What is the management and treatment of an aortic aneurysm?

Management and Treatment of Aortic Aneurysms

Aortic aneurysm management should be based on size, location, growth rate, and patient risk factors, with surgical intervention recommended when ascending thoracic aortic aneurysms reach ≥55 mm diameter or descending thoracic aortic aneurysms reach ≥55 mm. 1, 2

Definition and Classification

• An aortic aneurysm is defined as a permanent and localized dilatation of the aorta exceeding 50% of its normal diameter 1
• Thoracic aortic aneurysms (TAA) can be found in the ascending aorta (60%), aortic arch (10%), or descending aorta (40%) 1
• Abdominal aortic aneurysms (AAA) are particularly common, with a prevalence of approximately 5% in men older than 50 years 3
• Aneurysms can be asymptomatic or present with complications such as rupture, dissection, or compression of adjacent structures 1

Diagnosis and Evaluation

• Most aortic aneurysms are asymptomatic and discovered incidentally during imaging performed for other reasons or during screening 1, 4
• Clinical presentation may include back pain, a pulsatile abdominal mass, or symptoms related to compression of adjacent structures 1, 5
• When aortic dilation is suspected, comprehensive imaging with CT or MRI is essential to visualize the entire aorta and identify affected parts 1, 5
• Measurements should be taken perpendicular to the longitudinal axis of the aorta for accurate sizing 1
• Assessment should include evaluation for intramural hematoma, penetrating aortic ulcer, and branch vessel involvement 1

Screening Recommendations

• Ultrasonography screening for AAA is recommended for men aged 65-75 years who have ever smoked 3, 4
• Screening of first-degree relatives is well-established for patients with Marfan syndrome and should be considered for those with bicuspid aortic valve 1
• Regular imaging surveillance is essential for patients with known aortic aneurysms 2

Risk Factors and Natural History

• Major risk factors include age, hypertension, hypercholesterolemia, cardiovascular disease, and particularly smoking 3, 4
• Growth rates vary by location and underlying condition:
  • Ascending aortic aneurysms typically grow at 1 mm/year 1
  • Descending aortic aneurysms grow faster at approximately 3 mm/year 1
  • Familial thoracic aortic aneurysms grow faster, up to 2.1 mm/year 1
  • Marfan syndrome aneurysms grow at 0.5-1 mm/year 1
• Risk of rupture increases dramatically when ascending aortic diameter exceeds 60 mm and descending aortic diameter exceeds 70 mm 1
• Aneurysms 6.0-6.5 cm carry a 7% annual risk of rupture 2
• Growth rate ≥0.5 cm/year is an indication for intervention even if below size threshold 5

Medical Management

• Beta-blockers are the foundation of medical therapy to reduce the rate of aortic dilatation, with a target heart rate of 60 beats per minute or less 2
• Blood pressure should be controlled with beta-blockers and ACE inhibitors or ARBs to the lowest tolerated level 2
  • Target blood pressure <140/90 mmHg for patients without diabetes
  • Target blood pressure <130/80 mmHg for patients with diabetes or chronic renal disease
• For patients with Marfan syndrome, an ARB (losartan) is reasonable to reduce the rate of aortic dilatation 2
• Vasodilators should not be initiated prior to rate control to avoid reflex tachycardia 2
• Statin therapy is reasonable to achieve LDL cholesterol <70 mg/dL for patients with atherosclerotic aortic aneurysm 2
• Smoking cessation is strongly recommended as it significantly affects disease progression 2, 3

Imaging Surveillance

• For newly diagnosed thoracic aortic aneurysms, imaging is recommended at 1,3,6, and 12 months and, if stable, annually thereafter 2
• For asymptomatic patients with isolated tortuous aortic arch and normal diameter (<4.0 cm), CT or MRI surveillance at 12-month intervals is recommended 5
• For tortuous aortic arch with aneurysm 4.0-5.4 cm, more frequent imaging with CT or MRI at 6-month intervals is recommended 5
• After surgical repair, early postoperative imaging (within 1 month) followed by annual imaging for the first 2 years, then every 5 years if findings remain stable 5

Surgical Management

Indications for Intervention

• For ascending thoracic aortic aneurysm with tricuspid aortic valve: surgery when diameter reaches ≥55 mm 2
• For descending thoracic aortic aneurysm without heritable disease: elective repair when diameter reaches ≥55 mm 2
• For thoracoabdominal aortic aneurysms: elective repair when diameter reaches ≥60 mm 2
• Growth rate ≥1 cm/year indicates higher rupture risk and may warrant earlier intervention 2
• Symptomatic aneurysms should be considered for repair regardless of size 1

Surgical Approaches

• Open surgical replacement is the standard approach for isolated tortuous aortic arch requiring intervention 5
• For descending thoracic aortic aneurysms, thoracic endovascular aortic repair (TEVAR) is recommended over open repair when anatomy is suitable 2
• Hemiarch replacement is recommended when disease extends from the ascending aorta 5
• Elephant trunk or frozen elephant trunk procedure should be considered if disease extends into the proximal descending thoracic aorta 5
• Brain protection strategies during open arch surgery include profound hypothermia, direct antegrade perfusion of brachiocephalic arteries, or retrograde perfusion 5

Special Considerations

• Vertebral body erosion can occur with chronic contained rupture of thoracoabdominal aortic aneurysms, presenting with back pain and potentially neurological deficits 1
• Treatment approaches for vertebral erosion include conservative management (22.5% of cases), endovascular procedures (38%), open surgery (16.9%), or combined approaches (2.8%) 1
• Despite various treatment strategies for vertebral erosion, good outcomes are reported in approximately 80% of cases 1
• Acute thoracic aortic dissection involving the ascending aorta requires urgent surgical evaluation due to high risk of life-threatening complications 2

Common Pitfalls and Caveats

• Surgical risk assessment is critical, though mortality for elective arch surgery has decreased significantly in experienced centers to <1% 5
• Long-term follow-up imaging is essential even after successful repair to monitor for development of new aortic pathology 5
• No drug therapy has been shown to convincingly limit AAA growth in randomized controlled trials 6
• Patients with aortic aneurysms have a 10-year risk of mortality from other cardiovascular causes up to 15 times higher than the risk of aorta-related death 1