Long-term results after the Fontan operation

Chief, Division of Cardiothoracic Surgery, The Children's Hospital of Philadelphia,
Alice Langdon Warner Professor of Surgery, University of Pennsylvania School of Medicine,
Philadelphia, Pennsylvania, USA
Thomas L. Spray

The first Fontan procedures for physiologic correction of single ventricle malformations were performed in the late 1960's and reported in 1970. Despite over 30 years of experience with the Fontan procedure, the late outcomes continue to be largely unexplored. Major series of Fontan procedures followed over a significant postoperative interval have shown generally good outcomes with the majority of late survivors in NYHA Functional Class I or II. A report by Gentles in 1997 reported 500 consecutive patients undergoing the Fontan procedure at Boston Children's Hospital with a hospital mortality of 17% and 35 late failures with a median follow-up of 5.4 years. 317 of the 363 late survivors were in the New York Heart Association Class I or II, and protein-losing enteropathy was noted in 2.6% of the surviving patients. In a similar study from the Mayo Clinic in patients with tricuspid atresia over a 25-year period, 171 of 216 patients survived（79%）. Operative mortality steadily declined over the entire 25-year experience and has decreased to 2% in the last decade. Late survival also continued to improve over the follow-up interval. 89% of surviving patients were in NYHA Class I or II. These results suggest that the longterm survival in patients with the Fontan circulation will generally be good; however, as the procedure has been extended to more patients with single right ventricle and hypoplastic left heart syndrome, continued scrutiny of longterm outcome will be important.
  There has been a continued evolution of surgical technique of the Fontan procedure from the atriopulmonary connection to the lateral tunnel and now the extracardiac Fontan procedure. The potential benefits of the newer approaches with early volume loading with a bidirectional Glenn shunt followed by extracardiac Fontan at a young age are still unknown, however, there are theoretical reasons to consider that the incidence of late arrhythmias may be decreased with this approach. Nevertheless, the late complications of the Fontan procedure continue to include development of atrial tachyarrhythmias and bradyarrhythmias in a significant proportion of survivors, regardless of the technique of surgical repair. Late development of protein-losing enteropathy appears to be rare; however, the incidence is not completely known and it is unclear whether the incidence is decreasing as the newer modifications of the Fontan have achieved increased follow-up intervals. Previous studies have suggested that protein-losing enteropathy is in some fashion related to the incidence of pleural effusions in the immediate postoperative period and the newer modification of baffle fenestration has dramatically improved the incidence of early perioperative pleural effusions, suggesting that perhaps there will be an impact on late development of this complication. Exercise tolerance appears to be limited in patients with the Fontan circulation no matter which type of repair is performed; however, the majority of patients remain in Class I or Class II, suggesting that this exercise limitation does not significantly impact the activities of daily living.
  The Fontan patients have been noted to have a hypercoagulable state in some studies and the incidence of thromboembolism appears to be significant late following the Fontan procedure. There appear to be two times of greatest risk for thromboembolism: the initial risk being in the first year following the procedure, and the second at greater than 10 years of follow-up. The potential effects of the type of Fontan procedure, the amount of AV valve regurgitation and the effect of ventricular function on the development of late atrial tachyarrhythmias still remains to be clarified.
  Late failures of the Fontan procedure with inefficient hemodynamics and progressive atrial arrhythmias may now be treated with conversion to extracardiac or lateral tunnel type Fontan connections and atrial arrhythmia surgery. The effects of these operations on longterm outcome remain to be determined and heart transplantation will still be the procedure of choice for what appears to be a relatively small proportion of late survivors of single ventricle reconstruction.