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Commentary: Lateral tunnel or extracardiac conduit for a Fontan operation: Is that your final answer?

  • David Barron
    Correspondence
    Address for reprints: David Barron, MD, FRCS(CT), Division of Cardiovascular Surgery, The Labatt Family Heart Centre, The Hospital for Sick Children, 555 University Ave, Toronto, Ontario M5G 1X8 Canada.
    Affiliations
    Division of Cardiovascular Surgery, The Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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  • Alvise Guariento
    Affiliations
    Division of Cardiovascular Surgery, The Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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Published:December 31, 2020DOI:https://doi.org/10.1016/j.jtcvs.2020.12.108
      Figure thumbnail fx1
      What is the best surgical strategy for a Fontan operation? Is that your final answer?
      Outcomes for the Fontan circulation are excellent with no definitive answer regarding which surgical strategy is preferable.
      See Article page 1825.
      When Francis Fontan first performed the procedure that would bear his name, little did he know that 50 years later we would still be debating how best to do it.
      • Fontan F.
      • Baudet E.
      Surgical repair of tricuspid atresia.
      Despite the extracardiac conduit (ECC) having become the most widely practiced technique, the lateral tunnel (LT) is still commonly used. We are now faced with a growing list of large, single-institution studies and registry reports that seem to provide contradictory evidence regarding which is preferable. A recent study from Boston Children's Hospital has fueled the debate, suggesting that the LT may offer better outcomes despite the global trend toward the ECC.
      • Weixler V.H.M.
      • Zurakowski D.
      • Kheir J.
      • Guariento A.
      • Kaza A.K.
      • Baird C.W.
      • et al.
      Fontan with lateral tunnel is associated with improved survival compared with extracardiac conduit.
      The article by Daley and d'Udekem
      • Daley M.
      • d'Udekem Y.
      The optimal Fontan operation: lateral tunnel or extracardiac conduit?.
      is a welcome attempt to appraise the available literature to try and give us a final answer. The wealth of data look ripe for a detailed meta-analysis, but we acknowledge that it is not that simple. Indeed, it is nearly impossible to adjust for the myriad variables and missing data that confound so many of the published studies. Even more importantly, the exact pre-Fontan hemodynamic parameters vary from study to study. Data are frequently incomplete and an intrinsic confounding era effect is often present, considering the earlier development of an LT. All of these make the construction of a meaningful meta-analysis difficult, as previous authors have found.
      • Ben Ali W.
      • Bouhout I.
      • Khairy P.
      • Bouchard D.
      • Poirier N.
      Extracardiac versus lateral tunnel fontan: a meta-analysis of long-term results.
      Knowing the problems of the failing Fontan, it makes good sense to completely exclude the atria from the Fontan circuit, thus avoiding the atrial distension that can be a prequel to atrial arrhythmia and thrombosis. Daley and d'Udekem's analysis
      • Daley M.
      • d'Udekem Y.
      The optimal Fontan operation: lateral tunnel or extracardiac conduit?.
      does indeed suggest that ECC may reduce these risks, but that an appropriately sized conduit must be chosen (influenced by age at Fontan). Conversely, incorporation of the right atrium into the Fontan pathway does allow some distensibility and venous capacitance, which may explain why the LT is associated with less and shorter duration of pleural drainage.
      The truth seems to be that both provide extremely effective Fontan circulations with nearly entirely equivalent outcomes. In a Fontan physiology, good ventricular function and low pulmonary vascular resistance pretty much trump anything and are likely to be far more important in dictating outcomes than the exact type of the Fontan we choose.
      • Hosein R.B.M.
      • Clarke A.J.B.
      • McGuirk S.P.
      • Griselli M.
      • Stumper O.
      • De Giovanni J.V.
      • et al.
      Factors influencing early and late outcome following the Fontan procedure in the current era. The “Two Commandments”?.
      The roles of fenestrations and anticoagulation regimens may also have much more relevance than LT versus ECC.
      We can be reassured that both LT and ECC have excellent outcomes and, to some extent, we are free to choose what we are most comfortable with. The authors suggest a randomized clinical trial (always the ideal solution) but the reality is that there may be little appetite for this given that outcomes with both are so good. It may be that new large registries, such as the Australia and New Zealand Fontan Registry, may give us the answer.
      Given the efficacy of both techniques, future interest is likely to be more focused on providing augmentation for the existing Fontan circulations, whether as mechanical or bioassisted, temporary or permanent systems. Which is better, LT or ECC? Final answer: We don't know yet (Figure 1).
      Figure thumbnail gr1
      Figure 1What is the best surgical strategy for a Fontan operation? Is that your final answer?

      References

        • Fontan F.
        • Baudet E.
        Surgical repair of tricuspid atresia.
        Thorax. 1971; 26: 240-248
        • Weixler V.H.M.
        • Zurakowski D.
        • Kheir J.
        • Guariento A.
        • Kaza A.K.
        • Baird C.W.
        • et al.
        Fontan with lateral tunnel is associated with improved survival compared with extracardiac conduit.
        J Thorac Cardiovasc Surg. 2020; 159: 1480-1491.e2
        • Daley M.
        • d'Udekem Y.
        The optimal Fontan operation: lateral tunnel or extracardiac conduit?.
        J Thorac Cardiovasc Surg. 2021; 162: 1825-1834
        • Ben Ali W.
        • Bouhout I.
        • Khairy P.
        • Bouchard D.
        • Poirier N.
        Extracardiac versus lateral tunnel fontan: a meta-analysis of long-term results.
        Ann Thorac Surg. 2019; 107: 837-843
        • Hosein R.B.M.
        • Clarke A.J.B.
        • McGuirk S.P.
        • Griselli M.
        • Stumper O.
        • De Giovanni J.V.
        • et al.
        Factors influencing early and late outcome following the Fontan procedure in the current era. The “Two Commandments”?.
        Eur J Cardiothorac Surg. 2007; 31: 344-353

      Linked Article

      • The optimal Fontan operation: Lateral tunnel or extracardiac conduit?
        The Journal of Thoracic and Cardiovascular SurgeryVol. 162Issue 6
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          The most widely adopted variations of the Fontan procedure are the extracardiac conduit (ECC) and the lateral tunnel (LT). Over the last decade, there seemed to have been a shift in our practice, with the majority of the Fontan operations being the ECC, on the premise of the simplicity of this procedure and the expectation that it can better prevent the late occurrence of arrhythmias. A recent article in the Journal by a team from Boston demonstrated that in their hands, the ECC was associated with worse early outcomes compared with the LT.
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