In the majority of instances, the clinical diagnosis of angina pectoris can be made from the history alone. The chest discomfort is characteristically a sensation of deep pressure, is occasionally of burning quality, is found near the sternum, not sharply localized, and has a gradual buildup. Its duration is most often 2-10 min, but may be 30 sec to 30 min or more. Physical effort, emotional strain, large meals, nightmares, or sexual intercourse are common precipitating factors. Nitroglycerin tends to relieve the distress within 1-2 min, but the response is often difficult to evaluate, especially with angina of brief duration or with acute unstable rest angina. Physical examination of the anginal patient is often negative between attacks. During an attack of rest angina, the physical examination usually reveals increased systolic blood pressure and tachycardia. A fourth heart sound and a delayed apical systolic murmur may be found. Premature ventricular beats may develop.The resting electrocardiogram is normal in the majority of patients with angina pectoris. During the anginal attack, the electrocardiogram usually reveals an increase of the heart rate and ischemic flat or downsloping S-T-segment depressions of 0.08-sec duration or more. The exercise electrocardiogram is most useful when the stress is sufficient to increase the heart rate to 85 or 90% of the predicted maximum for the age of the patient. An abnormal exercise electrocardiogram is found in 80-90% of patients with angina when they are tested by the graded treadmill exercise test of Sheffield and Reeves, but in only 50-60% of those tested by the Master's exercise test.Varieties of angina pectoris which may differ from the foregoing include: Prinzmetal's variant angina, unstable angina (acute coronary insufficiency, crescendo angina), atypical angina, and angina with syncope.Angina pectoris must be distinguished from the discomfort of anxiety neurosis, hiatal hernia, cervical spine disease, gallbladder disease, Tietze's syndrome, and post-herpetic neuralgia.