Diagnosis and Treatment for Chest Pain

Diagnosis Testing

         The ECG is critical to the evaluation of chest pain. In fact, for the acutely ill patient, it is prudent to quickly review the ECG prior to completing the history and physical. ECG findings that should not be missed are outlined in Table A. Prior ECGs for comparison are invaluable. If ischemia is a concern. serial ECGs are useful to look for evolution of the infarct pattern. Suspicion for right ventricular infarct should be investigated with right-sided precordial leads, and suspicion for a posterior infarct should prompt evaluation with posterior chest leads.

              The CXR complements teh ECG by screening for many of the life-threatening conditions that ECG fails to identify, These include:

                  - Aortic dissection (widened mediastinum)

                  - Heart failure (pulmonary edema)

                  - Pericardial effusion (enlargement of the heart shadow)

                  - Pneumothorax (free air in the thorax, usually at the apices in an upright patient)

                  - Pulmonary infiltrates (pneumonia)

                  - Pulmonary embolism (Hampton's hump: peripherally based, wedge-shaped infarction)

                  - GI perforation (free air beneath the diaphragm)

            Evaluation for myocardial infarction should include measurement of serial cardiac biomakers. Because the levels of these biomakers rise several hours after the onset of infarction. It is important to know that the patient with myocardial infarction who has sought medical attention without delay may not yet have a positive test. Two negative tests 8 hours apart are ususally sufficient to rule out a myocardial infarction. The pattern of elevated biomaker levels can demonstrate the timing and severity of the infarction.

            Several assays are available, including troponin I, troponin T, creatine kinase MB fraction (CK-MB), and myoglobin, with specific advantages and disadvantages to each tests. In Barnes-Jewish hospital, Troponin I is the test of choice. Serum levels can rise quickly, and the test is extremely sensitive and specific for myocardial damage. Level stay elevated for several days after an infarct, which can be a disadvantage in understanding the timing of recuring chest pain in the days after in a infarction. CK-MB levels also rise quickly, and CK-MB is cleared more rapidly then Troponin. However, it is significantly less sensitive than troponin. CK-MB levels are useful for diagnosing reinfarction in patients with a recent myocardial infarction who have recurrent symptoms.

              Measurement of Brain Natriuretic Peptide (BNP) levels may be helpful to suggest previously undiagnosed heart failure, raising suspicion for underlying ischemic etiology in patients presenting with chest pain. Lipid profiles are useful for risk stratification for coronary artery disease but are little utility in evaluating acute chest pain. Clinical suspicion may warrant measurement of serum D-dimer pulmonary embolism, amylase/lipase (pancreatitis), or liver function tests (cholecystitis).

Differential Diagnosis for Chest Pain

            When it is clear that the patients is at lower risk and does not have a life-threatening condition, a broader differential diagnosis should include:

               - Cardiac:  stable angina. non-STEMI, pericarditis, coronary vasospasm

               - Pulmonary:  pneumonia, pleuritis

               - Gastrointestinal:  GERD, peptic ulcer, esophagitis, pancreatitis, cholecystitis

               - Neuromusculer: costochondritis, Herpes zooster, injury of pectoralis or intercostal muscle

               - Psychiatric: panic attack, anxiety disorder, pain syndromes

Chest Pain Treatment

            If one of the five most common like-threatening causes of chest pain is identified, an emergent treatment plan should be enacted.

 a. ST-segment elevation myocardial infarction (STEMI) requires rapid reestablishment of coronary blood flow (intravein thrombolytic therapy or percutaneous coronary intervention)

b. Cardiac tamponade is managed with urgent pericardiocentesis

c. Suspected aortic dissection should be confirmed with appropriate imaging (transesophageal echocardiography) CT scan, MRI. Type A dissection require  emergent surgical consultation.

d. Tension pneumothorax require immediate needle decompression followed by chest tube placement.

e. Suspected PE can be confirmed by appropriate imaging and treated with anticoagulation. Thrombolytic therapy is considered for patients with significant hemodynamic compromise.