What Causes Shortness Of Breath When Suffering From Bradycardia?

hi , i have been told by my dr i probably have bradycardia and am waiting to see a cardioligest. i have major problems sleeping and wake every night nearly faint and very short of breath , i also fainted at work. my question is , is it ok to take diazpam to help me sleep while i have this condision? my dr has prescribed them for me and i worry as i knoe they slow your heart beat down too. i also have low blood presure. i worry every night about going to sleep.