Heart failure may develop suddenly after myocardial infarction or gradually in valvular disease. Acute deterioration can also occur in compensated or established chronic heart failure.
Compensation and decompensation
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Compensated heart failure describes impaired cardiac function in which adaptive changes have prevented overt heart failure.
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An intercurrent infection or development of atrial fibrillation may precipitate acute heart failure in a compensated patient.
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Acute-on-chronic heart failure is an acute decompensating episode supervening on chronic heart failure.
Symptoms and circulatory findings
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Acute left heart failure causes sudden dyspnoea at rest, rapidly progressing to respiratory distress, orthopnoea and ultimately respiratory failure.
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Patients may appear agitated, pale and clammy, with cool peripheries and a rapid pulse. Inappropriate bradycardia can aggravate the episode.
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Blood pressure is usually high because of sympathetic nervous system activation, but may be normal or low in cardiogenic shock.
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Jugular venous pressure is usually elevated, especially with fluid overload or associated right heart failure.
Cardiac and respiratory examination
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The apex is not displaced in acute heart failure because there has been insufficient time for ventricular dilatation.
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A gallop rhythm with a third heart sound appears early in acute left-sided heart failure.
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A new systolic murmur may indicate acute mitral regurgitation or ventricular septal rupture.
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Pulmonary oedema may cause basal crepitations; severe oedema may produce crepitations throughout the lungs. Expiratory wheeze may occur.
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History and examination may identify precipitants such as an upper respiratory tract infection or inappropriate cessation of diuretic medication. Acute-on-chronic presentations may also show features of chronic heart failure.