In patients with bioprosthetic valve stenosis, 3D TEE or 4D CT imaging can be useful to rule out leaflet thrombosis.3 7 Synopsis Prosthetic valve stenosis can occur with both mechani- cal and bioprosthetic valves. Echocardiographic defi- nitions of stenosis severity have been provided by the American Society of Echocardiography.1 Obstruction of a mechanical valve may be caused by thrombus for- mation that leads to abnormal leaflet mobility, pannus ingrowth, or a combination of the two.8 Bioprosthetic valve stenosis may be caused by structural valve dete- rioration, with leaflet degeneration by thickening, cal- cification, or tear as the end stage of a slowly progres- sive process resulting in abnormal leaflet motion, or it may be attributable to other structural causes, includ- ing stent creep. Bioprosthetic valve stenosis may also be attributable to nonstructural causes, such as endocardi- tis, leaflet thrombus, or pannus. The progressive stages are defined by the Valve Academic Research Consor- Recommendation-Specific Supportive Text 1. TTE and TEE assessment can appropriately detect and quantify prosthetic valve stenosis.1 TTE within 3 months after valve implantation is useful to provide baseline data on valve hemodynamics and ventricular function. In some patients, the orifice area of the implanted prosthesis may be inadequate to meet the cardiac output demands of the patient, even when the prosthetic valve itself is functioning normally. This circumstance, termed patient prosthesis mismatch, is associ- ated with a high transvalvular gradient, per- sistent LV hypertrophy, and an increased rate of cardiac events after valve replacement.10,11 Diagnosis in the setting of bileaflet mechanical valves is complicated by nonlaminar patterns of blood flow, for which significant pressure recovery may be present; thus, a high velocity in the central narrow slit-like orifice may not cor- relate with prosthetic valve stenosis or patient prosthesis mismatch. 