The Fontan Operation is Not the End of the Road

Are we changing the natural history of the SV physiology?

Presently, this operation is the gold standard destination for patients with SV physiology. Along the years, techniques and strategies have evolved from the original right atrium to pulmonary artery connection to the lateral tunnel and the extra-cardiac conduit, including staged procedures and fenestrations. Better results with this operation have been assigned to these technical modifications. There are many data showing excellent early and long-term outcome with good survival rate.^– However, despite the remarkable improvements in quality of life and prognosis of patients treated by the FO, there is a decreased exercise capacity and a suboptimal ventricular performance, subsequent to the reduced preload of the functional SV. In addition, these patients often develop scoliosis, kyphosis, have small lungs and consequently a restrictive pulmonary pattern due to previous thoracic surgical procedures. Altogether, it affects different subsystems with a negative impact on functional status, quality of life and the long-term transplant-free survival ratio. Multiple studies assessing the results of the FO demonstrated a decrease in survival with a continuous attrition 15 years after the procedure, regardless of the surgical type of cavopulmonary connection. In a recent single-institutional study, the actuarial freedom from death or transplantation was 87%, 83%, and 70% at 15, 20, and 25 years respectively after surgery. In this group, death was sudden and unexplained in 9%, thromboembolic in 8%, and heart failure-related in 7%. In another study assessing morphologically left SV, actuarial survival was 73% at 15 years. Atrial arrhythmias were present in 57%, protein-losing enteropathy in 9%, and thromboembolic events in 6%. In other words, odds are 1 out of 4 that a child after FO will be dead by the time he or she reaches their late 20s. In a large multi-center cohort, the Pediatric Heart Network (PHN) reviewed 546 children that were on average 11.9 years of age at the time of the study and 8.5 years after the FO. Stroke or thromboembolism was seen in 8% of the patients, exercise performance was abnormal and peak oxygen consumption was only 65% of the predicted for age and gender in a relatively young group. Adolescents (“older” patients) fared worse than the younger children, suggesting a time-related decrement in functionality. In another PHN study, parent-reported patient morbidities included deficits in vision in 33%, speech in 27%, and hearing in 7%, as well as problems with attention in 46%, learning in 43%, development in 24%, behavior in 23%, anxiety in 17%, and depression in 8%.

In our center, Turquetto et al. recently reported suboptimal cardiac function, diminished lung volumes and capacities, as well as reduced respiratory muscle strength in asymptomatic patients – the so-called “perfect Fontan”.^, These are important components of a complex system in which performance and outcomes depend on intricate dynamic interactions that could explain the deficiencies found in the late postoperative period. In other words, despite the low early mortality, when we assess long-term morbidities, the number of patients that are free from problems is low. These findings cannot be ignored, and certainly do not reflect a successful management strategy for patients with single-ventricle physiology.

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