A balloon valvotomy is a minimally invasive procedure. A doctor uses a thin, flexible tube (catheter) that is inserted into an artery in the groin or arm and screwed into the heart. When the tube reaches the narrowed mitral valve, a balloon at the tip of the catheter is rapidly inflated. The narrowed or fused leaflets of the mitral valve separate and stretch when the balloon pushes against them. This process increases the opening of the mitral valve and allows more blood to flow from the left atrium into the left ventricle.