Pathology of atherosclerosis

This communication gives a brief account of the morphology and natural history of atherosclerosis. It defines atherosclerosis, in dynamic terms as the resultant of three interacting sets of processes: accumulation and modification of plasma-derived lipid within the arterial intima, connective tissue proliferation and connective tissue necrosis forming an atheromatous pool at the plaque base. The first of these leads to the accumulation of lipid-filled macrophages within the affected intima and this step is most probably mediated via oxidative modifications of the low density lipoprotein molecule. An alteration of the functional phenotype of the intimal smooth muscle cell as a result of interactions with growth factors (most notably PDGF) constitutes the basis for the connective tissue proliferation. Plaque necrosis, which is extremely important as a risk factor for acute thrombosis, is the least well understood area; the activated macrophage may well play a significant role in this connexion.