Blood Vessels Diseases PDF

11/28/2020 DISEASES OF BLOOD VESSELS Thrombosis Definition: A thrombus is a solid compact mass formed inside the cardiovascular system during life from circulating blood constitutes. Main features: 1.Intravascular 2.Mass of coagulated blood composed of platelets...

11/28/2020 DISEASES OF BLOOD VESSELS Thrombosis Definition: A thrombus is a solid compact mass formed inside the cardiovascular system during life from circulating blood constitutes. Main features: 1.Intravascular 2.Mass of coagulated blood composed of platelets, fibrin, cells and plasma proteins. Early the lines of Zahn are present which are alternating layers of platelets and fibrin. 3.Adherent to the internal surface of the vessel. 1  11/28/2020 Etiology: Virchow’s triad for thrombus formation: 1-Endothelial Injury 2-Abnormal Blood Flow 3-Hypercoagulability CLASSIFICATIONS OF THROMBI According to occlusion: 1. Non- occlusive (does not close the vessel) thrombi : in the heart and aorta 2. Occlusive thrombi (close the vessel): in vascular lumen According to site of thrombi: 1. Arterial thrombi 2. Cardiac (heart) thrombi 3. Venous thrombi 4. Capillary thrombosis COMPLICATIONS OF THROMBI: 1.Reduced blood flow to a tissue/organ: result in ischemia or infarction. 2.Part of the thrombus breaks off: results in thrombo-embolization 2  11/28/2020 FATE OF THROMBI: 1.Lysis: The role of fibrinolytic agents in the blood. 2.Propagation: Enlargement and extension of the thrombus. 3.Organization: Fibrosis of the thrombus. 4.Recanalization: during organization new channels may form within the thrombus; these may allow renewed blood flow through the obstructed vessel. Canalization of thrombus 3  11/28/2020 Embolism Definition: Occlusion of a vessel by a mass of material (i.e. embolus) that is transported in blood stream Most common type is due to fragments of circulating thrombus (Thromboemboli) Main types of embolus: 1. Thrombo-embolism 2. Fat embolism 3. Gas embolization 4. Liquid – Amniotic fluid in newborn 5. Bacterial Embolism 4  11/28/2020 Angiogram - Embolism Infarction ATHEROSCLEROSIS (ATHEROMA) This is patchy thickening of the intima of arteries by lesions composed of deposited lipids surrounded by proliferating connective tissue. Each of these lesions is called atheroma 5  11/28/2020 Risk factors: Hypertension : is a major risk factor High levels of plasma lipids (hypercholesterolemia) cause endothelial damage Smoking : causes endothelial damage Diabetes mellitus Life style: lack of exercise, stress, obesity Familial hereditary factors Pathological features Sites of atherosclerosis: Large arteries: aorta and its main branches Small arteries : coronaries, cerebral and renal arteries Medium sized arteries as femoral artery 6  11/28/2020 Atherosclerosis is mostly due to Chronic endothelial damage Caused by: Vascular stress (hypertension) Toxic products of cigarettes Endothelial injury  allows trapping of lipids (cholesterol) in the sub-endothelial part of the intima Also endothelial injury  enhance the adherence of platelets  release of platelet factors  stimulation of proliferation of connective tissue & smooth muscles Atheroma of Aorta 7  11/28/2020 Cholesterol deposition in atheroma Needle shaped crystals Effects and Complications: (A) Ischemic effects: Ischemia may be incomplete i.e. narrowing or complete i.e. occlusion Small arteries Coronaries: Narrowing  arteriosclerosis heart diseases Occlusion  myocardial infarction Femoral artery: Narrowing  intermittent claudication Occlusion  dry gangrene of leg Large arteries: Aorta Thrombosis may develop over atheromata and this may be detached to form thrombo-emboli which can cause systemic embolism leading to infarctions in different organs 8  11/28/2020 Narrowing of coronaries by atheroma Occlusion of coronaries by atheroma 9  11/28/2020 (B) Aneurysms formation: A local enlargement of an artery They are due to stretch of the atrophic media The most common are: The cerebral arteries The aorta HYPERTENSION Definition: Hypertension is persistent elevation of blood pressure above normal. The normal adult pressure is 140/90 Types of hypertension: Primary (essential) hypertension: (90%) Secondary hypertension: (10%) 10  11/28/2020 Primary (Idiopathic) Hypertension Is of unknown cause Occurs in 90% of the cases Causes Of Secondary hypertension I-Endocrinal Causes: 1-Thyrotoxicosis 2-Pheocromocytomaare: tumors arising from the adrenal gland. They may secrete catecholamines (adrenaline & noradrenaline) 3-Cushing’s syndrome: is due to prolonged exposure to cortisol. 4-Hyperaldosteronism: medical condition in which too much aldosterone is produced by the cortex adrenal glands. II-Toxaemia Of Pregnancy III-Renal Causes: 1-Polycystic Kidney 2-Renal stones 3-Inflammation of kidney (Glomerulonephritis –Pyelonephritis) 4-Amyloidosis (deposition of extracellular substances) 5-Renal artery stenosis IV-Vascular diseases: as Coarctation of the Aorta 11  11/28/2020 Effects and complications of Hypertension 1-Eye: Arterial narrowing and retinal damage 2-Heart: Left ventricular hypertrophy & heart failure 3-Cerebral haemorrhage 4-Kidney: Varying degrees of renal damage which may result in uraemia 12