Pulmonary stenosis and aortic stenosis

Any one of the heart's valves may suffer from narrowing (or stenosis). This narrowing, which can occur at, above or below the valve, can block blood flow.

In pulmonary stenosis, the area around the pulmonary valve can become blocked or the blood vessel beyond the valve can become narrowed, causing the right ventricle to have to pump harder to get blood past the blockage to the pulmonary artery. If the stenosis is severe, there will be a lack of blood flow to the lungs and the baby can become cyanotic. The condition requires treatment when the pressure in the right ventricle is high.

In aortic stenosis, the aortic valve also can become narrowed, requiring the left ventricle to pump harder to get blood past the blockage to the aorta and out to the body. The normal aortic valve has three cusps or leaflets and is described as tricuspid. In contrast, a stenotic aortic valve may have only two cusps (bicuspid) or even one cusp (unicuspid). The cusps in a stenotic valve are usually thick and stiff.

One treatment for stenosis is to insert a special catheter containing a balloon through the valve. The balloon is then inflated, stretching the valve open. This procedure is known as a balloon valvuloplasty and is performed during a cardiac catheterization (a procedure that is discussed in the following chapter). In most children, a valvuloplasty may be sufficient to alleviate the stenosis. In other children, surgery may be needed.

Diagram 2.11 Pulmonary stenosis (valvular) 1 - narrowed pulmonary valve Blood flow patterns are normal but blood flow through the pulmonary artery is reduced as indicated by the broken white arrows.

Diagram 2.12 Aortic stenosis (valvular) 1 - narrowed aortic valve Flow patterns are normal but blood flow to the aorta is reduced as indicated by the broken white arrows.