Coronary artery disease is a broad term which encompasses chronic stable angina and the acute coronary syndromes: unstable angina pectoris and acute myocardial infarction (Dechant, 2013). Atherosclerotic obstruction of the vessels supplying the myocardial tissue of the heart is the major cause of CAD (Brashers, 2012). There is a risk the heart muscle’s need for oxygen and nutrients will not be met if stable plaque or a thrombus (formed after a plaque rupture) limit the coronary arteries’ capability to deliver blood to the heart. When the myocardial tissue’s oxygen needs are not sufficiently met there is a possibility cellular injury or death will occur within the muscle (Dechant, 2013).
Insufficient blood flow to tissues that may
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After several minutes of sustained ischemia myocardial cells lose their ability to contract resulting in decreased cardiac output (Brashers, 2012). Decreased cardiac output can result in reduced cerebral profusion and cause syncope, this provides another potential explanation for P.S.’s loss of consciousness (Little, 2013). By converting to anaerobic processes during ischemic conditions myocardial cells are able to remain viable for about 20 minutes. If blood flow returns before the cells lose viability the cells convert back to aerobic metabolism, regain their ability to contract, and begin the process of cellular repair. If blood flow is not restored to the ischemic cells myocardial infraction (cell death) occurs. Unlike ischemia, myocardial infarction results in an area of permanent damage in the heart (Brashers, 2012).
During periods myocardial ischemia built-up lactic acid can cause substernal chest pain called angina pectoris. The pain associated with angina pectoris may also be associated with irritation of myocardial never fibers caused by abnormal stretching of the ischemic cardiac muscle (Brashers, 2012).
A major coronary artery with narrowing of more than 50% can limit blood flow enough to impede cellular metabolism when myocardial demands increase, such as with exertion or during times