Thorac Cardiovasc Surg 2021; 69(S 02): S93-S117
DOI: 10.1055/s-0041-1725930
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Histological Analysis of Subaortic Obstruction in Neonates with Mitral Stenosis, Coarctation, and Ventricular Septal Defect with Normal Segmental Connections (S-D-S) in Incomplete Shone's Complex without Supramitral Stenosis

M. Sigler
1   Göttingen, Deutschland
,
M. Pringsheim
2   München, Deutschland
,
K. Eildermann
1   Göttingen, Deutschland
,
R. Waldmann-Beushausen
1   Göttingen, Deutschland
,
U. Sauer
2   München, Deutschland
› Author Affiliations

Objectives: The morphological spectrum of Shone's complex is well described. In his original publication, Shone illustrated the protrusion of subaortic muscular tissue (“bulge”) of the left ventricular outflow tract (LVOT) or “subaortic stenosis,” respectively, in all of his eight patients. Yet, it is still unknown why some patients develop subaortic obstruction. Moreover, the developmental origin of this muscular “bulge” is unclear.

Methods: Seven neonatal heart specimens with muscular subaortic obstruction besides mitral valve stenosis, coarctation of the aorta and ventricular septal defect were identified in the anatomical collection of the German Heart Center (1974–1992). Histological analysis was performed in transmural biopsies of the subaortic “bulge” in the superior-anterior LVOT and inferior-posterior septum. Three biopsies of the infundibular septum, malaligned in two cases, and represented as an ALM (Moulaert 1976) in the third with none of the classical characteristics of the Shone complex associated in all three, as well as the biopsy of a distinct “bulge” in the LVOT of one structurally normal heart, served as controls.

Result: The median age at death was 12 days (5–33 days) in the Shone study group, and 40 days (20–45 days) in the controls. All myocardial specimens showed unspecific regressive changes and intercellular fibrosis of varying degree. In addition, the muscular subaortic stenotic “bulge” tissue biopsies from the cases with Shone's complex, and the LVOT “bulge” specimen of the normal neonatal heart demonstrated marked disarray of the cardiomyocytes. By contrast, six of seven inferior–posterior septal specimens and all three infundibular biopsies showed regular arrangement of muscular tissue.

Conclusion: Our results of histological analysis of subaortic obstructive muscular tissue reveal myocardial disarray as opposed to the regular arrangement of cardiomyocytes in three infundibular septum controls. The latter findings confirm that the subaortic “bulge” in cases with Shone's complex are not a displaced infundibular septum, as suspected by others. Further research including embryologic and genetic studies are necessary to elucidate the origin of the muscular subvalvular obstruction in patients with Shone's complex.



Publication History

Article published online:
21 February 2021

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