Comment
The initial diagnosis was given as “false Taussig Bing” malformation on fetal echo examination as a shorthand; we had been aware that the term is often confusing 2. The pattern of blood streaming on ventriculography also deceived us. We should have been super-cautious about the intracardiac morphology. Retrospectively, the 3-dimensional CT had been informative enough to recognize the variation of DORV. [Figure 2] At the preoperative stage, right aortic arch gathered more attention of the surgeons; whether any technical pitfalls were hidden. The arterial switch is relatively rare in such a circumstance 3. Fortunately, it did not turn out to be an issue.
Having admitted that the preoperative diagnosis could have been more precise, what would have been the alternative strategy? Initial banding of the pulmonary trunk would have been less invasive and provided broad strategical choices in the future. An immediate downside of the palliation would be considerable arterial desaturation persisting because of transposition physiology.
This streaming issue would be much less when banding is carried out concomitantly with the arterial switch maneuver. Oxygenated blood would mainly flow to the neo-aorta, providing a pinker circulation. When the patient became older beyond early infancy, intraventricular rerouting could be less demanding. A RV incision is dispensable at the neonatal stage.
The Réparation à l’Etage Ventriculaire (REV) procedure is an alternative, rerouting the LV to both semilunar valves4. The outlet septum was missing; therefore, nothing to resect. VSD enlargement is anatomically limited; better not to penetrate the ventriculo-infundibular fold. A downside of the REV procedure would be pulmonary regurgitation in the longer terms. Pulmonary valve replacement will not be straightforward because of the geometry around.
An intraventricular tunnel becomes long and tortuous in DORV with a non-committed VSD 5,6 when biventricularly repaired. Even for the REV procedure, the baffle design is compromised because of the presence of the tricuspid valve and its tension apparatus. As described by Belli et al. 7, the intraventricular tunnel becomes straighter and shorter by switching the great arteries. Still, the tricuspid valve interferes in accommodating a baffle. The septal leaflet would most likely adheres to the baffle, eventually causing tricuspid regurgitation. Thus, the Fontan type procedure remains as a definitive correction of the cyanotic circulation. Using the ventricles as a solitary chamber, the ventricular outlet is not compromised with a baffle. The tricuspid valve remains intact. Downside of this strategy is, of course, the unique circulation itself. It causes certain impediments in the longer terms. Heart failure and Fontan-associated liver disease are among current topics of concern. Biventricular physiology, if achievable, is preferred in this respect.
It is uncommon to repair of DORV of a non-committed VSD type during a neonatal period. We have come across only one case reported in literature 8. Although the doubly-committed VSD type has a morphological spectrum 1, the combination of DORV with a non-committed VSD type and lack of the outlet septum has not been described in a clinical series to the best of our knowledge. Sequelae could grow in due course. Obstruction across the LV outflow tract and tricuspid regurgitation would be related to the intraventricular baffle. Neonatal ventricular incision could consequently cause ventricular dysfunction or ventricular arrhythmia. Function of the semilunar valves might deteriorate eventually, despite the baffle was meticulously fixed there.
After all, what could we have done better? No definitive answer. As far as the results in the immediate postoperative term is concerned, our neonatal repair was not unreasonable. Should we take a similar approach in an identical case? Yes, although a rare form of DORV is to be preoperatively recognized next time.