If cardiogenic shock is caused by myocardial
infarction (in the absence of a ventricular septal defect,
ruptured papillary muscle, left ventricular outflow tract
obstruction,
32 cardiac tamponade, pulmonary embolism,
cardiac arrhythmia or right ventricular infarction with
hypovolaemia) there is a greater than 40% functional
loss of the left ventricle.33 This occurs in 7% - 10% of
patients with acute myocardial infarction and has a
mortality rate of 60% - 80%. The myocardial abnormality
is characterised by both systolic and diastolic
dysfunction.28,34 The ischaemic myocardial injury may
be reversible (e.g. myocardial stunning or hibernating
myocardium may be present which may recover
completely with restoration of myocardial blood flow)
or irreversible (leading to myocardial cell necrosis or
apoptosis)