Morphologic features of the rheumatic mitral regurgitant valve by three-dimensional echocardiography

Background Rheumatic fever remains a significant worldwide cause of mitral regurgitation (MR). We describe morphologic features of the rheumatic MR va lve by quantitative 3-dimensional (3D) echocardiography. Methods Eight healthy subjects and 16 patients with less than moderate (n = 7) or more than or equal to moderate (n = 9) rheumatic MR underwent 3D ech ocardiography by use of freehand transthoracic scanning. Left ventricular ( LV) borders, mitral chordae, papillary muscles and annuli were traced at en d-diastole (ED) and end-systole (ES) with LV surfaces and mitral annulus re constructed in 3D. Regional LV function was quantified by myocardial thicke ning. Regional LV shape was assessed by alignment of diseased ED endocardia l surfaces to a reference normal surface. Results In the diseased group, LVs were more spheric and had regional shape abnormality in the area of anterior papillary muscle attachment. LV volume s, ejection fraction, and regional function in the areas of papillary attac hment were not different. Mitral annular length and area were increased and correlated with LVED volume but were no different in height, sphericity, o r beat-to-beat deformity. Chordal and papillary muscle lengths were not red uced. The interchordal angle (between the anterior and posterior chordae) w as more acute in MR. Conclusion Alterations in LV geometry and mitral apparatus morphologic feat ures contribute to rheumatic regurgitant disease. Consequent changes includ e malalignment of the papillary muscles and a narrowed interchordal angle t hat is opposite to the widening seen in MR from dilated cardiomyopathy. We hypothesize that leaflet involvement with retraction causes increased tensi on on the chordae, a reduction in the interchordal angle, and a consequent coaptation defect.