Angina or angina pectoris is a discomfort in the middle of the chest, behind the breastbone.  It is described as a "tightness," "squeezing" or "burning" sensation.  It is sometimes accompanied by nausea, sweating or shortness of breath.  It is triggered by physical or emotional stress and typically lasts 5-10 minutes.  It is relieved by rest or nitroglycerine.  It is caused by narrowing in the coronary arteries resulting in reduced blood supply to the heart muscle.