A 68-year-old man is brought to the emergency department with chest pain. For the last year, the patient has had exertional chest pain that has progressively worsened. He was shoveling snow this morning when the pain became unbearable. He has smoked a pack of cigarettes daily for 40 years. Blood pressure is 140/100 mm Hg and pulse is 90/min. Examination showed mild diaphoresis. The lungs are clear to auscultation. ECG shows ST-and T-wave changes suggestive of ischemia. Cardiac enzymes are elevated. Emergent coronary angiography is performed, which demonstrates significant atherosclerotic involvement of the left anterior descending and circumflex arteries. Development of these vascular lesions most likely involved growth factors released from which of the following sources?

Question

A 68-year-old man is brought to the emergency department with chest pain.  For the last year, the patient has had exertional chest pain that has progressively worsened.  He was shoveling snow this morning when the pain became unbearable.  He has smoked a pack of cigarettes daily for 40 years.  Blood pressure is 140/100 mm Hg and pulse is 90/min.  Examination showed mild diaphoresis.  The lungs are clear to auscultation.  ECG shows ST-and T-wave changes suggestive of ischemia.  Cardiac enzymes are elevated.  Emergent coronary angiography is performed, which demonstrates significant atherosclerotic involvement of the left anterior descending and circumflex arteries.  Development of these vascular lesions most likely involved growth factors released from which of the following sources?

Quizplus · Accepted Answer

11ec160b_38bf_d4ba_9249_e380cac116ed_MD0001_00 The development of atherosclerotic plaque, or atheroma, involves a multistep process: Over time, progressive SMC proliferation and accumulation of necrotic debris (due to macrophage/foam cell and SMC death) lead to growth of the atheroma. SMCs encourage plaque stability by synthesizing collagen, whereas activated inflammatory cells break down collagen and contribute to plaque instability. HDL likely extracts lipids from the intima back into the bloodstream and helps slow atheroma development. (Choice A) B lymphocytes are not known to play a significant role in atheroma development. However, T lymphocytes in the arterial wall intima likely play a role in activating macrophages, endothelial cells, and SMCs by releasing inflammatory cytokines (eg, interferon-γ). (Choices B and D) Eosinophils and mast cells are important in IgE-mediated (Type I) hypersensitivity reactions; mast cells release histamine in the early phase, and eosinophils release leukotrienes and major basic protein in the late phase of the reaction. However, these cells are not significantly involved in atheroma development. (Choices C and E) Neither erythrocytes nor neutrophils release growth factors or play a significant role in atheroma development. Educational objective: During the development of atherosclerotic plaque (atheroma), activated macrophages, platelets, and endothelial cells release growth factors (eg, platelet-derived growth factor) that stimulate recruitment of smooth muscle cells from the arterial wall media and their subsequent proliferation in the intima.

A 68-Year-Old Man Is Brought to the Emergency Department with Chest