Page 424 - Textbook of Pathology, 6th Edition

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Figure 15.17 A, Dissecting aneurysm, (Type 1) beginning in the aortic arch and extending distally into the descending thoracic aorta as well as
proximally into the ascending aorta. An intimal tear is seen in the arch. B, The cross section shows dissection typically separating the intima and
inner two-thirds of the media on luminal side, from the outer one-third of the media and the adventitia. C, The ascending aorta is seen with the heart.
There is an intimal tear in the aortic wall (black arrow) extending proximally upto aortic valve dissecting the media which contains clotted blood
SECTION III
(white arrow)

II. Stanford classification. Depending upon clinical Histologically, the characteristic features of cystic medial
management, these are divided into 2 types: necrosis are found. These are as under:
Type A (Proximal dissection): Involves the ascending aorta Focal separation of the fibromuscular and elastic tissue
and includes type I and II of the above scheme because of the media.
clinical management of DeBakey type I and II is not Numerous cystic spaces in the media containing
different. basophilic ground substance.
Type B (Distal dissection): Limited to descending aorta Fragmentation of the elastic tissue.
and sparing the ascending aorta; it corresponds to Increased fibrosis of the media.
Systemic Pathology
DeBakey type III.
EFFECTS. The classical clinical manifestation of a dissecting
aneurysm is excruciating tearing pain in the chest moving
downwards. The complications arising from dissecting
aneurysms are as under:
1. Rupture. Haemorrhage from rupture of a dissecting
aneurysm in the ascending aorta results in mortality in 90%
of cases. Most often, haemorrhage occurs into the
pericardium; less frequently it may rupture into thoracic
cavity, abdominal cavity or retroperitoneum.
2. Cardiac disease. Involvement of the aortic valve results
in aortic incompetence. Obstruction of coronaries results in
ischaemia causing fatal myocardial infarction. Rarely,
dissecting aneurysm may extend into the cardiac chamber.
Figure 15.18 Two classification schemes of thoracic aortic
dissection: Stanford and DeBakey. Stanford type A involving ascending 3. Ischaemia. Obstruction of the branches of aorta by
aorta only includes DeBakey’s type I (involving ascending aorta and dissection results in ischaemia of the tissue supplied. Thus,
extending into descending aorta as well) and II (limited to ascending there may be renal infarction, cerebral ischaemia and
aorta only), while Stanford type B is limited to descending aorta
corresponds to DeBakey type III. infarction of the spinal cord.