Discussion

This case highlights the difficulty in both diagnosing and naming these rare variants of complex congenital heart disease.Reference Bravo-Valenzuela, Carrilho, Peixoto, Bezerra and Araujo Júnior¹ In addition, we describe the pitfalls in prenatal diagnosis, which was difficult due to the severe tortuosity of the pulmonary arteries. Finally, finding an accurate, complete, and non-ambiguous description for this arrangement of arterial trunks has been challenging using almost any method of nomenclature.

Initially, this conotruncal anomaly was thought to be embryologically impossible.Reference Vanmierop and Wiglesworth² However, in 1971, Van Praagh et al. described four patients with D-transposition of the great arteries with near normal appearing external positioning.Reference Van Praagh, Perez-Trevino and Lõpez-Cuellar³ They challenged the previous notions of conotruncal development in transposition and the definition of the term “transposition” itself.

Instead, they proposed the term “malposition” to describe all abnormal conotruncal relationships except when the aorta arises from the morphologic right ventricle and the pulmonary artery arises from the morphologic left ventricle in, otherwise, normal situs, true “transposition.” Two of the cases had two ventricles with ventriculoarterial concordance but malposition of the great arteries (levocardia with {S, D, L} and dextrocardia with {I, L, D}). These cases expounded upon the Van Praagh precedent and argued that “the term anatomically corrected malposition” describes not a discrete anomaly but only a ventriculo-arterial relation, which is one of ventricular-arterial concordances.Reference Van Praagh, Perez-Trevino and Lõpez-Cuellar³

In the current literature, anatomically corrected malposition describes concordant atrioventricular and ventriculoarterial connections where flow pathways through the heart are as expected but the arrangement of the arterial trunks – relative to each other – is not oriented in their anticipated manner.Reference Gupta, Ramakrishnan and Gulati⁴ This definition encompasses our patient’s anatomy; however, the nomenclature anatomically corrected malposition alone does not convey a complete description of the arterial trunk arrangement.

One of the characteristics that makes our case interesting is the presence of aortic-mitral continuity and the lack of subaortic conus, which, for some anatomists, would disqualify this anatomy from the definition of “anatomically corrected malposition.”Reference Kirklin, Pacifico, Bargeronjr and Soto⁵ The aortic mitral continuity seen in this case has been described previously by Cavalle et al. in several of their series of eight patients, and they argued that this should not disqualify them from this designation.Reference Cavalle-Garrido, Bernasconi, Perrin and Anderson⁶ Also, the absence of bilateral infundibulums does not disqualify the case as anatomically corrected malposition as it has also been discussed in previous publications.Reference Gupta, Ramakrishnan and Gulati⁴ In a schema proposed by Foran et al., our patient’s anatomy most closely fits with what they described as isolated infundibuloarterial discordance;Reference Foran, Belcourt and Nanton⁷ however, it can be a confusing descriptor for those unfamiliar with the article. Using a segmental sequential analysis, we can describe our aortic valve as being posterior and leftward of the pulmonary valve, Reference Bernasconi, Cavalle-Garrido, Perrin and Anderson⁸ with an “aortic arch” that is oriented horizontally in the transverse body plane.

Our case is also unusual in the clinical presentation and highlights the broad array of anatomic possibilities, illustrating the difficulty of prenatal diagnosis and range of postnatal complications.

Our patient’s moderately hypoplastic pulmonary arteries with such tortuosity are unusual and made prenatal diagnosis extraordinarily difficult. Fortunately, postnatal echocardiography was able to elucidate patent pulmonary arteries supplying pulmonary blood flow. Unfortunately, the degree of respiratory distress experienced by our patient is also unusual. Vascular compression from the low-lying, horizontal, and dilated transverse arch caused such significant obstruction, resulting in significant bronchopulmonary dysplasia necessitating tracheostomy, a complication not previously described in the literature. This case and cases like it highlight the difficulty in prenatal echocardiography, and how conotruncal anomalies can lead to complicated post-operative courses.