LAUSR

Zakaria and colleagues recently reported surgical outcomes for developmental syndromes associated with hypoplastic left heart syndrome (HLHS) [1]. We were surprised to see Down and DiGeorge syndromes associated with HLHS as the literature does not support this association [2–4]. A HLHS review at our own center, which provides fetal medicine and pediatric cardiology to North-East England, also revealed no cases of Down or DiGeorge syndrome over 16 years. In contrast, Turner syndrome, although predominantly associated with bicuspid aortic valve and aortopathy [5], is associated with HLHS. In up to 10% of cases, there is stenosis or atresia of the aortic and mitral valves, thickened ventricle, and endocardial fibroelastosis [6]. We therefore wonder if Zakaria’s manuscript actually reports the outcome of initial palliative surgeries for a wider range of physiologically single ventricle conditions. For example, relative hypoplasia of the left ventricle is well recognized in Down syndrome in the setting of complete atrioventricular septal defect (AVSD) which might be managed via a single ventricle approach [7]. The intercollegiate committee for nomenclature definition of HLHS [8] has since become incorporated within ICD11 as "A spectrum of congenital cardiovascular malformations with normally aligned great arteries without a common atrioventricular junction, characterized by underdevelopment of the left heart with significant hypoplasia of the left ventricle including atresia, stenosis, or hypoplasia of the aortic or mitral valve, or both valves, and hypoplasia of the ascending aorta and aortic arch" [9]. It specifically describes relative hypoplasia of the left ventricle with accompanying major malformations, such as unbalanced AVSD, double outlet right ventricle (DORV) and transposition of the great arteries, as distinct from HLHS. From our recent evaluation of an archival specimen series [10], we suggested an alternative anatomical classification in HLHS based on anatomical appearances and measurements of the left ventricle, rather than apparent stenosis or atresia of the aortic and mitral valves. The importance of this classification in the etiology and natural history of HLHS, and ventricular hypoplasia seen in conditions such as AVSD and DORV, is the subject of current research, but clearly grouping all such lesions together as HLHS creates confusion. We suggest that descriptions of HLHS and other lesions with left ventricular hypoplasia should be properly described within manuscripts using the segmental sequential methods developed by van Prague and Anderson almost 40 years ago [11, 12], and classifications such as ICD11 [9]. The description of actual anatomy will allow evaluation of findings within emerging developmentally relevant classifications.