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      The Fontan Circulation: Contemporary Review of Ongoing Challenges and Management Strategies

      , MD 1 , , MD 1 , , MD, PhD , 2

      Cardiovascular Innovations and Applications

      Compuscript

      Fontan, single ventricle

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          Abstract

          Since its original description, the Fontan operation has been widely used for the palliation of children with single ventricle physiology and has resulted in an increasing number of these patients surviving to adulthood. The Fontan operation is a unique approach to create a circulation in series without two distinct pumping chambers. Although the Fontan operation increased the survival rates of patients with single ventricle physiology, it carries an inevitable risk of long-term morbidities that impacts the outcomes and quality of life in these patients. In this review, we discuss the challenges resulting from the unique pathophysiology of Fontan circulation and propose management strategies.

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          Most cited references 106

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          Carvedilol for children and adolescents with heart failure: a randomized controlled trial.

          Although beta-blockers improve symptoms and survival in adults with heart failure, little is known about these medications in children and adolescents. To prospectively evaluate the effects of carvedilol in children and adolescents with symptomatic systemic ventricular systolic dysfunction. A multicenter, randomized, double-blind, placebo-controlled study of 161 children and adolescents with symptomatic systolic heart failure from 26 US centers. In addition to treatment with conventional heart failure medications, patients were assigned to receive placebo or carvedilol. Enrollment began in June 2000 and the last dose was given in May 2005 (each patient received medication for 8 months). Patients were randomized in a 1:1:1 ratio to twice-daily dosing with placebo, low-dose carvedilol (0.2 mg/kg per dose if weight or =62.5 kg), or high-dose carvedilol (0.4 mg/kg per dose if weight or =62.5 kg) and were stratified according to whether each patient's systemic ventricle was a left ventricle or not. The primary outcome was a composite measure of heart failure outcomes in patients receiving carvedilol (low- and high-dose combined) vs placebo. Secondary efficacy variables included individual components of this composite, echocardiographic measures, and plasma b-type natriuretic peptide levels. There was no statistically significant difference between groups for the composite end point based on the percentage of patients who improved, worsened, or were unchanged. Among 54 patients assigned to placebo, 30 improved (56%), 16 worsened (30%), and 8 were unchanged (15%); among 103 patients assigned to carvedilol, 58 improved (56%), 25 worsened (24%), and 20 were unchanged (19%). The rates of worsening were lower than expected. The odds ratio for worsened outcome for patients in the combined carvedilol group vs the placebo group was 0.79 (95% CI, 0.36-1.59; P = .47). A prespecified subgroup analysis noted significant interaction between treatment and ventricular morphology (P = .02), indicating a possible differential effect of treatment between patients with a systemic left ventricle (beneficial trend) and those whose systemic ventricle was not a left ventricle (nonbeneficial trend). These preliminary results suggest that carvedilol does not significantly improve clinical heart failure outcomes in children and adolescents with symptomatic systolic heart failure. However, given the lower than expected event rates, the trial may have been underpowered. There may be a differential effect of carvedilol in children and adolescents based on ventricular morphology. clinicaltrials.gov Identifier: NCT00052026.
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            The Fontan circulation after 45 years: update in physiology

            The Fontan operation was first performed in 1968. Since then, this operation has been performed on thousands of patients worldwide. Results vary from very good for many decades to very bad with a pleiad of complications and early death. A good understanding of the physiology is necessary to further improve results. The Fontan connection creates a critical bottleneck with obligatory upstream congestion and downstream decreased flow; these two features are the basic cause of the majority of the physiologic impairments of this circulation. The ventricle, while still the engine of the circuit, cannot compensate for the major flow restriction of the Fontan bottleneck: the suction required to compensate for the barrier effect cannot be generated, specifically not in a deprived heart. Except for some extreme situations, the heart therefore no longer controls cardiac output nor can it significantly alter the degree of systemic venous congestion. Adequate growth and development of the pulmonary arteries is extremely important as pulmonary vascular impedance will become the major determinant of Fontan outcome. Key features of the Fontan ventricle are early volume overload and overgrowth, but currently chronic preload deprivation with increasing filling pressures. A functional decline of the Fontan circuit is expected and observed as pulmonary vascular resistance and ventricular filling pressure increase with time. Treatment strategies will only be successful if they open up or bypass the critical bottleneck or act on immediate surroundings (impedance of the Fontan neoportal system, fenestration, enhanced ventricular suction).
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              Outcome of listing for cardiac transplantation for failed Fontan: a multi-institutional study.

              The Fontan procedure is a successful palliation for children with single-ventricle physiology; however, many will eventually require heart transplantation. The purpose of this study was to determine risk factors for death awaiting transplantation and to examine results after transplantation in Fontan patients. A retrospective, multi-institutional review was performed of 97 Fontan patients 30 days after transplantation. Heart transplantation is an effective therapy for pediatric patients with a failed Fontan. Although early posttransplantation survival is slightly lower than other patients with CHD, long-term results are encouraging, and protein-losing enteropathy can be expected to resolve.
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                Author and article information

                Journal
                CVIA
                Cardiovascular Innovations and Applications
                CVIA
                Compuscript (Ireland )
                2009-8782
                2009-8618
                May 2018
                May 2018
                : 3
                : 1
                : 107-122
                Affiliations
                1Division of Cardiology, Department of Medicine, University of California San Francisco, San Francisco, CA, USA
                2Division of Cardiology, Department of Pediatrics, Children’s National Health System, George Washington University, 111 Michigan Avenue Northwest, WW 3rd Floor, Washington, DC 20010, USA
                Author notes
                Correspondence: Anitha John, MD, PhD, Associate Professor of Pediatrics, George Washington University, Director, Adult Congenital Heart Program, Children’s National Health System, Washington, DC 20008, USA, Tel.: +1-202-4762728, Fax: +1-202-476-5700, E-mail: anjohn@ 123456childrensnational.org
                Article
                cvia20170041
                10.15212/CVIA.2017.0041
                Copyright © 2018 Cardiovascular Innovations and Applications

                This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 Unported License (CC BY-NC 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See https://creativecommons.org/licenses/by-nc/4.0/.

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