Thickening of the intima is due to proliferation of its components as a response to diminished lateral pressure or the suction effect of the flowing blood. The point is not that atherosclerotic changes (atheroma) occur where the intima is already normally thickened but that the first sign of developing atherosclerosis is a slight reactive thickening of the intima. A vessel may be considered to have a normally thickened intima only in the sense that no pathological or clinical findings are attributable to the diminution of volumetric flow due to encroachment on the lumen by the thickened intima. The thickening signals the start of the disease and the continued operation of local hydraulic factors produces progressive pathological changes which evolve into the atherosclerotic plaque. All the stages in this pathological process have been produced hemodynamically in our laboratory.
Hydrodynamics of flow are not "obviously the same" in the rich, the poor,