Andersons pediatric cardiology 1109

FIG 42.3 Idealized arrangement of the pulmonary valvar leaflets as seen from the arterial aspect The free edge of each leaflet is longer than the cord of the sinus supporting it, permitting the leaflets to close snugly along their zones of apposition (arrows) The zones of apposition are attached peripherally at the sinutubular junction (stars), with these areas described as the valvar commissures When closed, they meet at the valvar centroid (red circle) Fusion of the adjacent leaflets along their zones of apposition is the essence of valvar stenosis The fusion is typically uniform, so that the valvar orifice is narrowed to a central opening The more the fusion extends toward the center of the valve, the narrower will be the central opening and the more severe will be the valvar stenosis When the stenosis is mild to moderate, the opening will have a triangular configuration (Fig 42.4) FIG 42.4 This moderately stenotic valve is shown with the pulmonary trunk removed, permitting the specimen to be photographed from the arterial aspect The zones of apposition of the leaflets are fused from their peripheral attachments (stars) toward the centroid of the valvar orifice (arrows) This produces a narrowed central orifice Note the tethering of the leaflets at the sinutubular junction In contrast, in the most severe forms of stenosis, which produce the typical critical arrangement seen in neonates, the extent of fusion is sufficient to leave only a central pin-sized opening In this so-called domed stenosis, the central part of the cupola tends to be smooth, with evidence of the fused zones of apposition seen to varying degrees as peripheral raphes, with tethering at the sinutubular junction (Fig 42.5) FIG 42.5 In this critically stenotic valve, the valvar cupola is smooth, with evidence of the fused zones of apposition seen only at the margins of the valve Opening the critically stenotic valve shows that, because of the obliteration of the zones of apposition between the leaflets, the extent of their semilunar hinging is reduced Because of this, their line of attachment within the pulmonary root has a more circular configuration (Fig 42.6) FIG 42.6 Left, View of a critically stenotic valve as seen from the arterial