What is a bicuspid aorta?

Bicuspid Aortic Valve: Understanding and Management

A bicuspid aortic valve is not an aortic condition but rather the most common congenital abnormality affecting the aortic valve, characterized by two cusps instead of the normal three cusps, occurring in 1-2% of the population and associated with increased risk of aortic complications. 1

Anatomy and Morphology

• The normal aortic valve has three cusps, while a bicuspid valve has only two
• Most common fusion patterns:
  • Right and left coronary cusps fusion (80% of cases) - resulting in larger anterior and smaller posterior cusp with both coronary arteries arising from anterior cusp
  • Right and non-coronary cusps fusion (20% of cases) - resulting in larger right than left cusp with one coronary artery arising from each cusp
  • Left and non-coronary cusps fusion or "true" bicuspid valves with equally sized cusps are rare 1

Diagnostic Features

• Best visualized in short-axis view during systole showing only two commissures framing an elliptical orifice
• Long-axis views may show asymmetric closure line, systolic doming, or diastolic prolapse
• In adults, superimposed calcification often obscures the number of cusps
• Associated aortic root and ascending aorta dilatation may provide indirect hints of BAV presence 1

Clinical Significance and Complications

BAV should be viewed as a syndrome affecting both the valve and aorta:

1. Valve-related complications:

   • Aortic stenosis - more common in older patients
   • Aortic regurgitation - more common in younger patients
   • Infective endocarditis risk 1, 2

2. Aortic complications:

   • Aortic dilatation (20% of BAV patients develop ascending aortic aneurysms)
   • Aortic dissection (15% of acute aortic dissections occur in BAV patients)
   • Risk of aortic dissection even with aortic diameter <5 cm (12.5% of cases) 1, 3

3. Associated conditions:

   • Coarctation of the aorta
   • Turner syndrome
   • Ventricular septal defect
   • Patent ductus arteriosus 1, 2

Surveillance and Management

• All patients with BAV should have both the aortic root and ascending thoracic aorta evaluated for evidence of aortic dilatation (Class I recommendation, Level of Evidence: B) 1

• First-degree relatives of patients with BAV should be screened for BAV and asymptomatic thoracic aortic disease (Class I recommendation, Level of Evidence: C) 1, 3

• Imaging surveillance:

  • Regular echocardiography to monitor valve function and aortic dimensions
  • Consider CT or MRI when echocardiography is suboptimal or for more precise aortic measurements
  • More frequent monitoring if aortic growth ≥3 mm/year, family history of dissection, or aortic dimensions approaching surgical thresholds 3

• Medical management:

  • Beta-blockers to reduce hemodynamic stress on the aorta
  • Aggressive blood pressure control
  • Avoidance of intense isometric exercise when aortic dilatation is present 3, 2

Special Considerations

• Pregnancy: Increased risk of aortic complications during pregnancy and delivery in women with BAV and aortic dilatation 3

• Athletes: Those with aortic dimensions of 41-45 mm may participate in sports with low risk of bodily contact but require closer monitoring 3

• Surgical intervention: Consider earlier intervention for BAV patients with aortic dilatation compared to those with tricuspid valves, especially with family history of dissection or rapid aortic growth 1, 4

BAV repair for regurgitation has excellent long-term results, an important consideration given the young age of many patients and the limitations of prosthetic valves 1

Understanding BAV as a syndrome rather than an isolated valve abnormality is crucial for appropriate lifelong management and surveillance to prevent potentially fatal complications.