Editorial Comment: Arterial switch, Reparation a l'etage ventriculaire, Rastelli or Nikaidoh?

Abstract

Honjo and co-workers, from the Toronto group, proposed an anatomical complexity score of the left ventricular outflow tract obstruction (LVOTO) to help in choosing between a variety of surgical corrections in face of dextro-transposition of the great arteries (d-TGA) and LVOTO [1]. The decision on the best repair in the presented series of 28 patients was actually made in a standard fashion— with preoperative and intraoperative assessments—and the results were simply fantastic, apparently with no error of judgement. The proposed echocardiographically-derived scoring system was applied retrospectively and was subsequently correlated to the surgical procedure chosen. Not surprisingly, a correlation between the echocardiographic findings and the surgical option applied was found and coefficients of obstruction were further set. Will this new scoring system truly help us? We are not sure. The critical decision in this group of patients is mostly whether an arterial switch operation (ASO), with opening of the outflow tract, can still be achieved instead of an ‘intracardiac repair’, like the ‘Reparation a l’etage ventriculaire’ (REV), Rastelli or Nikaidoh procedures. The choice between these operations or a single ventricle pathway will continue to be guided by an ’eyeballing’ of the LVOT in echocardiographic views and will ultimately be influenced by intraoperative findings, as acknowledged by the surgical results of this study [2–4]. The preoperative echocardiography (with or without an obstruction scoring system) gives a clue—often a strong one—as to the possible options. Its value is certainly the clear definition of the multiple components of the obstruction, but a surgeon needs more than a crude anatomy to definitively plan his operation. He needs information on the resectability of these components, something that often appears only during surgery. A straddling papillary muscle will get a low obstructive score but will cause more trouble than an extensive tissue tag formation or a bulging conal septum. The two opposing philosophies in the repair of TGA-LVOTO relate to the choice of the second-best option after the ASO, namely either the REV/Rastelli procedure or the Nikaidoh procedure and its variant ‘the double root rotation’ [2–5]. Strong proponents of the Nikaidoh procedure, such as the Toronto group, do not really need a scoring system for the obstructive components as, per definition, they will reposition the aortic root beneath them. As a matter of fact, the decision between the two procedures in the presented study was not influenced by the obstructive components, but by the pattern of the coronary arteries alone. Strong proponents of the REV/Rastelli procedure consider that the relief of the obstructive components can be achieved in virtually all patients with an operation performed at the right time. To them, the Nikaidoh procedure is indicated mostly in cases of a restrictive ventricular septal defect, of a small right ventricle or when the whole ‘double root’ can be rotated, and the scoring system will merely remain an academic tool [5]. In their experience, the gap of the mitro-aortic discontinuity correlates more with the magnitude of the intracardiac repair (to ensure a wide open left outflow tract) than with the pattern of the obstructing components [6]. In this controversy, only surgeons undecided between these two schools of thought might take an interest in the scoring system [7]. Still, the scoring system is a valuable new tool, mostly in cases where it can identify these patients with a potential complete or partial function of the pulmonary valve. As for any scoring system established retrospectively, it must now be validated prospectively and further fine-tuned—especially in respect of the characteristics of the sub-pulmonary area and the pulmonary root and leaflets— because this is the component of the proposed complexity score that will reveal the patients for whom a successful ASO is still possible or on whom a ‘double root rotation’ can be performed [5].