Artefacts of localization of atherosclerosis in pinned aortas.

Detailed studies of aortas from 8 rabbits showed that serious artefacts occur if the aortas are pinned at their in vivo dimensions, rather than fixed at physiological pressure. In the pinned aortas, the proximal parts of the branches were pulled up onto the aortic wall. This was more pronounced for the large branches of the abdominal aorta than for the smaller intercostal branches. This artefact caused atherosclerotic lesions, which had developed at the origin of the branch, to appear as if they were entirely on the aortic wall. We found that a marked change in the elastin pattern was present at the origin of the branch; this can be used to mark the true origin of the branch. With the pressure technique we found that lesions had different shapes and locations at different branch points.