Arteriosclerosis and Atherosclerosis: Pathogenesis, Pathology, Causes, and Types

Arteriosclerosis and atherosclerosis are chronic vascular conditions that involve structural and functional changes in arterial walls, significantly impacting cardiovascular health worldwide.

Pathogenesis

Arteriosclerosis refers to the thickening and hardening of arterial walls due to aging or elevated blood pressure. In contrast, atherosclerosis is a specific form characterized by lipid accumulation within the intima, inflammation, and fibrotic plaque formation.

Endothelial Injury

The initiating step in atherosclerosis is endothelial injury, caused by factors such as hypertension, hyperlipidemia, smoking, and diabetes. This leads to increased permeability and leukocyte adhesion.

Lipid Accumulation and Foam Cell Formation

Low-density lipoproteins (LDL) infiltrate the intima and become oxidized, which triggers monocyte recruitment. These monocytes transform into macrophages and uptake lipids, forming foam cells and fatty streaks.

Histopathological Features

• Fatty Streaks: Composed mainly of lipid-laden foam cells.
• Fibrous Plaques: Comprise smooth muscle cells, collagen, lipids, and lymphocytes.
• Complicated Lesions: Include calcification, hemorrhage, ulceration, and thrombosis.

Types of Arteriosclerosis

1. Atherosclerosis: Large and medium muscular arteries, commonly the aorta and coronary arteries.
2. Arteriolosclerosis: Affects small arteries and arterioles, seen in hypertension and diabetes; types include hyaline and hyperplastic.
3. Monckeberg Medial Sclerosis: Calcification of the tunica media of muscular arteries, typically without luminal narrowing.

Causes and Risk Factors

• Age and gender (increased risk in older males)
• Genetic predisposition
• Hyperlipidemia and hypercholesterolemia
• Hypertension
• Diabetes mellitus
• Smoking and sedentary lifestyle

Clinical Significance

These vascular changes are major contributors to ischemic heart disease, stroke, peripheral artery disease, and aneurysms, highlighting the critical need for early detection and intervention.