Pathology
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Disturbances Of The Heart
The pathology of arteriosclerosis is a thickening and diminishing
elasticity of the arteries, beginning with the inner coat and
gradually spreading and involving all the coats, the larger arteries
often developing calcareous deposits or thickened cartilaginous
plates--an atheroma. If the thickening of the walls of the smaller
vessels advances, their caliber is diminished, and there may even be
complete obstruction (end
rteritis obliterans). On the other hand,
some arteries, especially if the calcareous deposits are
considerable, may become weakened in spots and dilation may occur,
causing either smaller or larger aneurysms.
Histologically the disease is a connective tissue formation
beginning first as a round-cell infiltration in the subendothelial
layer of the intima. This process does not advance homogeneously;
one side of an artery may be more affected than the other, and the
lumen may be narrowed at one side and not at the other, allowing the
artery to expand irregularly from the force of the heart beat. As
the disease continues, the internal elastic layer is lost, the
muscular coat begins to atrophy, and then small calcareous granules
may begin to be deposited, which may form into plates. In the large
arteries, the advance of the process differs somewhat. There may be
more actual inflammatory signs, fatty degeneration may occur, and
even a necrosis may take place.
However generally distributed arteriosclerosis is, in some regions
the disease is more advanced than in others, and in those regions
the most serious symptoms will occur. The regions which can stand
the disease least well are the brain and coronary arteries, and next
perhaps the legs, at the distal parts at least, where the
circulation is always at a disadvantage if the patient is up and
about.