Revisiting the anatomy of the right ventricle in the light of knowledge of its development

Abstract

Controversies continue regarding several aspects of the anatomy of the morphologically right ventricle. There is disagreement as to whether the ventricle should be assessed in bipartite or tripartite fashion, and the number of leaflets to be found in the tricuspid valve. In particular, there is no agreement as to whether a muscular outlet septum is present in the normally constructed heart, nor how many septal components are to be found during normal development. Resolving these issues is of potential significance to those investigating and treating children with congenitally malformed hearts. With all these issues in mind, we have revisited our own experience in investigating the development and morphology of the normal right ventricle. To assess development, we have examined a large number of datasets, prepared by both standard and episcopic microscopy, from human and murine embryos. In terms of gross anatomy, we have compared dissections of normal autopsied hearts with virtual dissections of datasets prepared using computed tomography. Our developmental and postnatal studies, taken together, confirm that the ventricle is best assessed in tripartite fashion, with the three parts representing its inlet, apical trabecular, and outlet components. The ventricular septum, however, has only muscular and membranous components. The muscular part incorporates a small component derived from the muscularised fused proximal outflow cushions, but this part cannot be distinguished from the much larger part that is incorporated within the free‐standing muscular infundibular sleeve. We confirm that the tricuspid valve itself has three components, which are located inferiorly, septally, and antero‐superiorly.

Revisiting the anatomy of the left ventricle in the light of knowledge of its development

“…Our purpose in producing our review was to provide a counterpart to our similar recent assessment of the morphologically right ventricle (Crucean et al., 2023 ). In so doing, we have concentrated exclusively on the anatomical changes taking place during development.…”

“…As we emphasised when describing the development of the right ventricle (Crucean et al, 2023), the relevance of interpretations depends very much on the quality of the material available for study.…”

“…As we emphasised when describing the development of the right ventricle (Crucean et al., 2023 ), the relevance of interpretations depends very much on the quality of the material available for study. We have again based our interpretations on the examination of datasets from human hearts prepared using the three‐dimensional technique of high‐resolution episcopic microscopy (Mohun & Weninger, 2011 ).…”

“…This is because the heart continues to be described as removed from the body and positioned on its apex rather than in an attitudinally appropriate fashion (Cook & Anderson, 2002). In a recent review of the anatomy of the right ventricle (Crucean et al, 2023), we showed how knowledge of cardiac development can now provide insights into the postnatal arrangement of the ventricular components. In this review, we show that a comparable situation is to be found when seeking to understand the nuances of left ventricular anatomy.…”