Cardiac Path Online
Pathology of Aortic Regurgitation
regurgitation is much less common than stenosis but has far more
The various aetiologies of pure aortic regurgitation can be sub-grouped into those conditions primarily affecting the aortic valve cusps or primarily affecting the aorta and those conditions affecting both:
1.Valve : Congenital ; Floppy ; Endocarditis ; Trauma ;
2. Valve and aorta : Syphilis ; Rheumatoid arthritis ; Systemic lupus Erythematosus ; Ankylosing spondylitis ; Marfan syndrome.
3. Aorta : Dilatation ; Dissection ; Marfan syndrome.
The most common causes of aortic insufficiency are : Aortic root dilatation ; Rheumatic /post-inflammatory disease ; Infective endocarditis.
|Aortic Root Dilatation:
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 years 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.
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.
The leaflets have a perforated or indented appearance with vegetations or combinations of these changes.
This can occur on previously damaged valves (bicuspid, rheumatic) or the valve can be normal.
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