The Subpulmonary Infundibulum in Normal Heart. A Morphologic Study and Embryologic Considerations

A previous morphologic investigation by one of us on the septomarginal trabeculation of 81 normal fetal and neonatal human hearts showed that the outlet compartment of the right ventricle included the root of the supraventricular crest and the left cranial limb of the septomarginal trabeculation, the latter occupying an anterior ventricular septal position.This study showed also that the root of the supraventricular crest was parietally attached to the ventricular septum, a septal surface of this root (infundibular septum) being present only in very few cases.Furthermore, based only on anatomic observations, it was found that the root of the supraventricular crest and the left cranial limb of the septomarginal trabeculation corresponded, on the left ventricular side, to the subaortic right and left coronary leaflet districts respectively.These observations were confirmed very recently by dissections performed on normal pig hearts.This study emphasizes also the free-standing structure and position in normal conditions of the subpulmonary infundibulum, which is essentially the supraventricular crest, due to the interposition of extracavitatary fibro-adipose tissue between the aortic root and the subpulmonary infundibulum itself.In this regard it is emphasized that the pulmonary valve root is mostly supported by the free standing subpulmonary infundibulum, however a small portion of it, corresponding to the left pulmonary valve leaflet, is out of the confines of the subpulmonary infundibulum and in relation to the underlying anterior ventricular septum, representing then the point of anchorage of the pulmonary root to the ventricular septum itself.