ORTHOPNOEA

In patients with heart failure lying flat causes a steep rise in left atrial pressure, resulting in pulmonary congestion and severe dyspnoea. To obtain uninterrupted sleep extra pillows are required, and in advanced disease the patient may choose to sleep sitting in a chair.

EXERTIONAL DYSPNOEA

This is the most troublesome symptom in heart failure. Exercise causes a sharp increase in left atrial pressure and this contributes to the pathogenesis of dyspnoea by causing pulmonary congestion (see above). However, the severity of dyspnoea does not correlate closely with exertional left atrial pressure, and other factors must therefore be important. These include respiratory muscle fatigue and the effects of exertional acidosis on peripheral chemoreceptors. As left heart failure worsens, exercise tolerance deteriorates. In advanced disease the patient is dyspnoeic at rest.

DYSPNOEA

Dyspnoea is an abnormal awareness of breathing occurring either at rest or at an unexpectedly low level of exertion. It is a major symptom of many cardiac disorders, particularly left heart failure, but its mechanisms are complex. In acute pulmonary oedema and orthopnoea, dyspnoea is due mainly to the elevated left atrial pressure that characterizes left heart failure. This produces a corresponding elevation of the pulmonary capillary pressure and increases transudation into the lungs, which become oedematous and stiff. The extra effort required to ventilate the stiff lungs causes dyspnoea. In exertional dyspnoea, however, other mechanisms apart from changes in left atrial pressure are also important.

Acute LVF

Typical patient
• Patient with acute myocardial infarction or known left ventricular disease

Major symptoms
• Severe dyspnoea and variable circulatory collapse

Major signs
• Low-output state (hypotension, oliguria, cold periphery); tachycardia; S3; sweating; crackles at lung bases

Diagnosis
• CXR: bilateral air space consolidation with typical perihilar distribution
• Echocardiogram: usually confirms left ventricular disease

Additional investigations
• ECG: may show evidence of acute or previous myocardial infarction
• Blood gas analysis: shows variable hypoxaemia

Comments
• Although most cases are caused by acute myocardial infarction or advanced left ventricular disease, it is vital to exclude valvular disease or myxoma, which are potentially correctable by surgery.

Aortic dissection

Typical patient
• Middle-aged or elderly patient with a history of hypertension or arteriosclerotic disease
• Occasionally younger patient with aortic root disease (e.g. Marfan's syndrome)

Major symptoms
• Chest pain

Major signs
• Often none
• Sometimes regional arterial insufficiency (e.g. occlusions of coronary artery causing myocardial infarction, carotid or verterbral artery causing stroke, spinal artery causing hemi- or quadriplegia); subclavian artery occlusion may cause differential blood pressure in either arm; aortic regurgitation; cardiac tamponade; sudden death

Diagnosis
• CXR: widened mediastinum, occasionally with left pleural effusion
• Transoesophageal echocardiogram: confirms dissection
• CT scan: confirms dissection
• MRI scan: confirms dissection

Additional investigations
• None

Comments
• Having estabished the diagnosis, emergency surgery is usually necessary, particularly if the dissection involves the ascending thoracic aorta

Causes of acute pericarditis

• Idiopathic
• Infective
• viral (Coxsackie B, influenza, herpes simplex)
• bacterial (Staphylococcus aureus, Mycobacterium tuberculosis)
• Connective tissue disease
• systemic lupus erythematosus
• rheumatoid arthritis
• polyarteritis nodosa
• Uraemia
• Malignancy (e.g. breast, lung, lymphoma, leukaemia)
• Radiation therapy
• Acute myocardial infarction
• Post myocardial infarction/cardiotomy (Dressler's syndrome)

Acute myocardial infarction

Typical patient
• Middle-aged (male) or elderly (either sex), often with a family history of coronary heart disease and one or more of the major reversible risk factors (smoking, hypertension, hypercholesterolaemia)
• In many patients there is no preceding history of angina

Major symptoms
• Chest pain and shortness of breath. Pain usually prolonged and often described as 'heaviness' or 'tightness', with radiation into arms, neck or jaw. Alternative descriptions include 'congestion' or 'burning', which may be confused with indigestion

Major signs
• Ischaemic myocardial damage, fourth heart sound, dyskinetic precordial impulse
• Autonomic disturbance, tachycardia (anterior MI), bradycardia (inferior MI), sweating, vomiting, syncope

Diagnosis
• Markers of injury: raised CKMB and troponins
• ECG: may be normal or show ST depression or T-wave change (non-ST elevation myocardial infarction). ST elevation myocardial infarction denotes higher risk

Additional investigations
• Biochemistry: blood sugar and lipids to rule out diabetes and dyslipidaemia
• Risk stratification: echocardiogram (LV function) and stress testing (reversible ischaemia)

Comments
• History and troponin testing most useful diagnostic tools

Rare cardiovascular causes of chest pain include mitral valve disease associated with massive left atrial dilatation. This causes discomfort in the back, sometimes associated with dysphagia due to oesophageal compression. Aortic aneurysms can also cause pain in the chest owing to local compression.