This term refers to midsternal, anterior chest pain due to a partially blocked coronary artery (see figures 53 and 54), often felt as a chest pressure like an elephant sitting on one's chest, spreading to the inner aspect of the upper left arm, neck and upper mid back, lasting anywhere from 5 to 10 or more minutes.

It is precipitated by excitement, exertion, or other stimuli that increase heart muscle oxygen requirements. The threshold for pain is usually fixed, but somewhat variable due to variations in the vasomotor tone and degree of vasospasm (see definition).

The blockage or occlusion of the coronary artery is due to atherosclerosis (see figure 70), which alters the ability of the coronary arteries to dilate. This contributes to the arteries being in vasospasm (see definition), which is abnormal. These arteries have enhanced vasospastic tone. 

Recommended Drug Therapy (Calcium Antagonist versus Beta Blocker) in Patients with Angina associated Conditions(Gibbons et al.ACC/AHA/ACP ASIM Guidelines for the Management of Patients with Chronic stable Angina,J Mm.Coll.Cardiol.!999:33:2097-2197.

Condition	Recommended Treatment and Alternative	Avoid
Medical conditions Systemic hypertension Migraine or vascular headaches. Asthma or chronic obstructive pulmonary disease with bronchospasm. Hyperthyroidism. Raynaud's syndrome. Insulin-dependent diabetes mellitus Non-insulin-dependent diabetes mellitus. Depression. Mild peripheral vascular disease Severe peripheral vascular disease with rest ischemia. Cardiac arrhythmias and conduction abnormalities. Sinus bradycardia. Sinus tachycardia (not due to heart failure). Supraventncular tachycardia. Atrioventricular block. Rapid artrial fibrillation (with digitalis). Ventricular arrhythmias Left ventricular dysfunction. Congestive heart failure. Mild (LVEF = 40%). Moderate to Severe (LVEF <40%). Left-sided valvular heart disease. Mild aortic stenosis. Aortic insufficiency. Mitral regurgitation. Mitral stenosis Hypertrophic cardiomyopathy	Betablockers (calcium antagonists) . Betablockers (verapamil or dilitiazem). Verapamil or Diltiazem. Beta blockers. Long-acting slow-release calcium antagonists. Beta blockers (particularly if prior myocardial infarction) or long-acting slow-release calcium antagonists Beta blockers or long-acting slow-release calcium antagonists. Long-acting slow-release calcium antagonists. Beta blockers or calcium antagonists Calcium antagonists Long-acting slow-release calcium antagonists that do not decrease heart rate Beta blockers. Verapamil, diltiazem, or beta blockers. Long-acting slow-release calcium antagonists that do not slow AV conduction. Verapamil, diltiazem, or beta blockers. Beta blockers. Beta blockers. Amlodipine or felodipine (nitrates). Beta blockers Long-acting slow-release dihydropyridines Long-acting slow-release dihydropyridines Beta blockers. Beta blockers. nondihydropyridine calcium antagonist Beta blockers Beta blockers	Beta blockers. Beta blockers. Beta blockers. Beta blockers . Beta blockers. Beta blockers.Verapamil, diltiazem. Verapamil, diltiazem. Nitrates, dihydropyridine, calcium antagonists.