Well, mitral balloon valvotomy is the procedure by which a catheter is introduced in your heart and valve is dilated with a balloon which is attached with catheter. Catheter is a small tube. Cause of this problem could be because of infection which may have happened in few years back in your case. This infection leads to rheumatic heart disease. The cost of this procedure is roughly Rs.1.0- 1.5 Lakh in Indian rupees in most of the centres. After that you have to continue treatment to prevent this infection happening again. So you may have to take injectable antibiotics called Penidura for few years.