Physical examination The focused physical examination is used to support or disprove hypotheses generated by the history. Thus, the extent of the examination is primarily determined by the diagnoses that are being considered. A brief, "core" examination may suffice to diagnose life-threatening and common etiologies of chest pain. The general appearance of the patient suggests the severity and possibly the seriousness of the symptoms. A full set of vital signs can provide valuable clues to the clinical significance of the pain, and may in some cases aid in establishing its origin. A marked difference in blood pressure between the two arms suggests the presence of aortic dissection. Palpation of the chest wall may evoke pain; if so the patient should be asked if this sensation is identical to the chief complaint. Chest wall tenderness may be present concomitantly with myocardial ischemia. Hyperesthesia, particularly when associated with a rash, is often due to herpes zoster. A complete cardiac examination including auscultation and palpation should be performed in a sitting and supine position to establish the presence of a pericardial rub or signs of acute aortic insufficiency or aortic stenosis. Ischemia may result in a mitral insufficiency murmur or an S4 or S3 gallop; there may also be abnormal precordial movement, especially at the apex. Determine if the breath sounds are symmetric and if wheezes, crackles or evidence of consolidation is present. A careful examination of the abdomen is important, with attention to the right upper quadrant, epigastrium. and the abdominal aorta.Ancillary studies Ancillary studies including an ECG (when a cardiac etiology is possible) and chest radiography (when cardiac or pulmonary disease is a consideration) may support the initial diagnosis and help avoid missing serious etiologies of chest pain such as acute myocardial infarction or pneumothorax. The absence of any acute or diagnostic ECG changes may therapeutically allay patient anxiety and reduce short-term disability. Further investigations, such as exercise ECG, myocardial perfusion, or echocardiographic stress testing, a diagnostic course of acid suppression, or lung perfusion, bone, or chest CT scanning may occasionally be required to establish specific etiologies for the chest pain.Normal electrocardiogram A normal ECG markedly reduces the probability that chest pain is due to acute myocardial infarction, but does not exclude a serious cardiac etiology (particularly unstable angina). ECG findings must be considered in the context of the history and physical examination. Patients with unstable angina are much more likely to have a normal ECG than those with acute myocardial infarction. The likelihood ratio of acute myocardial infarction in a patient with a normal initial ECG is 0.1 to 0.3. However, if the history and physical examination suggest a high pretest probability of an acute myocardial infarction, a normal ECG does not fully eliminate this diagnosis. A normal ECG in a patient with the recent onset of chest pain can also be found in patients with a less acute coronary syndrome such as table angina. Aortic dissection should be considered in patients with ongoing pain and a normal ECG.Abnormal electrocardiogram An abnormal ECG that contains specific findings (eg, ST segment elevation, ST segment depression, or new Q waves) remains an important predictor of an acute coronary syndrome (acute myocardial infarction or unstable angina). Patients with an acute myocardial infarction who present with a positive initial ECG are more likely to require invasive therapy, have a complicated hospital course, or die. An ECG that is nonspecifically abnormal (eg, there are nonspecific ST and T wave abnormalities) is commonly seen and may or may not indicate heart disease. Chest radiograph (See Table-2)A chest radiograph may assist in the diagnosis of chest pain if a cardiac, pulmonary, or neoplastic etiology is being considered. It is also useful in the acute setting to help avoid missing infrequent but dangerous diagnoses such as aortic dissection, pneumothorax, and pneumomediastinum.