Effects of impaired lung function and pulmonary regurgitation on maximal exercise capacity in patients with repaired tetralogy of Fallot.

Abstract

Long-term haemodynamic results and exercise capacity were studied in 34 patients with tetralogy of Fallot (24 men and 10 women) repaired 10.0 +/- 4.9 (mean +/- SD) years previously and compared to 34 healthy matched controls. All subjects were studied by resting spirometry, echocardiography and a symptom limited treadmill exercise test (modified Bruce protocol). The maximal oxygen consumption was 38.2 +/- 8.0 ml.kg-1.min-1 in patients and 48.1 +/- 8.1 ml.kg-1.min-1 in the control group (P < 0.001). Reduced maximal oxygen consumption was found in patients with low vital capacity (VC) and pulmonary regurgitation (PR). The ventilatory anaerobic threshold (VAT) was 23.8 +/- 0.6 ml.kg-1.min-1 and 29.9 +/- 0.6 ml.kg-1.min-1 in patients and controls, respectively (P < 0.001). VC was 3.4 +/- 1.21 in patients and 4.0 +/- 1.31 in controls (P < 0.02). In the patients, maximal ventilation was reduced and at submaximal exercise, the breathing frequency increased. Heart rates during exercise were similar in patients and controls. Tricuspid regurgitation (TR) was detected in 20 patients (58.8%); however, the exercise capacity was not reduced. Thus, impaired exercise capacity in tetralogy of Fallot is partly due to reduced resting lung function, pulmonary regurgitation and low ventilatory anaerobic threshold.