Atherosclerosis - Pathogenesis, risk factors and complications

Summary

This lecture on atherosclerosis by Dr. Matt outlines the risk factors, pathogenesis, and chronic complications of the disease. Atherosclerosis is characterized by fatty deposits in artery walls, primarily affecting large and medium-sized arteries. The risk factors are categorized into non-modifiable (age, sex, genetics) and modifiable (hypertension, dyslipidemia, diabetes, smoking). The disease progresses through five stages, starting with endothelial injury and culminating in advanced plaque formation. Complications include ischemia, unstable plaque leading to thrombus formation, and aneurysms. Understanding these aspects is crucial for prevention and management of atherosclerosis.

Takeaways

• 😀 Atherosclerosis is a chronic disease of the arteries characterized by fatty deposits in their inner walls.
• 🧑‍⚕️ The disease primarily affects large elastic arteries (like the aorta and carotid arteries) and medium-sized muscular arteries (like coronary and renal arteries).
• 🛑 Non-modifiable risk factors for atherosclerosis include age, biological sex (with males at higher risk), and genetics.
• ⚠️ Modifiable risk factors include hypertension, dyslipidemia (high LDL and low HDL), diabetes mellitus, and smoking.
• 🩺 The pathogenesis of atherosclerosis involves a cycle of endothelial injury and repair, leading to chronic inflammation.
• 🔬 The initial step in atherosclerosis involves endothelial injury caused by risk factors like smoking and hypertension.
• 💔 The injury leads to increased permeability of the endothelium, allowing LDL cholesterol to accumulate in the intima layer.
• 🧫 The accumulation of foam cells (macrophages filled with lipids) forms a fatty streak, which can progress to advanced plaques.
• 🚨 Chronic complications of atherosclerosis include ischemia due to stenosis, unstable plaques leading to thrombus formation, and aneurysms.
• ⚡ Advanced plaques can cause serious cardiovascular events such as myocardial infarction (heart attack) or transient ischemic attacks (strokes).

Q & A

What is atherosclerosis?

Atherosclerosis is a disease of the arteries characterized by fatty deposits in their inner walls, leading to complications that affect blood flow.

What are the primary arteries affected by atherosclerosis?

Atherosclerosis primarily affects large elastic arteries like the aorta, iliac arteries, and carotid arteries, as well as medium-sized muscular arteries such as coronary and renal arteries.

What are the non-modifiable risk factors for atherosclerosis?

The non-modifiable risk factors include age, biological sex, and genetics. As age increases, the risk of atherosclerosis also rises, with males being at higher risk than pre-menopausal females.

How does hypertension contribute to atherosclerosis?

Hypertension puts shear stress on artery walls, causing ongoing injury that contributes to the pathogenesis of atherosclerosis, particularly in areas of high shear stress such as branch points and the abdominal aorta.

What role does dyslipidemia play in the development of atherosclerosis?

Dyslipidemia involves high levels of low-density lipoproteins (LDLs) and low levels of high-density lipoproteins (HDLs), leading to oxidative stress on endothelial cells and contributing to atherosclerotic processes.

What is the significance of endothelial injury in atherosclerosis?

Endothelial injury is the first step in atherosclerosis. Risk factors like smoking and hypertension cause damage to the endothelium, allowing for the accumulation of harmful substances like LDLs and the recruitment of inflammatory cells.

What are foam cells, and how do they form?

Foam cells are formed from macrophages that have engulfed oxidized LDLs. This accumulation of foam cells leads to the development of the fatty streak stage in atherosclerosis.

What are the potential clinical manifestations of advanced atherosclerotic plaques?

Advanced plaques can lead to ischemia in various organs, causing conditions such as ischemic heart disease, reduced kidney perfusion, and peripheral vascular disease.

What is the difference between stable and unstable angina in relation to atherosclerosis?

Stable angina occurs due to predictable ischemia resulting from critical stenosis in coronary vessels, while unstable angina results from an unstable plaque that may lead to acute thrombus formation and potentially a myocardial infarction.

What are some chronic complications associated with atherosclerosis?

Chronic complications include stenosis leading to ischemia, unstable plaques that can result in thrombus formation, and aneurysms due to weakened vessel walls, which can lead to ruptures and hemorrhagic strokes.