When is a Transesophageal Echocardiogram (TEE) recommended for patients with suspected or known aortic stenosis?

Transesophageal Echocardiography (TEE) for Aortic Stenosis

Transesophageal echocardiography (TEE) is not routinely recommended as the initial imaging modality for evaluating aortic stenosis but should be performed when transthoracic echocardiography (TTE) is inadequate or inconclusive, or when specific complications are suspected. 1

Primary Indications for TEE in Aortic Stenosis

When TTE is Inadequate

• Poor acoustic windows due to:
  • Obesity
  • Chronic obstructive lung disease
  • Previous thoracic or cardiovascular surgery
  • Mechanical ventilation
  • Chest wall deformities 1

Specific Clinical Scenarios

1. Prosthetic Valve Assessment

   • Suspected prosthetic valve dysfunction
   • Evaluation of prosthetic valve endocarditis
   • Baseline assessment after valve placement 1

2. Suspected Complications

   • Infective endocarditis and its complications (abscesses, fistulas)
   • Perivalvular extension of infection
   • Vegetations 1

3. Discrepancy in Diagnostic Findings

   • When there is disagreement between TTE findings and clinical presentation
   • When there is discrepancy between TTE and cardiac catheterization measurements 2

4. Pre-procedural Planning

   • Before transcatheter aortic valve replacement (TAVR)
   • For accurate measurement of aortic annulus size and geometry
   • To determine mechanism of regurgitation and suitability for valve repair 1

Advantages of TEE for Aortic Stenosis Assessment

• Superior visualization of valve anatomy and morphology
• More accurate planimetry of aortic valve area in selected cases
• Better assessment of associated pathologies:
  • Aortic root abnormalities
  • Left ventricular outflow tract obstruction
  • Subvalvular or supravalvular stenosis 2, 3

Limitations and Caveats

• Sedation Effects: TEE under conscious sedation may overestimate AS severity compared to awake-state TTE due to hemodynamic changes 4
• Measurement Discrepancies: Mean gradients and peak velocities are often different between TTE and TEE 5
• Most Reliable Parameters: When using TEE for AS assessment:
  • Aortic valve area by continuity equation
  • Dimensionless index (DI)
  • These are more reliable than mean gradient and jet velocity measurements 5

Algorithm for TEE Use in Aortic Stenosis

1. Start with TTE as the initial imaging modality for all suspected AS cases

2. Consider TEE when:

   • TTE images are suboptimal or non-diagnostic
   • Prosthetic valve is present
   • Endocarditis is suspected
   • Planning for TAVR or surgical intervention
   • Discrepancy exists between TTE findings and clinical presentation

3. Avoid routine use of TEE for:

   • Initial diagnosis of AS in patients with adequate TTE windows
   • Routine follow-up of known AS with stable clinical status
   • Yearly evaluation of prosthetic valves with no suspicion of dysfunction 1

Best Practices for TEE in Aortic Stenosis

• Perform TEE expeditiously when indicated (within 12 hours of initial evaluation in urgent cases) 1
• Obtain multiple imaging planes for comprehensive assessment
• Compare TEE findings with previous TTE results when available
• Consider the hemodynamic state of the patient during interpretation (sedation effects)
• Use multiple parameters (not just gradients) to assess severity 1

TEE remains a valuable complementary tool to TTE in the assessment of aortic stenosis, particularly in complex cases where additional information is needed for clinical decision-making or when TTE is inadequate.