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Incision into the ventricular septum in complex biventricular repair is controversial, and has been blamed for impairing left ventricular function. This retrospective study evaluates the risk of a ventricular septal incision in patients undergoing double outlet right ventricle (DORV) repair and Ross–Konno procedure.
From January 2003 to September 2007, 11 patients with DORV had a ventricular septum (VS) incision and 12 DORV patients did not. Sixteen patients had a Ross–Konno, and 16 had an isolated Ross procedure. The ventricular septal incision was made to match at least the diameter of a normal aortic annulus. In DORV, the VSD was enlarged superiorly and to the left. In the Ross–Konno, the aortic annulus was enlarged towards the septum posteriorly and to the left.
The median follow-up for the study is 19 months (1 month–4 years). For DORV, there were no significant differences in discharge mortality ( p = 0.22), late mortality ( p = 0.48), or late mortality plus heart transplant ( p = 0.093). Although patients with DORV and VSD enlargement have a more complex postoperative course, there were no differences in ECMO use ( p = 0.093), occurrence of permanent AV block ( p = 0.55), left ventricular ejection fraction (LVEF) ( p = 0.40), or shortening fraction (LVSF) ( p = 0.50). Similarly, for the Ross–Konno there were no significant differences in discharge mortality ( p = 0.30), late mortality ( p = NS), LVEF (p = 0.90) and LVSF ( p = 0.52) compared to the Ross, even though the Ross–Konno patients were significantly younger ( p < 0.0001).
Making a ventricular septal incision in DORV repair and in the Ross–Konno operation does not increase mortality and does not impair the LV function. The restriction of the VSD remains an important issue in the management of complex DORV. These encouraging results need to be confirmed by larger series.
Making an incision in the interventricular septum is a controversial topic. Concerns include possibly increasing overall mortality, impairing left ventricular (LV) function, as well as the risk to the conduction system. These concerns are most relevant in two complex clinical scenarios, specifically cases of double outlet right ventricle (DORV) in which the ventricular septal defect (VSD) is restrictive, and in cases of critical aortic stenosis in which a Ross–Konno operation is performed.
The nomenclature by which DORV is classified according to the location of the VSD has evolved over time, beginning with Lev’s original 1972 description: subaortic, subpulmonary (i.e., the Taussig–Bing malformation), doubly committed, and non-committed . More recent classification schemes, including the STS-EACTS-AEPC classification  are based upon the particular physiology: VSD type, Fallot type, transposition type, non-committed type, and atrioventricular septal defect-heterotaxy type . Considering the intraventricular tunnel repair of DORV, the diameter of the VSD must be at least the diameter of the aorta (or even 2 mm larger) so as not to create LV outflow tract obstruction. A restrictive VSD is more commonly seen in non-committed type DORV , and would then mandate an enlargement of the VSD to allow unobstructed egress from the left ventricle. The VSD in non-committed type DORV is at great risk for restriction , and that phenomenon has recently been described in complex DORV patients undergoing Fontan operation .
In patients with aortic stenosis, the Ross operation  has gradually become widely applicable in the pediatric population. When the aortic annulus is hypoplastic, a Ross–Konno is indicated, and has been blamed for impairing left ventricular function. We attempt to demonstrate that making an incision in the septum, either to enlarge the VSD in DORV, or in the conduct of a Ross–Konno operation, does not carry with it the negative implications that have been feared.
Between January 2003 and September 2007, 55 patients underwent either surgical correction of DORV, or either Ross or Ross–Konno at the Children’s Hospital in Denver.
There were 23 patients in the DORV group, of which 11 (48%) required a ventricular septal incision to enlarge a restrictive VSD. The median age of patients requiring a VSD enlargement was 20 months (21 days–2 years), and of those not requiring enlargement 5 months (21 days–12 months). Median weight for DORV with VSD enlargement was 8.5 kg (3.2–20.2 kg), and without enlargement was 5.15 kg (4–11.1 kg). Table 1 describes the types of DORV patients. Classification was according to the STS nomenclature. The ventricular septal incision was made superiorly and leftward, in a manner that created an orifice at least the diameter of the aortic annulus (Fig. 1).
There were 32 patients in the valve replacement group, 16 (50%) in each subgroup, isolated Ross or Ross–Konno respectively. The median age of the isolated Ross patients was 10 years (6 weeks–20 years), and of the Ross–Konno patients 8.5 months (10 days–10 years, p < 0.0001). Median weight for the isolated Ross group was 31 kg (8.3–66.4 kg) and for Ross–Konno 5.75 kg (2.1–24.7 kg). Table 2 highlights the characteristics of the Ross and Ross–Konno patients, in particular the type and varied spectrum of aortic valve disease and previous procedures. The ventricular septal incision for the Ross–Konno was made posteriorly and to the left of the commissure between right and left cusps (Fig. 2).
Outcomes defined for this study were as follows: (a) early mortality (within 30 days postoperatively or prior to hospital discharge), (b) need for postoperative ECMO support, (c) atrioventricular (AV) conduction block requiring pacemaker insertion, (d) late death or need for heart transplantation, (e) mean left ventricular ejection fraction (LVEF), and (f) mean left ventricular shortening fraction (LVSF), the last two parameters based on most recent follow-up echocardiogram. All data collection was approved by the Colorado multiple institutional review board.
Patients with transposition of the great arteries with pulmonary stenosis and VSD, patients undergoing a Konno operation for aortic stenosis , and patients undergoing the Vouhé–Jonas [8,9] operation for subaortic tunnel were excluded from this study due to small sample size.
Results were expressed in mean with standard deviation or in median with minimum and maximum. Comparison of percentage used either Fisher’s exact test or Student’s t-test. Confidence intervals were calculated based on 95% confidence limit.
The median follow-up for this study is 19 months (1 month–4 years). Table 3 reflects the results from the DORV subset of patients. There were no statistically significant differences in discharge mortality ( p = 0.22), late mortality ( p = 0.48), or late mortality plus heart transplant ( p = 0.093). Patients with DORV and VSD enlargement did have a more ‘complicated’ postoperative course, evidenced by the need for ECMO support in 3 of the 11 patients who had a VSD enlargement. Although not significant ( p = 0.093), there was a trend in the data. Of note, however, the two patients that died were in the cohort that required ECMO support, and both of those children came to us with significant comorbid problems preoperatively. One was a 3-year old with a non-committed type DORV with some degree of right ventricular hypoplasia who already had a prior bidirectional Glenn procedure, and the other was a 5-month old with a Fallot type DORV who had a chromosome 9 defects and collagen abnormality. There was no significant difference in AV block between the two groups, and in fact the one patient that required a pacemaker was one who did not have a VSD enlargement. In terms of LV function, there was no significant difference in ejection fraction ( p = 0.40) or shortening fraction ( p = 0.50).
Similarly, for the Ross versus Ross–Konno patients (Table 4), there was no statistically significant difference in either early mortality ( p = 0.30) or late mortality ( p = NS). There was one postoperative AV block requiring pacemaker implantation in the Ross–Konno group ( p = 0.50), in an 8-year-old patient who had a previous repair of partial anomalous pulmonary venous connection. The need for postoperative ECMO support was actually identical in the two groups, but the two patients in the Ross–Konno group who needed ECMO were again exceptionally ill. One was a 4-month old who additionally had a type B interruption of the aortic arch along with a 6q chromosomal deletion, and the other was a 2-week-old baby suffering from cholestasis and Escherichia coli septicemia. The LV function, likewise, failed to demonstrate a statistically significant difference between patients getting an isolated Ross compared to a Ross–Konno (LVEF p = 0.90, LVSF p = 0.52). The only parameter to achieve a level of statistical significance in the study was the younger age of patients undergoing a Ross–Konno compared to a Ross (median age 8.5 months vs 10 years, respectively; p < 0.0001) (Fig. 3).
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 [10,11].
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 [3,14], 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 . Stellin et al. in 1991 described having to enlarge the VSD in 57% of their hearts with DORV and a non-committed VSD . In our personal experience the incidence of non-committed VSDs needing enlargement was 70% (7/10) with a 10% surgical mortality rate . 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 [4,14]. 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 [4,14]. 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 . Recently a Japanese case report detailed an extensive enlargement of a VSD in a patient with non-committed type .
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  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 [17,18]. 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%  and 10-year survival of 86% .
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.
Dr V. Hraska (Sankt Augustin, Germany): First, to avoid mixing apples with oranges, I’d like to discuss the DORV group first, because this is probably the most challenging part of this paper. First of all, let me congratulate Denver’s group for their continuous dedication to expand limits of biventricular correction of DORV.
I absolutely agree that one should consider enlargement of virtually all VSDs in DORV at the time of complete repair except isolated subaortic VSD where VSD is as large as aortic annulus. So I was really satisfied to read your conclusion that making a ventricular septal incision in DORV repair doesn’t increase mortality and does not impair the LV function. So I’m on your side.
Unfortunately, you don’t provide sufficient data to support your conclusion. In the DORV VSD enlargement, there was all together 27% mortality, 3 patients from 11, versus 0 mortality in DORV without VSD enlargement. I know that statistics of so small a cohort is peculiar. Nevertheless, if comparison of these two groups is provided by Kaplan–Meier method using a long-rank test, you will get a significant difference between these two groups undermining your conclusion. Can you elaborate on this issue?
I think one should avoid simplifying the problem of biventricular correction of DORV with restrictive VSD to incision only, not taking into account the complexity of the intraventricular tunnel. The function of both ventricles heavily depends on geometry of tunnel and commitments of enlarged VSD to aorta. The long and large intraventricular tunnel can impair left ventricular function by creating a significant akinetic area. LV function in your cohort of patients was broadly assessed by echo measuring ejection fraction and shortening fraction at the last follow-up and no differences between groups were found.
My second question is, did you include analysis of LV function parameters of patients who died? And if so, were there differences?
Nevertheless these parameters are not sensitive enough to determine original myocardial dysfunction typically seen, based on my experience in complex tunnels. If one analyzes LV function by tissue Doppler echo, I guess we will see problems with the heart function in complex tunnels more frequently than one can expect. Therefore, Fontan remains the reasonable option and one should elaborate exclusion criteria for biventricular repair not because of risk of incision to enlarge VSD but because of negative impact of too complex tunnels on myocardial performance.
In Boston’s paper, which you cited, all patients, before final single ventricle palliation, were banded. I think the essential problem of these patients was banding itself, exacerbating hypertrophy and restriction of VSD. Nevertheless one can enlarge the VSD in OR, without difficulties, decreasing the risk of Fontan operation.
So based on your experience, being aware about low mortality in your cohort of patients, which patient could benefit rather from single ventricular palliation than biventricular correction?
In Ross versus Ross–Konno group no differences in early mortality, ECMO use and LV function were demonstrated. And I think that this group is much better suited to demonstrate that making an incision in the septum does not have negative impact on LV function because there is simply no complex tunnel.
Dr Goldberg: The first question, we intentionally did not do a Kaplan–Meier curve, principally because we had relatively short-term follow-up. So we felt that we couldn’t draw long-term conclusions.
In terms of the mortalities in the DORV group and the LV function, to put things in kind of perspective, the patients who did not survive, at least 2 out of those 3 were on ECMO and died while on support, so their LV function was obviously inherently quite poor. Those were all early deaths, and there weren’t any late deaths to get any LV function data in the long-term. So those early mortalities were all inherently poor LV function, so I guess that could serve as an answer to what was the LV function in the group that died. They were already on ECMO.
Who should get a single ventricle operation? Clearly, obviously, a hypoplastic right ventricle should go towards single ventricle operation. We had one patient that we intraoperatively discovered had Swiss cheese VSD. There was an echo that showed 2 VSDs, but we found 5 in the operating room. That patient did not do well because of poor function of the ventricular septum after closing that, so Swiss cheese VSD would be another one. And then straddling AV valve type C, which is very hard to repair, probably associated with a suboptimal functional outcome and our philosophy is that we would favor doing a single ventricle Fontan-type pathway for those patients.
Presented at the 22nd Annual Meeting of the European Association for Cardio-thoracic Surgery, Lisbon, Portugal, September 14–17, 2008.