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Three-dimensional printing and virtual reconstruction in surgical planning of double-outlet right ventricle repair

  • Kevin Ponchant
    Correspondence
    Address for reprints: Kevin Ponchant, Cardiovascular Radiology Unit, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
    Affiliations
    Cardiovascular Radiology Unit, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
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  • Duy-Anh Nguyen
    Affiliations
    Pediatric Cardiology Unit, Children's University Hospital, Geneva, Switzerland
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  • Milan Prsa
    Affiliations
    Division of Pediatric Cardiology, Woman-Mother-Child Department, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland

    Centre Universitaire Romand de Cardiologie et Chirurgie Cardiaque Pédiatrique, Geneva University Hospitals/Lausanne University Hospital, Geneva/Lausanne, Switzerland
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  • Maurice Beghetti
    Affiliations
    Pediatric Cardiology Unit, Children's University Hospital, Geneva, Switzerland

    Centre Universitaire Romand de Cardiologie et Chirurgie Cardiaque Pédiatrique, Geneva University Hospitals/Lausanne University Hospital, Geneva/Lausanne, Switzerland
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  • Tornike Sologashvili
    Affiliations
    Centre Universitaire Romand de Cardiologie et Chirurgie Cardiaque Pédiatrique, Geneva University Hospitals/Lausanne University Hospital, Geneva/Lausanne, Switzerland

    Division of Cardiac Surgery, Geneva University Hospitals, Geneva, Switzerland
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  • Jean-Paul Vallée
    Affiliations
    Cardiovascular Radiology Unit, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
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Open AccessPublished:November 25, 2022DOI:https://doi.org/10.1016/j.xjtc.2022.11.005

      Abstract

      Objectives

      For more than a decade, 3-dimensional (3D) printing has been identified as an innovative tool for the surgical planning of double-outlet right ventricle (DORV). Nevertheless, lack of evidence concerning its benefits encourages us to identify valuable criteria for future prospective trials.

      Methods

      We conducted a retrospective study involving 10 patients with DORV operated between 2015 and 2019 in our center. During a preoperative multidisciplinary heart team meeting, we harvested surgical decisions following a 3-increment step process: (1) multimodal imaging; (2) 3D virtual valvular reconstruction (3DVVR); and (3) 3D-printed heart model (3DPHM). The primary outcome was the proportion of predicted surgical strategy following each of the 3 steps, compared with the institutional retrospective surgical strategy. The secondary outcome was the change of surgical strategy through 3D modalities compared with multimodal imaging. The incremental benefit of the 3DVVR and 3DPHM over multimodal imaging was then assessed.

      Results

      The operative strategy was predicted in 5 cases after multimodal imaging, in 9 cases after 3DVVR, and the 10 cases after 3DPHM. Compared with multimodal imaging, 3DVVR modified the strategy for 4 cases. One case was correctly predicted only after 3DPHM inspection.

      Conclusions

      3DVVR and 3DPHM improved multimodal imaging in the surgical planning of patients with DORV. 3DVVR allowed a better appreciation of the relationships between great vessels, valves, and ventricular septal defects. 3DPHM offers a realistic preoperative view at patient scale and enhances the evaluation of outflow tract obstruction. Our retrospective study demonstrates benefits of preoperative 3D modalities and supports future prospective trials to assess their impact on postoperative outcomes.

      Key Words

      Abbreviations and Acronyms:

      3D (3-dimensional), 3DPHM (3D-printed heart model), 3DVVR (3D virtual valvular annulus reconstruction), CTA (computed tomography angiogram), DORV (double-outlet right ventricle), LV (left ventricle), PA (pulmonary artery), PV (pulmonary valve), TGA (transposition of the great arteries), TTE (transthoracic echocardiography), VSD (ventricular septal defect)
      Figure thumbnail fx1
      3DVVR and 3DPHM used in the preoperative planning of surgical strategy.
      Both 3DVVR and 3DPHM improved standard multimodal imaging in the definition of surgical strategy of complex DORV repair.
      Future prospective studies would be appropriate to assess the postoperative impact of 3DVVR and 3DPHM in surgical planning on patient short- and long-term outcomes.
      Congenital heart disease is a global concern in child and adult health. Without the ability to substantially reduce the prevalence of congenital heart disease, interventions and resources must be invested to improve mortality, operative outcomes, survival, and quality of life.
      GBD 2017 Congenital Heart Disease Collaborators
      Global, regional, and national burden of congenital heart disease, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017.
      Double-outlet right ventricle (DORV) is a complex type of ventriculoarterial discordance accounting for 1% to 3% of all congenital heart diseases, with a reported incidence of 3-9/100,000 live births.
      • Loffredo C.A.
      Epidemiology of cardiovascular malformations: prevalence and risk factors.
      ,
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      • Jacobs M.L.
      Congenital heart surgery nomenclature and database project: double outlet right ventricle.
      As the result of its heterogeneity, each DORV case is unique, making surgical planning of its total repair one of the greatest challenges in the field of congenital heart disease.
      • Yim D.
      • Dragulescu A.
      • Ide H.
      • Seed M.
      • Grosse-Wortmann L.
      • van Arsdell G.
      • et al.
      Essential modifiers of double outlet right ventricle: revisit with endocardial surface images and 3-dimensional print models.
      Numerous surgical techniques have been validated for the repair of DORV, including intraventricular repair
      • Lu T.
      • Li J.
      • Hu J.
      • Huang C.
      • Tan L.
      • Wu Q.
      • et al.
      Biventricular repair of double-outlet right ventricle with noncommitted ventricular septal defect using intraventricular conduit.
      and arterial switch operation,
      • Fricke T.A.
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      Arterial switch operation: operative approach and outcomes.
      the Rastelli procedure,
      • Rastelli G.C.
      • Wallace R.B.
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      Complete repair of transposition of the great arteries with pulmonary stenosis. A review and report of a case corrected by using a new surgical technique.
      Réparation à l'Etage Ventriculaire,
      • Lecompte Y.
      Reparation a l'Etage Ventriculaire—the REV procedure: technique and clinical results.
      the Bex-Nikaidoh procedure,
      • Yeh Jr., T.
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      The aortic translocation (Nikaidoh) procedure: midterm results superior to the Rastelli procedure.
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      • Sojak V.
      Nikaidoh vs reparation a l'Etage Ventriculaire vs Rastelli.
      and the outflow tract rotation, also known as half-turned truncal switch operation
      • Hongu H.
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      • Maeda Y.
      • Taniguchi S.
      • Asada S.
      • et al.
      Late results of half-turned truncal switch operation for transposition of the great arteries.
      ,
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      • Shinkawa T.
      • Miyazaki T.
      • et al.
      Half-turned truncal switch operation for complete transposition of the great arteries with ventricular septal defect and pulmonary stenosis.
      or en-bloc rotation of the outflow tracts.
      • Mair R.
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      • Lechner E.
      • Tulzer G.
      En bloc rotation of the truncus arteriosus—an option for anatomic repair of transposition of the great arteries, ventricular septal defect, and left ventricular outflow tract obstruction.
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      • Tulzer G.
      Anatomic repair of complex transposition with en bloc rotation of the truncus arteriosus: 10-year experience.
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      • Tulzer G.
      Effects of surgical en bloc rotation of the arterial trunk on the conduction system in children with transposition of the great arteries, ventricular septal defect and pulmonary stenosis.
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      • Mair R.
      • Gierlinger G.
      • Tulzer A.
      • Saric D.
      • et al.
      En bloc rotation of the outflow tracts: intermediate follow up after 15 years of experience.
      The choice between these procedures is often difficult and dictated by the surgeon's preferences as well as the heart anatomy and associated abnormalities. Imaging plays an important role in this assessment.
      • Yim D.
      • Dragulescu A.
      • Ide H.
      • Seed M.
      • Grosse-Wortmann L.
      • van Arsdell G.
      • et al.
      Essential modifiers of double outlet right ventricle: revisit with endocardial surface images and 3-dimensional print models.

      Imaging and 3-Dimensional (3D) Printing

      Multimodal imaging, including transthoracic echocardiography (TTE), computed tomography angiogram (CTA), and magnetic resonance imaging (MRI), is a key element in surgical planning using both 2-dimensional visualization and well-established 3D-reconstruction techniques. Complex intracardiac anatomy visualization can be improved with new 3D modalities.
      • Garner K.H.
      • Singla D.K.
      3D modeling: a future of cardiovascular medicine (1).
      In particular, 3D virtual valvular reconstruction (3DVVR) and 3D-printed heart model (3DPHM) have the potential to revolutionize the care of pediatric cardiac patients.
      • Yoo S.J.
      • van Arsdell G.S.
      3D printing in surgical management of double outlet right ventricle.
      However, their impact on surgical planning is still not well established. Although some studies have tried to demonstrate the utility of 3D printing in surgical planning for patients with DORV,
      • Valverde I.
      • Gomez-Ciriza G.
      • Hussain T.
      • Suarez-Mejias C.
      • Velasco-Forte M.N.
      • Byrne N.
      • et al.
      Three-dimensional printed models for surgical planning of complex congenital heart defects: an international multicentre study.
      • Ryan J.
      • Plasencia J.
      • Richardson R.
      • Velez D.
      • Nigro J.J.
      • Pophal S.
      • et al.
      3D printing for congenital heart disease: a single site's initial three-year experience.
      • Zhao L.
      • Zhou S.
      • Fan T.
      • Li B.
      • Liang W.
      • Dong H.
      Three-dimensional printing enhances preparation for repair of double outlet right ventricular surgery.
      • Sun Z.
      • Lau I.
      • Wong Y.H.
      • Yeong C.H.
      Personalized three-dimensional printed models in congenital heart disease.
      • Lau I.W.W.
      • Sun Z.
      Dimensional accuracy and clinical value of 3d printed models in congenital heart disease: a systematic review and meta-analysis.
      • Batteux C.
      • Haidar M.A.
      • Bonnet D.
      3D-printed models for surgical planning in complex congenital heart diseases: a systematic review.
      Batteux and colleagues
      • Batteux C.
      • Haidar M.A.
      • Bonnet D.
      3D-printed models for surgical planning in complex congenital heart diseases: a systematic review.
      mentioned the lack of evidence for such benefits due to heterogeneity of studied congenital heart disease and suggested that retrospective comparison of 3D models with standard multimodal imaging should be the first step to perform. Therefore, this study aimed to compare retrospectively the added value of 3DVVR and 3DPHM with standard multimodal imaging in the planning of DORV surgical repair.

      Methods

      Study Design

      We conducted a retrospective study of 10 pediatric patients with DORV who underwent surgical repair by a single surgeon in 2 tertiary hospitals between 2016 and 2019. The study was approved by the institutional review board (authorization 2017-00716, 31.01.2018). The inclusion criteria were patients with DORV transposition of great arteries (TGA) type who could undergo surgical repair and the availability of preoperative echocardiogram as well as a cardiac MRI or CTA. Patient data were deidentified and uploaded to an institutional secured cloud server. Patients were discussed among the members of a multidisciplinary pediatric heart team, which included 2 pediatric cardiologists, 1 cardiac surgeon, and 1 cardiovascular radiologist. The incremental value of 3DVVR and 3DPHM was determined by a 3-step evaluation process (Figure 1).
      Figure thumbnail gr1
      Figure 1Design of our study. DORV, Double-outlet right ventricle; TTE, transthoracic echocardiography; CTA, computed tomography angiogram; MRI, magnetic resonance imaging; 3DVR, 3-dimensional virtual reconstruction; 3DPHM, 3-dimensional printed heart model.

      Step 1: Multimodality Imaging

      All patients had complete TTE, presented by a pediatric cardiologist (Figure E1). Seven patients had MRI, and 3 patients had CTA, including a volume rendering of the blood pool, presented by the cardiovascular radiologist (Figure E2). A first decision about the type of surgical repair was recorded at this point.

      Step 2: 3D Virtual Valvular Annuli Reconstruction

      3DVVR was carried out by segmentation of a model from either CTA or MRI scans using the open-source software 3D Slicer.
      • Fedorov A.
      • Beichel R.
      • Kalpathy-Cramer J.
      • Finet J.
      • Fillion-Robin J.C.
      • Pujol S.
      • et al.
      3D slicer as an image computing platform for the Quantitative Imaging Network.
      A semiautomated segmentation was completed by manual correction when needed. All 4 valvular annuli were manually depicted and kept opaque, whereas the blood pool was made semitransparent. Chordal attachment aberrations and straddling were only analyzed on multimodal imaging (TTE, CTA/MRI) and were not represented on 3DVVR nor 3DPHM. Each segment can be selectively faded or hidden, allowing user-defined visualization of the cavities and valves (Figure 2). A second decision about the type of surgical repair was recorded following 3DVVR visualization.
      Figure thumbnail gr2
      Figure 2A sequential 3D virtual reconstruction of anatomical segments. (A) Postsegmentation 3D virtual reconstruction. (B) Myocardium is hidden; (C) RA, LV, and RV hidden, to appreciate intervalvular relationship with VSD. Aortic and mitral valves are shown in red, pulmonary and tricuspid in blue, and VSD in purple. (D) Complete valvular visualization with VSD in purple. S, Superior; A, anterior; L, left; R, right; P, posterior; I, inferior.

      Step 3: 3DPHM

      The process of 3D printing included image segmentation and exporting in standard tessellation language (ie, STL) file format using 3D Slicer, correction of the standard tessellation language model by MeshMixer (Autodesk, Inc) and 3D printing with a Stratasys Objet260 Connex 3 printer (version 29.11.0.19189). The resins used were VeroWhite Plus, VeroBlack, and VeroMagenta for the valves and TangoPlus for the cardiac chambers and vessels. A 1:1 scale 3DPHM (Figure E3) was presented in 3 parasagittal slices allowing complete visualization of cardiac chambers and great vessels. A third and final decision was then recorded.
      At the end of the simulation, the previous original heart team decision as well as operative records with perioperative findings and performed surgical procedure were revealed. On the basis of the latter, an institutional retrospective surgical strategy, defined as a composite of the performed procedure and the final simulated heart team decision considering currently available expertise, was finally defined as the gold standard and compared with each of the 3-step decisions.

      Primary and Secondary Outcomes

      The primary outcome was the proportion of correctly predicted surgical repair strategies following multimodal imaging, 3DVVR, and 3DPHM. The secondary outcome was the change of surgical strategy between the multimodal imaging step and the two 3D modalities steps (3DVVR and 3DPHM). The incremental benefit of 3DVVR and 3DPHM was then compared separately. We also reported patients' outcomes, such as intensive care unit length of stay, hospitalization length of stay, in-hospital survival, reoperation rate, need of permanent pacemaker, and up-to-follow-up survival.

      Results

      Ten patients with DORV who underwent operation in our institution between 2015 and 2019 were included in the study. All had DORV TGA-type with anteroposterior (n = 7) and side-by-side aortopulmonary positions (n = 3). Sex repartition was 6 male and 4 female patients. The mean age of pediatric patients was 4.4 years ± 4.1 years. Mean time between the surgical repair and the study was an average of 19 months (Tables E1 and E2).
      Surgical repair included 3 arterial switch operations, 3 Bex-Nikaidoh procedures, 1 intraventricular repair, 1 outflow tract rotation, 1 postponed Bex-Nikaidoh after previous pulmonary artery (PA) banding and atrioseptotomy, and 1 single-ventricle palliation. The retrospective institutional surgical strategies following the 3 steps process resulted in 4 outflow tract rotations, 3 Bex-Nikaidoh procedures, 2 arterial switch operations, and 1 intraventricular repair. There were discrepancies between operative records and simulated heart team final decision for 4 patients resulting from temporal evolution of surgical expertise (for p01, single-ventricle palliation changed to Bex-Nikaidoh; for p03, Bex-Nikaidoh changed to outflow tract rotation; for p05, PA banding and atrioseptotomy before Nikaidoh changed to PA banding and atrioseptotomy before outflow tracts rotation; for p10, arterial switch operation changed to outflow tract rotation).

      Primary Outcome: Predictive Value of Multimodal Imaging and 3D Modalities

      Decisions for each case following the 3-step simulation are summarized in Figure 3. According to retrospective institutional surgical strategies, the prediction after multimodal imaging concurred for 5 cases (p02, p05, p06, p07 p09). The evaluation of 3DVVR confirmed the prediction of theses 6 cases and brought 4 additional correct predictions (p01, p02, p03, p04, p05, p06, p07, p09, p10). Finally, 3DPHM analysis confirmed those 9 cases and brought 1 additional correct prediction (p08), resulting in correct prediction for all 10 cases.
      Figure thumbnail gr3
      Figure 3Sequential predicted surgical strategies, compared with original heart team decision, and medical records to define retrospective institutional surgical strategy. 3DVR, Changes due to 3-dimensional reconstruction; 3DPHM, change due to printed models; OTR, outflow tract rotation; SVP, single ventricular palliation; ASO, arterial switch operation; IVR, intraventricular repair.

      Secondary Outcomes: Optimization of Surgical Strategy Through 3D Modalities and Patient Outcomes

      3D modalities contributed to optimization in surgical strategy for 5 cases. 3DVVR were involved in the modification of 4 cases (p01, p03, p04, p10), and 3DPHM in 1 case (p08). Concerning 3DVVR modifications, 2 Bex-Nikaidoh were preferred to outflow tract rotation (for p01 and p04) due to the better appreciation of pulmonary valve (PV) stenosis by the 3D rendering (Figure 4) (see p04 case description in Table E3). In addition, 2 outflow tract rotations were preferred to arterial switch operation as the result of better evaluation of PV stenosis for p03 and PV dilation for p10 due to the high risk of neoaortic valve insufficiency in case of arterial switch operation (Figure 5) (see p10 case description in Tables E3).
      Figure thumbnail gr4
      Figure 43D virtual valvular reconstruction and printed model of p04.
      Figure thumbnail gr5
      Figure 53D virtual valvular reconstruction and printed model of p10.
      3DPHM contributed to correct the prediction for 1 patient (p08) (Figure 6). This case was a complex anatomical DORV with a side-by-side aortopulmonary position, a noncommitted ventricular septal defect (VSD) with inlet extension, and an important straddling of the tricuspid valve with a chordal attachment on the left side of the septum. This makes intraventricular repair (left ventricle [LV]-to-aorta baffle) impossible. Nikaidoh or outflow tract rotation was compromised as the result of complex abnormal coronary pathway. The left coronary artery gave rise to the interventricular artery, the circumflex artery, and the right coronary artery. An abnormal coronary artery with a suprasinusal ostium gave rise to conal and infundibular perforating arteries. This would have led to a high-risk root harvesting with potential coronary damage. Therefore, multimodal imaging advocated for single-ventricle palliation as the best surgical strategy. 3DVVR suggested a seemingly shorter distance between the LV and PA but was not sufficiently convincing for a biventricular repair with arterial switch operation. 3DPHM, with its 1:1 scale, gave the best appreciation of the actual short LV-to-PA distance for resectability of subpulmonary conus, making an arterial switch operation with LV-to-PA (neoaorta) baffling feasible. Retrospectively, the original heart team decision was a single-ventricle palliation, but peroperative findings changed the strategy to an arterial switch operation with LV to PA/neoartic valve baffling. In conclusion, 3DVVR was not convincing enough to support a biventricular repair. Only 3DPHM in this case allowed us to foresee intraoperative findings and to correctly anticipate the applied surgical strategy.
      Figure thumbnail gr6
      Figure 63D virtual valvular reconstruction and printed model of p08.
      The mean intensive care unit length of stay was 9.4 days (±7 days). Hospitalization length of stay was 19.8 days (±11.6 days). In-hospital survival was 100%. P01 went through a single-ventricle palliation, which meant 3 operations at a 2-year interval. P06 was reoperated at 5 days for a revision of the intraventricular tunnelization due to residual left to right shunt. Three days after the reoperation, complete atrioventricular block motivated a bicameral permanent pacemaker implantation. P07 needed a reoperation for tricuspid repair due to complete rupture of a tricuspid chordae at 4 days postoperatively. Only 1 patient needed a permanent pacemaker after the reoperation. Survival could have been evaluated for 2 patients (p01 and p05), respectively 2 and 7 years after their operations.

      Discussion

      The main result of our study showed that surgical strategy was correctly predicted in 50% (5/10) by multimodal imaging, 90% (9/10) by 3DVVR, and 100% by the 3DPHM. Both 3DVVR and 3DPHM improved the definitive surgical strategy prediction.
      Our results are in accordance with current literature. Several studies demonstrate promising results concerning the use of 3D printing in preoperative planning. Valverde and colleagues
      • Valverde I.
      • Gomez-Ciriza G.
      • Hussain T.
      • Suarez-Mejias C.
      • Velasco-Forte M.N.
      • Byrne N.
      • et al.
      Three-dimensional printed models for surgical planning of complex congenital heart defects: an international multicentre study.
      reported a multicentric prospective case-crossover study including 10 centers, 80 pediatric cardiologists, and 22 surgeons using 3D models of various complex congenital heart disease, comparing the surgical indication using standard multimodality imaging alone with the same process with 3DPHM, finally confronted to surgical findings. In this study, 3D models were considered helpful in optimizing surgical planning in 19 of 40 patients (48%). No data were provided on specific anatomical structures or key elements triggering modification of the decision with a wide heterogeneity of included heart defects.
      Ryan and colleagues
      • Ryan J.
      • Plasencia J.
      • Richardson R.
      • Velez D.
      • Nigro J.J.
      • Pophal S.
      • et al.
      3D printing for congenital heart disease: a single site's initial three-year experience.
      retrospectively compared a presurgical 3DPHM group of 33 pediatric patients with DORV and dextro-TGA with a routine imaging group of 113 cases, showing a reduction trend of mean operative time for the 3DPHM group. These results mirror findings from Zhao and colleagues,
      • Zhao L.
      • Zhou S.
      • Fan T.
      • Li B.
      • Liang W.
      • Dong H.
      Three-dimensional printing enhances preparation for repair of double outlet right ventricular surgery.
      who compared 8 DORV cases in the 3DPHM group with 17 cases in the control group. The 3DPHM group had shorter operative, cardiopulmonary bypass, aortic crossclamping, and mechanical ventilation times than the control group. These findings implicitly indicate 3DPHM could play a critical role in enhancing preoperative planning. However, Lau and Sun
      • Lau I.
      • Sun Z.
      Three-dimensional printing in congenital heart disease: a systematic review.
      stressed that both studies did not achieve statistical significance, probably because of small sample size, rather than unfavorable outcomes.
      Our study entails multiple strengths. First, the capacity of a multidisciplinary pediatric heart team to orchestrate and manage pre-, per-, and postoperative care of those complex cases allowed 3DPHM evaluation for complex cases planning. Second, we focused on DORV TGA-type exclusively, evaluating a homogenous group of patients. Third, the free and open-source 3D virtual reconstruction 3D Slicer software represents a low-cost and effective segmentation tool allowing easy deployment in clinical workflow.
      Interestingly, 3DVVR was the most useful 3D modality for the optimization of surgical strategy. 3DVVR incremental value resided in the evaluation of relative size of valvular annuli and their relation to VSD. TTE offers noninvasive bedside valvulopathy assessment but lacks accuracy in measuring valvular dimensions in some patient categories compared with MRI.
      • Cawley P.J.
      • Maki J.H.
      • Otto C.M.
      Cardiovascular magnetic resonance imaging for valvular heart disease: technique and validation.
      ,
      • Myerson S.G.
      CMR in evaluating valvular heart disease: diagnosis, severity, and outcomes.
      Nevertheless, MRI does not confer tridimensional intracardiac reconstruction. 3DVVR conveys a pragmatic solution to this. This modality could also alleviate the cost, time, and availability of 3DPHM. Nevertheless, 3DPHM was particularly helpful to evaluate 3DVVR findings at patients 1:1 scale, offering a realistic preoperative view and a better prediction of postoperative potential outflow tracts obstruction. Hence, the surgeon could consider with more confidence certain complex surgical strategies, such as outflow tract rotation. Other 3DPHM benefits, although not investigated in our study, are currently discussed in the literature
      • Lau I.W.W.
      • Liu D.
      • Xu L.
      • Fan Z.
      • Sun Z.
      Clinical value of patient-specific three-dimensional printing of congenital heart disease: quantitative and qualitative assessments.
      : clinical communication, discussion with the patient's family, and surgical rehearsal or training of complex cases. New 3D tools, such as virtual reality, are beginning to appear, with the potential of alleviating the need of printed models. Milano and colleagues
      • Milano E.G.
      • Kostolny M.
      • Pajaziti E.
      • Marek J.
      • Regan W.
      • Caputo M.
      • et al.
      Enhanced 3D visualization for planning biventricular repair of double outlet right ventricle: a pilot study on the advantages of virtual reality.
      reported a retrospective study of 10 patients with DORV with complex VSD types undergoing 3DPHM and virtual reality in the surgical planning. Multimodal imaging left 25% of patients with an univentricular repair, which was then reduced to 15% after 3DPHM evaluation, and only 5% after virtual reality. This latter option helped to consider biventricular repair, the arterial switch operation, for 95% of patients, in accordance with the actual surgical planning.
      Lau and colleagues
      • Lau I.
      • Gupta A.
      • Sun Z.
      Clinical value of virtual reality versus 3D printing in congenital heart disease.
      enrolled 29 practitioners to study the additional benefit of virtual reality and 3DPHM. The study demonstrated no significant differences between both technologies, but 72% of practitioners supported both the additional benefits of virtual reality and 3DPHM compared with multimodal imaging visualization. Whether virtual reality is able to challenge the need for 3DPHM remains to be investigated in larger clinical trials.
      Several limitations of our study were identified. Primary and secondary end points could be inherently biased due to the nonmeasurability of human factors that drive decision-making. Important confounders such as the evolving experience of the surgeon, the awareness of alternative strategies, personal/institutional bias, preferences of referring provider, as well as risk aversion cannot be avoided. The retrospective virtual decision-making approach is not always correlated with real-time decisions secondary to potential clinical variables regarding a patient at the time of actual surgical planning. The same heart team took care of these cases several years ago, introducing a potential recognition bias in our study. We tried to minimize those biases with a multidisciplinary and consensual approach and a blinded analysis of the cases with an average surgery-to-study meantime of 19 months, but we acknowledge that they could still be present. Even if the choice of surgery strategy has inherently a subjective component, we believed that the present results are still valuable because they emphasized the objective part of our decision supported by imaging and that they could help other centers in their decision-making. Finally, we could not include all patients with DORV in our institution because of absence of CTA and MRI for the patients operated on the basis of echocardiographic imaging only.

      Clinical Studies and Future Evolution

      3DVVR and 3DPHM demonstrated great potential to be routinely implemented for the surgical planning of patients with DORV. As the experience expands, the demand for reconstructions and models will increase and its use will be integrated systematically. 3D rendering of the heart represents strong clarifying tools to assess the complexity of intracardiac architecture, to identify critical steps, and to anticipate anatomical pitfalls, thus bringing strategic and technical solutions for surgical planning of patients with DORV. Future prospective studies are needed to quantitatively measure whether 3DPHM implementation reduces operative time, hospital length of stay, as well as morbidity and mortality rate. From there, cost–benefit analysis can be carried out to evaluate the efficiency of 3D modalities in the surgical planning of patients with DORV.

      Conclusions

      Both 3DVVR and 3DPHM improved standard multimodal imaging for the surgical strategy planning of patients with complex DORV TGA-type according to our practice. 3D modalities contributed to strategy optimization in 5 of 10 cases. 3DVVR was involved in 4 optimizations and allowed us to better appreciate 3D relationships between great vessels, their valves, and VSD, which makes it the most useful 3D modality for surgical strategy planning. 3DPHM, contributing to optimize 1 case and correctly predicting all of them, was particularly helpful to assess 3DVVR findings at a 1:1 patient scale and improve the evaluation of any outflow tract obstruction, offering a realistic preoperative view. This retrospective study confirms the added value of 3DVVR and 3DPHM for surgical strategy planning and supports future prospective studies to assess their postoperative impact on patient outcomes.

      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 fx2
      Figure E1TTE images. A, TGA. B, Size discrepancy between aorta and pulmonary trunk. C, Large subpulmonary VSD. D, VSD with posterior extension. E, Doppler of pulmonary trunk.
      Figure thumbnail fx3
      Figure E2MRI acquisition: TGA with anteroposterior aortopulmonary position, subpulmonary VSD with posterior extension.
      Figure thumbnail fx4
      Figure E3The model allowed a hands-on anatomical analysis with scale respecting dimensions. On the first image (right), a pseudo-sagittal cut of the RV can be appreciated. The black shows the aortic annulus and magenta shows the TV. On the left, VSD is subpulmonary, and the pulmonary stenosis is denoted in black (arrow). A, Anterior; S, superior; L, left.
      Table E1Patient characteristics at admission
      PatientsSexAge, yWeight, kgWeight percentileHeight, cmHeight percentileSpO2, %Position of great arteriesImaging to study interval, mo
      p01M0315.3P5096.3P2580TGA57
      p02F029.28P3-1070<P398Side-by-side14
      p03M0110.9P2588P7574TGA27
      p04M0618P3-10109P365TGA34
      p05F044.57<P363P3-1075TGA42
      p06F018.5<P384.5P25-5096Side-by-side5
      p07M0212.5P25-5090P5075TGA4
      p08M1323.5<P3141<P375Side-by-side3
      p09M1024.6<P3136P10-P2572TGA3
      p10F29.5<P384P3-P1086TGA2
      SpO2, Oxygen saturation; M, male; TGA, transposition of the great arteries; F, female.
      Table E2Description of DORV types and associated findings
      DORV typeVSDASDValvular anomalyStenosis
      p01TGASubpulmonary with inlet extensionSubpulmonary and valvular
      p02Side-by-sidesubaortic and trabecularSubaortic
      p03TGAinletOstium primum (OP) + otium secundum (OS)Mitral valve (MV), pulmonary valve (PV)Subpulmonary
      p04TOFSubaortic and trabecularOSSub-, supra-, and pulmonary (hypoplasia of PT from RPA)
      p05TGASubpulmonary with posterior extensionOSSubpulmonary and valvular
      p06TGASubpulmonary with posterior extension and trabecularStraddling tricuspid valve (TV) and MVSubpulmonary and valvular
      p07Side-by-sideRestrictive perimembraneoussubaortic (TV attaches to septal crest), outlet septum
      p08TGASubpulmonary with posterior extension and trabecularsubpulmonary, leveled (hypoplasia PT, from LPA)
      p09Side-by-sideInlet and trabecularTV straddlingRVOTO (conus + anterior pap.)
      p10TGASubpulmonary and inletSubpulmonary
      p11TGASubpulmonaryOSAortic hypoplasia, PAs dilation
      Case description with 3DVVR and 3DPHM of 3 DORV cases: p01: DORV TGA-type with severe pulmonary stenosis and subpulmonary VSD. The panel opted for an OTR after multimodality imaging step. The 3DM led in favor of a Nikaidoh due to severe pulmonary stenosis convincingly assessed after 3DVR, and confirm after the 3DPHM. An SVP was realized at the time of intervention according to medicosurgical decision. The temporal surgical expertise may explain the discrepancy. p03: TGA anteroposterior aortopulmonary orientation, with subpulmonary stenosis and inlet VSD. The pulmonary integrity suggested an ASO or OTR at multimodality imaging step. However, after the 3DVR visualization, OTR seemed more suitable due to better perceived stenotic pulmonary valve. 3DPHM confirmed the suspicion that convinced the team for an OTR. At the time of intervention, a Nikaidoh procedure was performed due to temporal surgical expertise. p05: DORV D-TGA type, with subvalvular and pulmonary stenosis, and subpulmonary VSD with posterior extension. 3DVR and 3DPHM resulted in a Nikaidoh procedure compared with a OTR after MI. In the medical records, OTR has been surgically attempted but a residual transpulmonary gradient made PVR necessary, adopting a Nikaidoh procedure. The 3DVR and 3DPHM would have facilitated the early adoption for a Nikaidoh procedure and could have reduced the operative time. p09: DORV TGA type, side-by-side aortopulmonary position, with inlet and trabeculated VSD and TV straddling as well as a medioventricular obstacle due to double conus. After multimodality imaging, SVP seemed better suited. The 3DVR brought consideration for biventricular reparation through ASO. 3DPHM changed the surgical strategy for a biventricular repair with ASO through representations of the aortic and pulmonary annuli relative matching size, the inlet VSD relation with the PV and the resectability of the second conus making a baffle from VSD to PV conceivable. Retrospectively, the original heart team decision was an SVP but peroperative findings changed the strategy for an ASO with VSD to neoartic valve baffling. The 3D modalities could have convinced for a straight away ASO. p11: DORV TGA-type, subpulmonary stenosis, hypoplastic aortic arch, and dilation of pulmonary arteries. An ASO was first considered after multimodal imaging, considering an integer pulmonary valve with a moderate dilated caliber. Then, OTR was finally preferred to ASO after 3DVR and 3DPHM, due to better appreciation of dilated pulmonary annulus at increased risk of neoaortic valve insufficiency in the future following an ASO. In the operative records, an ASO was attempted due to temporal surgical expertise. DORV, Double-outlet right ventricle; VSD, ventricular septal defect; ASD, atrial septal defect: TGA, transposition of the great arteries; TOF, tetralogy of Fallot; PT, pulmonary trunk; RPA, right pulmonary artery; LPA, left pulmonary artery; RVOTO, right ventricular outflow tract obstruction; PA, pulmonary artery.
      Table E3Case description with 3DVVR and 3DPHM of 3 DORV cases
      p01: DORV TGA-type with severe pulmonary stenosis and subpulmonary VSD. The panel opted for an OTR after multimodality imaging step. The 3DM led in favor of a Nikaidoh due to severe pulmonary stenosis convincingly assessed after 3DVR and confirm after the 3DPHM. SVP was realized at the time of intervention according to medicosurgical decision. The temporal surgical expertise may explain the discrepancy.
      p03: D-TGA anteroposterior aortopulmonary orientation, with subpulmonary stenosis and inlet VSD. The pulmonary integrity suggested an ASO or OTR at multimodality imaging step. But after the 3DVR visualization, OTR seemed more suitable due to better perceived stenotic pulmonary valve. 3DPHM confirms the suspicion that convinced the team for an OTR. At the time of intervention, a Nikaidoh procedure was performed due to temporal surgical expertise.
      p04: DORV D-TGA type, with subvalvular and pulmonary stenosis, and subpulmonary VSD with posterior extension. 3DVR and 3DPHM resulted in a Nikaidoh procedure compared to a OTR after MI. In the medical records, OTR has been surgically attempted but a residual transpulmonary gradient made PVR necessary, adopting a Nikaidoh procedure. The 3DVR and 3DPHM would have facilitated the early adoption for a Nikaidoh procedure and could have reduced the operative time.
      p08: DORV TGA type, side-by-side aortopulmonary position, with inlet and trabeculated VSD and TV straddling as well as a medioventricular obstacle due to double conus. After multimodality imaging, SVP seemed to better suit. The 3DVR brought consideration for biventricular reparation through ASO. 3DPHM changed the surgical strategy for a biventricular repair with ASO through representations of the aortic and pulmonary annuli relative matching size, the inlet VSD relation with the PV and the resectability of the second conus making a baffle from VSD to PV conceivable. Retrospectively, the original heart team decision was an SVP but perioperative findings changed the strategy for an ASO with VSD to neoaortic valve baffling. The 3D modalities could have convinced for a straight away ASO.
      p10: DORV TGA-type, subpulmonary stenosis, hypoplastic aortic arch and dilation of pulmonary arteries. An ASO was first considered after multimodal imaging, considering a integer pulmonary valve with a moderate dilated caliber. Then, OTR was finally preferred to ASO after 3DVR and 3DPHM, due to better appreciation of dilated pulmonary annulus at increased risk of neoaortic valve insufficiency in the future following an ASO. In the operative records, an ASO was attempted due to temporal surgical expertise.

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