<prompt> Answer this question truthfullyWhat is the function of cardiac catheterization in the diagnosis of mitral stenosis?  <response>: <reason> While echocardiography remains the diagnostic imaging modality of choice, cardiac catheterization is useful to evaluate mitral stenosis when the results of the non-invasive testing are insufficient. Simultaneous left and right heart catheterization demonstrate a pressure gradient such that the pulmonary capillary wedge pressure a surrogate of the left atrial pressure exceeds the left ventricular end diastolic pressure. 