instrument to view mitral valve?

i just found out my mother has atrial fibrillation and a valve (mitral) that is not working properly. my mom states the physician will do a procedure to view the valve to see how bad it is. she is under the impression they will be using an instrument that will go through her mouth. is this correct?
is she having a trans esophageal echo?

Can't give advice but GOOGLE what XING said.

Sorry we are unable to offer medical advice