The independence of the infundibular building blocks in the setting of double-outlet right ventricle

Abstract

It has long been contentious as to whether the presence of bilateral infundibulums, or conuses, is a prerequisite for the diagnosis of double-outlet right ventricle. As the use of such a criterion would abrogate the so-called "morphological method", which correctly states that one variable entity should not be defined on the basis of another entity that is itself variable, it is now accepted that double outlet can exist in the setting of fibrous continuity between the leaflets of the atrioventricular and arterial valves. Although this debate has now been resolved, there are other contentious areas still requiring clarification in the setting of hearts unified because of the presence of this particular ventriculo-arterial connection -for example, it is questionable whether the channel between the ventricles should be described as a "ventricular septal defect", whereas it is equally arguable that the mere presence of fibrous continuity between the leaflets of the arterial valves does not necessarily place the channel in a doubly committed location. In this review, we describe a series of autopsied hearts in which the anatomical features serve to illuminate these various topics. We then discuss recent findings regarding cardiac development that point to the individuality of the building blocks of the ventricular outflow tracts, specifically the outlet septum, the inner heart curvature, or ventriculo-infundibular fold, and the septomarginal trabeculation, or septal band.

Visualising the Cardiovascular System of Embryos of Biomedical Model Organisms with High Resolution Episcopic Microscopy (HREM)

“…In selected cases HREM also permits 3D visualisation of gene expression and gene product patterns and the characterisation of cell distributions in their natural context. Hence, it was already successfully employed in several projects studying normal embryogenesis [60,61,62,63,64,65] and the role genes play in selected human diseases [66,67,68,69,70]. But, most importantly, HREM was introduced for the deciphering the mechanisms of the developmental disorders program (DMDD, ) as a method for screening the morphological phenotype of mouse embryos harvested at embryonic day (E) 14.5.…”

Prenatal diagnosis of double outlet right ventricle with intact ventricular septum in two foetuses

“…4 The exact embryological mechanism of this anomaly is not yet understood, although there is some evidence in support of aetiological factors that are important in the development of a double outlet right ventricle associated with a ventricular septal defect in a genetically modified mouse model. 6 An association with deletion of 22q12 and trisomy 18 has also been reported. 7,11 The very first reported heart with double outlet right ventricle with intact ventricular anomaly was that of a similar anomaly.…”

Double Outlet of Both Ventricles With an Unusual Relationship of the Great Arteries

“…7 The infundibulums are no more than parts of the "building blocks" of the outflow tracts. 8 Double outlet ventricles are now defined as the origin of the greater parts of both arterial roots from the same ventricle, be it morphologically right or morphologically left. 9,10 We now need also to recognize, however, that there is a "halfway house" between these connections.…”