venous atrium because failure of the Fontan circulation is characterized by an increase in pulmonary collateral flow and high pulmonary venous return Others are exploring the possibility of inserting an assist device in the position of the missing subpulmonary ventricle This strategy may be particularly beneficial for the large number of Fontan cases where failure occurs in the context of preserved systolic ventricular function Although this strategy is feasible, its limits remain to be determined Another line of research is focused on the design of a right-sided assist device for the Fontan circulation that would compensate for the missing subpulmonary ventricle.422 Novel Treatments for Lymphatic Drainage Abnormalities (Plastic Bronchitis and ProteinLosing Enteropathy) It is only in the recent years that the relative contribution of the lymphatic circulation to the demise of the Fontan circulation has been unveiled (see earlier) It seems that the increased venous loading of the liver at the time of the Fontan circulation is responsible for the generation of a large amount of lymph that may overload the capacity of the lymphatic circulation to be drained by the thoracic duct.187,197,423 This overload of pressure may result in prolonged pleural effusion, particularly chylothorax, at the time of the Fontan, and subsequently plastic bronchitis or PLE It is currently possible to intervene directly in and obstruct selectively the connecting lymphatic channel responsible for these complications, and some early successes have been reported To decrease the production of lymph by the liver, operations have also been designed that divert the hepatic venous circulation into the pulmonary venous atrium.424,425 Another approach has been to reconnect the thoracic duct to a lower venous pressure by anastomosing the innominate vein to the pulmonary venous atrium.426 Further studies will better define the role of these procedures in the treatment of these debilitating conditions Annotated References d'Udekem Y, Iyengar AJ, Galati JC, et al Redefining expectations of long-term survival after the Fontan procedure: twenty-five years of follow-up from the entire population of Australia and New Zealand Circulation 2014;130:S32– S38 In this publication the long-term outcome is better than anticipated This may be because the series is population based and therefore unselected but may also be because there is a smaller proportion of patients with hypoplastic left heart syndrome—the latter being a well-identified risk factor for poor outcome Paridon SM, Mitchell PD, Colan SD, et al A crosssectional study of exercise performance during the first 2 decades of life after the Fontan operation J Am Coll Cardiol 2008;52(2):99– 107 In this large cross-sectional study of children and adolescents with a Fontan circulation, peak exercise capacity was markedly decreased with only approximately one-quarter having a normal peak VO2 Older age and male gender were associated with a lower exercise capacity Interestingly, submaximal exercise was less likely to be impaired, suggesting that the absence of a subpulmonary ventricle impairs maximal (anaerobic) exercise to a greater extent Carins TA, Shi WY, Iyengar AJ, et al Long-term outcomes after first-onset arrhythmia in Fontan physiology J Thorac Cardiovasc Surg 2016;152(5) [1355–63 e1] The onset of arrythmia is detrimental for the Fontan circulation In this large populationbased registry report, one-third of patients had a tachyarrhythmia or bradyarrhythmia 20 years after their Fontan operation After developing arrythmia, freedom from death was 74% 10 years and freedom from Fontan failure 55% An atriopulmonary Fontan and atrial isomerism were risk factors for arrhythmia Hebert A, Mikkelsen UR, Thilen U, et al Bosentan improves exercise capacity in adolescents and adults after Fontan operation: the TEMPO (Treatment with Endothelin Receptor Antagonist in Fontan patients, a Randomized, PlaceboControlled, Double-Blind Study Measuring Peak Oxygen Consumption) study Circulation 2014;130(23):2021–2030 In this randomized trial there was a small but