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Commentary: One size fits some—additional pulmonary blood flow at the Glenn operation and patient-specific factors

  • Neel K. Prabhu
    Affiliations
    Duke Congenital Heart Surgery Research & Training Laboratory, Duke University, Durham, NC
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  • Nicholas D. Andersen
    Affiliations
    Duke Congenital Heart Surgery Research & Training Laboratory, Duke University, Durham, NC

    Division of Thoracic and Cardiovascular Surgery, Duke University, Durham, NC

    Duke Children's Pediatric & Congenital Heart Center, Duke Children's Hospital, Durham, NC
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  • Joseph W. Turek
    Correspondence
    Address for reprints: Joseph W. Turek, MD, PhD, MBA, Division of Thoracic and Cardiovascular Surgery, Duke University Medical Center, 2301 Erwin Rd, DUMC 3443, Durham, NC 27710.
    Affiliations
    Duke Congenital Heart Surgery Research & Training Laboratory, Duke University, Durham, NC

    Division of Thoracic and Cardiovascular Surgery, Duke University, Durham, NC

    Duke Children's Pediatric & Congenital Heart Center, Duke Children's Hospital, Durham, NC
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Published:January 29, 2021DOI:https://doi.org/10.1016/j.jtcvs.2021.01.082
      Figure thumbnail fx1
      A “one-size-fits-all” approach to additional pulmonary blood flow at the Glenn operation.
      Outcomes after the Glenn operation may improve by identifying quantitative criteria that define an individual patient's chance of survival if additional pulmonary blood flow is preserved or not.
      See Article page 1346.
      Preservation of additional pulmonary blood flow (APBF) at the Glenn operation is a controversial topic that has been discussed in the literature since the mid-1990s.
      • Knott-Craig C.J.
      • Fryar-Dragg T.
      • Overholt E.D.
      • Razook J.D.
      • Ward K.E.
      • Elkins R.C.
      Modified hemi-Fontan operation: an alternative definitive palliation for high-risk patients.
      In this issue of the Journal, Baek and colleagues
      • Baek J.S.
      • Park C.S.
      • Cdhoi E.S.
      • Yun T.J.
      • Kwon B.S.
      • Yu J.J.
      • et al.
      The impact of additional antegrade pulmonary blood flow at bidirectional Glenn shunt upon long-term outcomes.
      perform a long-term, retrospective analysis of a cohort of more than 200 single-ventricle patients to further investigate. The authors found that the group of patients who received the Glenn operation with preservation of APBF had more than 2-fold greater risk of death or transplant (hazard ratio, 2.37) as well as a 3-fold greater probability of prolonged chest tube drainage and readmission (odds ratio, 3.204) after Glenn—a striking result.
      Overall, the authors should be commended for their work. Few publications on outcomes after the Glenn operation have a study period (15 years), follow-up length (mean 8.4 years after Fontan), cohort size (more than 200 patients), and distribution of cardiac diagnoses as robust as the study here. In addition, the use of propensity matching is thoughtful, as it controls for the presence of ventricular dysfunction, oxygen saturation, atrioventricular valve morphology, and other preoperative variables. However, the study is not without its limitations. For one, despite propensity matching, there is a high likelihood of selection bias with patients presenting at Glenn with smaller pulmonary arteries (PAs) more likely to be in the APBF group. This confounds the analysis, since the propensity score did not incorporate the key variable of pre-Glenn PA size. Furthermore, the supplementary data suggest that patients who likely had pulmonary overcirculation at birth (ie, those that underwent PA banding or arch repair rather than systemic-pulmonary shunt) were represented more heavily in the no-APBF group.
      Historically, proponents of preserving APBF have shown that the strategy makes patients better candidates for the Fontan procedure by increasing systemic oxygen saturations and the growth of pulmonary vasculature.
      • Miyaji K.
      • Shimada M.
      • Sekiguchi A.
      • Ishizawa A.
      • Isoda T.
      Usefulness of pulsatile bidirectional cavopulmonary shunt in high-risk Fontan patients.
      • Ferns S.J.
      • El Zein C.
      • Multani K.
      • Sajan I.
      • Subramanian S.
      • Polimenakos A.C.
      • et al.
      Is additional pulsatile pulmonary blood flow beneficial to patients with bidirectional Glenn?.
      • Yoshida M.
      • Yamaguchi M.
      • Yoshimura N.
      • Murakami H.
      • Matsuhisa H.
      • Okita Y.
      Appropriate additional pulmonary blood flow at the bidirectional Glenn procedure is useful for completion of total cavopulmonary connection.
      However, APBF may be associated with increased loading on the single systemic ventricle and sequelae related to elevated pulmonary pressures such as prolonged chest tube drainage.
      • Ferns S.J.
      • El Zein C.
      • Multani K.
      • Sajan I.
      • Subramanian S.
      • Polimenakos A.C.
      • et al.
      Is additional pulsatile pulmonary blood flow beneficial to patients with bidirectional Glenn?.
      ,
      • Frommelt M.A.
      • Frommelt P.C.
      • Berger S.
      • Pelech A.N.
      • Lewis D.A.
      • Tweddell J.S.
      • et al.
      Does an additional source of pulmonary blood flow alter outcome after a bidirectional cavopulmonary shunt?.
      ,
      • McElhinney D.B.
      • Marianeschi S.M.
      • Reddy V.M.
      Additional pulmonary blood flow with the bidirectional Glenn anastomosis: does it make a difference?.
      While this framework is helpful, the reality is that whether a given patient will benefit from APBF depends on their individual anatomy and physiology. For instance, the patient with hypoxemia, pulmonary atresia, and intact ventricular septum with hypoplastic PAs will likely benefit from pulsatile APBF at Glenn more than the patient with common atrioventricular valve morphology and severe atrioventricular valve regurgitation who is at risk with ventricular volume overload.
      Single-ventricle palliations such as the Glenn operation are nowadays indicated for an ever-increasing number of index diagnoses, many of which were nonsurvivable just a few decades ago. Future research in the optimization of single-ventricle palliation should focus on developing nuanced, quantitative criteria that define the “ideal” patient for various operations, such as preservation versus elimination of APBF at the time of Glenn. For now, however, Baek and colleagues should be commended for their valuable contribution to the literature showing selective elimination of APBF at the time of Glenn can be beneficial for long-term survival.

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