Aortic stenosis is the main reason for removing the aortic valve .

This functional entity has only three common causes which can be determined by macroscopic examination in most cases :

1. Degeneration calcification of tricuspid valve : 2. Calcification of congenital bicuspid valves : 3. Post inflammatory disease.

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Calcified bicuspid valves and post inflammatory valves tend to occur in patients less than 70 years. Degenerative calcification predominates in the older age groups.

 In Egypt, South America and India, rheumatic aortic stenosis remains common.

Congenital Aortic Atresia:

This is a rare entity. Atresia of the valve may take the form of an imperforate membrane or it can be due to muscular or fibromuscular obliteration of the orifice.

Both supravalvar and subvalvar stenosis may also occur.

Unicuspid and Unicommissural Valvar Stenosis:

This stenosis is characterized by a keyhole-shaped eccentric orifice in which a single leaflet takes origin from the aortic wall and swings around to insert close to its point of departure.

Two raphes can often be recognized, suggesting that the lesion results from failure of formation of two of the commissures of tricommissural valve.

Bicuspid Aortic Valve:

Degenerative changes:

Most of these valves are excised from patients aged 65 years and older. This valve is characterised by the following features, trileaflet morphology, absent commissural fusion and nodular calcific deposits in two or three cusps .

Commissural fusion is minimal or absent and the valvular orifice assumes a triangular shape with inward bowling.

These features serve to differentiate the degenerative form of aortic valve disease from other causes, particularly post-inflammatory cases.

Rheumatic:

Stenotic aortic valves of rheumatic origin are characterised by fusion of at least one and usually two or three commissures with fibrous thickening of the valve leaflet.

The classic stenotic aortic valve of rheumatic origin has extensive fusion of all three commissures producing a central triangular orifice.

Secondary calcification often develops on the aortic and ventricular aspects and may further hinder cusp motion.

Post Inflammatory Disease:

The post inflammatory form of aortic valve disease is a chronic non-infectious fibrosing process that produces valvular distortions indistinguishable from those in confirmed cases of chronic rheumatic valvulitis.

Such valves should not however be labelled as rheumatic unless there is a clinical history of previous acute rheumatic fever, because it is possible that non-rheumatic disorders such as ankylosing spondylitis, rheumatoid arthritis, psoriatic arthritis, Reiter's syndrome, SLE or possibly even viral infection may produce similar lesion.

Aortic Regurgitation: