressure.

Surgical intervention is required if the aneurysm is large (five to six centimeters or larger) or when the risk of rupture is greater than the risks associated with the surgery. Surgical interventions include:

• Open Chest Surgery: During this procedure, the aneurysm-damaged portion of the aorta is removed. A synthetic tube or graft is inserted and sewn to replace the aorta’s damaged portion. Complete recovery could take a month or more.

• Aortic Root Surgery: This is also a type of open chest surgery performed to treat a larger portion of the aorta damaged due to the aneurysm. It is also done to prevent a rupture. In this surgery, the surgeon removes the damaged portion and may also remove the aortic valve. The aortic segment removed is replaced with a graft, and a mechanical or biological valve may be inserted to replace the aortic valve. If the surgery does not involve the removal of the aortic valve, it is known as valve-sparing aortic root repair.

• Thoracic Endovascular Aortic Repair (TEVAR): It is a non-invasive procedure and is an alternative to conventional open-chest surgery. With the aid of thin, lengthy tubes (known as catheters), this procedure is carried out inside the aorta. The catheters are deployed to guide and transport a stent (graft) through the blood vessel to the desired location by entering through a small incision in the groin. The damaged portion of the aorta is sectioned out and is then fitted with a stent graft. Individuals who are not the best candidates for conventional open chest surgery may benefit from this less invasive approach, decreasing hospital stays and accelerating recovery.

What Complications Are Associated With Thoracic Aortic Aneurysm (TAA)?

If not treated promptly, a thoracic aortic aneurysm (TAA) can progress to a condition known as aortic dissection, characterized by splitting the aortic wall. It is a life-threatening condition and can lead to internal bleeding.

Conclusion

A thoracic aortic aneurysm is a clinically silent condition and progresses slowly. The majority of the cases are detected incidentally during workup for another disease. The true incidence of a thoracic aortic aneurysm is challenging to determine. Thoracic aortic aneurysms should be detected, monitored, and managed promptly to prevent a severe consequence of acute aortic syndrome, such as acute dissection. The prognosis depends on the presence of other comorbidities; hence, to avoid such complications, it is essential to have a healthy lifestyle and routine body check-ups.