What echo parameters should be checked when assessing a Watchman (Left Atrial Appendage Closure Device) on Transesophageal Echocardiography (TEE)?

Echo Parameters for Watchman Device Assessment on TEE

When assessing a Watchman device on TEE, you must systematically evaluate device position, stability, peridevice leak, device-related thrombus, and potential complications including pericardial effusion and pulmonary vein obstruction. 1, 2

Device Position and Stability

Proper device positioning is critical to prevent complications and ensure adequate LAA occlusion. The following parameters must be assessed:

• Device depth from the pulmonary vein limbus: Measure the distance from the device to the left upper pulmonary vein ostium. Deep implantation (>10 mm from pulmonary vein limbus) is associated with increased risk of device-related thrombus (OR 2.41) and should be documented. 2

• Device orientation relative to LAA ostium: Assess whether the device is positioned at the ostium versus deeply within the LAA body. Ostium-fitted positioning is preferred over deep implantation, as deep positioning leads to more residual blood stasis, lower wall shear stress, and higher endothelial cell activation potential—all surrogate markers for increased thrombus risk. 3

• Device axis alignment: Evaluate if the device is aligned with the LAA axis or positioned off-axis. Off-axis orientation results in more residual blood and higher thrombogenic potential compared to proper alignment. 3

• Device compression: Confirm appropriate device compression (typically 8-20% compression from nominal size) to ensure adequate anchoring without excessive force on LAA walls. 4

Peridevice Leak Assessment

Any peridevice leak, regardless of size, is associated with increased risk of thromboembolism and must be carefully characterized. 2

• Leak size measurement: Measure the maximal width of any peridevice flow using color Doppler in multiple views. Document whether leak is ≤3 mm (trivial), 3-5 mm (mild), or >5 mm (significant). 5

• Leak location: Identify the specific location of the leak (superior, inferior, anterior, posterior) as this may guide management decisions. 1

• Multiple views required: Assess for peridevice leak in multiple TEE views including mid-esophageal views at 0°, 45°, 90°, and 135° to avoid missing leaks that may only be visible in certain planes. 1

Device-Related Thrombus Detection

Device-related thrombus is a critical complication that significantly increases stroke risk (HR 4.6) and requires systematic evaluation. 2, 6

Echocardiographic Criteria for Device-Related Thrombus

Based on consensus criteria from the PROTECT-AF trial, assess for the following five features 6:

• Distinct echodensity: Presence of a distinct mass separate from the device fabric
• Mobility: Independent motion of the mass relative to device movement
• Location: Thrombus typically appears on the atrial surface of the device or device shoulders
• Persistence: Findings present on multiple views and throughout the cardiac cycle
• Differentiation from normal healing: Distinguish from expected tissue incorporation (which appears as smooth, uniform tissue coverage)

Hypoattenuated Thickening (HAT)

While this is primarily a CT finding, TEE should document any irregular thickening on the device surface, particularly 7:

• Location on device gutter and shoulders: HAT in these locations combined with large device size and peridevice gap >4 mm increases suspicion for device-related thrombus
• Correlation with clinical risk factors: Non-paroxysmal atrial fibrillation (OR 1.90-2.24), renal insufficiency (OR 4.02), and history of TIA/stroke (OR 2.31) increase DRT risk 2

Complete LAA Occlusion

Confirm complete occlusion of the LAA orifice without flow inside the appendage. 1

• Color Doppler assessment: Use color Doppler with optimized settings (low velocity scale, low wall filter) to detect any residual flow into the LAA beyond the device
• Multiple cardiac cycles: Assess throughout multiple cardiac cycles as flow may be intermittent
• 3D TEE advantage: When available, 3D TEE provides en face views of the device and LAA ostium for comprehensive assessment of complete occlusion 1

Complications Screening

TEE must systematically screen for procedural complications that can be life-threatening. 1

• Pericardial effusion: Assess for any pericardial fluid collection, particularly in the immediate post-procedural period. Even small effusions warrant close monitoring as they may indicate perforation. 1

• Left upper pulmonary vein obstruction: Evaluate the left upper pulmonary vein for any flow obstruction or impingement by the device. Measure peak velocities and assess for aliasing on color Doppler. 1

• Mitral valve impingement: Although rare with Watchman devices, assess mitral valve leaflet motion to ensure no interference from the device, particularly if the device extends beyond the LAA ostium. 1

• Air embolism: During the procedure, monitor for air bubbles that may be introduced during device deployment. 1

Timing of TEE Surveillance

Standard surveillance protocol requires TEE at specific intervals to guide anticoagulation management. 2

• 45-day TEE: Perform TEE at 45 days post-implantation to evaluate for device-related thrombus and peridevice leak before discontinuing warfarin and transitioning to dual antiplatelet therapy. 2

• 1-year TEE: Perform follow-up TEE at 1 year to confirm continued adequate device position, absence of device-related thrombus, and assess for any late complications before continuing with aspirin monotherapy indefinitely. 2

Technical Considerations for Optimal Assessment

• Multiplane imaging: Use multiplane TEE with systematic sweeps through 0°, 45°, 90°, and 135° views to fully visualize all aspects of the device and surrounding structures. 1

• 3D TEE when available: 3D TEE provides superior assessment of device morphology, position, and relationship to surrounding structures with en face views from the left atrial perspective. 1

• Adequate sedation: Ensure adequate sedation for patient comfort and optimal image quality, though recognize that hemodynamic changes from sedation are less critical for device assessment than for valvular assessment. 1

• Comparison with pre-procedural imaging: When available, compare findings with pre-procedural TEE or CT measurements of LAA anatomy to assess for any changes or complications. 4