Myocardial infarction is cardiac necrosis caused by a cessation of blood fl ow
to the myocardium. This is usually the result of a blockage to one of the
major epicardial coronary arteries supplying the myocardium with oxygenated
blood (Figure 7.1 ). Commonly the blockage is caused by a blood clot
(thrombus) that forms over a ruptured atherosclerotic plaque. When a vulnerable
atherosclerotic plaque ruptures, a chain of events occurs resulting
in coronary artery occlusion and a medical emergency (Figure 7.2 ). If the
thrombus fully occludes the coronary artery then STEMI will occur (Moser
and Riegal, 2008 ). Other less common causes of STEMI include coronary
artery spasm, coronary dissection, coronary embolism and pericardiac interventions.
Anaemia, arrhythmias, hypertension and hypotension can also lead
to myocardial injury (Thygesen et al., 2007 ).