http://en.wikipedia.org/wiki/Broken_heart

Although "heartbreak" is usually a metaphor, there is a condition -- appropriately known as Broken Heart Syndrome -- where a traumatizing incident triggers the brain to distribute chemicals that weaken heart tissue.

The symptoms of a "broken heart" can manifest themselves through psychological pain but for many the effect is physical. Although the experience is regarded commonly as indescribable, the following is a list of common symptoms that occur:
A perceived tightness of the chest, similar to an anxiety attack
loss of appetite
Anger
Suicidal thoughts (in extreme cases)
Nausea
Constant or frequent crying
A feeling of complete emptiness
Apathy (loss of interest)
Feelings of loneliness
Feelings of hopelessness and despair
Loss of self-respect and/or self-esteem
Partial or complete insomnia