Morphological and topographical variations of the outlet chamber in complex congenital heart disease: an...

The outlet chamber of the human heart can show considerable variations in its morphology and topography (relationship to main ventricular chamber), and such variations in anatomy and spacial relationship may be predictive of the associated intracardiac anatomy. Although there is considerable debate about whether the position of the outlet chamber is indicative of the type of bulboventricular loop (whether D- or L-), a right-sided and anterior outlet chamber has different implications than a left-sided, superior, and more posterior positioned one. The inflows into the outlet chamber can vary anatomically, and progressive changes in the calibers of these communications can adversely alter the natural history. One or both of the greak vessels, or neither, or a persistent truncus arteriosus can originate from the outlet chamber, and any significant morphological change in the outlet chamber may or may not adversely affect either the pulmonary or systemic blood supply, or both. Finally, any consideration of the outlet chamber raises important conceptual difference in terminologies. At present, there is not unanimity as to what constitutes either an outlet chamber (as compared to a "small right ventricle" in tricuspid atresia) or a single (primitive) ventricle. Any discussion of the morphological and topographical variations of the outlet chamber must be viewed with respect to the terminology employed.