FIG 55.6 (A) Left atrium opened to show the thickened mitral valve with a characteristic “fish mouth” opening The asterisk indicates the mural (posterior) leaflet (B) Opened mitral valve with chronic rheumatic lesions characterized by short and thick cords and fusion of the ends of the zone of apposition (From Grinberg M, Sampaio RO, editors Doenỗa Valvar Sóo Paulo, Brazil: Editora Manole, 2006.) FIG 55.7 Morphologic features of a surgically excised stenotic rheumatic mitral valve (A) Atrial aspect, revealing the stenotic orifice and thickened leaflets (B) Ventricular aspect, with fused tendinous cords and obliteration of intercordal spaces In the setting of RHD, the entire MV apparatus must be interrogated carefully to clarify the mechanism and nature of valvar dysfunction The international standard to describe the segments of anterior (A) and posterior (P) MV leaflets divides these into a total of six scallops: A1, A2, A3, and P1, P2, P3 (Fig 55.8) On the anterior MV leaflet, A1 is the most anterior scallop and A3 is the closest to the AV.36 Each segment must be carefully inspected, as the disease process may involve different segments in different ways, with some areas having restricted and others excessive leaflet motion based on the complex interplay of the chordal apparatus, leaflets, and annulus The key elements of echocardiographic evaluation of the MV apparatus in RHD are listed in Box 55.2 FIG 55.8 Anatomy of the mitral valve—left atrial or surgeon's perspective Box 55.2 Key Elements in the Echocardiographic Assessment of Mitral Valve Anatomy ▪ MV annulus ▪ Measurement of annular diameter and comparison with normal zscore measurements ▪ MV leaflets ▪ Evaluation of leaflet motion during systole and diastole ▪ Identification of scallops of leaflets that are restricted or have excessive leaflet motion or prolapse ▪ Quantification of leaflet thickening and calcification ▪ Planimetry of the MV to measure effective orifice ▪ MV commissures ▪ Assessment of degree of commissure fusion/prolapse