Atherosclerosis of Coronary Artery

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Atherosclerosis of Coronary Artery (PH 804, 813, 814) (Fig 7-11 and 7-12, pp. 102-103)
(Be able to identify these slides at low power as showing atherosclerosis, identify the plaque, and differentiate between the normal and abnormal regions.)

First observe a slide of an early atherosclerotic lesion (PH 813). The pink, noncellular material in the intima of the coronary artery is the atherosclerotic plaque. This lesion has already reduced the lumen by about 20%. Now observe one of the later atherosclerotic plaques (PH 804 or PH 814). Note the degree of occlusion by the lesion. It may take years for plaque to reach this size.

                                          Early lesion (40X1.0 - a1)

                                        Normal artery wall at left, lumen in center,
                                        lesion (thickened wall) at right.

Normal region (100X2.0 - a1)                                                               Early lesion (100X2.0 - a2)

Layers are areolar tissue (left), externa (thick pink                     Lumen at upper left, endothelium (thin layer),
collagen fibers), smooth muscle (thick middle layer),              intima, fibrous plaque within intima, intima (darker granular
tunica intima (thick granular layer), endothelium                      layer), smooth muscle (thick pink), externa (lower right)
(thin red layer), lumen at right

                                          Advanced lesion (40X1.0 - b1)

                                             Lumen at left of center, lesion at right

Normal region (100X2.0 - b1)                                                               Advanced lesion (100X2.0 - b2)

Externa at left, lumen at right                                                     Lumen at far lower left corner, lesion of mixed
                                                                                                       substances and cells fills center region

                                            Occlusive lesion (40X1.0 - c1)

                                          Lumen at far left of center, crystalline lesion fills center

Fibrous plaque (100X2.0 - c1)                                                          Plaque replaces intima and smooth muscle (100X2.0 - c2)

Layers are areolar tissue (left), externa (red collagen              Amorphous acellular material (upper left) and cellular
fibers), smooth muscle (thin red middle layer), tunica           and fibrous plaque (center) replace intima and smooth muscle,
intima (blue granular layer), fibrous plaque (thick, pink),       externa (collagen fibers) remains at lower right
endothelium (thin layer along lumen), lumen (at right)

Center of plaque (100X2.0 - c3)                                                          Endothelium (400X2.0 - c4)

Center of amorphous acellular region                                      Normal endothelium (lower right bordering lumen), plaque
of plaque, much of which appears crystalline                     (right, underlies endothelium), lumen (left), damaged
                                                                                                        endothelium with adhering RBCs (middle and top)

* Clinically significant lesions (which produce myocardial ischemia) usually obstruct over percent of the vessel lumen. (p. 461)

Do you think any of these lesions would be clinically significant? Which ones?

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This material may not be reproduced or distributed in any form or by any means, or stored in any data base or retrieval system without prior written permission is obtained from Augustine G. DiGiovanna, Ph.D., Professor of Biology, Salisbury University, Salisbury, MD 21801.