Chapter 1
Introduction
History and background
Atherosclerosis:
Atherosclerosis is a type of arteriosclerosis. Arteriosclerosis is a general term for the thickening and hardening of arteries. Atherosclerosis, or hardening of the arteries, is a pathological situation in which plaque builds up inside the arteries. Plaque is usually made of cholesterol, fatty substances, cellular products, calcium and fibrin (a clotting material in the blood). Atherosclerosis is the leading cause of mortality and morbidity from cardiovascular disease (CVD) around the world. The magnitude of this problem is so high that atherosclerosis claims more lives than all types of cancer combined and the financial burden are considerable1. It a complex, chronic pathological
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Many of the vaso-protective function of endothelium is provide by the Nitric Oxide(NO)20.Endothelium damaged by turbulent or non-laminar blood causes decreased production of NO.Such kind of blood flow also stimulates endothelial cells to produce adhesion molecules, which recruit and bind inflammatory cells. Hypercholesterolemia seems to inactivate the normal function of NO. The net effect is endothelial binding of monocytes and T cells, migration of these cells to the subendothelial space, and initiation of a local vascular inflammatory response. Lipids in the blood, particularly low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL), also bind to endothelial cells. 18Firstly LDL is transported across the healthy intima and become trapped in intima of a vessel wall.It undergoes oxidative modification and then oxidized LDL(OxLDL) is formed5.OxLDL is mighty inducer of inflammatory molecules.It adds up to the inflamotory signaling by endothelium that activates chemotactic substances, growth factors that attracts monocytes to vessel wall21Eventually OxLDL transforms monocytes into macrophages which makes the Forms cells, which are the hallmark of atherosclerosis. Oxidized LDL impair the signal transduction between endothelial cell surface receptors and NO production, inhibit NO synthase activity and inactivates NO realese from endothelial cells.22.Once the endothelium is impaired, oxidized LDL is stored in vascular endothelium and by the process of series of mechanism, foam cells are formed and then eventually fatty plaque that occludes the vessel along with the decreased amount of NO which decreases the ability of the vessel to dilate. As the plaque grows arterial wall narrowing and thickening occurs5. This plaque and narrowing of vessel results in decreased blood flow
6. Atherosclerosis, pp.1157. is a form of arteriosclerosis in which thickening and hardening of the vessel are caused by the accumulation of lipid-laden macrophages w/I the arterial wall, which leads to the formation of a lesion called a plaque. It is not a single disease but rather a pathologic process that can affect vascular syustemns throughtout the body, resulting in ischemic syndromes that can vary widely in their severity and clinical manisfestations. It is the leading contributor to coronary artery and cerebrocascular disease. Athrosclerosis is an inflammatory disease, the lesions progress from endothelial injury and dysfunction
Coronary artery disease affects the circulatory system. Chemically, this disease develops when blood vessels that are necessary for living become badly damaged. Cholesterol plaques become inflamed in the arteries. The most common signs and symptoms are chest pains which tighten the chest as if someone were standing on it. Shortening of breath also affects those with this disease because the heart is unable to supply enough blood. A major sign of this disease is having a heart attack. This indicates an artery that is completely blocked. This disease is caused by damaging the coronary arteries by smoking, diabetes, high blood pressure or high cholesterol. To diagnose this disease, medical physicians will perform physical exams and examine blood
Nevertheless, there is an understandable and noticeable link between circulatory related diseases and lifestyle diseases, such as Coronary Heart Disease. Coronary heart disease can occur when fatty acids, such as cholesterol in an inadequate diet, build up in the walls of the coronary artery. These fatty deposits collect minerals and harden to become a plaque. Eventually, this plaque grows and can swells up, forming an aneurism. In some cases, this aneurism may burst leading to instant death. As it continues to grow and swell up, it finally blocks the artery completely and forms blood clots. This is known as coronary thrombosis. A myocardial infarction, or in other words as heart attack, occurs when no oxygen is able to reach the coronary artery and thus it is unable to fulfil its role in providing the heart muscle with a sufficient supply of blood. Heart attacks are very common in the society nowadays, especially occurring in smokers or obesity related diseases (Millar, June 2014)
Atherosclerosis is associated with the major killer ailments in America, which include strokes, heart attacks, as well as peripheral vascular disease. The condition arises when there are a narrowing and hardening of the arteries. This is usually a gradual process, and it slowly blocks the arteries. When this happens, it will impede smooth blood flow. It is estimated that at least one million Americans lost their lives to a condition associated with atherosclerosis for the past few years.
Coronary illness is the development of plaque (fat store on the inward dividers of the veins) in the coronary conduits that supply O2 rich blood to the heart muscle, the development of plaque is called atherosclerosis. After some time passes plaques may solidify therefore limiting blood stream or totally obstructing the corridor. The development of plaque is straightforwardly identified with a people way of life, normal danger elements incorporate stoutness, high blood cholesterol and diabetes. At the point when the endothelium is harmed by blood stream, the cholesterol and fats in the blood get stuck shaping plaques. This outcomes in hypertension due the heart endeavoring to supply obliged levels of blood to the body. In the event that the blood stream to the heart muscles is limited or blocked it may
The development of an atherosclerotic plaque is relatively a very a complicated process where Plaque rupture accounts for about 76% of fatality lead by thrombi. The evolution of atherosclerosis begins with foam cell accumulation where the macrophages accumulate within arterial wall intima, progresses to form fatty streak where further accumulation of intra and extracellular lipids, this is a potentially reversible stage (Greenland p, 2013) further atheroma/fibroatheroma forms where cholesterol and phospholipids accumulate intramurally. This is a vulnerable state as it is predisposed to spontaneous rupture by inflammation and thrombus deposition may occur. Hemodynamic changes during this stage may cause ischemia or silent infarction, if large plaque rupture total occlusion may cause myocardial infarction or sudden cardiac death. Finally a complex lesion can develop where fibro muscular tissue can be seen with repair efforts followed by repeated plaque formation, this may slowly increase in size and produce significant arterial narrowing.
Coronary Artery Disease, also known as CAD, is the most common form of heart disease. (Heart and Stroke Foundation, 2009) Coronary Artery Disease obstructs the blood flow in vessels that provides blood to the heart which is caused by the buildup of plaque on the artery walls. (Rogers, 2011, p.87) (Heart and Stroke Foundation, 2009) Plaque is a yellow substance that consists of fat substances, like cholesterol, and narrows or clogs the arteries which prevents blood flow. (Heart and Stroke Foundation, 2009) Plaque can build up in any artery but usually favors large and medium sized arteries. (Heart and Stroke Foundation, 2009)
Many of the risk factors for cardiovascular disease cause problems because they lead to atherosclerosis. Atherosclerosis is the narrowing and thickening of arteries and develops for years without causing symptoms. It can happen in any part of the body. Around the heart, it is known as coronary artery disease, in the legs it is known as peripheral arterial disease. The narrowing and thickening of the arteries is due to the deposition of fatty material, cholesterol and other substances in the walls of blood vessels. The deposits are known as plaques. The rupture of a plaque can lead to stroke or a heart attack. (World Heart Federation).
One source of great mortality and morbidity in Europe and North America is the cardiovascular disease, Atherosclerosis. It is recognized as a chronic inflammatory disease of the intermediate and large arteries characterized by the thickening of the arterial wall and is the primary cause of coronary and cerebrovascular heart disease (Wilson, 2005). It accounts for 4.35 million deaths in Europe and 35% death in the UK each year. Mortality rate are generally higher in men than pre-menopausal woman. Past the menopause, a woman’s risk is similar to a man’s (George and Johnston, 2010). Clinical trials have confirmed that lipid accumulation, endothelial dysfunction, cell proliferation, inflammation matrix alteration and foam cell formation are
Atherosclerosis (ath"er-o-skleh-RO'sis) comes from the Greek words athero (meaning gruel or paste) and sclerosis (hardness). It's the name of the process in which deposits of fatty substances, cholesterol, cellular waste products, calcium and other substances build up in the inner lining of an artery. This buildup is called plaque. It usually affects large and medium-sized arteries. Some
Atherosclerosis is a disease in which fatty materials and plaque buildup on the inner lining of arteries. Arteries are blood vessels which carry rich blood to the heart and throughout the body. They’re lined by the endothelium, a thin layer of cells. The endothelium keeps blood flowing by keeping the inside of arteries smooth. However, when Atherosclerosis starts due to high blood pressure, smoking, or high cholesterol, it damages the endothelium. Atherosclerosis tends to happen throughout the body and arises when people grow older. This disease is mainly due to the deposition of fatty materials i.e., cholesterol, calcium and other substances found in the blood. The buildup of fat then hardens causing narrowing of the arteries. This
INTRODUCTION Cardiovascular disease, currently the leading cause of death and illness in the United States, Europe and most developed countries, is fast growing to become the preeminent health problem worldwide (Murray & Lopez, 1997). Atherosclerosis is a progressive disease of the large and intermediate-sized arteries characterized by accumulation of lipids and fibrous elements which cause development of fatty lesions called atheromatous plaques on the inside surfaces of the arterial walls; and is the single most important contributor to this growing burden of cardiovascular disease. Studies on the pathophysiology of this disease has evolved over the past three decades, and a fusion of these views has led to the concept of the
If our body produces more LDL than the requirement which is needed for the function of the cells, it builds up in our blood. This increase in LDL levels in the blood stream leads to process called atherosclerosis. Atherosclerosis is a condition in which the blood vessels are hardened.
Atherosclerosis is the leading cause of death in the world. This pathology is an inflammatory disease that results from an initial
Atherosclerosis is the process in which substances known as plaques, which are made up of cholesterol and platelets, adhere to tears in the walls of arteries. Over time these plaques build up to the point where they occlude blood flow in the arteries. When this happens in the coronary arteries, either directly, as the result of buildup in the arteries themselves, indirectly in the form a clot from another part of the body breaking loose and becoming lodged in the coronary arteries, the usual result is a heart attack.3