Paramedic Science (Medical) Essay Example | Topics and Well Written Essays - 2000 words

Paramedic Science (Medical) - Essay Example The area deprived of blood supply is said to have suffered ischemic injury. The ischemic injury, if severe enough to cause the complete block of oxygen and nutrients causes death of the heart tissue, which is termed as Myocardial Infarction (Guyton et al 200, Ganong 2005). The blood vessels supplying the heart are called coronary arteries. There are three main coronary arteries which supply different areas of heart along with their branches. These are 1) Right coronary artery, 2) Left anterior descending artery, 3) Left circumflex artery. Above 90% cases of myocardial infarction occur as a result of coronary artery blockage, thus the disease is also referred to as coronary artery disease (CAD). The most common and dangerous cause of coronary artery obstruction, and thus MI is Atherosclerosis. Atherosclerosis refers to the narrowing of arteries because of accumulation of atherosclerotic plaques. These plaques are basically thrombi composed of lipid foam cells (cholesterol) and differe nt cell components including smooth muscle, macrophages and collagen fibres. In most instances, the ischemic myocardial infarction is precipitated by the phenomenon called acute plaque change. Acute plaque change results from the rupture of pre-existing thrombi that partially occlude the lumen. The rupture exposes the underlying thrombogenic endothelium. The plaques are also termed as vulnerable plaques as they contain lipids in high amounts, along with collagen fibres and inflammatory cells. When ruptured, the reactivity of these components causes the inflammatory destabilization and result in the infarction (Libby P 2001). The acute phase reactant, C reactive protein (CRP) is thus found to be high during the acute myocardial infarction (Blake et al 2003). The infarction can occur in either of the two patterns, complete occlusion of a single coronary artery referred to as transmural infarct, which results in complete ischemia of the area supplied by that particular coronary artery. Subendocardial infarcts on the other hand occlude the arteries incompletely, and thus allow some perfusion. But since subendocardium is the least perused area of the myocardium, it is more prone to ischemic death. The aim of reperfusion is to save the viable muscle from necrosis (Huber et al 1996). The myocardial injury is reversible for up to 30 minutes after the ischemic attack, thereafter the injury becomes irreversible. The entire muscle becomes necrotic within six hours, if the collateral arteries are not well developed (Robbins et al 2005, Mohan 2007). The development of atherosclerotic plaques and pathogenesis of the process into the myocardial infarction is a complex one. It is a chronic disease taking years to evolve before it causes any modifiable consequences. The evolvement is subtle and the resultant damage is severe. The pathogenesis of the disease involves several factors. The balance among these factors in the long run determines the outcome of the condition. These factors can either be modifiable or non-modifiable. The modifiable factors are the ones that a person can control by bringing about certain changes. They include controlling the level of fats in diet, cessation of smoking, regular exercise and maintaining the blood pressure in the normal range (Manson et al 1996). The hyperlipidemias, i.e. elevated low density lipoproteins and