The aorta is the body’s largest blood vessel, carrying oxygen-rich blood from the heart to all organs and limbs. It extends from the heart up into the chest before curving down through the abdomen. An aneurysm occurs when part of an artery wall weakens and bulges, increasing its diameter by more than 50%. A thoracic aortic aneurysm is a bulge in the section of the aorta that passes through the chest.
Causes and Risk Factors
The development of a thoracic aortic aneurysm is due to a weakness in the wall of the aorta. One of the most common causes is atherosclerosis, a condition where plaque builds up inside arteries, causing them to harden and weaken. Chronic high blood pressure, or hypertension, also contributes by placing sustained stress on the aortic wall, which can cause it to expand and form an aneurysm.
Genetic conditions are strongly associated with these aneurysms, accounting for about 20% of cases. Connective tissue disorders like Marfan syndrome and Ehlers-Danlos syndrome affect the proteins that provide strength and elasticity to artery walls, making them more susceptible to weakening. Other genetic syndromes, such as Loeys-Dietz syndrome and Turner syndrome, are also recognized risk factors. These inherited conditions are often a primary cause for aneurysms that develop in younger individuals.
Several demographic and lifestyle factors also increase a person’s risk.
- Advanced age, with individuals over 65 being more susceptible
- A family history of aortic aneurysms
- Being male
- Smoking
- High cholesterol
- Untreated infections like syphilis or salmonella, in rare instances
Symptoms and Diagnosis
A challenge in identifying thoracic aortic aneurysms is that they often develop slowly without noticeable symptoms. It is estimated that only about 5% of individuals with the condition experience symptoms, which appear as the aneurysm grows larger. Consequently, many aneurysms are discovered incidentally during imaging tests, such as a chest X-ray or CT scan, performed for unrelated medical reasons.
When symptoms occur, they are often the result of the enlarging aneurysm pressing on adjacent structures in the chest. This pressure can lead to:
- Persistent pain deep in the chest or upper back
- A persistent cough, wheezing, or shortness of breath
- Difficulty or pain with swallowing
- Hoarseness or a weak, scratchy voice if the nerve to the voice box is affected
The diagnosis of a thoracic aortic aneurysm relies on medical imaging to visualize the aorta and measure its size. A computed tomography (CT) scan is a common tool that uses X-rays to create detailed cross-sectional images of the chest. Magnetic resonance imaging (MRI) is another option that uses magnetic fields to produce detailed images without radiation. An echocardiogram, which uses sound waves, can also be used to detect and monitor these aneurysms.
Treatment Approaches
The management strategy is determined by the aneurysm’s size, its rate of growth, and the presence of symptoms. For smaller, asymptomatic aneurysms, an approach of “watchful waiting” or active surveillance is recommended. This involves regular monitoring with imaging tests like CT scans or MRIs to track any changes in the aneurysm’s size over time.
Alongside surveillance, medical management is used to reduce stress on the aortic wall and slow the aneurysm’s growth. Beta-blockers are commonly used to lower blood pressure and decrease the force of the heart’s contractions. Other blood pressure-lowering medications may also be part of the treatment plan.
Surgical intervention becomes necessary for aneurysms that are large, growing quickly, or causing symptoms, as these are at a higher risk of rupturing. One surgical option is open-chest repair, which involves a surgeon removing the weakened section of the aorta and replacing it with a synthetic graft.
A less invasive alternative for some patients is endovascular aneurysm repair, known as TEVAR. In this procedure, a stent graft is inserted through a small incision, usually in the groin, and guided up to the aneurysm. The graft is then expanded, creating a new pathway for blood flow and sealing off the aneurysm from pressure. This method avoids a large chest incision and generally involves a shorter recovery period.
Aortic Dissection and Rupture
The most serious complications of a thoracic aortic aneurysm are aortic dissection and rupture, both of which are life-threatening medical emergencies. An aortic dissection occurs when a tear forms in the inner layer of the aorta’s wall, allowing blood to flow between the layers. This can lead to an aortic rupture, where the aneurysm bursts completely, causing massive internal bleeding.
The hallmark symptom of an aortic dissection or rupture is the sudden onset of severe pain. This pain is frequently described as a “tearing” or “stabbing” sensation that often begins in the chest or upper back. Other acute symptoms can include shortness of breath, a rapid heart rate, heavy sweating, dizziness, and a sudden drop in blood pressure.
These events require immediate medical intervention. The high mortality rate associated with rupture is the primary reason that surveillance and timely surgical repair are used to manage the condition.