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We have observed a group of patients with mitral valve disease and severe symptoms but also with low transmitral gradients and normal cardiac outputs who defy the traditional hemodynamic explanation of mitral stenosis. We performed a 10-year retrospective chart review of all mitral valve replacements at our institution to further characterize this population. The study group consisted of 16 of 132 patients (12%) with symptomatically severe (New York Heart Association [NYHA] class 3.3 +/- 0.5) mitral stenosis but a low (< 10 mm Hg) transmitral gradient, a normal cardiac output (4.8 +/- 1.2 L/min), and a preserved valve area (1.6 +/- 0.4 cm2). Sixteen patients were randomly chosen from the remaining group to serve as a comparison population. Study patients were noted to have less atrial fibrillation, lower wedge and mean pulmonary artery pressures, and a higher incidence of subvalvular disease identified at the time of surgery than did the comparison population. Left ventricular end-diastolic pressure and cardiac output did not differ. Study patients did well with surgery and reported an excellent functional benefit. We believe that this subgroup of patients with mitral valve disease is important, may be missed by using conventional criteria of valve area to determine timing of surgical intervention, and may have their symptoms primarily because of subvalvular disease. Further and perhaps most important, this group illustrates the ongoing need for careful clinical assessment skills and judgement in the face of ever-increasing technology.

Ten patients with roentgenographically demonstrable mitral annulus calcification (MAC) were found to have distinctive echocardiographic patterns. MAC was confirmed at the time of cardiac catheterization in six of these patients. Standard M-mode echocardiograms revealed a dense band of echoes in the region of the mitral annulus in contrast to the thin and delicate echoes generally recorded from the normal mitral annulus. Intraoperative and pathologic confirmation of thickening and calcification limited to the mitral annulus was made in two patients who underwent mitral valve replacement for severe mitral regurgitation due to myxamatous "floppy" valve. Patients with marked MAC may have coexisting aortic valve or papillary muscle calcification which can be recognized by echocardiography. Over-attenuation of left ventricular wall echoes in patients with marked MAC, and reduction in E-F slope of the anterior mitral valve leaflet in others can simulate pericardial effusion and mitral stenosis, respectively. Thus, recognition of MAC can avoid confusion with similar echocardiographic patterns due to other common cardiac abnormalities.