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General and Systemic Histopathology, C601&C602
     
    Slide 53: Dissecting aortic aneurysm
     
     
    It may be a little hard to imagine what's happening here, but if you study this scan of the tissue and try to sketch, it may become clear. Somewhere in the wall of the aorta, a tear in the intima developed (no, you can see the tear in this picture), allowing the blood to "dissect" into and separate the muscle layers of the aortic wall. Here we see what appears to be a "double barreled" lumen, but in fact only one "true" aortic lumen is present.  The other blood filled space is the compartment created by the tearing and separation of the aortic wall by means of the blood pressure pushing the blood into the wall through the intimal defect.

    See this slide with the virtual microscope.

    Again, look at this slide on a white background first. You should easily be able to see the advancing edge of the dissecting aneurysm. This condition may complicate an atherosclerotic aneurysm, but may also be seen in the absence of atherosclerosis. It sometimes happens in people with hypertension. Typically it is very painful as the leading edge of the dissection tears the muscle of the aorta. The dissection may stop, "blow" through the wall into the surrounding fat or pericardial space, or even open another "rent" in the intima and reenter the lumen of the aorta.


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