Cause of pain:
In mitral valve prolapse (MVP), abnormalities of the mitral valve cause it to flop backwards into the left atrium as the left ventricle contracts. This flopping, or prolapse, is occasionally perceived as a form of chest pain.
Characteristics of pain:
There is controversy as to how often MVP actually causes chest pain - it probably does so far less often than is alleged. When MVP does cause chest pain, the pain is most often described as a "catching" discomfort, and is often positional in nature (i.e., it may occur, for instance, only when the patient is lying on the left side.)
The evaluation of MVP consists of listening to the heart through the stethoscope and doing an echocardiogram.