Mikhail is a 60 year old man with a history of hypertension, diabetes and dyslipidemia who presents to your clinic complaining of sudden-onset retrosternal chest pain associated with shortness of breath. He has a 35-pack-a-year smoking history, and he mentions that he also develops lower limb pain when walking for more than 15 minutes. His father underwent a below the knee amputation of his right lower extremity and died from a stroke. On physical examination, his BMI is 32. On further workup, his ECG and high troponin levels suggest a myocardial infarction. Mikhail goes to the cath lab to undergo per-cutaneous coronary intervention, which showed a clot occluding the left anterior descending coronary artery. After the procedure, his chest pain resolved. However, he started developing a web-like skin rash.
Mikhail suffers from arteriosclerosis, which is a hardening and thickening of the arterial wall, causing it to lose its elasticity. A specific type of arteriosclerosis is atherosclerosis, which is a chronic inflammatory disorder that affects the endothelium of medium and large arteries, and is characterized by the buildup of cholesterol plaques within the arterial lumen. In a descending order, the most common arteries affected by atherosclerosis are the abdominal aorta, coronary artery, popliteal artery and then the carotid artery.
Risk factors for atherosclerosis can be divided into modifiable and nonmodifiable risk factors. Modifiable risk factors include hypertension, diabetes mellitus, smoking and dyslipidemia, particularly an increase in LDL levels or a decrease in HDL levels. Non-modifiable risk factors include age, family history, and being of African-American descent.
The pathogenesis of atherosclerosis is essentially an inflammatory response to endothelial cell injury. The endothelium is injured by stress against the arterial wall, like in hypertension. This is especially more prominent at arterial bifurcations, such as the carotid artery bifurcation. Other causes of endothelial injury include tobacco smoking and homocysteinemia, which is elevated levels of the amino acid, homocysteine.