Angina (angina pectoris - Latin for squeezing of the chest) is the chest discomfort that occurs when the blood oxygen supply to an area of the heart muscle does not meet the demand. In most cases, the lack of blood supply is due to a narrowing of the coronary arteries as a result of arteriosclerosis (see below). Angina is usually felt as a squeezing, pressure, heaviness, tightening, or aching across the chest, particularly behind the breastbone. This pain often radiates to the neck, jaw, arms, back, or even the teeth. Patients may also complain of indigestion, heartburn, weakness, sweating, nausea, cramping, and shortness of breath. Angina usually occurs during exertion, severe emotional stress, or after a heavy meal. During these periods, the heart muscle demands more blood oxygen than the narrowed coronary arteries can deliver. Angina typically lasts from 1 to 15 minutes and is relieved by rest or by placing a nitroglycerin tablet under the tongue. Nitroglycerin relaxes the blood vessels and lowers blood pressure. Both resting and nitroglycerin decrease the heart muscles demand for oxygen, thus relieving angina.