Fontan Circulation Over Time

Abstract The unique, unphysiologic Fontan circulation is associated with an impaired functional status of the patients that is suggested to deteriorate over time. Unfortunately, previous studies did not integrate both pulmonary and cardiac determinants of functional status. In addition, a comparison with the natural decline in exercise capacity in healthy individuals (in both children and adults) is lacking. This single-center study aims to investigate the functional status in a cohort of Fontan patients in relation to time since Fontan completion, and to identify its determinants, including cardiac characteristics and pulmonary characteristics. Eighty-five consecutive Fontan patients ≥ 10 years of age who performed adequate cardiopulmonary exercise testing (respiratory exchange ratio > 1.01), were included. Mean time since Fontan completion was 15 ± 9 years (range 2 - 37 years). New York Heart Association Functional Class (NYHA-FC) was I in 36 patients (42%), II in 41 patients (48%) and III in 8 patients (9%). Peak oxygen uptake during exercise (VO2 index) was 25.7 ± 7.9 ml/min/m2 (58±14% of predicted). NYHA-FC and peak VO2 index both correlated with time since the Fontan operation, however peak VO2 as % of predicted (VO2 [pred]) did not. In multivariate analyses, peak VO2 [pred] was independently associated with maximum heart rate, oxygen pulse at peak exercise and forced expiratory volume in 1 second (Rsquare = 0.579), but not with cardiac output in rest. In conclusion, the current data suggest that functional status in Fontan patients is impaired already shortly after Fontan completion, whereas its subsequent deterioration seems to follow the natural decline of aging. Furthermore, functional status in Fontan patients correlates with pulmonary function and cardiac functional parameters during exercise, but not with conventional cardiac measurements at rest.