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Contemporary outcomes of the double switch operation for congenitally corrected transposition of the great arteries

      Abstract

      Objective

      To determine the contemporary outcomes of the double switch operation (DSO) (ie, Mustard or Senning + arterial switch).

      Methods

      A single-institution, retrospective review of all patients with congenitally corrected transposition of the great arteries undergoing a DSO.

      Results

      Between 1999 and 2019, 103 patients underwent DSO with a Mustard (n = 93) or Senning (n = 10) procedure. Segmental anatomy was (S, L, L) in 93 patients and (I, D, D) in 6 patients. Eight patients had heterotaxy and 71 patients had a ventricular septal defect. Median age was 2.1 years (range, 1.8 months-40 years), including 34 patients younger than age 1 year (33%). Median weight was 10.9 kg (range, 3.4-64 kg). Sixty-one patients had prior pulmonary artery bands for a median of 1.1 years (range, 14 days-12.9 years; interquartile range, 0.7-3.1 years). Median intensive care unit and hospital lengths of stay were 5 and 10 days, respectively. Median follow-up was 3.4 years (interquartile range, 1-9.8 years) and 5.2 years (interquartile range, 2.3-10.7 years) in 79 patients with >1 year follow-up. At latest follow-up, aortic, mitral, tricuspid valve regurgitation, and left ventricle dysfunction was less than moderate in 96%, 98%, 96%, and 93%, respectively. Seventeen patients underwent reoperation: neoaortic valve intervention (n = 10), baffle revision (n = 5), and ventricular septal defect closure (n = 4). At latest follow-up, 17 patients (17%) had a pacemaker and 27 (26%) had cardiac resynchronization therapy devices. There were 2 deaths and 2 transplants. Transplant-free survival was 94.6% at 5 years. Risk factors for death or transplant included longer cardiopulmonary bypass time and older age at DSO.

      Conclusions

      The outcomes of the DSO are promising. Earlier age at operation might favor better outcomes. Progressive neoaortic regurgitation and reinterventions on the neo-aortic valve are anticipated problems.

      Graphical abstract

      Key Words

      Abbreviations and Acronyms:

      AR (aortic regurgitation), ASD (atrial septal defect), ccTGA (congenitally corrected transposition of the great arteries), CPB (cardiopulmonary bypass), CRT (cardiac resynchronization therapy), DSO (double switch operation), d-TGA (dextro transposition of the great arteries), LVOTO (left ventricular outflow tract obstruction), PAB (pulmonary artery band), TR (tricuspid regurgitation), VSD (ventricular septal defect)
      Figure thumbnail fx2
      Competing risk outcomes after double switch operation.
      Contemporary outcomes of the double switch operation are promising. Neoaortic regurgitation could be a concern in the future.
      Anatomic repair is among the treatment strategies for patients with ccTGA. However, rarity of the lesion and limited experience make evaluation of contemporary outcomes challenging. Our study indicates older age might be a risk factor for mortality and therefore early anatomic repair should be considered in suitable candidates.
      See Commentary on page 1991.
      The surgical treatment of double discordance in patients with congenitally corrected transposition of the great arteries (ccTGA) has evolved over the past 2 decades.
      • Tweddell J.S.
      What do we really know about the management of patients with congenitally corrected transposition of the great arteries?.
      It has been shown that the right ventricle does not function optimally in the systemic position in the long term.
      • Filippov A.A.
      • del Nido P.J.
      • Vasilyev N.V.
      Management of systemic right ventricular failure in patients with congenitally corrected transposition of the great arteries.
      Consequently, whenever possible, in suitable patients, anatomic repair involving restoration of the left ventricle as the systemic ventricle should be considered. In 1990, Ilbawi and colleagues
      • Ilbawi M.N.
      • DeLeon S.Y.
      • Backer C.L.
      • Duffy C.E.
      • Muster A.J.
      • Zales V.R.
      • et al.
      An alternative approach to the surgical management of physiologically corrected transposition with ventricular septal defect and pulmonary stenosis or atresia.
      first described anatomic repair of ccTGA with the atrial switch and Rastelli procedure. Subsequently in the 1990s, the atrial and arterial switch or double switch operation (DSO) was introduced and popularized.
      • Yamagishi M.
      • Imai Y.
      • Hoshino S.
      • Ishihara K.
      • Koh Y.
      • Nagatsu M.
      • et al.
      Anatomic correction of atrioventricular discordance.
      • Karl T.R.
      • Weintraub R.G.
      • Brizard C.P.
      • Cochrane A.D.
      • Mee R.B.B.
      Senning plus arterial switch operation for discordant (congenitally corrected) transposition.
      • Stümper O.
      • Wright J.G.C.
      • De Giovanni J.V.
      • Silove E.D.
      • Sethia B.
      • Brawn W.J.
      Combined atrial and arterial switch procedure for congenital corrected transposition with ventricular septal defect.
      More recently, the use of pulmonary banding for left ventricular training in patients with ccTGA and an intact ventricular septum has further expanded the applicability of the DSO.
      • Winlaw D.S.
      • McGuirk S.P.
      • Balmer C.
      • Langley S.M.
      • Griselli M.
      • Stümper O.
      • et al.
      Intention-to-treat analysis of pulmonary artery banding in conditions with a morphological right ventricle in the systemic circulation with a view to anatomic biventricular repair.
      Being a challenging surgical procedure in a relatively rare patient subset, single-institution reports in the literature are limited by small sample size. The aim of this study was to report the contemporary outcomes of DSO from our institution over the past 20 years.

      Methods

      Patient Population

      The study was approved by the Institutional Review Board at Boston Children's Hospital and waived the need for informed written consent (IRB-P00033262 dated September 6, 2019). All patients who underwent anatomic repair with DSO (atrial + arterial switch) between 1999 and 2019 were included. Patients who had ventricular septal defect (VSD) routing to aorta along with right ventricle to pulmonary artery conduit (Rastelli procedure) or aortic root translocation were excluded. Patients who underwent DSO in outside hospitals, patients with pulmonary venous disease, who were receiving preoperative extracorporeal membrane oxygenation, and those who had staged biventricular repair were excluded. Medical records, echocardiography reports, and operative notes were reviewed.

      Surgical Strategy and Techniques

      Pulmonary artery banding (PAB) was employed for left ventricle training for unprepared morphologic left ventricles. We try to achieve anatomic repair in suitable patients whenever possible. Our approach to patients with ccTGA is in Figure 1. When anatomic repair is considered, patients who have an intact ventricular septum and are unable to maintain a prepared left ventricle undergo PAB as soon as clinically possible. We have previously described our technique and outcomes following PAB for left ventricle preparation.
      • Myers P.O.
      • Del Nido P.J.
      • Geva T.
      • Bautista-Hernandez V.
      • Chen P.
      • Mayer J.E.
      • et al.
      Impact of age and duration of banding on left ventricular preparation before anatomic repair for congenitally corrected transposition of the great arteries.
      Through a median sternotomy, direct left ventricle and pulmonary artery pressures were monitored. Simultaneous echocardiography was performed to assess septal shift, tricuspid, mitral valve, and ventricle function. A silastic band was tightened until the following end points: morphologic left ventricle pressure reaches at least two-thirds systemic pressure, acceptable septal shift with resolution or improvement of tricuspid regurgitation (TR), no morphologic left ventricle dysfunction, and no new-onset mitral regurgitation (MR).
      Figure thumbnail gr1
      Figure 1Flow chart delineating surgical approach to patients with congenitally corrected transposition of the great arteries (ccTGA) at Boston Children's Hospital. The criteria for left ventricle (LV) preparedness are ideal measurements with decisions on individual patients made on case-by-case basis. VSD, Ventricular septal defect; PS, pulmonary stenosis; LVOTO, left ventricular outflow tract obstruction; TR, tricuspid regurgitation; RV, right ventricle; PA, pulmonary artery; LV, left ventricle; REV procedure, Reparation a l'Etage Ventriculaire; mLV, morphologic left ventricle; EF, ejection fraction; mLVEDV, morphologic left ventricle end-diastolic volume; mLVEDP, morphologic left ventricle end-diastolic pressure; MR, mitral regurgitation.
      The DSO was performed with mildly hypothermic cardiopulmonary bypass (CPB). Fibrillatory arrest was generally used for the atrial switch. The Senning procedure was used in the earlier era, and more recently the Mustard procedure was used per surgeons' preference. The arterial switch component is performed following cardioplegic arrest generally using a single dose of del Nido cardioplegia solution. Our protocol for cardiac resynchronization therapy (CRT) in pediatric patients has been previously reported.
      • Cecchin F.
      • Frangini P.A.
      • Brown D.W.
      • Fynn-Thompson F.
      • Alexander M.E.
      • Triedman J.K.
      • et al.
      Cardiac resynchronization therapy (and multisite pacing) in pediatrics and congenital heart disease: five years experience in a single institution.

      Echocardiography

      Aortic stenosis was assessed by peak gradients with the following categories: none–trivial, <15 mm Hg; mild, 15 to 25 mm Hg; mild–moderate, 26 to 35 mm Hg; moderate, 36 to 49 mm Hg; moderate–severe, 50 to 59 mm Hg, and severe, ≥60 mm Hg. Aortic regurgitation (AR) was determined by width of vena contracta and measured in parasternal long axis views where the diastolic retrograde color flow converged to the narrowest diameter and was indexed to the square root of body surface area. AR was estimated as none–trivial if vena contracta indexed to body surface area was <2 mm/m2, mild if 2 to 3.9 mm/m2, moderate if 4 to 6 mm/m2, and severe if >6 mm/m2. Left and right ventricle function were assessed qualitatively by experienced echocardiographers.

      Assessment of Left Ventricle Preparedness

      Cardiac catheterization and cardiac magnetic resonance imaging was used to assess preparedness of morphologic left ventricle. Indices utilized included indexed left ventricle mass, left ventricle ejection fraction, and left ventricle mass-to-volume ratio (Figure 1).

      Outcomes and Predictor Analysis

      Primary outcomes were death and transplant. Secondary outcomes were need for neoaortic valve reintervention, other surgical reinterventions (excluding pacemaker placement), new-onset left ventricle dysfunction, need for post-DSO pacemakers, and need for post-DSO CRT. Additionally, a composite end point called adverse neoaortic valve function defined as a combination of neoaortic valve reintervention and/or moderate or greater AR was evaluated. Candidate risk factors for the study outcomes included VSD, atrial septal defect (ASD), presence of heterotaxy, dysplastic tricuspid valve, left ventricular outflow tract obstruction (LVOTO), prior tricuspid valve repair, preoperative left ventricle function, PAB, need for PAB adjustment, age at PAB, time from initial PAB to DSO, ASD at PAB, presence of preoperative pacemaker or CRT, era of surgery (early era, 1999-2008), type of atrial switch, concomitant mitral and/or tricuspid valve repair, pulmonary artery plasty, crossclamp time, CPB time, and need for pacemaker and CRT.

      Statistical Analysis

      Descriptive statistics are presented as mean ± SD, median with range, or median with interquartile range (IQR). Cumulative incidence competing risks event rates were estimated for death, transplant, and reintervention. Risk factors for the composite of death or transplant were identified using a proportional hazards subdistribution model.
      • Fine J.P.
      • Gray R.J.
      A proportional hazards model for the subdistribution of a competing risk.
      Associations between the candidate risk factors and the other study outcomes were estimated using exact logistic regression. Selected continuous clinical measures were also compared according to the presence versus absence of the study outcome using the Wilcoxon rank sum test. Analyses were performed using SAS version 9.4 (SAS Institute, Inc) and R version 3.5.1 (R Foundation for Statistical Computing).

      Results

      Baseline Data

      Overall results have been summarized in Figure 2. Patient demographic characteristics are detailed in Table 1. Between 1999 and 2019, 103 patients underwent a DSO. Median age at operation was 2.1 years (range, 1.8 months-40 years), including 33% (n = 34) patients younger than age 1 year. Median weight was 10.9 kg (range, 3.4-64 kg), including 44% (n = 45) <10 kg. Segmental anatomy was (S, L, L) in 90% (n = 93) and (I, D, D) in 6% (n = 6). Eight percent (n = 8) patients had heterotaxy, 69% (n = 71) patients had a VSD, and 37% (n = 38) had pulmonary stenosis and/or LVOT obstruction. Before DSO, 5 patients (5%) had a pacemaker, 11 patients (11%) had a CRT device, 18 patients (17%) had moderate or greater TR, and 2 patients (2%) had a tricuspid valve repair.
      Figure thumbnail gr2
      Figure 2Outcomes following the double switch operation in 103 patients with congenitally corrected transposition of the great arteries are satisfactory. Interventions on the neoaortic valve are likely in the future. Shaded area indicates 95% CIs, which are detailed in . CI, Confidence interval.
      Table 1Demographic data, before double switch operation (DSO)
      VariableResult
      Era DSO performed
       Early: 1999-200832 (31)
       Late: 2009-201971 (69)
      Gender
       Male66 (64)
       Female37 (36)
      Age at DSO (y)
       Overall2.1 (0.79-5.6)
       <134 (33)
       1-1055 (53)
       >1014 (14)
      Weight at DSO (kg)
       Overall10.9 (7.5-18)
       <1045 (44)
       10-2037 (36)
       >2021 (20)
      Neonate0
      Segmental anatomy
       SLL93 (90)
       IDD6 (6)
       SLD2 (2)
       ALL1 (1)
       SLA1 (1)
      Heterotaxy8 (8)
      CAVC2 (2)
      ASD49 (48)
      VSD71 (69)
      Dysplastic tricuspid valve29 (28)
      PS/LVOTO38 (37)
      Prior procedure
      One procedure is not exclusive of others.
       PA band61 (59)
       Readjustment of PA band
      Two underwent concomitant tricuspid valve repair.
      ,
      N = 61.
      13 (21)
       ASD creation at PA band
      N = 61.
      4 (7)
       Coarctation/arch repair5 (5)
       BT shunt2 (2)
       BDG1 (1)
       Tricuspid valve repair
      With concomitant readjustment of PA band.
      2 (2)
       Mitral valve repair1 (1)
      Pre-DSO pacing
       Pacemaker5 (5)
       CRT device11 (11)
      Echocardiographic data
       Moderate or greater TR18 (17)
       Moderate or greater PS19 (18)
       Moderate or greater PR0
       Moderate or greater MS0
       Moderate or greater MR2 (2)
       Moderate or greater AS0
       Moderate or greater AR0
       Moderate or greater RV dysfunction1 (1)
       Moderate or greater LV dysfunction4
      All 4 had PA bands.
      (4)
      Values are presented as n (%) or median (interquartile range). SLL, Situs solitus L-looped ventricles levo; IDD, inversus D-looped ventricles dextro; SLD, situs solitus L-looped ventricles dextro; ALL, ambiguous L-looped ventricles levo; SLA, situs solitus L-looped ventricles ambiguous; CAVC, complete atrioventricular canal; ASD, atrial septal defect; VSD, ventricular septal defect; PS, pulmonary stenosis; LVOTO, left ventricular outflow tract obstruction; PA, pulmonary artery; BT, Blalock-Taussig; BDG, Bidirectional Glenn; CRT, cardiac resynchronization therapy; TR, tricuspid regurgitation; PR, pulmonary regurgitation; MS, mitral stenosis; MR, mitral regurgitation; AS, aortic stenosis; AR, aortic regurgitation; RV, right ventricle; LV, left ventricle.
      One procedure is not exclusive of others.
      Two underwent concomitant tricuspid valve repair.
      N = 61.
      § With concomitant readjustment of PA band.
      All 4 had PA bands.

      Patients With PAB

      Sixty-one (59%) patients underwent prior PAB at a median age of 0.86 years (range, 3 days-16 years). No patients had concomitant tricuspid valve repair. Thirteen patients required tightening of the PAB within a median of 2.4 years (range, 2 days-6.3 years). Of these, 2 patients also needed concomitant tricuspid valve repair. Four patients had creation of atrial septal communication. Of these, 1 patient had it at the time of PAB readjustment with concomitant tricuspid valve repair, whereas a second patient had it along with tricuspid valve repair post-PAB. Median duration of PAB before DSO was 1.1 years (range, 14 days-12.9 years). Forty patients were banded for left ventricle training, 16 had a VSD and were banded to prevent pulmonary overcirculation, and 5 had PAB with coarctation/arch repair.
      Details of patients who had PAB for left ventricle training are in Table E1 (n = 40). The median time to DSO after placement of a PAB for left ventricle training was 3.1 years (IQR, 1.1-6.7 years) in those aged 3 years or older (n = 19) and was 1.0 years (IQR, 0.7-1.3 years) in those younger than age 3 years (n = 21) at DSO (P = .002). Additionally, 17 (43%) of the left ventricle training patients had a patent foramen ovale/ASD. Their time to DSO was similar to the left ventricle training patients without a patent foramen ovale/ASD (P = .606) and their late left ventricle function also did not differ (P = .67). Of all patients with PAB, 2 patients had moderate or greater left ventricle dysfunction at discharge after PAB that remained persistent at the time of DSO. Two other patients referred from outside hospitals for DSO after PAB had moderate or greater left ventricle dysfunction at the time of DSO. Of these 4 patients who had moderate or greater left ventricle dysfunction at the time of DSO after PAB, the left ventricle dysfunction resolved in 3 patients, whereas it stayed unchanged in 1 patient. All banded patients were alive at late follow-up. Two patients (3%) needed transplant. Six patients (10%) needed surgical reinterventions, including neoaortic valve repair (n = 3), atrial baffle revision (n = 3), residual VSD closure (n = 2), tricuspid valve repair (n = 1), and mitral valve replacement (n = 1). Six patients (10%) had moderate or greater left ventricle dysfunction at latest follow-up.

      Patients Who Did Not Need PAB

      Forty-two patients (41%) did not require PAB. All of these patients had a VSD. Twenty-nine out of these 42 (69%) also had LVOTO in the form of subvalvular obstruction. However, this LVOTO was either resectable or just a consequence of septal bowing. The pulmonary valve annulus (neoaortic) was adequate in all of these patients. The median age at DSO for this group of patients was 1.06 years.

      Operative Data

      Operative details are in Table 2. Of the 103 patients, 93 (90%) underwent a Mustard procedure and 10 (10%) had a Senning procedure. Median time for CPB was 207 minutes (range, 136-796 minutes), crossclamp time was 116 minutes (range, 35-364 minutes), and fibrillation (n = 59) was 58 minutes (range, 14-177 minutes). Most common concomitant procedures were VSD patch closure (n = 64), pulmonary artery plasty (n = 30), and subpulmonary resection of LVOTO (n = 28).
      Table 2Operative details
      ProcedureResult
      Atrial switch
       Senning10 (10)
       Mustard93 (90)
      Material used for atrial switch
       Autologous pericardium82 (80)
       Polytetrafluoroethylene9 (9)
       Polyethylene terephthalate6 (6)
       Bovine pericardium5 (5)
       Cormatrix
      DuPont, Wilmington, Del.
      1 (1)
      Concomitant procedures
      One procedure is not exclusive of others.
       None13 (13)
       VSD patch closure64 (62)
       Pulmonary artery plasty30 (29)
       Subpulmonary/LVOTO resection28 (27)
       Tricuspid valve repair17 (17)
       Ascending aortic/root reduction6 (6)
       Pulmonary (neoaortic) valve repair8
      One patient had neoaortic valve replacement at the time of double switch.
      (8)
       Mitral valve repair3 (3)
       Arch repair2 (2)
       RVOT patch2 (2)
       RV-PA conduit1
      A 15-year-old patient where Lecompte maneuver was not possible.
      (1)
       Tricuspid valve replacement0
       Mitral valve replacement0
      Pacing
       Pacemaker5 (5)
       CRT device8 (8)
      CPB time (min)207 (177-240)
      ACC time (min)116 (82-116)
      Second bypass run8 (8)
      Values are presented as n (%) or median (interquartile range). VSD, Ventricular septal defect; LVOTO, left ventricular outflow tract obstruction; RVOT, right ventricular outflow tract; RV-PA, right ventricle to pulmonary artery; CRT, cardiac resynchronization therapy; CPB, cardiopulmonary bypass; ACC, aortic crossclamp.
      DuPont, Wilmington, Del.
      One procedure is not exclusive of others.
      One patient had neoaortic valve replacement at the time of double switch.
      § A 15-year-old patient where Lecompte maneuver was not possible.

      Early Results

      Early outcomes and reoperations are presented in Table 3. Median intensive care unit and hospital length of stays were 5 and 10 days, respectively. Hospital length of stay was shorter in older patients (median 9.0 vs 11.0 days for patients aged 3 years or older vs younger than age 3 years; P = .002). Three patients (3%) needed pacemaker placement and 3 patients (3%) needed a CRT device. Apart from pacemaker procedures, reoperation before discharge was required in 5 (5%) patients.
      Table 3Follow-up data
      OutcomeResult
      30-d mortality1 (1.6)
      ECMO1 (1.6)
      Length of stay
       ICU stay (d)5 (3-7)
       Hospital stay (d)10 (8-14)
      Early reoperation before discharge
      One procedure is not exclusive of others.
       Pacemaker implantation3 (3)
       CRT device implantation3 (3)
       Neoaortic valve repair3 (3)
       Closure of residual VSD3 (3)
       Atrial baffle revision2 (2)
       Mitral valve repair1 (1)
       Mitral valve replacement1 (1)
      Late outcomes (postdischarge/>30 d)
       Death1 (1.6)
       Transplant2 (2)
      Late reoperation
      One procedure is not exclusive of others.
       Pacemaker implantation4 (4)
      One patient needed pacemaker after aortic valve replacement performed at an outside hospital.
       CRT device implantation5 (5)
       Neoaortic valve7 (7)
       Atrial baffle revision4 (4)
       Tricuspid valve repair1 (1)
       Closure of residual VSD1 (1)
       Subaortic membrane resection1 (1)
      Echocardiographic data
       Moderate or greater TR4 (4)
       Moderate or greater PS3 (3)
       Moderate or greater PR0
       Moderate or greater MS0
       Moderate or greater MR2 (2)
       Moderate or greater AS3 (3)
       Moderate or greater AR4 (4)
       Moderate or greater RV dysfunction1 (1)
       Moderate or greater LV dysfunction7 (7)
      Values are presented as n (%) or median (interquartile range). ECMO, Extracorporeal membrane oxygenation; ICU, intensive are unit; CRT, cardiac resynchronization therapy; VSD, ventricular septal defect; TR, tricuspid regurgitation; PS, pulmonary stenosis; PR, pulmonary regurgitation; MS, mitral stenosis; MR, mitral regurgitation; AS, aortic stenosis; AR, aortic regurgitation; RV, right ventricle; LV, left ventricle.
      One procedure is not exclusive of others.
      One patient needed pacemaker after aortic valve replacement performed at an outside hospital.

      Follow-up and Late Reoperations

      Follow-up data and late reoperations are presented in Table 3. The latest clinical evaluation was taken as the follow-up date. The clinical follow-up exceeded echocardiographic follow-up in only 4 patients and this difference was <6 months. Median follow-up was 3.4 years (IQR, 1-9.8 years) and 5.2 years (IQR, 2.3-10.7 years) in 79 patients with more than 1-year follow-up. Apart from pacemaker procedures, 12 patients (12%) needed late reoperation.
      Of the 61 patients who had prior PAB, only 3 patients (5%) required neoaortic valve reintervention. One patient required reintervention on the tricuspid valve after DSO. This patient had moderate to severe TR before DSO and had undergone tricuspid valve repair at DSO.
      We examined the primary outcomes of death, transplant, and reoperation in a competing risks framework. The cumulative incidence competing risks estimates for each outcome are shown in Figure 3, Table 4, and Figure E1. At 5 years, the death rate was 2.7% (95% CI, 0.5%-9.0%), transplant rate was 2.7% (95% CI, 0.5%-8.5%), rate of reoperation on the neoaortic valve was 13.3% (95% CI, 6.6%-22.4%), and rate of other surgical reintervention (excluding pacemaker placement) was 6.1% (95% CI, 2.2%-12.9%).
      Figure thumbnail gr3
      Figure 3Cumulative incidence of competing risk outcomes of death and transplant, neoaortic valve reintervention, and other surgical reintervention, excluding pacemaker placement in 103 patients following double switch operation. The x-axis is restricted to 12 years after surgery. One other surgical reintervention at 19.82 years is not shown. provides the 95% CIs for the event rates. CI, Confidence interval.
      Table 4Estimated marginal probability (%) of competing risk primary outcomes by time since double switch operation (N = 103)
      See Tables E5 and E6 for additional point estimates and confidence limits.
      Competing risk primary outcomeCumulative incidence rate (95% CI)
      Time (y)135
      Death1.0 (0.1-4.9)1.0 (0.1-4.9)2.7 (0.5-9.0)
      Transplant1.2 (0.1-5.7)2.7 (0.5-8.5)2.7 (0.5-8.5)
      Reoperation on neoaortic valve4.1 (1.3-9.6)11.6 (5.6-20.2)13.3 (6.6-22.4)
      Surgical reintervention
      Excluding neoaortic valve reinterventions and pacemakers.
      3.2 (0.9-8.4)6.1 (2.2-12.9)6.1 (2.2-12.9)
      CI, Confidence interval.
      See Tables E5 and E6 for additional point estimates and confidence limits.
      Excluding neoaortic valve reinterventions and pacemakers.

      Deaths

      There was 1 early and 1 late death. The first patient (early death) underwent a Mustard arterial switch operation, closure of VSD, resection of subpulmonary stenosis, and neoaortic valve repair at age 13.7 years. The pre-DSO left ventricle function in this patient was normal. Her postoperative course was complicated by bleeding, need for mechanical support as a part of cardiopulmonary resuscitation, and she died on postoperative day 13 following neurological complications. The second patient (late death) had a primary Mustard arterial switch with VSD closure and resection of subpulmonary tissue at age 17.4 years. His pre-DSO left ventricle function was normal as well. He developed complete heart block postprocedure and needed a permanent pacemaker. He subsequently developed progressive morphologic left ventricle dysfunction and needed upgrade to a CRT device. He died 3.5 years after DSO in an outside hospital of unclear causes.

      Transplants

      There were 2 transplants. Both patients had PAB for left ventricle preparation and underwent DSO with normal left ventricle function, and both developed progressive left ventricle dysfunction after DSO. The first patient had a pre-DSO CRT device, underwent DSO at age 2.4 years and needed transplant after 5 months. The second patient had a CRT device at the time of DSO at age 5.1 years and needed transplant after 2.1 years.

      Predictors of Death or Transplant

      Risk factors for the composite outcome of death and transplant included longer CPB time (hazard ratio [HR], 1.28 per 30-minute increase; 95% CI, 1.12-1.45; P = .002), older age at DSO (HR, 1.07 per year; 95% CI, 1.01-1.13; P = .034), and greater weight at DSO (HR, 1.05 per kg; 95% CI, 1.02-1.09; P = .005). All 4 death or transplant events occurred in patients who had the DSO performed after age 2 years. However, with only 4 events, our data are too sparse to reliably propose an age threshold for optimal performance of the DSO. No other predictors were associated with death or transplant.

      Adverse Neoaortic Valve Function

      Apart from the 10 patients who had reintervention on the neoaortic valve, 4 patients (4%) had moderate or greater neo-AR at latest follow-up. Factors associated with adverse aortic valve function (n = 14) included (Table 5): at least moderate preoperative pulmonary stenosis or LVOTO (odds ratio [OR], 9.14, 95% CI, 2.31-38.98; P = .001) and concomitant LVOTO resection at the time of DSO (OR, 6.48; 95% CI, 1.72-27.71; P = .004). Presence of a PAB was protective (OR, 0.15; 95% CI, 0.03-0.62; P = .005).
      Table 5Univariate modeling results for composite outcome of neoaortic intervention and/or at least moderate aortic regurgitation (N = 103 patients; 14 events)
      VariableMet outcome (n = 14)Did not meet outcome (n = 89)Exact odds ratio (95% CI)P valueC statistic
      DSO before 200842.9 (6)29.2 (26)1.81 (0.47-6.62).470.57
      VSD92.9 (13)65.2 (58)6.86 (0.95-304.64).060.64
      ASD42.9 (6)48.3 (43)0.80 (0.21-2.89).930.53
      Dysplastic TV, Ebstein7.1 (1)31.4 (28)0.17 (0.02-1.35).100.62
      Any degree of preoperative PS and/or LVOTO64.3 (9)32.6 (29)3.67 (1.00-15.28).050.66
      Complete atrioventricular canal defect7.1 (1)1.1 (1)6.56 (0.08-337.13).510.53
      Heterotaxy14.3 (2)6.7 (6)2.28 (0.20-14.83).600.54
      At least moderate preoperative TR21.4 (3)21.4 (19)1.01 (0.16-4.36)1.000.50
      At least moderate preoperative PS and/or LVOTO57.1 (8)12.4 (11)9.14 (2.31-38.98).0010.72
      At least moderate preoperative LV dysfunction7.1 (1)4.5 (4)1.63 (1.03-18.23)1.000.51
      PAB21.4 (3)65.2 (58)0.15 (0.03-0.62).0050.72
      Age at PAB (n = 61)3.7 (0.6-5.3)0.9 (0.2-2.0)1.11 (0.78-1.44).410.72
      Time from first PAB to DSO (n = 61)3.1 (1.1-7.2)1.1 (0.7-2.8)1.14 (0.79-1.51).400.74
      Prior TV repair0 (0)2.3 (2
      n = 87.
      )
      2.58 (0-22.05).740.51
      Presence of preoperative pacemaker21.4 (3)14.6 (13)1.59 (025-7.23).750.53
      Mustard vs Senning atrial switch92.9 (13)89.9 (80)1.46 (0.17-68.97)1.000.52
      Concomitant VSD closure71.4 (10)60.7 (54)1.61 (0.42-7.61).650.55
      Concomitant LVOTO resection64.3 (9)21.4 (19)6.48 (1.72-27.71).0040.72
      Concomitant TV intervention7.1 (1)18.0 (16)0.35 (0.01-2.70).560.55
      Concomitant MV intervention7.1 (1)2.3 (2)3.29 (0.05-67.48).720.52
      Concomitant PA plasty14.3 (2)31.5 (28)0.37 (0.04-1.82).320.59
      CPB time (min)220 (204-254)200 (169-235)1.00 (1.00-1.01).560.66
      Crossclamp time (min)114 (101-122)91 (78-111)1.01 (1.00-1.02).290.69
      Arrest time (min)0.0 (0.0-0.0)0.0 (0.0-0.0)1.05 (0.81-1.28).510.52
      Age at surgery (y)2.1 (0.9-7.8)6.0 (5.6-6.9)1.04 (0.95-1.12).370.56
       <128.6 (4)33.7 (30)0.79 (0.17-3.03).960.53
       <357.1 (8)66.3 (59)0.68 (0.19-2.61).700.55
       <657.1 (8)82.0 (73)0.30 (0.08-1.19).090.62
      Values are presented as % (n), median (interquartile range), or % (n/N). Due to sparsity of data, multivariable model was not constructed. Values in boldface type indicate statistically significance. CI, Confidence interval; DSO, double switch operation; VSD, ventricular septal defect; ASD, atrial septal defect; TV, tricuspid valve; PS, pulmonary stenosis; LVOTO, left ventricular outflow tract obstruction; TR, tricuspid regurgitation; LV, left ventricle; PAB, pulmonary artery band; MV, mitral valve; PA, pulmonary artery; CPB, cardiopulmonary bypass.
      n = 87.

      Left Ventricle Function

      Seven patients (7%) had moderate or greater ventricular dysfunction at latest follow-up, of whom 1 patient had pre-DSO moderate or greater left ventricle dysfunction. Thus, 6 patients had new-onset moderate or greater left ventricle dysfunction after DSO apart from the 2 patients who needed transplant for left ventricle dysfunction and 1 death after progressive left ventricle dysfunction. Details of these 9 patients are in Table E2. No correlates of new-onset moderate or greater left ventricle dysfunction were identified.

      Post-DSO Permanent Pacemaker

      Patients with procedures that took place during the early era (before 2008) were more likely to receive a postoperative pacemaker compared with those undergoing procedures during the later era (19% [6 out of 32] vs 1% [1 out of 71]; exact P = .003 and OR, 15.87; 95% CI, 1.8-753.2; P = .007). A postoperative pacemaker was also more common in patients without a PAB (OR, 9.8; 95% CI, 1.12-500; P = .035) and with a longer CPB time (OR, 1.89 per each 0.25 log day; 95% CI, 1.06-3.35; P = .037).

      CRT

      Overall, 27 patients (26%) had CRT. The timing of CRT was pre-DSO in 11 patients, at the time of DSO in 8 patients and after DSO in 8 patients. Of the 27 patients, 11 patients had CRT as an upgrade from a prior pacemaker (secondary CRT) and 16 had a CRT as a primary device. These 11 patients had an upgrade to CRT for any degree of left ventricle dysfunction. Of these, 9 patients (82%) had PAB. Seven of 11 patients (64%) undergoing secondary CRT showed improved left ventricle function and none of them developed new-onset left ventricle dysfunction after DSO. Four of the 16 patients (25%) had worsening of left ventricle function despite undergoing primary resynchronization therapy. The early-era patients were also more likely to undergo post-DSO CRT than those with DSO between 2009 and 2019 (19% [6 out of 31] vs 3% [2 out of 71]; exact P = .011 and OR, 7.8; 95% CI, 1.3-83.6; P = .021).

      Mitral and Tricuspid Valve Function

      At latest follow-up, mitral and tricuspid valve regurgitation was less than moderate in 98% and 96%, respectively. One patient needed replacement of the mitral valve, another required mitral valve repair, and 2 patients had moderate or greater mitral regurgitation at latest follow-up. Moderate or greater TR occurred in 4 patients (4%), among whom 2 had significant TR before DSO.

      Late DSO (Age 10 Years or Older)

      There were 14 patients who underwent DSO at age older than 10 years. Of these, 6 were between ages 10 and 15 years, 7 were between ages 15 and 20 years, and 1 patient was aged 40 years at DSO. Details of patients who underwent DSO at a later age are in Tables E3 and E4.

      Discussion

      Double discordance in ccTGA results in a physiologically corrected circulation. Consequently, in the absence of any associated lesions like VSD or LVOTO, patients with ccTGA are asymptomatic, at least in the initial decades of life. However, leaving the right ventricle in the systemic position leads to inevitable right ventricle failure and associated TR by late adulthood.
      • Filippov A.A.
      • del Nido P.J.
      • Vasilyev N.V.
      Management of systemic right ventricular failure in patients with congenitally corrected transposition of the great arteries.
      Initial surgical strategies for ccTGA focused on physiological repair—correcting only the associated lesions; however, suboptimal results became evident. In 2005, Hraska and colleagues
      • Hraska V.
      • Duncan B.W.
      • Mayer J.E.
      • Freed M.
      • del Nido P.J.
      • Jonas R.A.
      Long-term outcome of surgically treated patients with corrected transposition of the great arteries.
      demonstrated a 10-year survival after physiological repair of only 68% and worse outcomes compared with a Fontan cohort. Similarly, Yeh and colleagues
      • Yeh T.J.
      • Connelly M.S.
      • Coles J.G.
      • Webb G.D.
      • McLaughlin P.R.
      • Freedom R.M.
      • et al.
      Atrioventricular discordance: results of repair in 127 patients.
      reported a 20-year survival of 48% after physiological repair. In 1990, Ilbawi and colleagues
      • Ilbawi M.N.
      • DeLeon S.Y.
      • Backer C.L.
      • Duffy C.E.
      • Muster A.J.
      • Zales V.R.
      • et al.
      An alternative approach to the surgical management of physiologically corrected transposition with ventricular septal defect and pulmonary stenosis or atresia.
      introduced anatomic repair with the atrial switch–Rastelli operation, whereby the left ventricle is restored to the systemic position. Since then, several groups have also reported encouraging outcomes of the DSO.
      • Duncan B.W.
      • Mee R.B.B.B.
      • Mesia C.I.
      • Qureshi A.
      • Rosenthal G.L.
      • Seshadri S.G.
      • et al.
      Results of the double switch operation for congenitally corrected transposition of the great arteries.
      • Ly M.
      • Belli E.
      • Leobon B.
      • Kortas C.
      • Grollmüss O.E.
      • Piot D.
      • et al.
      Results of the double switch operation for congenitally corrected transposition of the great arteries.
      • Sharma R.
      • Talwar S.
      • Marwah A.
      • Shah S.
      • Maheshwari S.
      • Suresh P.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries.
      • Murtuza B.
      • Barron D.J.
      • Stumper O.
      • Stickley J.
      • Eaton D.
      • Jones T.J.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries: a single-institution 19-year experience.
      • Brizard C.P.
      • Lee A.
      • Zannino D.
      • Davis A.M.
      • Fricke T.A.
      • D'Udekem Y.
      • et al.
      Long-term results of anatomic correction for congenitally corrected transposition of the great arteries: a 19-year experience.
      Despite the availability of multiple treatment strategies, the ideal approach and decision making in patients with ccTGA remains challenging.
      • Tweddell J.S.
      What do we really know about the management of patients with congenitally corrected transposition of the great arteries?.
      ,
      • Hraska V.
      • Mitchell M.E.
      • Woods R.K.
      • Frommelt M.A.
      What surgical improvements are needed to prove that anatomic repair is superior to physiologic repair in the majority of patients with corrected transposition of the great arteries?.
      ,
      • Sun J.
      • Brizard C.
      • Winlaw D.
      • Alphonso N.
      • D'Udekem Y.
      • Eastaugh L.
      • et al.
      Biventricular repair versus Fontan completion for patients with d- or l-transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction.
      In this study we have evaluated the outcomes of DSO to help this decision making.
      Several studies label a combination of atrial switch and ventricular routing with conduit (Rastelli) as double switch,
      • Duncan B.W.
      • Mee R.B.B.B.
      • Mesia C.I.
      • Qureshi A.
      • Rosenthal G.L.
      • Seshadri S.G.
      • et al.
      Results of the double switch operation for congenitally corrected transposition of the great arteries.
      ,
      • Hiramatsu T.
      • Matsumura G.
      • Konuma T.
      • Yamazaki K.
      • Kurosawa H.
      • Imai Y.
      Long-term prognosis of double-switch operation for congenitally corrected transposition of the great arteries.
      but this group should not be considered to be the same as true double switch—atrial and arterial switch. Patients with ccTGA and intact ventricular septum present a challenge similar to patients with dextro TGA (d-TGA) with intact ventricular septum: regressed morphologic left ventricle. Consequently, the concept of left ventricle training used to retrain d-TGA ventricles is also used in patients with ccTGA.
      • Yacoub M.H.
      • Radley-Smith R.
      • Maclaurin R.
      Two-stage operation for anatomical correction of transposition of the great arteries with intact interventricular septum.
      ,
      • Poirier N.C.
      • Mee R.B.B.
      Left ventricular reconditioning and anatomical correction for systemic right ventricular dysfunction.
      The proportion of patients needing PAB for left ventricle training across different series ranges from 10.8% to 46.6%.
      • Duncan B.W.
      • Mee R.B.B.B.
      • Mesia C.I.
      • Qureshi A.
      • Rosenthal G.L.
      • Seshadri S.G.
      • et al.
      Results of the double switch operation for congenitally corrected transposition of the great arteries.
      ,
      • Sharma R.
      • Talwar S.
      • Marwah A.
      • Shah S.
      • Maheshwari S.
      • Suresh P.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries.
      • Murtuza B.
      • Barron D.J.
      • Stumper O.
      • Stickley J.
      • Eaton D.
      • Jones T.J.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries: a single-institution 19-year experience.
      • Brizard C.P.
      • Lee A.
      • Zannino D.
      • Davis A.M.
      • Fricke T.A.
      • D'Udekem Y.
      • et al.
      Long-term results of anatomic correction for congenitally corrected transposition of the great arteries: a 19-year experience.
      ,
      • Shin'oka T.
      • Kurosawa H.
      • Imai Y.
      • Aoki M.
      • Ishiyama M.
      • Sakamoto T.
      • et al.
      Outcomes of definitive surgical repair for congenitally corrected transposition of the great arteries or double outlet right ventricle with discordant atrioventricular connections: risk analyses in 189 patients.
      In contrast, in our series, more than half of patients underwent PAB for left ventricle training. The interval between PAB and DSO seems to be impressively constant across several large series at around 1.5 years.
      • Duncan B.W.
      • Mee R.B.B.B.
      • Mesia C.I.
      • Qureshi A.
      • Rosenthal G.L.
      • Seshadri S.G.
      • et al.
      Results of the double switch operation for congenitally corrected transposition of the great arteries.
      ,
      • Murtuza B.
      • Barron D.J.
      • Stumper O.
      • Stickley J.
      • Eaton D.
      • Jones T.J.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries: a single-institution 19-year experience.
      ,
      • Brizard C.P.
      • Lee A.
      • Zannino D.
      • Davis A.M.
      • Fricke T.A.
      • D'Udekem Y.
      • et al.
      Long-term results of anatomic correction for congenitally corrected transposition of the great arteries: a 19-year experience.
      Our finding was similar with a median interval of 1.1 years. With respect to the actual age at PAB, studies have previously demonstrated that early age of PAB is associated with more favorable outcomes.
      • Myers P.O.
      • Del Nido P.J.
      • Geva T.
      • Bautista-Hernandez V.
      • Chen P.
      • Mayer J.E.
      • et al.
      Impact of age and duration of banding on left ventricular preparation before anatomic repair for congenitally corrected transposition of the great arteries.
      ,
      • Cui B.
      • Li S.
      • Yan J.
      • Shen X.
      • Wang X.
      • Yang K.
      • et al.
      The results of a two-stage double switch operation for congenital corrected transposition of the great arteries with a deconditioned morphologically left ventricle.
      The need to readjust PABs is common, including in our series. Zartner and colleagues
      • Zartner P.A.
      • Schneider M.B.
      • Asfour B.
      • Hraška V.
      Enhanced left ventricular training in corrected transposition of the great arteries by increasing the preload.
      advocate the concept of enhanced left ventricle training—addition of a volume load to the left ventricle by addition of an ASD along with a relatively loose PAB.
      • Zartner P.A.
      • Schneider M.B.
      • Asfour B.
      • Hraška V.
      Enhanced left ventricular training in corrected transposition of the great arteries by increasing the preload.
      They reported the use of this approach in 6 patients none of whom needed readjustment of the PAB. We have utilized this approach in 4 patients and all of them underwent successful DSO with no adverse outcomes. In patients with d-TGA, previous PAB has been found to be a predictor of late neoaortic dilation and neo-AR.
      • Schwartz M.L.
      Long-term predictors of aortic root dilation and aortic regurgitation after arterial switch operation.
      Although in our series, only 3 of 61 patients with PAB required neoaortic valve reintervention, these patients need to be closely observed for occurrence of late neo-AR. On the other hand, 41% of our patients did not need PAB. Although all of these patients had a VSD, 29 of them (69%) also had LVOTO. We could achieve a DSO in these patients after careful echocardiographic and intraoperative assessment.
      Although the early mortality following double switch is low, there has been a predictable midterm attrition reported in several series with midterm survival between 75% and 90%.
      • Yeh T.J.
      • Connelly M.S.
      • Coles J.G.
      • Webb G.D.
      • McLaughlin P.R.
      • Freedom R.M.
      • et al.
      Atrioventricular discordance: results of repair in 127 patients.
      ,
      • Sharma R.
      • Talwar S.
      • Marwah A.
      • Shah S.
      • Maheshwari S.
      • Suresh P.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries.
      ,
      • Murtuza B.
      • Barron D.J.
      • Stumper O.
      • Stickley J.
      • Eaton D.
      • Jones T.J.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries: a single-institution 19-year experience.
      ,
      • Shin'oka T.
      • Kurosawa H.
      • Imai Y.
      • Aoki M.
      • Ishiyama M.
      • Sakamoto T.
      • et al.
      Outcomes of definitive surgical repair for congenitally corrected transposition of the great arteries or double outlet right ventricle with discordant atrioventricular connections: risk analyses in 189 patients.
      ,
      • Langley S.M.
      • Winlaw D.S.
      • Stumper O.
      • Dhillon R.
      • de Giovanni J.V.
      • Wright J.G.
      • et al.
      Midterm results after restoration of the morphologically left ventricle to the systemic circulation in patients with congenitally corrected transposition of the great arteries.
      Brizard and colleagues
      • Brizard C.P.
      • Lee A.
      • Zannino D.
      • Davis A.M.
      • Fricke T.A.
      • D'Udekem Y.
      • et al.
      Long-term results of anatomic correction for congenitally corrected transposition of the great arteries: a 19-year experience.
      from Melbourne report 3 late deaths out of 21 DSO patients. All late deaths seem to have a predictable progressive decline in left ventricle function after restoration to the systemic position. Both our transplants and 1 late death followed a similar pattern of progressive left ventricle dysfunction. Consequently, it is essential to critically evaluate the etiopathogenesis of left ventricle failure. A previous study from our institution attempted to look at this issue and found only need for pacemaker and prolonged QRS duration to be associated with late left ventricle dysfunction.
      • Bautista-Hernandez V.
      • Marx G.R.
      • Gauvreau K.
      • Mayer J.E.
      • Cecchin F.
      • del Nido P.J.
      Determinants of left ventricular dysfunction after anatomic repair of congenitally corrected transposition of the great arteries.
      Few studies in the past have shown previous PAB for left ventricle training and age to be a predictor.
      • Quinn D.W.
      • McGuirk S.P.
      • Metha C.
      • Nightingale P.
      • de Giovanni J.V.
      • Dhillon R.
      • et al.
      The morphologic left ventricle that requires training by means of pulmonary artery banding before the double-switch procedure for congenitally corrected transposition of the great arteries is at risk of late dysfunction.
      However these findings have not been reproduced in several large series.
      • Sharma R.
      • Talwar S.
      • Marwah A.
      • Shah S.
      • Maheshwari S.
      • Suresh P.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries.
      ,
      • Brizard C.P.
      • Lee A.
      • Zannino D.
      • Davis A.M.
      • Fricke T.A.
      • D'Udekem Y.
      • et al.
      Long-term results of anatomic correction for congenitally corrected transposition of the great arteries: a 19-year experience.
      ,
      • Bautista-Hernandez V.
      • Myers P.O.
      • Cecchin F.
      • Marx G.R.
      • Del Nido P.J.
      Late left ventricular dysfunction after anatomic repair of congenitally corrected transposition of the great arteries.
      Mainwaring and colleagues
      • Mainwaring R.D.
      • Patrick W.L.
      • Arunamata A.
      • Chan F.
      • Newman B.
      • Rosenblatt T.R.
      • et al.
      Left ventricular retraining in corrected transposition: relationship between pressure and mass.
      recently demonstrated that a small proportion of patients who undergo left ventricle training accrue excessive ventricular mass and the hypertrophy in these patients is abnormal. Thus, it is possible that nuances of PAB like age, timing, tightness, and duration might have an influence on long-term ventricular function.
      Although patients with ccTGA have inherently abnormal conduction systems, iatrogenic heart block is a formidable challenge.
      • Brizard C.P.
      • Lee A.
      • Zannino D.
      • Davis A.M.
      • Fricke T.A.
      • D'Udekem Y.
      • et al.
      Long-term results of anatomic correction for congenitally corrected transposition of the great arteries: a 19-year experience.
      Previous reports have consistently demonstrated that the need for pacing was associated with worse long-term systemic ventricular function.
      • Bautista-Hernandez V.
      • Marx G.R.
      • Gauvreau K.
      • Mayer J.E.
      • Cecchin F.
      • del Nido P.J.
      Determinants of left ventricular dysfunction after anatomic repair of congenitally corrected transposition of the great arteries.
      ,
      • Bautista-Hernandez V.
      • Myers P.O.
      • Cecchin F.
      • Marx G.R.
      • Del Nido P.J.
      Late left ventricular dysfunction after anatomic repair of congenitally corrected transposition of the great arteries.
      However, we also found that primary CRT rather than univentricular pacing had significantly less left ventricular dysfunction.
      • Hofferberth S.C.
      • Alexander M.E.
      • Mah D.Y.
      • Bautista-Hernandez V.
      • Del Nido P.J.
      • Fynn-Thompson F.
      Impact of pacing on systemic ventricular function in L-transposition of the great arteries.
      Consequently, we have a very low threshold of using CRT for these patients. In this current study, we found no association between use of pacemakers and/or CRT and left ventricular dysfunction.
      The timing of performing the DSO is also critical. Few studies have demonstrated the feasibility of neonatal DSO.
      • Bautista-Hernandez V.
      • Serrano F.
      • Palacios J.M.
      • Caffarena J.M.
      • Bautista-Hernandez D.
      Successful neonatal double switch in symptomatic patients with congenitally corrected transposition of the great arteries.
      ,
      • Sebastian V.A.
      • Cooley A.
      • Ramaciotti C.
      • Guleserian K.J.
      • Forbess J.M.
      Neonatal double switch for congenitally corrected transposition with Ebstein anomaly and bilateral superior venae cavae.
      However, the atrial switch component of the operation is challenging and might require reintervention in the long term. In our previously reported experience, age younger than 3 years seems to be the ideal window to perform the DSO.
      • Myers P.O.
      • Del Nido P.J.
      • Geva T.
      • Bautista-Hernandez V.
      • Chen P.
      • Mayer J.E.
      • et al.
      Impact of age and duration of banding on left ventricular preparation before anatomic repair for congenitally corrected transposition of the great arteries.
      In this current study, all 4 death or transplant events occurred in patients with DSO performed older than age 2 years. Studies have also reported that older age (ie, older than age 15 years) seems to be a challenging subset.
      • Winlaw D.S.
      • McGuirk S.P.
      • Balmer C.
      • Langley S.M.
      • Griselli M.
      • Stümper O.
      • et al.
      Intention-to-treat analysis of pulmonary artery banding in conditions with a morphological right ventricle in the systemic circulation with a view to anatomic biventricular repair.
      ,
      • Talwar S.
      • Ahmed T.
      • Saxena A.
      • Kothari S.S.
      • Juneja R.
      • Airan B.
      Morphology, surgical techniques, and outcomes in patients above 15 years undergoing surgery for congenitally corrected transposition of great arteries.
      Overall, this cumulative information as well as our study suggest that younger age might favor better outcomes.
      A significant proportion of patients with ccTGA have dysplastic tricuspid valves. Systemic pressures in uncorrected patients leads to TR. PAB for left ventricle training results in septal shift and near resolution of TR or restoration of the tricuspid valve to the subpulmonary ventricle often significantly reduces the degree of TR. However, few studies have identified patients with TR to be a subset at high risk.
      • Yeh T.J.
      • Connelly M.S.
      • Coles J.G.
      • Webb G.D.
      • McLaughlin P.R.
      • Freedom R.M.
      • et al.
      Atrioventricular discordance: results of repair in 127 patients.
      ,
      • Shin'oka T.
      • Kurosawa H.
      • Imai Y.
      • Aoki M.
      • Ishiyama M.
      • Sakamoto T.
      • et al.
      Outcomes of definitive surgical repair for congenitally corrected transposition of the great arteries or double outlet right ventricle with discordant atrioventricular connections: risk analyses in 189 patients.
      In our study, 17% of patients had moderate or greater TR preoperatively. Seventeen patients (17%) needed intervention on the tricuspid valve along with the DSO, of whom 1 patient had moderate TR at follow-up and 1 patient needed reintervention on the tricuspid valve. Apart from them, 3 other patients had moderate or greater TR at follow-up.
      Apart from pacemakers, several studies report need for reintervention on the atrial switch component of the DSO.
      • Murtuza B.
      • Barron D.J.
      • Stumper O.
      • Stickley J.
      • Eaton D.
      • Jones T.J.
      • et al.
      Anatomic repair for congenitally corrected transposition of the great arteries: a single-institution 19-year experience.
      ,
      • Brizard C.P.
      • Lee A.
      • Zannino D.
      • Davis A.M.
      • Fricke T.A.
      • D'Udekem Y.
      • et al.
      Long-term results of anatomic correction for congenitally corrected transposition of the great arteries: a 19-year experience.
      In our series, 5 patients (5%) needed surgical reintervention on the atrial switch. Yet, transplant-free survival without reoperation is still acceptable, at 75% at 5 years postprocedure. Like for patients with d-TGA, the neoaortic root and neoaortic valve might develop dysfunction in the long term and will need close follow-up. Ten patients (10%) in our series needed intervention on the neoaortic valve, 4 patients (4%) had moderate or greater AR, and 3 patients (3%) had moderate or greater aortic stenosis at follow-up, including 1 patient with a prosthetic aortic valve.
      Our study has limitations of being a retrospective observational study. Although the outcomes of the procedure seem promising because the majority of our patients are more contemporary, the duration of follow-up is limited (median, 3.4 years). We were unable to ascertain the predictors of left ventricle preparedness based on imaging data. Ventricle size and function analysis would have been aided by magnetic resonance imaging studies for both the right ventricle and left ventricle. Due to the low event rates of new-onset left ventricle dysfunction, we were unable to identify predictors for this outcome. The echocardiographs were not independently reviewed by a single observer, and qualitative analysis was performed by different readers. We have not been able to ascertain the utility of the DSO in comparison with other treatment strategies like physiological repair or nonsurgical management because this was not the topic of our study.

      Conclusions

      In the contemporary era, the outcomes of the DSO (atrial + arterial switch) are promising. The need for pacemakers continues to be a challenge. The need for overall reoperations and intervention on the tricuspid valve is low. Earlier age at operation might favor better outcomes. Progressive neo-AR and reinterventions on the neoaortic valve is an anticipated problem.

      Conflict of Interest Statement

      The authors reported no conflicts of interest.
      The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest.

      Appendix E1

      Figure thumbnail fx3
      Figure E1Cumulative incidence of competing risk outcomes of death, transplant, and surgical reintervention, excluding pacemaker placement in 103 patients following the double switch operation. The x-axis is restricted to 12 years after surgery. One surgical reintervention at 19.82 years is not shown. Shaded area indicates 95%CIs, which are detailed in . CI,Confidence interval.
      Table E1Details of patients who needed pulmonary artery banding (PAB) for left ventricle (LV) training (n = 40)
      DetailResult
      Age at PAB (y)<11-3>3
       n (%)18 (45)12 (30)10 (25)
      Median age at PAB (y)0.32 (0.16-0.70)1.86 (1.46-1.97)5.78 (3.93-8.97)
      Readjustment of PAB2 (11)5 (42)3 (30)
      Creation of ASD with PAB022
      Duration of PAB to DSO (d)379 (268-876)514 (385-1137)426 (300-1339)
      Age at DSO (y)1.80 (0.91-2.86)3.04 (2.74-4.62)8.69 (6.46-11.23)
      Death000
      Transplant101
      Moderate or greater neo-AR001
      Neo-AV reintervention001
      New onset LV dysfunction002
      Values are presented as n (%), median (interquartile range), or n, unless otherwise noted. ASD, Atrial septal defect; DSO, double switch operation; AR, aortic regurgitation; AV, aortic valve.
      Table E2Details of patients who had new onset of moderate or greater left ventricle (LV) dysfunction after double switch operation (DSO) (n = 9)
      DetailResult
      Patient No.123456789
      GenderFemaleFemaleFemaleFemaleMaleMaleMaleMaleMale
      Segmental anatomySLLSLLSLLSLLSLLSLLSLLSLLSLL
      VSDYesYesNoYesNoNoYesNoYes
      ASDNoNoNoYesYesNoNoNoNo
      Degree of TR before DSONoneNoneNoneNoneMildMildModerateMildModerate
      PABNoYesYesYesYesYesYesYesNo
      Indication of PABRestrict PBFLV trainingRestrict PBFLV trainingLV trainingLV trainingLV training
      Age at PAB (y)0.120.180.110.844.258.976.24
      Readjustment of PABNoYesNoNoNoNoNoNoNo
      Duration from PAB to DSO (d)2442684665623003372500
      Peak gradient across PAB before DSO (mm Hg)65908035455640
      Use of CRTNoYesYesYesYesYesNoNoYes
      Was CRT an upgrade from univentricular pacing?YesNoNoNoYesYes
      Timing of CRTPre-DSOAt DSOPost-DSOPre-DSOAt DSOPost-DSO
      Age at DSO (y)0.440.790.911.392.385.089.8913.0817.36
      Weight at DSO (y)4.76.98.87.613.218.243.848.167.0
      Type of atrial switchMustardMustardMustardMustardMustardMustardMustardMustardMustard
      CPB time (min)210194289224178136181169251
      CC time (min)85861301046258998592
      Length of hospital stay (d)1799137861212
      Length of ICU stay (d)9659554212
      Follow-up (y)0.046.551.114.700.452.145.981.923.56
      ReoperationNoNoNoNoNoNoNoNoNo
      AR at latest follow-upMildMildNoneMild–moderateMildMildMildMild–moderateMild–moderate
      MR at latest follow-upMildNoneNoneMildMildMildNoneNoneMild
      TR at latest follow-upMildNoneNoneNoneNoneNoneNoneNoneMild
      RV function at latest follow-upNormalNormalNormalNormalNormalNormalNormalNormalNormal
      Degree of LV dysfunction at latest follow-upModerateModerateModerateModerateSevereSevereModerateModerateModerate
      OutcomeAliveAliveAliveAliveTransplantTransplantAliveAliveDeath
      SLL, Situs solitus L-looped ventricles levo; VSD, ventricular septal defect; ASD, atrial septal defect; TR, tricuspid regurgitation; PAB, pulmonary artery band; PAF, pulmonary blood flow; CRT, cardiac resynchronization therapy; CPB, cardiopulmonary bypass; CC, crossclamp; ICU, intensive care unit; AR, aortic regurgitation; MR, mitral regurgitation; TR, tricuspid regurgitation; RV, right ventricle.
      Table E3Details of patients who underwent double switch operation (DSO) between age 10 and 15 years
      DetailResult
      Patient No.123456
      GenderMaleMaleMaleMaleFemaleMale
      Segmental anatomySLLSLLSLLSLLSLLSLL
      VSDNoNoNoNoYesYes
      ASDNoYesNoNoNoYes
      Dysplastic TVYesNoYesNoNoNo
      LVOTONoNoNoNoYesYes
      Degree of TR before DSOMildNoneSevereMildMildNone
      Degree of RV dysfunction before DSOModerateNoneMildNoneNoneMild
      Degree of LV dysfunction before DSOSevereModerateNoneNoneNoneMild
      PABYesYesYesYesNoNo
      Indication of PABLV trainingLV trainingLV trainingLV training
      Age at PAB (y)9.823.932.026.24
      Readjustment of PABNoYesYesNo--
      Duration between PAB and readjustment of PAB (y)6.271.59
      Duration from PAB to DSO (y)0.757.2910.416.84
      Creation of ASD at PABNoNoNoNo
      Pacemaker neededYesNoNoNoNoNo
      Type of pacemakerDual chamber (univentricular)
      Use of CRTNoNoNoNoNoNo
      Timing of pacemakerPost DSO
      Duration between DSO and pacemaker (y)15
      Age at DSO (y)10.5711.2312.4413.0813.7314.09
      Weight at DSO (kg)34.133.630.048.153.036.9
      Type of atrial switchSenningMustardMustardMustardMustardMustard
      Tricuspid valve repair at DSONoNoYesNoNoNo
      LVOTO resection at DSONoNoNoNoYesYes
      VSD closure at DSONoNoNoNoYesYes
      Second bypass run neededNoNoNoNoYesNo
      Fibrillation time (min)047974517770
      CPB time (min)NA180179169796185
      CC time (min)NA78578536480
      Length of hospital stay (d)67712146
      Length of ICU stay (d)3332133
      ECMO needed post-DSONoNoNoNoYesYes
      OutcomeAliveAliveAliveAliveDeathAlive
      Time to death from DSO (d)13
      TransplantNoNoNoNoNoNo
      Follow-up (y)17.531.080.021.920.041.56
      ReoperationNoNoNoNoNoNo
      AR at last follow-upNoneMildNoneMild–moderateNone
      AS at last follow-upNoneMildNoneNoneSevere
      MR at last follow-upMild–moderateNoneNoneNoneNone
      MS at last follow-upNoneNoneNoneNoneNone
      TR at last follow-upMild–moderateNoneNoneNoneNone
      Degree of RV dysfunction at follow-upNoneNoneNoneNoneNone
      Degree of LV dysfunction at follow-upNoneNoneNoneModerateNone
      SLL, Situs solitus L-looped ventricles levo; VSD, ventricular septal defect; ASD, atrial septal defect; TV, tricuspid valve; LVOTO, left ventricular outflow tract obstruction; TR, tricuspid regurgitation; RV, right ventricle; LV, left ventricle; PAB, pulmonary artery band; CRT, cardiac resynchronization therapy; CPB, cardiopulmonary bypass; NA, not available; CC, crossclamp; ICU, intensive care unit; ECMO, extracorporeal membrane oxygenation; AR, aortic regurgitation; AS, aortic stenosis; MR, mitral regurgitation; MS, mitral stenosis.
      Table E4Details of patients who underwent double switch operation (DSO) at age 15 years or older
      DetailResult
      Patient No.12345678
      GenderMaleMaleFemaleMaleMaleMaleFemaleFemale
      Segmental anatomySLASLLSLLSLLSLLSLLSLLSLL
      VSDYesYesYesYesYesYesNoYes
      ASDNoNoYesNoNoNoYesNo
      Dysplastic TVNoNoNoNoNoNoYesNo
      LVOTONoNoNoNoYesYesNoYes
      Degree of TR before DSOModerate–severeMildMildModerate–severeModerateNoneMildMild–moderate
      Degree of RV dysfunction before DSONoneNoneNoneNoneNoneNoneMildNone
      Degree of LV dysfunction before DSONoneNoneNoneNoneNoneNoneMildNone
      PABYesNoNoYesNoNoYesNo
      Indication of PABRestrict PBFRestrict PBFLV training
      Age at PAB (y)2.565.9715.78
      Readjustment of PABYesNoYes
      Duration between PAB and readjustment of PAB (y)6.233.09
      Duration from PAB to DSO (y)12.9311.203.66
      Creation of ASD at PABNoNoYes
      Pacemaker neededNoYesNoYesYesYesNoYes
      Timing of pacemakerPost-DSOPre-DSOPost-DSOPost-DSOPre-DSO
      Type of pacemakerDual chamber (univentricular)CRTCRTCRTDual chamber (univentricular)
      Was CRT an upgrade?NoYesNo
      Did CRT improve LV functionYesNoYes
      Age at DSO (y)15.4915.5415.5517.1817.3518.4019.4439.60
      Weight at DSO (kg)3864.241.452.36752.242.366
      Type of atrial switchMustardMustardMustardMustardMustardMustardMustardMustard
      Tricuspid valve repair at DSOYesYesNoNoNoNoNoNo
      LVOTO resection at DSONoYesNoNoYesYesNoNo
      RV to PA conduit insertedYesNoNoNoNoNoNoNo
      VSD closure at DSOYesYesYesYesYesYesNoYes
      Second bypass run neededNoYesNoNoNoNoNoNo
      Fibrillation time (min)1470437500490
      CPB time (min)430292199215251254163284
      CC time (min)21815412286921177689
      Length of hospital stay (d)1399111212913
      Length of ICU stay (d)363212944
      ECMO needed post-DSONoNoNoNoNoNoNoNo
      OutcomeAliveAliveAliveAliveDeathAliveAliveAlive
      Time to death from DSO (d)1302
      TransplantNoNoNoNoNoNoNoNo
      Follow-up (y)0.659.813.080.173.5611.953.8517.86
      ReoperationYesYesYesNoNoNoNoNo
      Years to reoperation0.482.992.89
      Reason from reoperationAtrial baffle, tricuspid valve, and otherNeoaortic valveNeoaortic valve
      AR at last follow-upMildMildNoneMildModerateNoneNone
      AS at last follow-upNoneMildNoneNoneMildNoneModerate
      MR at last follow-upNoneMildNoneNoneMildNoneMild–moderate
      MS at last follow-upNoneNoneNoneNoneNoneNoneNone
      TR at last follow-upMildNoneNoneMildMildNoneMild
      Degree of RV dysfunction at last follow-upNoneNoneNoneNoneNoneNoneNone
      Degree of LV dysfunction at last follow-upMildNoneMildNoneNoneMildNone
      SLA, Situs solitus L-looped ventricles ambiguous; SLL, situs solitus L-looped ventricles levo; VSD, ventricular septal defect; ASD, atrial septal defect; TV, tricuspid valve; LVOTO, left ventricular outflow tract obstruction; TR, tricuspid regurgitation; RV, right ventricle; LV, left ventricle; PAB, pulmonary artery band; CRT, cardiac resynchronization therapy; PA, pulmonary artery; CPB, cardiopulmonary bypass; CC, crossclamp; ICU, intensive care unit; ECMO, extracorporeal membrane oxygenation; AR, aortic regurgitation; AS, aortic stenosis; MR, mitral regurgitation; MS, mitral stenosis.
      Table E5The 95% CIs for competing risks cumulative incidence estimates displayed in Figure 3
      Time since procedure (y)Death/transplantReoperation on neoaortic valveSurgical reintervention excluding pacemakers
      12.18 (0.41-6.95)4.15 (1.34-9.55)3.23 (0.85-8.41)
      22.18 (0.41-6.95)8.24 (3.56-15.45)4.58 (1.46-10.53)
      33.67 (0.95-9.59)11.62 (5.55-20.15)6.09 (2.20-12.86)
      45.41 (1.68-12.50)13.33 (6.64-22.38)6.09 (2.20-12.86)
      55.41 (1.68-12.50)13.33 (6.64-22.38)6.09 (2.20-12.86)
      65.41 (1.68-12.50)13.33 (6.64-22.38)8.30 (3.18, 16.61)
      105.41 (1.68-12.50)13.33 (6.64-22.38)8.30 (3.18-16.61)
      125.41 (1.68-12.50)13.33 (6.64-22.38)8.30 (3.18-16.61)
      Table E6The 95% CIs for competing risks cumulative incidence estimates displayed in Figure E1
      Time since procedure (y)DeathTransplantAll surgical re-intervention
      11.00 (0.09-4.94)1.17 (0.10-5.73)7.37 (3.22-13.83)
      21.00 (0.09-4.94)1.17 (0.10-5.73)12.82 (6.70-20.98)
      31.00 (0.09-4.94)2.67 (0.49-8.45)17.72 (10.02-27.20)
      42.75 (0.47-8.96)2.67 (0.49-8.45)19.43 (11.23-29.28)
      52.75 (0.47-8.96)2.67 (0.49-8.45)19.43 (11.23-29.28)
      62.75 (0.47-8.96)2.67 (0.49-8.45)21.64 (12.68-32.16)
      102.75 (0.47-8.96)2.67 (0.49-8.45)21.64 (12.68-32.16)
      122.75 (0.47-8.96)2.67 (0.49-8.45)21.64 (12.68-32.16)

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