ISCHEMIC HEART DISEASE
Myocardial ischemia, meaning a lack of oxygen to the
myocardium, is the result of an imbalance between the demand of the myocardium
for oxygen and the amount supplied. There are several possible causes of this
condition. Firstly, the blood flow through the coronary arteries may be reduced
because of mechanical blockages, such as atheroma (plaque), thrombosis (a
clot), spasm, ostial stenosis, arteritis or any sort of blockage (an embolism)
due to, for example, tumor cells or an air bubble. Secondly, a decreased flow
of oxygenated blood to the myocardium because of anemia , hypotension (low blood pressure) or carbon monoxide poisoning.
Thirdly, an increased demand for oxygen caused by exercise or
myocardialhypertrophy that requires an increase in cardiac output. Note that in
the last two scenarios, the coronary arteries may be healthy. The commonest
cause of ischemic heart disease is coronary atheroma, which obstructs the flow
of blood through the coronary arteries.