Cardiogenic shock - Cardiac failure

Cardiogenic shock

Definition

Severe circulatory failure resulting from a low cardiac output usually characterised by severe hypotension.

Aetiology

This is an extreme type of acute cardiac failure the most common cause of which is myocardial infarction. Other causes include acute severe valve incompetence, or ventricular septal defect post-MI.

Pathophysiology

Cardiogenic shock is severe heart failure despite an adequate or elevated central venous pressure, distinguishing it from hypovolaemic or septic shock. Hypotension may result in a reduction in coronary blood flow, which can aggravate myocardial ischaemia and cause further reduction in cardiac output.

Clinical features

The patient has cool peripheries with a rapid low volume pulse. There is tachypnoea, oligo/anuria and extreme distress. There may be associated symptoms of left ventricular failure, including pulmonary oedema.

Investigations

ECG to look for evidence of myocardial infarction or any cardiac arrhythmias.

Chest X-ray to look for evidence of cardiomegaly and cardiac failure.

Echocardiogram should ideally be performed urgently to identify any correctable valve lesions and assess cardiac structure and function.

Management

Patients require intensive care, high flow oxygen and careful fluid management.

Cardiac inotropes are usually necessary to maintain systemic blood pressure. Increasing skin temperature and oxygen saturation are a guide to improvement.

Any cardiac arrhythmia should be corrected and angioplasty considered in patients with cardiogenic shock in the setting of acute myocardial infarction.

Intra-aortic balloon pumping may be instituted but it does not improve mortality unless there is an under-lying correctable cause.

Surgical intervention may be life saving in cases of mitral valve incompetence, acquired ventricular septal defect or critical coronary artery disease.

Prognosis

Mortality of 80%.