Circulatory Disorders IIi PDF

Circulatory Disorders IIi Dr.Noor Al-Mustafa Emad In this lecture…… Atherosclerosis Hypertension  Atherosclerosis Atherosclerosis is a type of arteriosclerosis or hardening of the arteries. It means the formation of fibro-fatty lesions (Activated macrophages...

Circulatory Disorders IIi Dr.Noor Al-Mustafa Emad In this lecture…… Atherosclerosis Hypertension  Atherosclerosis Atherosclerosis is a type of arteriosclerosis or hardening of the arteries. It means the formation of fibro-fatty lesions (Activated macrophages ) in the intimal lining of the large and medium-sized arteries such as the aorta and its branches, the coronary arteries, and the cerebral arteries that supply the brain. The disorder remains a leading cause of coronary artery disease, stroke, and peripheral artery disease. Risk Factors for Atherosclerosis Some of the risk factors are constitutional and cannot be changed and others are affected by lifestyle and can be modified. Constitutional risk factors such as increasing age, male gender, and family history of premature coronary artery disease cannot be changed. The tendency toward the development of atherosclerosis appears to run in families. The incidence of atherosclerosis increases with age. Other factors being equal, men are at greater risk for the development of CAD than are premenopausal women, probably because of the protective effects of natural estrogens. The major risk factor, hypercholesteremia, has both constitutional (non- modified) and lifestyle components (modified). Risk Factors for Atherosclerosis The major risk factors that can be modified by a change in health care behaviors include cigarette smoking, obesity, hypertension, hyperlipidemia and elevated LDL cholesterol, and diabetes mellitus (traditional cardiovascular risk factors). Smoking affects atherosclerosis by several mechanisms other than its unfavorable effects on blood pressure, sympathetic vascular tone, and reduction in myocardial oxygen supply. It has adverse hemostatic and inflammatory effects and it may enhance the oxidation of LDL cholesterol, causing damage to the endothelial lining of blood vessels. Obesity, type 2 diabetes, high blood pressure, and high blood cholesterol levels often can be controlled with a change in health care behaviors and medications.  Mechanisms of Development The lesions associated with atherosclerosis are of three types: (the fatty streak, the fibrous atheromatous plaque, and the complicated lesion). The latter two are responsible for the clinically significant manifestations of the disease. Fatty streaks are thin, flat, yellow intimal discolorations that progressively enlarge by becoming thicker and slightly elevated as they grow in length. Histologically, they consist of macrophages and smooth muscle cells that have become distended with lipid to form foam cells. Fatty streaks are present in children, often in the first year of life, and they increase in number until about 20 years of age, and then remain static or regress.  Mechanisms of Development The fibrous atheromatous plaque is the basic lesion of clinical atherosclerosis, characterized by the accumulation of intracellular and extracellular lipids, proliferation of vascular smooth muscle cells, formation of scar tissue, and calcification. The lesions begin as a gray to pearly white, elevated thickening of the vessel intima with a core of extracellular lipid covered by a fibrous cap of connective tissue and smooth muscle. As the lesions increase in size, they encroach on the lumen of the artery and eventually may occlude the vessel or predispose to thrombus formation, causing a reduction of blood flow. The more advanced atherosclerotic lesions contain hemorrhage, ulceration, and scar tissue deposits. Thrombosis is the most important complication of atherosclerosis. It is caused by slowing and turbulence of blood flow in the region of the plaque and ulceration of the plaque.  Development of Atherosclerosis The development of atherosclerotic lesions is a progressive process involving: (1) endothelial cell injury (2) migration of inflammatory cells (3) smooth muscle cell proliferation and lipid deposition (4) gradual development of the atheromatous plaque with a lipid core. Development of Atherosclerosis Development of Atherosclerosis  Clinical Manifestations The clinical manifestations of atherosclerosis depend on the vessels involved and the extent of vessel obstruction. Atherosclerotic lesions produce their effects through narrowing of the vessel and production of ischemia; sudden vessel obstruction due to plaque hemorrhage or rupture; thrombosis and formation of emboli resulting from damage to the vessel endothelium; and aneurysm formation due to weakening of the vessel wall. In larger vessels, such as the aorta, the important complications are those of thrombus formation and weakening of the vessel wall. In medium-sized arteries, such as the coronary and cerebral arteries, ischemia and infarction due to vessel occlusion are more common. Although atherosclerosis can affect any organ or tissue, the arteries supplying the heart, brain, kidneys, lower extremities, and small intestine are most frequently involved. Hypertension  Hypertension Hypertension (HTN or HT), also known as high blood pressure or arterial hypertension, is a chronic medical condition in which the blood pressure in the arteries is persistently elevated. Hypertension is defined as systolic blood pressure (SBP) of 140 mmHg or greater, diastolic blood pressure (DBP) of 90 mmHg or greater, different numbers apply to children.  Hypertension Hypertension is classified as either primary (essential) hypertension or secondary hypertension. Essential hypertension – 90-95% – No underlying cause Secondary hypertension – 5-10% – Underlying cause  Factors Influencing the Development of Essential Hypertension - Family history of hypertension - Overweight - Excess Consumption of Sodium Chloride Certain segments of the population are «salt sensitive» because their blood pressure is affected by salt consumption - Exercise Less active individuals are 30-50% more likely to develop hypertension. Mechanisms of Eessential Hypertension -  activity of renin-angiotensin-aldosteron - Hyperfunction of sympathetic system - Vasoactive substances - endothelial dysfunction - Insulin resistance - Renal defect to excrete sodium Symptoms of Essential Hypertension High blood pressure usually has no symptoms (Silent Killer ), but it can cause serious problems such as stroke, heart failure, heart attack, and kidney failure. A few people with high blood pressure may have headaches, shortness of breath or nosebleeds, but these signs and symptoms aren't specific and usually don't occur until high blood pressure has reached a severe or life-threatening stage.  What can high blood pressure do to your body? Stroke Heart Attack High blood pressure is the most important risk factor for stroke. Very high pressure can cause a break in a High blood pressure is a major weakened blood vessel, which then risk factor for heart attack. bleeds in the brain. This can cause a The arteries bring oxygen- stroke. If a blood clot blocks one of carrying blood to the heart the narrowed arteries, it can also muscle. If the heart cannot get cause a stroke. enough oxygen, chest pain, can occur. If the flow of blood is blocked, a heart attack Blindness results. High blood pressure can eventually cause blood vessels in the eye to burst or bleed. Vision may become blurred or otherwise impaired and can result in blindness. Heart failure The heart is unable to Kidney disease pump enough blood to supply the body's needs. Kidneys act as filters to rid As people get older, arteries the body of waste. High throughout the body blood pressure can narrow "harden," especially those in the heart, brain, and and thicken the blood vessels kidneys. High blood of the kidneys. The kidneys pressure is associated with filter less fluid and waste Arteries these "stiffer" arteries. This, builds up in the blood. The in turn, causes the heart kidneys may fail altogether. and kidneys to work harder.  Secondary Hypertension Secondary hypertension (secondary high blood pressure) is high blood pressure that's caused by another medical condition. It can be caused by conditions that affect: - kidneys - Arteries - Heart - Endocrine system. Secondary hypertension can also occur during pregnancy.  Symptoms of Secondary Hypertension - No specific complains or manifestations other than elevated systolic and/or diastolic BP - Morning occipital headache - Dizziness - Fatigue - In severe hypertension, epistaxis or blurred vision.  Malignant Hypertension Malignant hypertension is a serious condition caused by very high blood pressure. It can quickly cause serious damage to eyes, kidneys and brain. Some of the changes can be reversed by treatment but some permanent damage may occur. - It is sometimes called accelerated phase hypertension. - Malignant hypertension is uncommon and much more severe than 'ordinary' high blood pressure. Although all high blood pressure can damage arteries, that damage usually occurs slowly over many years. In malignant hypertension, severe damage occurs over weeks or less.  Symptoms of Malignant Hypertension - Headache is uncommon with hypertension unless blood pressure is very high. It is very high in malignant hypertension. - Brain involvement sometimes causes (convulsions). Eyesight may be blurred or there may be black spots in patient’s vision. - Kidney damage can occur rapidly and it may cause complete renal failure. - Malignant hypertension causes severe damage to tiny arteries called arterioles. Arterioles anywhere in the body can be affected, but it is the eyes, the brain and the kidneys that are most commonly worst affected. Thank You