An aortic aneurysm is a serious medical condition characterized by an abnormal dilation or bulging of the aorta, the largest artery in the body responsible for carrying oxygen-rich blood from the heart to the rest of the body.

This localized weakens the vessel wall and poses life-threatening risks if rupture or dissection occurs.

Pathophysiology and Types of Aortic Aneurysm

The aorta is composed of three layers: the intima (inner), media (middle), and adventitia (outer). Aortic aneurysms result from the weakening of the medial layer, which compromises arterial wall integrity. This weakening leads to progressive dilation under the continuous mechanical stress of blood flow and pressure. Over time, the aneurysm can enlarge to a critical size where the risk of rupture exponentially increases.

Aneurysms are classified primarily by their anatomical location along the aorta:

Abdominal Aortic Aneurysm (AAA): Arising below the diaphragm in the abdominal portion of the aorta, AAA is the most common form of aortic aneurysm. It often develops slowly and silently, making routine screening vital for at-risk populations, particularly men over 65.

Thoracic Aortic Aneurysm (TAA): Located in the chest region, TAAs are less common but potentially more complex due to proximity to the heart and major arteries supplying the brain and upper body. These aneurysms may involve the aortic root, ascending aorta, aortic arch, or descending thoracic aorta.

Thoracoabdominal Aortic Aneurysm: Spanning both thoracic and abdominal parts of the aorta, this type presents surgical challenges due to involvement of critical branch vessels supplying.

Causes and Risk Factors

Hypertension: Elevated blood pressure increases mechanical stress on the aortic wall.

Genetic Disorders: Conditions like Marfan syndrome, Ehlers-Danlos syndrome, and Loeys-Dietz syndrome impair connective tissue integrity and promote aneurysm formation, especially in the thoracic aorta.

Infections and Trauma: Rarely, infections (mycotic aneurysms) and traumatic injuries contribute.

Clinical Features and Symptoms

Most aortic aneurysms are asymptomatic until they enlarge significantly or rupture. When symptoms occur, they vary depending on the aneurysm location:

- Abdominal Aortic Aneurysm symptoms may include a pulsatile abdominal mass, deep aching pain in the abdomen or back, and leg ischemic symptoms if embolization occurs.

- Thoracic Aortic Aneurysm can cause chest pain, hoarseness, difficulty swallowing due to compression of adjacent structures, shortness of breath, or cough.

The most feared complication is rupture, manifesting as sudden, severe pain, hypotension, shock, and often death without rapid surgical intervention.

Diagnostic Evaluation

Diagnosis often begins with physical examination, where a pulsatile abdominal mass may be palpable in AAA cases. Imaging is essential for confirmation and assessment:

Ultrasound: Preferred screening tool for AAA due to its safety, accessibility, and accuracy.

Computed Tomography Angiography (CTA): Provides detailed anatomical information on aneurysm size, extent, and relationship to branch vessels.

Magnetic Resonance Angiography (MRA): An alternative for patients with contraindications to CT contrast.

Treatment Options

Management depends on aneurysm size, growth rate, symptoms, and patient comorbidities:

Surveillance: Small aneurysms (<5.5 cm for AAA) are monitored with periodic imaging and risk factor modification including blood pressure control.

Surgical Repair: Indicated for large, symptomatic aneurysms, or those enlarging rapidly. Open surgical repair involves graft replacement of the affected aortic segment.

Endovascular Aneurysm Repair (EVAR): A minimally invasive technique inserting a stent-graft via femoral arteries, offering reduced recovery times and complications for suitable patients.

Dr. Brinster, Vascular Surgeon at Northwell Health: “We don't see many aneurysms that size because usually they've either been treated before then or they've ruptured.”

Aortic aneurysm is a critical vascular condition marked by abnormal dilation of the aorta that, if left untreated, can lead to fatal rupture or dissection. Recognition of its types—abdominal, thoracic, and thoracoabdominal is crucial due to their differing presentations and treatment complexities. Comprehensive evaluation using imaging modalities enables early diagnosis and monitoring. Treatment ranges from vigilant surveillance in small aneurysms to advanced surgical or endovascular repair in high-risk cases. This condition demands multidisciplinary expertise to optimize patient care and survival rates.