| Aortic
Root Dilatation:
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This entity has
become relatively more common. Dilatation of the aorta causes
stretching of the commissures.
Patients under 40
years of age tend to develop aortic root dilatation in association
with Marfan syndrome and other connective tissue disorders with
widespread severe cystic degeneration of the aortic media.
Over the age of
40 the dilatation is associated with age-related medial aortic cystic
degeneration which is usually milder in degree compared to Marfan
syndrome.
Often the valve
leaflets only show rolling and thickening of the edges with no other
pathology.
It is important
to include a piece of aorta for histology in order to establish the
pathology in the aortic wall, either cystic degeneration or aortitis.
Aortitis:
During the early
part of this century, aortitis has been linked with several other
diseases and not just syphilis alone.
These include
giant cell arteritis, ankylosing spondylitis, rheumatoid arthritis,
scleroderma, relapsing polychondritis, Bechet's syndrome, Reiter's
syndrome and systemic lupus erythematosus.
In any form of
aortitis, the inflammation centres around the media and adventitia
especially the vasa vasorum.
With repair, the
cellular infiltrate disappears and the damaged media is replaced by
collagen. Retraction of this collagen results in wrinkling and gives
the classical "tree-barking" appearance to the intima.
Inflammatory
conditions of the aorta can be divided into infectious and
non-infectious.
The infectious
causes include syphilis, tuberculosis, pyogenic and mycotic aortitis
which is often lead to aneurysm formation.
The non
infectious causes include Takayasu's arteritis, giant cell arteritis
and the collagen vascular diseases as mentioned above. In classical
cases of these conditions with positive serology, HLA typing etc, the
diagnosis is easy but in some patients the clinical history is not
staightforward and the cause of the aortitis remains unclassifiable
and these are labelled as idiopathic.
As the aortic
valve is an intimate part of the ascending aorta this is frequently
involved in the inflammatory process with thickening and retraction of
the semilunar cusps leading to aortic regurgitation.
There is usually
a nonspecific chronic inflammatory infiltrate in all these conditions
making them indistinguishable from each other involving the valve.
Rarely, a rheumatic nodule may be seen with rheumatoid arthritis.
Rheumatic/Post Inflammatory
Aortic Valve Disease:
In some patients
fibrosis primarily produces scar retraction of the cusps without
appreciable commisural fusion, thereby resulting in valvular
incompetence.
When
insufficiency occurs, calcification tends to be milder or absent.
Combination of
the above lesions may produce valves that are both stenotic and
regurgitant.
It is unclear why
chronic rheumatic disease produces stenotic commissural fusion in one
patient and regurgitant scarring retraction in another.
Regardless of the
functional state, however, annular dilatation is not a feature of
post-inflammatory valve disease.
Infective Endocarditis:
The leaflets have
a perforated or indented appearance with vegetations or combinations
of these changes. This can occur on previously damaged valves ie,
bicuspid, rheumatic or the valve can be normal.
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