An appreciation of the structural variability in the components of the ventricular outlets in congenitally malformed hearts

The morphology of the outlet septum, the ventriculo-infundibular fold, the infundibulum and the septomarginal trabeculation has been well described. These structures are closely interrelated, such that variations in the morphology and orientation of any one of them inevitably affect the morphology and orientation of the others. In this review, we seek to clarify how these normal relationships change within the setting of congenitally malformed hearts. This is of immense surgical significance, since the surgical correction of many congenital cardiac malformations involves procedures on, or in the vicinity of, these structures. We provide an insight into how the appearance of the components of the ventricular outlets can vary with the underlying pathology. We first define the relevant structures and describe how their location can vary in different malformations. We will then describe how the variations in that interrelationship may result in malalignment and deviation of the outlet septum, emphasising the surgical implications of these specific features.