The membranous portion of the interventricular septum in neonates An anatomic study in neonatal cadavers

Abstract

The membranous portion of the interventricular septum (MPIS) has been described as a small, oval portion of the cardiac septum that lies immediately below the aortic valve. Its location and relationship with the aortic valve are very important in surgical interventions. Several studies have been reported in adults but few in neonates. For this reason, studies of the MPIS were made in the hearts of 26 (12 male, 14 female) fulterm neonates. The left side of the MPIS was photographed with transillumination from the right ventricle. The shapes of the septum were assessed from the photographic images. In addition, in accordance with the ruler in the photographs a millimetric scale was prepared on the tracing paper and the surface area of the MPIS and its distance from the superior border of the aortic valve were measured. In these 26 cases, the following shapes of MPIS were found: semilunar, 7 (26.92%); triangular, 6 (23.07%); quadrangular, 5 (19.23%); oval, 4 (15.38%); circular, 2 (7.69%); irregular, 2 (7.69%). Its surface area varied from 2-21 mm2 (mean 5.84 mm2). The superior border of MPIS was in close relationship with the aortic valve. In 10 cases (38.46%) the MPIS was in direct continuity with the attachments of both the right and posterior aortic cusps, in 8 (30.76%) only with the posterior aortic cusp, in 5 (19.23%) only with the right aortic cusp, while in 3 (11.53%) the superior border of MPIS was below the attached portion of both cusps. The distance between the superior border of the MPIS and the attachment of the right or posterior aortic cusps did not exceed 3.5 mm. There were no statistically significant sex-related differences in shape, surface area and relationship with the aortic valve.

The Ciliary Protein Ftm Is Required for Ventricular Wall and Septal Development

“…The most prevalent VSD subtype is the perimembranous VSD [5], [6] which is characterized by the loss of the membranous part of the ventricular septum (VS) and a defect in the development of a second part of the VS - the muscular septum. Interestingly, the membranous VS does not start to grow before the muscular VS generation has been finished [7] indicating that membranous VS development is probably initiated by an interaction of the inlet muscular VS and the atrioventricular endocardial cushion cells (ECCs) [8], [9]. The membranous VS arises solely from the ECCs and not from the muscular VS [4].…”

Cyp26b1 restrains murine heart valve growth during development

“…The muscular VS grows first, followed by the membranous VS. The membranous VS arises due to interactions between the muscular VS and the AV endocardial cushion cells (Icten and Tetik, 1996). Studies have shown that the membranous VS is derived from the AV endocardial cushion lineage, and that proper morphogenesis of the OFT cushions is required for proper alignment and movement of the AV cushions (Komatsu et al, 2007).…”

Interventricular membranous septal aneurysm: CT and MR manifestations

“…The fibrous portion of the IVMS closes 3 weeks later. Finally, the fused aortopulmonary septum and the fused atrioventricular cushions assemble the muscular portion of the interventricular septum [ 8 , 9 ].…”