Final answer:
In a M-mode echocardiogram, features of mitral valve stenosis include anterior and systolic anterior motion of the mitral valve leaflets, as well as left atrial dilatation. However, decreased aortic root dimension is not a feature of mitral valve stenosis.
Step-by-step explanation:
In the M-mode echocardiogram, the features of mitral valve stenosis include anterior motion of the posterior mitral valve leaflets, systolic anterior motion of the mitral valve leaflets, and left atrial dilatation. However, decreased aortic root dimension is not a feature of mitral valve stenosis. Mitral valve stenosis is characterized by narrowing or blockage of the mitral valve, which can lead to restricted blood flow from the left atrium to the left ventricle.