Decreased lung function and exercise capacity in Fontan patients. A long-term follow-up

OBJECTIVE: The haemodynamic situation for patients with Fontan circulation is characterized by a reduced, non-pulsatile pulmonary blood flow. To evaluate if this has any impact on lung function and exercise capacity, we studied the surviving 20 patients operated upon at our institution between 1980 and 1991. The median age was 17.5 years, the median follow-up time was 11.5 years. DESIGN: Lung volumes, flow-volume curves, the ventilatory distribution and the diffusion capacity for carbon monoxide were obtained using routine methods. The exercise tests were performed on a bicycle ergometer with determination of ventilation, oxygen uptake, carbon dioxide production, respiratory rate and heart rate. RESULTS: The lung volumes, maximal expiratory flows and diffusion capacity were significantly lower than expected. The median maximal oxygen uptake was 1.39 for the females and 1.63 l/min for the males, corresponding to 25.1 and 25.2 ml/kg/min, respectively. The maximal heart rates varied from 104 to 177 beats/min. All patients reached a respiratory exchange ratio above 1.0. CONCLUSION: Fontan patients have small lungs. They have a markedly reduced exercise capacity and a low maximal heart rate.