What is the echocardiographic (echo) appearance of a dehisced prosthetic mitral valve?

Echocardiographic Appearance of Dehisced Prosthetic Mitral Valve

A dehisced prosthetic mitral valve on echocardiography is characterized by abnormally increased mobility/instability of the entire prosthesis (rocking motion) with severe paraprosthetic regurgitation, most commonly occurring in the posterior or lateral region of the sewing ring. 1

Key Echocardiographic Features

Morphological Findings

• Rocking motion: Abnormal mobility of the prosthesis sewing ring during the cardiac cycle is the hallmark finding 1
• Location of dehiscence: Primarily in the posterior or lateral region, rarely in the anterior region 1
• Sewing ring instability: Abnormal mobility of the sewing ring nearly always implies severe paraprosthetic regurgitation 1
• Circumferential extent: Can be assessed in short-axis views to determine severity of dehiscence 1

Color Doppler Findings

• Paraprosthetic regurgitation: Typically presents as a jet originating outside the prosthetic ring 1
• Severity assessment: Regurgitation involving >20% of the prosthesis circumference indicates severe regurgitation 1
• Jet characteristics: Often appears as large eccentric jets adhering to and swirling along the posterior left atrial wall 1

Imaging Approaches

• Transesophageal echocardiography (TOE): Superior to transthoracic echocardiography (TTE) for detecting and determining the location and mechanism of prosthetic mitral regurgitation 1
• 3D echocardiography: Ideal for imaging the entire mitral prosthesis, the whole sewing ring, and the extent of paravalvular regurgitation 1
• Best views for assessment:
  • TOE: Low-esophageal four-chamber view with rotation to two- and three-chamber views with anteflexion and retroflexion 1
  • Transgastric short-axis view: Useful for imaging the entire circumference of the valve/sewing ring 1

Clinical Implications

Diagnostic Challenges

• Acoustic shadowing may limit visualization of the left atrial side of mitral prostheses, particularly with mechanical valves 1
• Visualization can be improved by orienting the ultrasound beam parallel to the direction of occluder opening 1
• Subcostal views can help visualize para-prosthetic jets by minimizing acoustic shadowing effects 1

Associated Findings

• New paraprosthetic leakage in the acute/emergency setting is predominantly due to endocarditis 1
• Unlike native valve endocarditis, vegetations may be frequently absent with the only abnormalities being paraprosthetic regurgitation and/or valve instability 1
• Systolic flow reversal in pulmonary veins is a specific indicator of severe mitral regurgitation 1

Recommended Imaging Protocol

1. Urgent TTE is mandatory in all patients with suspected acute prosthetic valve dysfunction to define the extent and mechanism of regurgitation 1
2. TOE is required except in cases where TTE is entirely conclusive 1
3. 3D echocardiography (especially during TOE) provides superior assessment of the entire prosthesis, sewing ring, and extent of paravalvular regurgitation 1
4. Multiple imaging planes should be used to fully characterize the dehiscence, including the site, size, shape, and area of the dehisced segment 2

Pitfalls and Caveats

• Prosthetic valves are more difficult to evaluate than native valves and should be assessed by experts in both TTE and TOE when prosthesis-related emergency is suspected 1
• The severity of regurgitation may be difficult to judge, especially in aortic prostheses, using standard measures 1
• Dehiscence must be distinguished from other causes of prosthetic valve dysfunction such as thrombosis, pannus formation, or structural valve deterioration 1
• In cases of uncertainty about the mechanism of dysfunction, echocardiography should be used in parallel with other diagnostic techniques 1