Atherosclerosis

Atherosclerosis

1. By Rajasri Manimaran Group 2 ATHEROSCLEROSIS

2. Definition: Arteriosclerosis occurs when the blood vessels that carry oxygen and nutrients from your heart to the rest of your body (arteries) become thick and stiff — sometimes restricting blood flow to your organs and tissues. Healthy arteries are flexible and elastic, but over time, the walls in your arteries can harden, a condition commonly called hardening of the arteries.

3. Atherosclerosis is a specific type of arteriosclerosis, but the terms are sometimes used interchangeably. Atherosclerosis refers to the build-up of fats, cholesterol and other substances in and on your artery walls (plaques), which can restrict blood flow. These plaques can burst, triggering a blood clot. Although atherosclerosis is often considered a heart problem, it can affect arteries anywhere in your body. Atherosclerosis usually is preventable and is treatable.

4. Types of atherosclerosis: Atherosclerosis can occur anywhere in the body, including the heart, legs, and  kidneys. Coronary Artery Disease This condition occurs when the coronary arteries of the heart become hard. The coronary arteries are blood vessels that provide the heart’s muscle tissue with oxygen and blood. Plaque prevents blood flow to the heart. Carotid Artery Disease The carotid arteries are found in your neck and supply blood to your brain. These arteries may be compromised if plaque builds up in their walls. The lack of circulation may cause a decrease of blood and oxygen to the brain’s tissue and cells.

5. Peripheral Artery Disease Your legs, arms, and lower body depend on your arteries to supply blood and oxygen to their tissues. Hardened arteries can cause circulation problems in these areas of the body. Kidney Disease The renal arteries supply blood to the kidneys. Kidneys filter waste products and extra water from your blood. When they cannot filter properly, waste products build up inside the renal arteries, making them hard. The hardened vessels may lead to kidney failure.

6. Symptoms: Most symptoms of atherosclerosis do not show until a blockage occurs. Common symptoms include: chest pain (angina) pain in the leg, arm, and anywhere else that an artery is blocked shortness of breath fatigue confusion (if the blockage affects circulation to the brain) muscle weakness in the legs from lack of circulation

7. Epidemiology: Despite advances in medical, interventional, and surgical treatment, atherosclerotic disease remains the most important cause of death in developed and underprivileged nations .   In the United States alone, coronary artery disease causes approximately 1 of every 6 deaths, accounting for more than 400,000 deaths annually. Each year, an estimated 785,000 Americans have an initial myocardial infarction, and 470,000 Americans have a recurrent attack . The prevalence and severity of atherosclerosis among individuals and groups are related to several risk factors.

8. Major risk factors: Increasing age Male gender Family history Genetic abnormalities Hyperlipidemia Hypertension Cigarette smoking Diabetes C- reactive protein Non modifiable Modifiable Additional risk factors: Inflammation Hyperhomocystinemia Metabolic syndrome Lipoprotein Factors affecting hemostasis Stressful lifestyle and obesity

9. Pathogenesis:

10. Hypothetical sequence of cellular interaction:

11. Morphology: Fatty streak: Earliest lesion Composed of lipid- filled foamy macrophages Begin as multiple minute flat yellow spots , which eventually turns up to elongated streak May be precursors of plaques Not all fatty streak are destined to become advanced lesions

12. Atherosclerotic plaque : Impinge on the lumen of the artery and grossly appear white to yellow. Plaque vary from 0.3 to 1.5cm in diameter but can coalesce to form larger masses. Have 3 principal components: Cells, including smooth muscle cells, macrophages, and T cells. ECM, including collagen, elastic fibers , and proteoglycans, and Intracellular and extracellular lipids.

13. Atherosclerotic plaques are susceptible to the following clinically important changes: Rupture, ulceration or erosion of the intimal surface of atheromatous plaques exposes the blood to highly thrombogenic substances and induces thrombosis. Hemorrhage into a plaque: rupture of the overlying fibrous cap, or of the thin-walled vessels in the areas of neovascularization, can cause intra-plaque hemorrhage Atheroembolism : ruptured plaque discharge artherosclerotic debris into bloodstream, producing microemboli Aneurysm formation : atherosclerosis- induced pressure or ischemic atrophy of the underlying media, with loss of elastic tissue, causes weakness resulting in aneurysmal dilation and potential rupture.

14. Consequences of atherosclerotic disease:

15. Screening and diagnosis: Stress Test measures blood supply to heart Coronary Angiography specific shows coronaries Narrowing in Sites of Electro- cardiogram measures electrical impulses

16. Other test: Blood tests: used to evaluate kidney and thyroid function as well as to check cholesterol levels and the presence of anemia. Chest X-ray: shows the size of your heart and whether there is fluid build up around the heart and lungs. Echocardiogram: shows a graphic outline of the heart’s movement Ejection fraction (EF): determines how well your heart pumps with each beat . Treatment: Lifestyle changes Medications Angiography and stenting Bypass surgery

17. Treatment: