A Mass in the Left Ventricular Outflow Tract After Mitral Valve Replacement

Abstract

A 34-year-old woman presented with a four-year history of shortness of breath and dyspnea on exertion that had worsened over the preceding six months. The patient had a stroke two years before her current presentation but had no residual neurologic deficits. Transthoracic 2 two-dimensional echocardiography revealed severe mitral stenosis (peak/mean gradients = 21/14 mmHg), with a mitral valve area of 0.7 cm2 by the pressure-half time method, and calcific thickened mitral valve leaflets with commissural fusion and subvalvular thickening. Pulmonary hypertension was present (right ventricular systolic pressure of 45 mmHg). Left ventricular (LV) ejection fraction was normal (62%). The left atrium (LA) was dilated (60 mm) but LA thrombus was absent. Normal sinus rhythm was present. During surgery, the native mitral valve was replaced with a 25-mm bileaflet mechanical prosthesis. Preservation of both the mitral leaflets and the subvalvular apparatus was carried out. Repeat transesophageal echocardiography (TEE) showed the mechanical prosthesis to be functioning well. In the midesophageal aortic valve (AV) long-and short-axis views, a new mass measuring 8 × 7 mm was seen moving into the aortic root in systole and the left ventricular outflow (LVOT) tract in diastole (Fig. 1, A-C and Video loop 1). Color-flow Doppler did not reveal any systolic flow turbulence (Fig 1, D and Video loop 1). What is the diagnosis?