When faced with the challenging problem of a patient with DORV whose VSD is inherently restrictive, and would thereby be inadequate as the principal outflow from the left ventricle, or in cases of important hypoplasia of an aortic annulus with the consequent inability to perform an adequate valve replacement, the clinician must make a decision as to the candidacy of that heart for a decision between biventricular repair. It has always been our personal and institutional policy to favor a biventricular reconstruction whenever there are two viable ventricles. Others have leaned more towards converting those patients to a Fontan pathway [10
Even if there is no significant difference between DORV patients requiring a VSD enlargement and those who did not; the VSD enlargement surgery is associated with a higher morbidity with an elevated risk of ECMO requirement. There were no late deaths or re-operation for subaortic obstruction in the follow up period observed. A patient, who had an associated multiple VSD repair, required a late heart transplantation. As already reported [3
], the presence of a Swiss cheese VSD is a contra-indication for biventricular repair and should indicate a Fontan palliation. It is noticeable that the patients requiring a VSD enlargement did not have a significantly higher risk for both total mortality plus late heart transplant ( p
= 0.093). However, the numbers are small and these favorable outcomes would need to be confirmed by a larger series.
The need to enlarge restrictive VSDs in DORV is not a new or uncommon phenomenon. Belli et al. have reported 11 cases of DORV that required enlargement of a VSD to improve subaortic outflow tract obstruction [12
]. Stellin et al. in 1991 described having to enlarge the VSD in 57% of their hearts with DORV and a non-committed VSD [13
]. In our personal experience the incidence of non-committed VSDs needing enlargement was 70% (7/10) with a 10% surgical mortality rate [14
]. In order to preserve a two-ventricle system without creating unnecessary LV outflow/subaortic obstruction, an intraventricular tunnel baffle to the pulmonary artery, combined with arterial switch, has been our preferred method of treating non-committed type DORV [4
]. When the baffle tunnel from the VSD to the aorta is either too long or at risk for the tricuspid valve, then a baffle tunnel to the pulmonary artery with arterial switch is the technique of choice [4
]. This new approach is likely to decrease both the risk of LV dysfunction due to a long akinetic interventricular patch and also the potential for late subaortic obstruction. In the face of uncertainty about the future of Fontan patients, enlarging the VSD must obviously become an integral part of this paradigm, given the 86%, 10-year actuarial survival of DORV patients [15
]. Recently a Japanese case report detailed an extensive enlargement of a VSD in a patient with non-committed type [16
The question becomes: what is the alternative? Conversion to a ‘two-ventricle’ Fontan in the setting of a small VSD has serious negative consequences. It has been recently reported by the group in Boston Children’s Hospital [5
] that the late restriction of the VSD is a significant problem in Fontan operations done in DORV patients. The authors described eight Fontan patients presenting with a hypertrophied, hypertensive, aneurysmal and excluded left ventricular cavity due to either the full closure or the severe restriction of the VSD. Three patients had a failed surgical attempt at enlarging the VSD. Not enlarging a restrictive VSD when establishing a Fontan circulation in DORV-nc-VSD is taking the risk of a disastrous total obstruction of the left ventricle.
Regarding the problem of aortic valve replacement in children, the Ross operation has become a very valuable asset, as it provides a biological substitute with excellent longevity, no need for anticoagulation, and quite uniquely, the capacity for somatic growth with the child [17
]. In the very young, and in neonates in particular, the size mismatch between the native pulmonary root and the aorta makes standard pulmonary autograft replacement usually impossible. Excellent mid- and long-term survival has been previously reported in older children and adolescents, with 5-year survival of greater than 98% [19
] and 10-year survival of 86% [20
When incising the septum in DORV and in the Ross–Konno, there is a potential risk of injuring a major coronary artery. Actually, the first septal perforator branch is more at risk when harvesting the pulmonary autograft than when enlarging the annulus or enlarging a VSD.
In both situations presented in this analysis, the critical point is that the surgical options are limited if the ultimate goal is preservation of a sound, two-ventricle system. In DORV with a restrictive VSD, if the left ventricle is abandoned, and a Fontan pathway chosen, the VSD is also likely to become restrictive with time. Enlarging the VSD does not impact negatively on survival, conduction abnormalities, or LV function. Likewise in patients requiring a Ross–Konno, the lack of a negative impact on survival or LV function is encouraging.