In the current issue of the Journal, the group based at the Narayana Institute of Cardiac Sciences in Bengalaru, India, describe their recent experiences in treating patients with aortic atresia in the setting of deficient ventricular septation. ^{Reference Prabhu, Maiya and Kasturi1} They suggest that such patients can mimic the much more common group of patients having a common arterial trunk. This may well be true in terms of clinical presentation. In morphological terms, however, it is questionable as to whether there is now any excuse for failing to distinguish between a common arterial trunk and the arrangement where the pulmonary trunk provides the solitary pathway for vascular egress from the ventricular mass when the aortic root is atretic. The group practising in Bengalaru were confronted by three patients in which the situation produced a diagnostic conundrum. ^{Reference Prabhu, Maiya and Kasturi1} They explain how, in two of their cases subsequently accepted for surgical correction, the initial diagnosis had, indeed, been presence of a common arterial trunk. Part of the diagnosis, furthermore, was that the coronary arteries were arising anomalously from the brachiocephalic trunk. This diagnosis, allegedly, had been “confirmed” by examination of three-dimensional computed tomographic datasets. After consultation with further colleagues, they realised that the correct diagnosis was the presence of aortic atresia in the setting of deficient ventricular septation. Both patients had well-formed left ventricles and mitral valves. The initial mistake, of course, was to interpret the hypoplastic extrapericardial aorta, which was feeding the coronary arteries in retrograde fashion, as an anomalous coronary artery arising from a brachiocephalic vessel. Those who initially offered this diagnosis in Bengalaru are not the first to have made this egregious error. The authors cite a recent example published in the Journal in which the same inappropriate diagnosis had been made. ^{Reference Li, Li and Chen2} They also cite the letter to the Editor in which I pointed out the mistake. ^{Reference Anderson3} The question must be posed, therefore, as to why, in the current era, when availability of the three-dimensional computed datasets provides images that demonstrate the anatomy in just as much detail as the pathologist who holds the heart in his or her hands, investigators continue to make such a fundamental mistake.

Some of the problems, without question, reflect our ongoing inability to agree on the terms we use to describe the anatomical and clinical findings. As is discussed by the authors from Bengalaru, ^{Reference Prabhu, Maiya and Kasturi1} significant advances have been made in this regard. They explain how initial proposals, made by the Congenital Heart Surgery Nomenclature and Database Project, ^{Reference Tchervenkov, Jacobs and Tahta4} have now been overtaken by the definitions provided by the International Nomenclature Committee. The latter terms are now enshrined in the eleventh iteration of the International Classification of Diseases provided by the World Health Organization. ^{Reference Franklin, Béland and Colan5} The Bengalaru team failed to explain that the codes now adopted by the World Health Organization emerged because of the need to meld the terms produced by the Congenital Heart Surgeons with an alternative system that had been proposed, at more-or-less the same time, by the Association for European Paediatric Cardiology. ^{Reference Franklin6} In the approach taken by the European group, lesions such as aortic atresia had not been “wrapped up” in larger groupings such as “hypoplastic left heart syndrome.” Instead, the Europeans had adopted a system in which the individual lesions could be coded separately. In this way, they could be recognised when found in less familiar combinations. As is indicated by the Bengalaru authors, ^{Reference Prabhu, Maiya and Kasturi1} the Congenital Heart Surgeons had included aortic atresia as part of the hypoplastic left heart syndrome, even when found in association with a ventricular septal defect. The essence of the hypoplastic left heart syndrome, of course, is hypoplasia of the morphologically left ventricle. As in the two cases successfully treated at the Narayana Institute, ^{Reference Prabhu, Maiya and Kasturi1} the major feature of the patients presenting with aortic atresia in the setting of deficient ventricular septation is that the left ventricle can be of sufficient size to permit biventricular repair,

Problems still exist, therefore, not only with the approach to aortic atresia but also in the definitions currently offered for the hypoplastic left heart syndrome. The Bengalaru team specifically cite the definition offered for the syndrome by the International Committee, namely “a spectrum of congenital cardiovascular malformations with normally aligned great arteries without a common atrioventricular junction, characterised 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.” ^{Reference Franklin, Béland and Colan5} This is a very poor definition. In the first instance, it uses the term “normally aligned great arteries.” Does this mean that the arterial trunks are simply normally related? If so, it would not exclude the occasions in which such normally related arterial trunks are found when both are taking their origin from the morphologically right ventricle. Or does it mean that the arterial trunks take their origin from morphologically appropriate ventricles? If the latter interpretation is intended, which seems likely, then it is much more preferable to describe the arrangement as indicating the presence of concordant ventriculo-arterial connections. More significantly, the current definition fails to take note of the integrity of the ventricular septum. And this is the key feature when there is aortic atresia. The team from Bengalaru argue, with justification, that when aortic atresia is found with deficient ventricular septation, it should not be considered as part of the hypoplastic left heart syndrome. ^{Reference Prabhu, Maiya and Kasturi1} Their justification for making this statement was the fact that patients with this combination can be treated surgically so as to restore biventricular circulations. At the same time, they recognised that those producing the definitions in the International Committee have argued that morphological terms should not be based on functional criteria. But there is a much better reason for excluding individuals with deficient ventricular septation from the syndrome. This is because all the morphological evidence points to the changes in the spectrum of malformations making up the syndrome as representing an acquired disease of fetal life. ^{Reference Anderson, Spicer and Crucean7} The inference can be made that the changes found when the ventricular septum is intact reflect an insult occurring during embryonic development subsequent to closure of the interventricular foramen. By the same token, the presence of an interventricular communication implies that the insult causing the left ventricle to become hypoplastic must have occurred prior to closure of the embryonic interventricular foramen. At all events, I agree with the Bengalaru authors that cases of aortic atresia co-existing with a ventricular septal defect should not be included as part of the hypoplastic left heart syndrome. The same arguments apply when mitral atresia is found in the setting of deficient ventricular septation. ^{Reference Anderson, Spicer and Crucean7}

But what of the relationship with common arterial trunk? It is of note that those suggesting that the coronary arteries can arise from the brachiocephalic trunk all indicate that this combination is found in association with “truncus arteriosus.” Problems still exist, however, with the definition of the “truncus arteriosus,” just as they do with identification of the embryonic “truncus.” ^{Reference Anderson, Lamers and Hikspoors8} It is much better simply to describe the lesions grouped together because of the presence of a common ventriculo-arterial junction as common arterial trunks. ^{Reference Russell, Jacobs and Anderson9} And attention to the definition offered by the International Committee for this lesion indicates why there is now no good reason to confuse the entity with aortic atresia, even in the setting of deficient ventricular septation. Thus, the International Committee defines a common arterial trunk as one in which “a single arterial trunk arises from the heart, giving origin sequentially to the coronary arteries, one or more pulmonary arteries, and the systemic arterial circulation.” ^{Reference Franklin, Béland and Colan5} Attention to this definition shows that the trunk in question cannot be common when the coronary arteries are arising from a brachiocephalic artery, since such an origin would no longer be sequential. And in the setting of the hypoplastic intrapericardial aorta, the trunk in question is no longer “single.” It is simply a mistake to consider an arterial channel supplying the entirety of the coronary arterial supply from the aortic arch to be anything other than a grossly hypoplastic aorta. Recognition of this feature immediately points the investigator to the presence of aortic atresia. The authors from Bengalaru suggest that a single coronary artery arising from the brachiocephalic trunk is “exceedingly rare.” On the contrary, to the best of my knowledge such an entity does not exist. All cases described in this fashion thus far have been no more than reflections of an incorrect diagnosis of common arterial trunk, with the investigators alleging that the coronary arteries are fed in retrograde fashion from the aortic arch. There are three reported cases of which I am aware, however, in which the left coronary artery was, indeed, found arising from the brachiocephalic trunk. In each instance, nonetheless, the right coronary artery was arising from the normally positioned aortic root. ^{Reference Santucci, Bredikis, Kavinsky and Klein10–Reference Kim, Choi and Lee12} There are then further problems with the account offered by the Bengalaru team. They suggest that their references 12 through 20 provide accounts of the situation in which “others have misdiagnosed this entity as common arterial trunk.” This is not true. As far as I can ascertain, these accounts all provide descriptions of surgical repair for patients correctly diagnosed as having aortic atresia in association with a ventricular septal defect.

Despite my criticisms, the major point made by the Indian authors retains its validity. No longer should patients having the coronary arteries supplied in retrograde fashion by a hypoplastic ascending aorta be diagnosed as demonstrating common arterial trunk with coronary arterial origin from the aortic arch. This is a fundamental mistake. It should not be made in the current era.