Thursday, March 19, 2009

Chest Pain

Chest pain (or chest discomfort) is a common symptom that can occur as a result of cardiovascular, pulmonary, pleural, or musculoskeletal disease, esophageal or other gastrointestinal disorders, or anxiety states. The frequency and distribution of life-threatening causes of chest pain, such as acute coronary syndrome (ACS), pericarditis, aortic dissection, pulmonary embolism, pneumonia, and esophageal perforation, vary substantially between clinical settings. Systemic lupus erythematosus, rheumatoid arthritis, and HIV are conditions that until only recently have been recognized as conferring a strong risk for coronary artery disease. Because pulmonary embolism can present with a wide variety of symptoms, consideration of the diagnosis and rigorous risk factor assessment for venous thromboembolism (VTE) is key. Classic risk factors include cancer, trauma, recent surgery, prolonged immobilization, pregnancy, oral contraceptives, and family history and prior history of VTE. Other conditions associated with increased risk of pulmonary embolism include CHF and COPD. Although uncommon in the office setting, delays in diagnosing life-threatening causes of chest pain can result in serious morbidity and mortality.

A. Symptoms

Myocardial ischemia is usually described as dull, aching sensation of “pressure,” “tightness,” “squeezing,” or “gas”, rather than as sharp or spasmodic. Ischemic symptoms usually subside within 5–20 minutes but may last longer. Progressive symptoms or symptoms at rest may represent unstable angina due to coronary plaque rupture and thrombosis. Prolonged chest pain episodes might represent myocardial infarction, although one-third of patients with acute myocardial infarction do not report chest pain. When present, the pain is commonly accompanied by a sense of anxiety or uneasiness. The location is usually retrosternal or left precordial. Because the heart lacks somatic innervation, precise localization of pain due to cardiac ischemia is difficult; the pain is commonly referred to the throat, lower jaw, shoulders, inner arms, upper abdomen, or back. Ischemic pain may be precipitated or exacerbated by exertion, cold temperature, meals, stress, or combinations of these factors and is usually relieved by rest. However, many episodes do not conform to these patterns; and atypical presentations of ACS are more common in the elderly, women, and persons with diabetes. Other symptoms that are associated with ACS include shortness of breath; dizziness; a feeling of impending doom; and vagal symptoms, such as nausea and diaphoresis.
In the elderly, fatigue is a common presenting complaint of ACS. Likelihood ratios for cardinal symptoms considered in the evaluation of acute myocardial infarction. Hypertrophy of either ventricle or stenotic aortic valvular disease may also give rise to chest pain with less typical features. Pericarditis may produce pain that is greater supine than upright and may increase with respiration, coughing, or swallowing. Pleuritic chest pain is usually not ischemic, and pain on palpation should signal a musculoskeletal cause. Aortic dissection classically produces an abrupt onset of tearing pain of great intensity that often radiates to the back; however, this classic presentation occurs in a small number of cases. Anterior aortic dissection can also lead to myocardial or cerebrovascular ischemia. Pulmonary embolism has a wide range of clinical presentations, with chest pain present in only 75% of cases. The chief objective in evaluating patients with suspected pulmonary embolism is to assess the patient's clinical risk for VTE based on medical history and associated signs and symptoms. Esophageal perforation of the thoracic region is another cause of chest pain, with most cases resulting from medical procedures of the esophagus.

B. Physical Examination

Findings on physical examination can occasionally yield important clues to the underlying cause of chest pain; however, a normal physical examination should never be used as the sole basis for ruling-out ACS or aortic dissection. Vital sign measurement, including pulse oximetry, is always the first step for assessing the urgency and tempo of the subsequent examination and diagnostic work-up. Findings that increase the likelihood of ACS include diaphoresis, hypotension, S3 or S4 gallop, pulmonary crackles, or elevated jugular venous pressure. Although chest pain that is reproducible or worsened with palpation strongly suggests a musculoskeletal cause, up to 15% of patients with ACS will have reproducible chest wall tenderness. Pointing to the location of the pain with one finger has been shown to be highly correlated with nonischemic chest pain. Aortic dissection can result in differential blood pressures (> 20 mm Hg), pulse amplitude deficits, and new diastolic murmurs. Although hypertension is considered the rule in patients with aortic dissection, systolic blood pressure <> 10 mm Hg) and inspection of jugular venous pulsations. Subcutaneous emphysema is common following cervical esophageal perforation but present in only about one-third of thoracic perforations (ie,those most commonly presenting with chest pain).
The absence of physical examination findings in patients with suspected pulmonary embolism usually serves to increase the likelihood of pulmonary embolism, although a normal physical examination is also compatible with the much more common conditions of panic/anxiety disorder and musculoskeletal disease.

Treatment

Treatment of chest pain should be guided by the underlying etiology. The term “noncardiac chest pain” is used to describe patients who evade diagnosis after receiving extensive work-up. Although under-studied, one small trial found that about half of the patients fulfilled criteria for anxiety or depression and almost half reported symptom improvement with high-dose proton-pump inhibitor therapy.

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