Atherosclerosis: Meaning, Risk Factor and Development

The below mentioned article provides a short note on the Atherosclerosis:- 1. Meaning of Atherosclerosis 2. Conventional Risk Factor for Coronary Artery Disease 3. New and Emerging State in Women 4. Development with Ageing 5. Thrombogenesis.

Contents:

1. Meaning of Atherosclerosis
2. Conventional Risk Factor for Coronary Artery Disease
3. New and Emerging Atherosclerosis State in Women
4. Development of Atherosclerosis with Ageing
5. Thrombogenesis

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1. Meaning of Atherosclerosis:

Atherosclerosis is defined by the variable combi­nation of focal accumulation of lipids, complex carbohydrates, blood and constituents, fibrous tis­sue and calcium deposits combined with its changes of the media (as per WHO). So it is a patchy, nodu­lar type of arteriosclerosis.

The three major clinical forms arise from nar­rowing of the coronary arteries, the cerebral arter­ies and the femoral artery and its branches, but other arteries can be affected, such as the renal or me­senteric. Coronary atherosclerosis is almost invariably associated with aortic atherosclerosis.

Types of Lesion:

It is customary to separate the lesions of athero­sclerosis into fatty streaks, plaques and complicated lesions. Fatty streaks are short, thin, slightly raised yel­low lines running longitudinally along the inter­nal surface of arteries and consist of an intracellu­lar accumulation of lipids within the intima.

Plaques are the lesions of atherosclerosis. They are raised, focal, circumscribed lesions up to 1 cm in diameter, consisting of various amounts of fi­brous tissue and lipid. The lipid accumulates mostly in extracellular amorphous masses; plaques in which this process is prominent are called soft or atheromatous plaques.

In others, fibrous tissue is prominent and lipid is widely scattered or local­ized to the deeper portions of the lesion; these are called hard or fibrous plaques.

Four other processes may complicate the le­sions:

(i) The endothelium may be lost so that the surface ulcerates and the fatty contents may be ex­posed to the blood stream.

(ii) Fibrin is commonly deposited, and thrombosis occurs on the plaque surface.

(iii) Free blood can be found in plaque.

(iv) Calcification may occur.

2. Conventional Risk Factor for Coronary Artery Disease:

a. Dyslipidemia elevated LDL-C and low HDL-C.

b. Smoking.

c. Diabetes.

d. Hypertension.

e. Obesity.

f. Sedentary life style.

g. Positive family history.

h. Advancing age.

i. Postmenopausal state in women.

3. New and Emerging Atherosclerosis State in Women:

a. Hyperhomocysteinaemia.

b. Small dense LDL phenotype.

c. Inflammation and infectious agents.

d. Hyperfibrinogenaemia.

e. Elevated LP (a) [Lipoprotein (a)].

4. Development of Atherosclerosis with Ageing:

A few small lesions are seen in most adolescents and they increase in number and size throughout life. It does not usually lead to clinical disease un­til middle age.

5. Thrombogenesis:

An arterial thrombus almost always forms at the site of an atheromatous plaque, these are present in most of us from an early age. Small thrombi form frequently in the circulation. These micro-thrombi are then attached to the arterial wall where they are rapidly lysed.

A failure of the fibrolytic mechanism could in this way allow a thrombus to grow. Hence one of the primary faults responsible for athero­sclerosis might lie in an increased tendency to thrombosis or in an efficient fibrinolytic mecha­nism.