How do you assess flow reversal in the pulmonary vein on Transesophageal Echocardiography (TEE)?

Assessment of Flow Reversal in the Pulmonary Vein on TEE

To assess flow reversal in the pulmonary vein on TEE, use pulsed Doppler with the sample volume placed 1 cm deep into the pulmonary vein, examining all accessible pulmonary veins, as systolic flow reversal is a specific sign of severe mitral regurgitation.

Optimal TEE Views and Technique

Positioning and Views

• Best TEE approach: Use the longitudinal imaging plane (superior to transverse plane, especially for right pulmonary vein) 1
• Specific views:
  • Horizontal plane imaging at the level of the short-axis aortic valve ("inflow-outflow view")
  • Deep gastric view in the 120° imaging plane (outflow view) 2
  • Optimize visualization of the right upper pulmonary vein, which is most commonly assessed

Pulsed Doppler Technique

1. Position the sample volume approximately 1 cm deep into the pulmonary vein 2
2. Ensure proper alignment with minimal angle between the ultrasound beam and blood flow
3. Minimize the angle between the transducer beam and pulmonary vein (affects quality of recordings) 1
4. Use color Doppler first to locate the pulmonary vein and guide sample volume placement
5. Record at a sweep speed that allows clear visualization of systolic and diastolic components

Normal vs. Abnormal Pulmonary Venous Flow

Normal Flow Pattern

• Positive systolic wave (S) followed by a smaller diastolic wave (D)
• S wave represents forward flow into the left atrium during ventricular systole
• D wave represents forward flow during ventricular diastole

Abnormal Flow Patterns

• Blunted S wave: Decreased systolic forward flow (may indicate moderate MR)
• Systolic flow reversal: S wave becomes frankly reversed - specific sign of severe MR 2
• Complete reversal: Indicates severe mitral regurgitation with high sensitivity (87%) and specificity (93%) 3

Important Considerations

Technical Factors

• Sample all accessible pulmonary veins when possible, as flow reversal may be unilateral 2
• Left atrial size affects ability to obtain quality images (larger LA makes assessment more difficult) 1
• Angle of insonation significantly impacts quality of flow recordings 1

Clinical Interpretation

• Systolic pulmonary venous flow reversal is highly specific for severe mitral regurgitation 2, 3
• Blunting of forward systolic flow lacks specificity as it can occur with:
  • Atrial fibrillation
  • Elevated left atrial pressure from any cause
  • Other conditions affecting left atrial compliance

Common Pitfalls

• Sampling error: Ensure sample volume is properly positioned within the pulmonary vein
• Eccentric jets: Unilateral flow reversal can occur when an eccentric MR jet is directed into the sampled vein 2
• Inadequate alignment: Poor angle of insonation leads to underestimation of velocities
• Anesthesia effects: In anesthetized patients, different cutoff values may be needed for jet measurements 3

Additional Applications

• Detection of pulmonary vein stenosis: Peak velocity ≥110 cm/s plus turbulence and reduced flow variation is diagnostic 4, 5
• Assessment of pulmonary vein anastomoses after lung transplantation 6

By following these techniques, pulmonary venous flow assessment on TEE provides valuable diagnostic information, particularly in the evaluation of mitral valve regurgitation severity.