What are the necessary preoperative workups for a patient with a bicuspid aortic valve?

Preoperative Workup for Patients with Bicuspid Aortic Valve

The necessary preoperative workup for a patient with bicuspid aortic valve must include transthoracic echocardiography (TTE) as the primary diagnostic imaging, followed by CT or MRI angiography to fully assess aortic dimensions, with special attention to the ascending aorta and aortic root.

Initial Imaging Assessment

Transthoracic Echocardiography (TTE)

• First-line diagnostic tool to confirm the presence, severity, and etiology of valve dysfunction 1
• Essential for evaluating:
  • Valve morphology and function
  • Presence and severity of aortic stenosis or regurgitation
  • Left ventricular size and function
  • Initial assessment of aortic dimensions

Advanced Aortic Imaging

• CT or MRI angiography is indicated when:
  • The morphology of aortic sinuses, sinotubular junction, or ascending aorta cannot be fully assessed by TTE 1
  • For all patients with bicuspid aortic valve to establish baseline aortic dimensions 2
  • MRI is preferred in younger patients to minimize radiation exposure 3

Specific Measurements to Obtain

• Aortic dimensions at multiple levels:
  • Aortic annulus
  • Sinuses of Valsalva
  • Sinotubular junction
  • Ascending aorta
  • Transverse arch
• Left ventricular dimensions and function:
  • End-diastolic diameter
  • End-systolic diameter
  • Ejection fraction
• Valve function parameters:
  • Valve area
  • Peak/mean gradients (for stenosis)
  • Regurgitant fraction/volume (for regurgitation)
  • Vena contracta width (>0.6 cm indicates severe AR) 1

Additional Testing

Coronary Assessment

• Invasive coronary angiography is recommended in:
  • Patients with symptoms of angina
  • Evidence of ischemia
  • Decreased LV systolic function
  • History of CAD
  • Men >40 years of age
  • Post-menopausal women
  • Patients with ≥1 cardiovascular risk factors 1

CT Coronary Angiography

• Reasonable alternative to invasive angiography in patients with:
  • Low to intermediate pre-test probability of CAD 1
  • When invasive angiography is technically challenging or high-risk

Surveillance Protocols

For Patients with Aortic Dilation

• Aortic imaging at least annually when aortic diameter >4.5 cm 2
• More frequent imaging (every 6 months) if:
  • Aortic diameter ≥5.0 cm
  • Rapid growth rate (≥0.5 cm per year) 2
  • Family history of aortic dissection

For Patients with Normal Aortic Dimensions

• TTE every 3-5 years for mild valve dysfunction 3
• TTE every 1-2 years for moderate valve dysfunction 1
• TTE every 6-12 months for severe asymptomatic valve dysfunction 1

Risk Assessment for Aortic Complications

• Document specific risk factors for aortic dissection:
  • Family history of aortic dissection
  • Growth rate of aortic diameter
  • BAV morphology (right-non coronary cusp fusion carries higher risk) 2
  • Associated conditions (Turner syndrome, Marfan syndrome)

Surgical Planning Considerations

• Operative intervention is indicated when:
  • Aortic diameter ≥5.5 cm in asymptomatic patients 1, 2
  • Aortic diameter ≥5.0 cm with risk factors (family history of dissection, growth rate ≥0.5 cm/year) 1, 2
  • Aortic diameter ≥4.5 cm in patients undergoing AVR for severe stenosis or regurgitation 1, 2

Important Caveats and Pitfalls

• Ensure consistent measurement techniques between imaging modalities, as CT measurements are generally more accurate than echocardiography 2
• Be aware that 38% of patients with ascending aorta diameter ≤4.5 cm may have moderate/severe histological alterations of the aortic wall 4
• Recognize that bicuspid aortic valve patients tend to present with aortic dissection at younger ages than those with tricuspid valves 2
• Understand that the mean rate of aortic diameter progression is approximately 0.5-0.9 mm/year, with the proximal ascending aorta showing the fastest growth 2

By following this comprehensive preoperative workup protocol, clinicians can effectively assess and manage patients with bicuspid aortic valve, minimizing the risk of catastrophic aortic complications while optimizing timing for surgical intervention.