How is mitral insufficiency usually diagnosed?

Stethoscope: It is usually first suspected when a doctor listens to your heart and hears a heart murmur. The characteristics of the murmur such as where on your chest it is heard would suggest mitral insufficiency. Then an echocardiogram would let the doctor see the structure of the valve. A doppler study would show that the flow across the valve is going in the wrong direction.

Stethoscope: It can be reliably detected, if it's significant, with a stethoscope. If there's no audible murmur, it's probably not very severe and not important. An echo is the best way to determine the presence & severity but be aware that echo will detect even the most trivial and least important mr so take it under advisement.