In the 10th part of our series, Sandeep Ghandi, Richard Marshall, Hugh Montgomery, David Howell, and Neil Goldsack tell you how to differentiate the various causes of chest pain

In this article we shall discuss the non-cardiac causes of acute chest pain (box 1), including potential fatal causes (box 2). Chest pain can arise from any of the structures in the chest. The approach to the management of patients with chest pain is as outlined in the previous article.

Pericarditis

History
The pain tends to be retrosternal, radiating to the shoulders and neck. It differs from pain of myocardial ischaemia in that it is pleuritic and is relieved by leaning forwards.

Examination
The pathognomonic sign is a pericardial friction rub. This is a superficial scratchy sound, typically heard best at the lower left sternal edge.

Investigations
Investigation with an electrocardiogram classically shows a saddle shaped ST elevation (ST segments face concave upwards) throughout all or most of the leads of the electrocardiogram.
 

Dissecting aortic aneurysm

History
The patient is typically male with hypertension, aged over 40 years. Alternatively, the patient could be a younger person with Marfan's syndrome. The pain can resemble that of an myocardial infarction but differs in that it occurs abruptly and is of maximum intensity at the outset, whereas myocardial infarction pain builds up to a peak over minutes or hours. The pain is described as tearing and tends to be interscapular. It can radiate down the back or anteriorly as the dissection spreads distally or proximally respectively.

Examination
Look for signs caused by the dissection: unequal pulses or blood pressure, hemiparesis (dissection of the carotid artery), paraplegia (spinal artery occlusion), murmur of aortic regurgitation, and signs of a pericardial effusion (raised jugular venous pressure which increases with inspiration, pulsus paradoxus--a fall in blood pressure of more than 10 mm Hg with inspiration--and hypotension).

Investigations
A chest x ray film may show a widened mediastinum. Transoesophageal echocardiography, computed tomography and magnetic resonance imaging scanning are diagnostic.

Lungs and pleura
Pain from these structures is pleuritic in nature. It is usually a well localised, sharp pain. Acute pleuritic pain is produced by the following:

• Small peripheral pulmonary emboli
• Pneumothorax
• Pneumonia

Pulmonary embolus

History
Small emboli cause well defined pleuritic pain, often associated with haemoptysis. A large pulmonary embolus occluding a pulmonary artery in its proximal section causes central crushing chest pain that is often indistinguishable from myocardial infarction pain. It is associated with dyspnoea and presyncope. Ask about the following risk factors:

• Immobility
• Recent operation
• Hormone replacement therapy, contraceptive pill containing oestrogen
• History of thromboembolic disease
• Malignancy

Examination
>The patient may have tachycardia. A large pulmonary embolus can cause signs of acute right ventricular failure (raised jugular venous pressure, parasternal heave). It can also cause haemodynamic collapse resulting in a pale, cool, clammy, and hypotensive patient. Small pulmonary emboli can cause mild pyrexia but otherwise may not produce any other signs. Look for the signs of a deep venous thrombosis.

Investigation
The electrocardiogram in a patient with a large pulmonary embolus can show a sinus tachycardia, new onset atrial fibrillation, and signs of right ventricular strain: SI, QIII, TIII. Arterial blood gas analysis may show hypoxia and hypocapnia. Note, however, that normal blood gases do not rule out small emboli. Further diagnostic certainty is gained by ventilation or perfusion lung scanning. It is estimated that up to 70% of pulmonary emboli are missed. Have a low threshold for admitting patients with pleuritic chest pain for the subsequent investigation for pulmonary emboli.
 

Pneumothorax

History
Sudden onset of pleuritic pain. Often associated with dyspnoea.

Examination
Unilateral decreases in expansion, hyperresonant percussion note and decreased breath sounds.

Investigation
Chest x ray film is diagnostic. Look carefully for small apical pneumothoraces.

Pneumonia

History
Gradual onset of pleuritic pain, with fever and productive cough. Dyspnoea may be a feature.

Examination
Pyrexia and tachycardia are common. There is decreased expansion, dullness to percussion, and bronchial breathing over the area of consolidation. The latter sign is not always present; you may just hear coarse crepitations over the affected area.

Investigation
Chest x ray picture. Full blood count, urea and electrolytes, atypical pneumonia serology, blood and sputum cultures, and arterial blood gases.

Oesophageal pain
Reflux oesophagitis

History

Very common. It may mimic cardiac pain. Typical oesophagitis pain occurs after meals, is made worse by bending over or lying, and is relieved by standing and taking alkalis. The mouth fills with saliva (waterbrash).

Investigation
Twenty four hour monitoring of oesophageal pH is the best test to assess the correlation between symptoms and oesophageal acidity.

Oesophageal rupture

History
Provoked by recent oesophageal instrumentation or prior vomiting. It is characteristically a severe pain made worse with swallowing.

Examination
The patient may be shocked (pale, cold, clammy, hypotensive). In addition there may be signs of left pleural effusion.

Investigation
A chest x ray picture will show mediastinal gas and evidence of a pleural effusion. A gastrograffin swallow confirms the diagnosis.

Thoracic spine

History
Collapse of osteoporotic or metastatic vertebrae can give rise to pain that starts in the back and can be referred to the anterior chest. Certain postural movements reproduce the pain.

Examination
Tenderness of the spine. There may be dermatomal sensory loss.

Investigation
Thoracic spine x ray film. Remember that degenerative changes of the spine and vertebral body collapse are not uncommon findings among elderly people, and care should be taken before attributing a patient's symptoms to these.

Chest wall

History
Costochondritis is a very common cause of chest pain. It is reproduced by rotation of the trunk, deep breathing, and direct pressure. Musculoskeletal chest pain causes pain in the back and neck muscles after strenuous exertion (and may also cause a rise in total creatine kinase). These are diagnoses to be made by exclusion of other more serious conditions, and they should not be entertained lightly by junior medical staff. These pains are common, and the presence of chest pain reproduced by direct palpation does not exclude serious cardiac pain.

Conclusion

You should now be able to diagnose the cause of chest pain in the casualty setting and, more importantly, know when to call for help if unsure, or the patient has a potentially life threatening ailment.