Blood flow atherosclerosis

Vascular grafts are tubular devices implanted throughout the body to replace blood vessels which have become obstmcted by plaque, atherosclerosis, or otherwise weakened by an aneurysm. Grafts are used most often in peripheral bypass surgery to restore arterial blood flow in the legs. 

Thrombolytic Enzymes. Although atherosclerosis and the accompanying vascular wall defects are ultimately responsible for such diseases as acute pulmonary embolism, arterial occlusion, and myocardial infarction, the lack of blood flow caused by a fibrin clot directly results in tissue injury and in the clinical symptoms of these devastating diseases (54). Thrombolytic enzyme therapy removes the fibrin clot by dissolution, and has shown promise in the treatment of a number of thrombo-occlusive diseases (60). 

When drug therapy fails or if extensive coronary atherosclerosis is present, PCI is often performed to restore coronary blood flow, relieve symptoms, and prevent major adverse cardiac events. Patients with one or more critical coronary stenoses (i.e., greater than 70% occlusion of the coronary lumen) detected during coronary angiography may be candidates for PCI. Several catheter-based interventions maybe used during PCI, including ... 

Ceresini G, Marchini L, Rebecchi I, Morganti S, Bertone L, Montanari I, Bacchi-Modena A, Sgarabotto M, Baldini M, Denti L, Ablondi F, Ceda GP, Valenti G (2003) Effects of raloxifene on carotid blood flow resistance and endothelium-dependent vasodilation in postmenopausal women. Atherosclerosis 167 121-127... 

The treatments nsed to improve the brain s oxygen supply include vasodilators, anticoagulants, and raising the oxygen content of the blood. Vasodilators work by dilating arteries. When the arteries supplying the brain are opened wide, the plaques of atherosclerosis are less likely to block blood flow. Vasodilators including papaverine, cyclandelate, isoxsuprine, vincamine, and cinnarizine have all been tried. 

Atherosclerosis in a coronary artery can lead to an infarct (see below). If the atherosclerosis is less severe, the reduction in the blood flow cannot provide enough oxygen in some conditions to support the work of the heart, for example during exercise or acute anxiety, and the resulting pain, angina pectoris, if frequent reduces the quality of life of the patient (Box 22.2). 

Atherosclerosis is a condition of the organism characterized by elevated levels of atherogenic lipoproteins in blood plasma, lipid deposits (including cholesterol) in the form of esters inside walls of the arterial system, and it is expressed by a gradual difficulty of blood circulation. The most appropriate name for this disease is lipoproteinemia. Clinically, it is manifested in the form of ischemic heart disease, stroke, abnormal cerebral blood flow, and peripheral ischemia. 

Peripheral artery disease (PAD) patients usually feel leg pain when walking, which is caused by insufficient blood flow to keep up with energy demand. The P MRS data collected in a PAD patient group showed prolonged PCr recovery rate (or time constants) in the calf muscle after exhaustive exercise, suggesting the transition from anaerobic to aerobic energy metabolism is delayed due to impaired oxygen supply or mitochondria fimction caused by atherosclerosis. ... 

The atherosclerotic lesions develop in a complex, chronic process. The first detectable lesion is the so-called fatty streak, an aggregation of lipid-laden macrophage foam cells. The next stage of development is the formation of plaques consisting of a core of lipid and necrotic cell debris covered by a layer of connective tissue and smooth muscle cells. These plaques hinder arterial blood flow and may precipitate clinical events by plaque rupture and thrombus formation. Platelets from the thrombi, activated macrophages, and smooth muscle cells release growth factors and cytokines resulting in an inflammatory-fibroproliferative response that leads to the advanced lesions of atherosclerosis. 

Additionally, AAS users experience lower triglyceride levels than non-users. High triglyceride levels are also associated with heart disease. Low HDL levels and high LDL levels increase the risk of atherosclerosis, the condition where fatty substances are deposited on the inner walls of arteries. The disruption in blood flow can cause a stroke when blood is prevented from reaching the brain, or a heart attack when blood does not reach the heart muscle. Cholesterol levels return to normal when AAS use stops. The potential development of blood clots also increases with AAS use, which can disrupt blood flow. The changes in cholesterol levels appear to return to the person s baseline levels after AAS discontinuation. 

Like any muscle, the heart requires a constant supply of oxygen and nutrients, which are carried to it by the blood in the coronary arteries. In CHD, plaques or fatty substances build up inside the walls of the arteries. The plaques also attract blood components (e.g., platelets) that stick to the artery wall lining. This process, called atherosclerosis, develops gradually, over many years. It often begins early in life, even in childhood. The fatty accumulation can break open and lead to the formation of a blood clot that seals the break. The presence of the blood clot occludes the vessel and reduces blood flow. 

Q1 A stroke involves significant reduction in blood flow to a part of the brain. It can be caused either (i) by an embolus or by intravascular clotting, which blocks blood flow to an area (approximately 85% of strokes), or (ii) by haemorrhage from a ruptured blood vessel, which compresses the brain tissue (approximately 15% of strokes). Patients with extensive atherosclerosis are at risk of intravascular coagulation and blockage of cerebral blood flow, but a vessel can be blocked by a thrombus originating in another part of the circulation. This cause of stroke is common in elderly patients >60 years of age. Aneurysms which rupture suddenly are a more common cause of stroke in younger patients. 

Q8 Risk factors for stroke include hypertension, hyperlipidaemia, hypercoagulability of blood, sluggish blood flow (e.g. following surgery or myocardial infarction) and atherosclerosis. All these predispose patients to stroke. Age could also be included here as the incidence of thromboembolism increases in those over 50 years of age. 

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