Atherosclerosis

Atherosclerosis derives from Greek words “athere” (gruel, porridge) and “skleros” (hard). It describes a pathological process that transforms arterial walls. Lipids accumulate, fibrous tissue forms, and atherosclerotic plaques develop, narrowing blood vessel lumens. Atherosclerosis affects both elastic arteries (like the aorta and its branches) and muscular-elastic arteries (such as those in the heart, brain, and legs). Lipid deposits, typically cholesterol, form in the inner walls of arteries (atheromatous plaques), leading to narrowing or complete blockage (obliteration) of these vessels. As blood serum cholesterol levels rise, atherosclerotic plaques multiply in the intima of blood vessels. These plaques, consisting of cholesterol, immune cells, and connective tissue, damage the endothelium of blood vessels.

Risk Factors and Complications of Atherosclerosis

Risk factors significantly contribute to atherosclerosis, a polygenic disease. Factors include age, family history, smoking, hypertension, obesity, sedentary lifestyle, diabetes, and high levels of LDL. The LDL to HDL ratio plays a crucial role; LDL and VLDL, rich in cholesterol, are the most atherogenic. HDL, despite its high cholesterol content, prevents atherosclerotic plaque formation by transporting cholesterol from tissues to the liver. The body can only eliminate 1.2-1.5 g of cholesterol daily. Lipoproteins become atherogenic upon peroxidation, creating lipid peroxides and other compounds that chemically modify them. Peroxide-modified LDL forms in arterial walls and are targeted by macrophages, sometimes acquiring antigenic properties.
Antibodies form complexes with these modified lipoproteins, which macrophages phagocytize, turning into cholesterol-rich “foamy” cells. These cells release free cholesterol upon dying, damaging arterial walls and promoting platelet adhesion and aggregation. Damaged cells produce connective tissue proteins, forming a fibrous capsule around cholesterol, which later calcifies. These processes create rigid, fragile blood vessels prone to rupture under high blood pressure. Atherosclerotic plaques can completely narrow blood vessel lumens, initiating thrombosis and tissue necrosis. Common complications include heart attacks, aneurysms, leg gangrene, and more, primarily affecting the abdominal aorta, coronary arteries, brain, and leg arteries.

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė