Dissecting aneurysm

on 17.3.09 with 0 comments

  • dissection is an intimal tear with hemorrhage into the wall of the vessel

  • most often occurs in the thoracic aorta

  • two main groups at risk

    • hypertensive men, 40-60 years old

    • people with connective tissue disorders (e.g. Marfan syndrome)

  • hypertension is present in 94% of cases

  • technically a type of false aneurysm


  • there is a little transverse tear spreading from the aortic valve

  • another specimen: carotid has blood accumulating in the media and compressing the lumen

Sequence of events

  • intimal tear

  • hemorrhage into aortic media

  • extension of hemorrhage

  • rupture


  • hemorrhage dissecting along lengthwise

  • vessel with hemorrhage into the media


  • clearly related to hypertension

  • cystic medial degeneration (CMD)

    • elastic fragmentation of media

    • cystic faces are filled with amorphous proteoglycan material

  • CMD is not seen in all cases of dissection and CMD is pretty commonly seen without dissection

Histological stains

  • elastic stain: normal aorta: parallel fibers

  • elastic stain: cystic medial degeneration: a little degeneration, a little cystic space

  • mucin stain: the orifice in the elastic material really lights up

Clinical course

  • classically described as abrupt onset of tearing chest pain radiating to the back

  • most common cause of death is rupture

  • dissection to the aortic root can cause cardiac tamponade, aortic insufficiency, MI

Classification schemes

  • Stanford type A and B: ascending aortic involvement vs. descending aortic involvement

  • or, Debakey I, II, III; DeBakey I is the most common (60% cases)

  • Stanford A (DeBakey I and II) are more common and more dangerous; require surgery

  • previously almost uniformly fatal, better now

  • require immediate antihypertensives

Category: Medical Subject Notes , Pathology Notes



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