International Working Group for Mapping and Coding of Nomenclatures for Paediatric and Congenital Heart Disease It discusses the evolution of nomenclature and surgical treatment for the spectrum of lesions making up the hypoplastic left heart syndrome and related malformations Associated codes for diagnoses and procedures are also presented Van Praagh R, David I, Wright GB, Van Praagh S Large RV plus small LV is not single lv Circulation 1980;61:1057–1058 It was this letter to the editor that identified a crucial flaw in the approach taken by the European school in analyzing patients with allegedly “single ventricles” or “univentricular hearts.” The Bostonians pointed out that it was philosophically unsound to base definitions of a given structure on one of its parts that was variable Instead, they established the crucial principle of the “morphologic method,” stating that the structures must be identified on the basis of their most constant components It was this concept, in turn, which revealed that almost all hearts with a double-inlet ventricle were functionally but not anatomically univentricular Van Praagh R, Ongley PA, Swan HJC Anatomic type of single or common ventricle in man Morphologic and geometric aspects of 60 necropsied cases Am J Cardiol 1964;13:367– 386 This was the investigation that continued the notion, initially put forward by Maude Abbott, that the anterior chamber in the setting of double-inlet left ventricle was no more than an infundibular outlet chamber In this investigation, however, hearts with atrioventricular valvar atresia were excluded from the “univentricular” category, albeit without any scientific reason being offered for their exclusion References Van Praagh R, Ongley PA, Swan HJC Anatomic type of single or common ventricle in man Morphologic and geometric aspects of 60 necropsied cases Am J Cardiol 1964;13:367– 386 Edwards JE Discussion Davila JC 2nd Henry Ford Hospital International Symposium on Cardiac Surgery Appleton Century-Crofts: New York; 1977:242 Deanfield JE, Tommasini G, Anderson RH, Macartney FJ Tricuspid atresia: analysis of coronary artery distribution and ventricular morphology Br Heart J 1982;48:485–492 Anderson RH, Macartney FJ, Tynan M, et al Univentricular atrioventricular connexion – the single ventricle trap unsprung Ped Card 1983;4:273–280 Anderson RH, Becker AE, Tynan M, et al The univentricular atrioventricular connection: getting to the root of a thorny problem Am J Cardiol 1984;54:822–828 Kiraly L, Hubay M, Cook AC, Ho SY, Anderson RH Morphologic features of the uniatrial but biventricular atrioventricular connection J