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Common Congenital Heart Lesions - page 27 / 126

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Atherosclerosis

Chapter 5, pp.111-129

Definition: “hardening of the arteries” as a result of the abnormal accumulation of lipids, cells, and ECM within the arterial wall, creating lesions known as atherosclerotic (fibrous) plaques.

  • The formation of plaques can result in:

    • o

      Stenosis or narrowing of the arteries

      • o

        Rupture, which may then lead to thrombosis

*Note that in either event, that blood supply to tissues is limited, resulting in major

complications like angina, MI, stroke, and/or impaired blood flow to the kidneys and lower body—thus, atherosclerosis is the leading cause of morbidity & mortality in the U.S.

The following is a brief review of the normal arterial wall and its consitutents...

Arteries: Consist of 3 layers (intima, media, & adventitia) that all play a role in the development of atherosclerosis

  • Intima

    • o

      Innermost layer, most “intimate” with the blood

      • o

        Single layer of endothelial cells

      • o

        Metabolically active barrier between the blood and vessel

  • Media

    • o

      Middle layer separated from the intima and adventitia by the internal & external elastic laminae respectively

      • o

        Mostly SMCs with some ECM (produced by the SMCs)

      • o

        Contractile (esp. small arteries & arterioles)Æ alterations in Resistance & Flow

*Recall: Q=P/R (Q=Flow; P=Pressure; R=Resistance)

      • o

        Elastic (esp. large arteries like the aorta)Æ forward propulsion of blood

  • Adventitia

    • o

      Outermost layer

  • o

    Has blood vessels (vasa vasorum), nerves & lymphatics that nourish the vessel

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