The Ross procedure is generally performed in young patients (under the age of 60 years). In Western Society, the most common cause or aetiology for aortic valve disease in this age group is congenital bicuspid aortic valve, which affects approximately 2% of the population. The affected person is born with a two-cusp valve, or more commonly, is born with the usual three cusps, however two are fused from intra-uterine life. Either way, a bicuspid valve carries more than the usual workload and tends to degenerate prematurely with either obstruction or progressive leakage, thus requiring replacement earlier in life. An example of a congenitally bicuspid valve can be seen in Figure 3. A small minority of patients with this congenital abnormality, have in fact only one cusp (monocuspid valve).

The next most common aetiology seen is the post-rheumatic valve (seen in Figure 4). In this condition, patients born with a normal tricuspid aortic valve, develop rheumatic fever in childhood or early adulthood, and this causes pathological changes to occur in the valve with the leaflets thickening and retracting, usually causing mild to moderate obstruction, and progressively severe leakage.

Other aortic valve disease states that may lead to the patients needing aortic valve replacement include degenerative causes, damage secondary to infection, as well as degeneration of a previously inserted prosthesis, either mechanical or tissue.

Some disease states that affect the aortic valve, are not suitable for the Ross procedure. These include Marfan’s syndrome, connective tissue diseases, and other aortic root aneurysm pathologies.