The best way to detect a defective heart valve would be by an echocardiogram
. This is an ultrasound
of the heart, which if they use it with doppler and determine the blood flow, and also they can see your heart to know if anything looked abnormal. Surgery is another way of detecting it. Also by going in for a routine physical, Doctors can usually tell just by listening to your heart through a stethascope. But, and echo can confirm.