atherosclerosis

atherosclerosis is a chronic inflammatory disease characterized by the buildup of plaques within the walls of arteries. This process, which can begin in youth and progress over decades, involves the accumulation of lipids, cholesterol, calcium, and cellular debris, leading to the hardening and narrowing of arteries. The resulting reduction in blood flow can cause severe complications, including heart attack and stroke, making it a primary contributor to cardiovascular disease worldwide.

Pathophysiology

The development begins with endothelial injury, often triggered by factors like hypertension or hyperlipidemia, which increases the permeability of the endothelium to low-density lipoprotein particles. These lipids undergo oxidation and are taken up by macrophages, transforming them into foam cells that form the early fatty streak. Over time, smooth muscle cells migrate from the tunica media and proliferate, secreting extracellular matrix components like collagen to form a fibrous cap over a necrotic core of apoptotic cells and cholesterol crystals. This complex plaque can become unstable, with rupture or erosion leading to acute thrombosis, a key event in myocardial infarction or ischemic stroke.

Risk factors

Major modifiable risk factors include dyslipidemia, particularly elevated low-density lipoprotein and reduced high-density lipoprotein, as well as hypertension, cigarette smoking, and diabetes mellitus. Non-modifiable factors encompass advanced age, male sex, and a positive family history of premature cardiovascular disease. Additional contributors are obesity, a sedentary lifestyle, diets high in saturated fat, and certain inflammatory conditions like rheumatoid arthritis. The Framingham Heart Study was instrumental in identifying and quantifying many of these risks.

Clinical manifestations

Symptoms depend entirely on the affected vascular bed and the degree of luminal obstruction. Coronary artery involvement typically presents as stable angina or acute coronary syndrome, including unstable angina and ST-elevation myocardial infarction. Cerebrovascular disease can manifest as transient ischemic attack or ischemic stroke, while aortoiliac or lower extremity disease causes intermittent claudication and, in severe cases, critical limb ischemia. Renal artery stenosis may lead to renovascular hypertension or chronic kidney disease.

Diagnosis

Diagnostic methods vary by suspected location. For coronary arteries, coronary angiography remains the gold standard, often preceded by non-invasive tests like exercise stress testing, myocardial perfusion imaging, or coronary computed tomography angiography. Carotid disease is typically assessed using duplex ultrasonography, while ankle-brachial index measurement is key for peripheral artery disease. Advanced imaging, such as intravascular ultrasound or optical coherence tomography, can characterize plaque morphology. Biomarkers like elevated high-sensitivity C-reactive protein may indicate inflammatory activity.

Prevention and management

Primary prevention focuses on aggressive modification of risk factors through lifestyle interventions, including Mediterranean-style diets, regular physical activity, and smoking cessation. Pharmacotherapy often involves statins to lower LDL cholesterol, antihypertensive agents like ACE inhibitors, and antiplatelet drugs such as aspirin. For established disease, secondary prevention intensifies these measures. Revascularization procedures, including percutaneous coronary intervention with stent placement or coronary artery bypass grafting, are indicated for significant obstructions. The American Heart Association and American College of Cardiology provide detailed guidelines.

Epidemiology

It is the leading underlying cause of morbidity and mortality globally, responsible for most cases of coronary heart disease and cerebrovascular disease. Prevalence increases dramatically with age and varies geographically, with higher rates observed in industrialized nations, though the burden is rising rapidly in developing countries like India and China. According to the World Health Organization, cardiovascular diseases are the number one cause of death worldwide, with atherosclerosis as the principal pathology. Significant disparities exist based on socioeconomic status and ethnicity. Category:Cardiovascular diseases Category:Chronic diseases Category:Inflammation