VALVULAR STENOSIS

Valvar aortic stenosis is a spectrum, with significant valve obstruction treated in infancy or childhood. The other end of the spectrum is mild stenosis or commonly just a bicuspid aortic valve. As aortic stenosis can be progressive, even mild stenosis should be followed regularly until adulthood. Similarly, a bicuspid valve which may remain non-stenotic for decades, only to calcify and develop severe stenosis in the 6th to 7th decade of life. Symptoms of severe stenosis may include angina, labored breathing in response to exertion, or fainting (syncope). Some patients with a bicuspid aortic valve may also develop dilation (enlargement) of the aorta.

For infants, the most common treatment of valvar aortic stenosis is a balloon valvuloplasty, in which the narrowed aortic valve is relieved by the inflation of a balloon. However, this technique is not a permanent fix as the narrowing may return with further growth. Also, the valvuloplasty technique is not very effective in adults whose aortic valve leaflets have become calcified. One limiting factor to the success of balloon valvuloplasty is the careful balance between improving the opening of the valve without over-dilating the valve. Over-dilation of the valve can result in severe insufficiency. Nonetheless, balloon or surgical valvotomy (incision to improve the opening of the valve) always results in some degree of valve insufficiency. Moderate aortic insufficiency, especially if some degree of stenosis persists, is poorly tolerated by the left ventricle and will likely result in aortic valve replacement.

If the balloon valvuloplasty is not feasible, then a surgical valvotomy will often be performed. This involves the surgical widening of the valve opening. In adult patients, however, calcification of the valve may make a valve replacement operation necessary. Even for patients who are treated with the valvotomy only, an aortic valve replacement is ultimately often necessary because of calcification or valve regurgitation.

Valve replacement in older children and adults is usually done with a mechanical prosthetic valve. The a mechanical prosthetic valve may be expected to last for at least 10 years, depending on the age of the patient and the type of valve used, but it will eventually require replacement at some point in the future. A mechanical prosthetic valve requires lifelong anticoagulation to prevent thrombosis of the valve. Other common methods for aortic valve replacement is the Ross procedure. This surgical repair replaces the aortic valve with the patient's own pulmonary valve and then replacing the pulmonary valve with a human donated valve (the Ross repair shown in the animation).

Aortic Valve Stenosis - Subvalvar

In Discrete Subvalvar Aortic Stenosis (DSVAS), a fibrous ridge obstructs the outflow tract from the left ventricle into the aorta. This ridge may gradually become more prominent, leading to significant obstruction. Often, the subvalvular ridge may remain relatively small with only mild obstruction. However, because of its proximity to the aortic valve, it can often result in the development of aortic insufficiency. When aortic insufficiency develops most cardiologists recommend surgical removal of the sub-valvular stenosis in order to halt any further progression of the aortic insufficiency. Most commonly, however, late-developing DSVAS is recognized because of a heart murmur before symptoms are recognized.

Aortic Valve Stenosis - Supravalvar

In this form of aortic stenosis, an hour glass-like narrowing or, less frequently, a more irregular narrowing, exist in the aorta above the aortic valve. Some forms of this defect are associated with Williams Syndrome, a hereditary disorder involving mild mental retardation and a tendency for the development of pulmonary and other arterial stenoses.
Because of the possibility of progressive obstruction, patients with this defect should be closely monitored through life. Also, there may be a tendency for the narrowing of other vessels, such as the renal and coronary arteries, especially in the adult.

In many cases, the subvalvar stenosis is moderate and stable and no surgical treatment is necessary. If the narrowing is more serious, surgery may be performed to widen the aorta

Surgical repair involves removing the obstructing portion and the remaining parts of the aorta are sutured together (see animation at right) or as an alternative for long stenosis, the aorta is patch enlarged.