QCM : Understanding Atherosclerosis Development — 21 questions

Explication

Endothelial dysfunction in atherosclerosis is mainly initiated by decreased nitric oxide availability and increased oxidative stress, which impair the endothelium's normal function. This state promotes LDL infiltration, oxidation, and subsequent inflammatory responses, setting the foundation for plaque formation.

Explication

Endothelial dysfunction starts the process of atherogenesis by allowing LDL infiltration and oxidation, which are critical initial events.

Explication

The initial cellular event in fatty streak formation involves monocytes adhering to the dysfunctional endothelium. These monocytes then migrate beneath the endothelium and transform into foam cells after ingesting oxidized LDL cholesterol. This process is crucial in the early stages of atherogenesis.

Explication

The sheet mentions coronary, carotid, and peripheral arteries as mainly affected, while cerebral arteries are not explicitly listed, making 'Cerebral arteries' the correct answer.

Explication

Collagen production by vascular smooth muscle cells during plaque development results in the formation of a fibrous cap, which stabilizes the plaque and reduces the risk of rupture.

Explication

The sheet notes that atherosclerosis begins early but becomes symptomatic around ages 35-40.

Explication

An advanced atherosclerotic plaque with a lipid core is typically characterized by a large, soft, lipid-rich necrotic core. This core is often covered by a thin fibrous cap composed mainly of collagen and smooth muscle cells. Such plaques are considered vulnerable and prone to rupture, leading to thrombus formation. The other options describe more stable plaques or different plaque components.

Explication

Unstable plaques have a thin fibrous cap and a large lipid necrotic core, making them prone to rupture.

Explication

A vulnerable plaque is characterized by a high lipid content and a soft, unstable structure, making it more prone to rupture. In contrast, stable plaques have a thick fibrous cap and are collagen-rich, making them less likely to rupture. Extensive calcification is more typical of stable, mature plaques but is not a primary feature of vulnerability.

Explication

The sheet specifies hypercholesterolemia, especially LDL >160 mg/dl, as a major risk factor.

Explication

Elevated LDL cholesterol levels above 160 mg/dl are a key risk factor for hypercholesterolemia, which promotes the formation of atheromatous plaques in arteries, leading to atherosclerosis.

Explication

Plaque rupture exposes thrombogenic material, resulting in thrombus formation and potential vessel occlusion, causing ischemic events.

Explication

Unstable plaques are typically characterized by a lipid-rich, soft core with a thin fibrous cap, making them more prone to rupture. Stable plaques tend to be collagen-rich, dense, and calcified, providing structural stability and a lower risk of rupture.

Explication

Stable angina pectoris is a clinical manifestation associated with significant, yet stable, narrowing of coronary arteries (>70-75%), leading to chronic ischemia during exertion. Patients experience predictable chest pain on exertion, which subsides with rest. Acute myocardial infarction and unstable angina are typically related to plaque rupture and thrombus formation, resulting in sudden and more severe symptoms. Asymptomatic states are common in early disease stages but are not specific to advanced ischemia.

Explication

The threshold for critical stenosis where ischemia is likely to occur is generally considered to be greater than 70-75%. At this level of narrowing, blood flow reduction becomes significant enough to cause tissue ischemia during increased demand.

Explication

Unstable plaques are characterized by a lipid-rich, soft composition with a thin fibrous cap, making them prone to rupture. Rupture exposes thrombogenic material to the bloodstream, leading to thrombus formation and potentially causing acute events such as myocardial infarction or stroke. Stable plaques are collagen-rich, hard, and have a low rupture risk, typically causing chronic symptoms.

Explication

Atherosclerosis primarily affects medium and large arteries, notably the coronary arteries (leading to angina and myocardial infarction), carotid arteries (risk of stroke), and peripheral arteries (causing claudication and gangrene). These vessels' large caliber and high flow make them susceptible to plaque formation that can lead to ischemic symptoms.

Explication

Clinical symptoms of atherosclerosis usually become evident around ages 35-40 when significant stenosis (>70-75%) develops, leading to ischemic manifestations such as angina or other organ-specific symptoms.

Explication

The initial stage of atherogenesis involves endothelial dysfunction which allows LDL cholesterol to cross into the intima, where it becomes oxidized. This promotes monocyte adhesion, marking the beginning of fatty streak formation. Subsequent steps include monocyte transformation into foam cells and development of fatty deposits. The other options describe later stages or complications in plaque development.

Explication

Vulnerable plaques are characterized by a large, lipid-rich necrotic core and a thin fibrous cap, making them prone to rupture. In contrast, stable plaques tend to have a thick, collagen-rich fibrous cap that provides stability and reduces rupture risk.

Explication

Plaque rupture exposes the inner core contents to the bloodstream, which triggers thrombus formation. This thrombus can occlude the artery completely, resulting in acute ischemic events like myocardial infarction or stroke.