Saturday 27 August 2011

Atherosclerosis

Definition

Atherosclerosis is characterized by intimal lesions called atheromas (also called atheromatous or atherosclerotic plaques) that protrude into vessel lumens

atherosclerotic plaques mechanically obstructing blood flow, atherosclerotic plaques can rupture, leading to catastrophic vessel thrombosis; plaques also weaken the underlying media and thereby lead to aneurysm formation

Importance

Atherosclerosis causes far more morbidity and mortality (roughly half of all deaths) in the Western world than any other disorder
coronary artery disease is an important manifestation of the disease and therefore myocardial infarction is responsible for almost a quarter of all deaths in the United States.
Significant morbidity and mortality are also caused by aortic and carotid atherosclerotic disease and stroke.

SYMPTOMS:
Symptoms may develop
in any organ system with a blood supply
diminished by atherosclerosis. Commonly
these symptoms include angina
pectoris, intermittent claudication,
strokes, transient ischemic attacks, and
renal insufficiency.

EPIDEMIOLOGY

atherosclerosis is much less prevalent in Central and South America, Africa, and parts of Asia. It is more prevalent in United States so the mortality rate due to ischemic heart disease (IHD) in the United States is highest

Risk Factors

NONMODIFIABLE

Increasing age
Male gender
Family history
Genetic abnormalities

MODIFIABLE

Hyperlipidemia
Hypertension
Cigarette smoking
Diabetes
C-reactive protein
Other Risk Factors

Inflammation
Hyperhomocystinemia.
glucose intolerance,
elevated plasminogen activator inhibitor 1
lack of exercise;
competitive, stressful life style (“type A” personality)
obesity (which is often associated with hypertension, diabetes, hypertriglyceridemia, and decreased HDL).

Mechanism of Athrosclerosis
Endothelial injury, which causes (among other things) increased vascular permeability, leukocyte adhesion, and thrombosis
Endothelial injury, which causes (among other things) increased vascular permeability, leukocyte adhesion, and thrombosis
Accumulation of lipoproteins (mainly LDL and its oxidized forms) in the vessel wall
Monocyte adhesion to the endothelium, followed by migration into the intima and transformation into macrophages and foam cells
Platelet adhesion
Factor release from activated platelets, macrophages, and vascular wall cells, inducing smooth muscle cell recruitment, either from the media or from circulating precursors
Smooth muscle cell proliferation and ECM production
Lipid accumulation both extracellularly and within cells (macrophages and smooth muscle cells)

TREATMENT
Treatment includesregular exercise, smoking cessation,and a dietary regimen of low-cholesterol and low-fat foods. Medical treatment ofhypertension, lipid disorders, and diabetesmellitus is also helpful. Angioplasty,
atherectomy, or arterial bypass
graft operations are beneficial for selected
patients
If atherosclerosis is caused by hyperlipidemia then it is treated by Competitive Inhibitors of HMG-CoA Reductase which include Lovastatin, atorvastatin, fluvastatin, pravastatin, simvastatin, and rosuvastatin

No comments:

Post a Comment